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Full text of "Turning and mechanical manipulation intended as a work of general reference and practical instruction on the lathe, and the various mechanical pursuits followed by amateurs"




TURNING 



AND 



MECHANICAL MANIPULATION. 

BY 

CHARLES HOLTZAPFFEL, 

ASSOCIATE OF THK INSTITUTION OF CIVIL ENGINEERS, LONDON ; 

HONOBART MEMBER OP THE ROYAL SCOTTiSH SOCIETY OW ARTS, EDINBURGH , 

CORRESPONDING MEMBER OF THE AMERICAN INSTITUTE OP NEW TOUK ; 

ALSO Or THE FRANKLIN INSTITUTE, PHILADELPHIA, 

ETC., ETC. 



VOL. I. 

MATERIALS; THEIR DIFFERENCES, CHOICE, AND PREPARATION; VARIOUS 
MODES OF WORKING THEM, GENERALLY WITHOUT CUTTING TOOLS. 

VOL. II. 

THE PRINCIPLES OF CONSTRUCTION, ACTION, AND APPLICATION, OF 

CUTTING TOOLS USED BY HAND ; AND ALSO OF MACHINES 

DERIVED FROM THE HAND TOOLS. 



VOL. III. 

ABRASIVE AND MISCELLANEOUS PROCESSES, WHICH CANNOT BE 
ACCOMPLISHED WITH CUTTING TOOLS. 

VOL. IV. 
THE PRINCIPLES AND PRACTICE OF HAND OR SIMPLE TURNING. 

VOL. V. 
THE PRINCIPLES AND PRACTICE OF ORNAMENTAL OR COMPLEX TURNING. 

VOL. VI. 

THE PRINCIPLES AND PRACTICE OF AMATEUR MECHANICAL 
ENGINEERING. 



Ercry Volume will bo complete in itaelL 



x; 

X 



TURNING 

tan 

MECHANICAL MANIPULATION. 

INTENDED AS 

A WORK OF GENERAL REFERENCE AND PRACTICAL INSTRUCTION 

ON THE LATHE, 

AND THE VARIOUS MECHANICAL PURSUITS 
FOLLOWED BY AMATEURS. 



BY 

CHARLES HOLTZAPFFEL, 

ASSOCIATE OF THE INSTITUTION OF CIVIL ENGINEERS, LONDON; 
HONORARY MEMBER OF THK KOTAL SCOTTISH SOCIETT OK ARTS, EDINBURGH 
CORRESPONDING MEMBKR OF TUB AMERICAN INSTITUTE OF NEW TOBK ; 
AU80 OF THE FRANKLIN INSTITUTE, PHILADELPHIA, 
ETC., ETC. 



TO BE COMPRISED IN BIZ VOLUMES. 



VOL II. 

THK rill NVI l-LES OF CONSTRUCTION, ACTION, AND APPLICATION, 

OF CUTTING TOOLS USED BY HAND ; AND ALSO OF 

MACHINES THRIVED FROM THE HAND TOOLS. 



JlltutroUd fry upward* of Seven Hundred WoodcuU. 




LONDON: 

PUBLISHED FOR THE AUTHOR, 

BY Hol.T/Al'rTKL & Co., 64, CHARINO CROSS, AND 127, LONG ACRE. 

And to be had of cUl BooktcUen. 

L8ML 






LONDON : 
BRADBURY AND EVANS, PRINTERS, WHITEFRIAR& 



PREFACE TO THE SECOND VOLUME. 

IN submitting'the second volume of the work on Turning and 
Mechanical Manipulation to public scrutiny, two subjects call 
for the Author's especial notice ; the delay in its appearance, 
and the reason for the proposed augmentation of the number of 
the volumes, intended to constitute the work, from five to six. 

The delay has been caused principally by the unexpected 
manner in which the subject matter of this volume has been 
extended by additional examples and illustrations also by great 
and unavoidable interruptions caused by the Author's general 
engagements and by some domestic calamities, the most severe 
of which has been the loss of the Author's eldest son. 

The division of the matter that was originally meant to com- 
the second volume, has been mainly caused by a desire to 
lessen the disappointment, which has been repeatedly expressed 
at the delay in the progress of the work. This division, although 
it lias increased the number of the volumes from five to six, has 
not caused any further departure from the original scheme of 
the work, as will be seen on the perusal of the titles of the 
distinct t of which it is proposed to consist. 



viii 

A few unimportant errors in the references to the several 
volumes, will naturally ensue from this augmentation in their 
number, but as the references to the pages, to the woodcuts, 
and to the appendix notes, will be consecutive throughout the 
three preliminary volumes, it is hoped that no confusion will be 
experienced in consequence. 

In conclusion the Author has to repeat his former request 
that any omissions, errors, or ambiguities may be pointed out 
for correction in the subsequent appendixes; and as he has 
bestowed an equal amount of care on the production of this, as 
on the first volume, a second edition of which is also this day 
published, the Author hopes to be again rewarded with some 
measure of public approval. He promises to use his best exer- 
tions in the furtherance of the work, and as some of the matter 
is in preparation, and none of the remaining volumes are ex- 
pected to exceed the first in extent, he hopes not to be again 
compelled to trespass so long on the patience of his readers. 



CHARING CROSS, LOWDON, 

November 10, 1846. 



GENERAL SKETCH 

or TV* 

CONTENTS OF THE WORK. 



VOL. I. 
MATERIALS. TIIKIU I'lll IHi:v< | <. ( IKHCE. AND PREPARATION; VARIOUS 

MODES OP WORKING TIIBM. OEM.ItAI.I.Y WITIHH'T < I i n\., TOOLS. 

Introduction Material* from the Vegetable, the Animal, and the Mineral Kingdom*. ThHr 

MM la the Mechanical Art* depend on their ttructural difference*, and pliynlral charactert. 

The mode* of severally preparing, working, and joining the material*, with the practical deecrlp- 

tioa of a variety of Procwst*. which do not, generally, require the ue of TooU with cutting dft*. 

VOL. II. 

TIIK riUNClPLKS OP CONSTRUCTION, ACTIOK. AND APPLICATION. OP CUT1 1 
TOOLS L'SKD HY HAM) ; AM> ALSO OP MACHINES DERIVI |i 

FROM THE HAND TOOLS. 

The principle* and descriptions of Cutting TooU generally namely . Chltcli and Plane*, Turning 
Tool*, Boring Tool*, Screw-cutting TooU, Saw*. Pile*, Shear*, and Punches, The hand tooU 
and their mode* of u*e are drat described ; anil subsequently various machine* In which the 
hand pmce**e* are more or lew clonelr followed. 

VOL. III 
ABRASIVP. AND MISCELLANEOUS PROCESSES, WHICH CANNOT BE ACCOM- 

H.IMIEI) WITH rCTTINO TOOLS. 

Grinding and Polishing, viewed as extreme* of the came prooe**, and a* applied both to the pro- 
duction of form, and the embellishment of surface. In numerous rase* to which, from the 
nature of the materials operated upon, and other cause*. Cutting Tool* are altogether inappll. 
cable. Varnishing and Lackering. 

VOL. IV. 

I UIN( Il'I.I.S AND PRACTICE OP HAND OR SIMPLE TTTRNINO. 

Descriptions of various Lathe* ; application* of numerous Chucks, or apparatu* for fixing work* 
in the Lathe. Elementary instructions In turning tho soft and hard wood*, ivory and metal*, 
and also In Screw-cutting. With numerous Practical Examples, some plain and aimple, other* 
difficult and complex, to show how much may be done with hand tool* alone. 

VOL. V. 

THE PHINCII'LES AND PRACTICE OP ORNAMI NTAT, OR COMPLEX TURNING. 
Ming Re*t with Fixed Tools Revolving Cutter*, used in the Sliding Rest with the Division 
Plate and Overhead Motion. Various kind* of Eccentric, Oval, Spherical. Right-line and other 
Chucks. Ibbetson's Geometric Chuck. The Row Engine, and analogon* contrivance*. Ac. 
With numerous Practical Example*. 

VOL. VI 

THE PIMNCIPLES AND PRACTICE OP AMATEUR MECHANICAL I NO 

Lathe* with Sliding Recta for metal turning. Self-acting and Screw-cutting Lathe* Drilling 
Machine* Planing Engln^-Key-groove, Slotting and Paring Machines Wheel cutting and 
Shaping Engine*, *c. 

With numerou* Practical Examples. 

Tkf Pint, Stftmd, and Tklrd I'nlumet tif t*tt teork, art teritten at aeeompanfina 
book*, ami karr one Inittx in fnmmon, to at to conttitutf a ptntrai and preliminary teorft. 
Ike addition to teHifk of any n/ lltt other t;,l,imrt, trill render Ike tvtyet eompltt* /or Ike tkrft 
tlaitetof Amatturt rt/erred to in Ikt Introductory Chapter. 

A fr<f addition*! eopiti of tkt Index kare been frinUd far Ike eonvenlfnee of tkott vko may 
dttirt to bind tke Indt* tritk Volt. I. an 



\l 



TABLE OF CONTENTS 

OF THE SECOND VOLUME. 



CHAP. XXIL GENERAL" REMARKS UPON CUTTING TOOLS. 

MM 

SCT. 1 . The anylti and position* of tool* at regard* the ad of cutting Their 

division into poring, fcraping, and shearing toola-vangles and petition* 

of the edges of tools ....... 457 

SECT. 2. Tie form* and motion* of tool* a* reyardt thr production of line*, 
tuprrfcie*, and tolidt, theoretically contidered The guide or slide 
principle may be traced both in the manual processes, and in the 
machinery directed to the above purposes .... 463 



CHAP. XXIII. CHISELS AND PLANES. 

SECT. 1. Introduction The axe,hatchet, adze, baasoOlih or Indian adze, paring- 
knife, drawing-knife, chisel and planing-tool for metal contrasted. 

Bench-plane* of varioui kintit, or those used for flat surfaces, the 
mouths of planes described, the spokeshave, planes with single and 
double irons ; planes of low, middle, half, mitre and upright pitches, 
and the joiner's scraper . . . . . . 472 

SECT. 2. Qrooving-plane* For cutting with the grain or across the grain 
The fillister, plough, grooving, drawer-bottom, and slit-deal planes 
The router, various gages, the cooper's croze, banding-planes, and 
rounding-planes for cylindrical rods ..... 484 

SECT. 3. Moulding-plane* Their general character difficulty of applying 
them to the vertical parts of mouldings, remedy proposed by the author 
On working or sticking mouldings, explanations of the terms, the 
tpring, the on and the down . . . . . . 489 

SECT. 4. Remark* on the bench, and the v*e of planes On the construction of 
joiner's benches, bench-stops, hooks, and holdfasts On sharpening, 
adjusting, and using bench-planes; straight-edges, winding-sticks, 
squaring thick and thin works, the shooting-board . . . 494 

Srcr. 5. Plating-machine* for wood Those invented by Bentham, Bramah, 

Brunei, Muir, Paxton, Burnet & Poyer, briefly considered . . 503 

CHAP. XXIV. TURNING TOOLS. 

SECT. 1. Facility of turning compared with carpentry General remarks on the 
sections of woods, and on the tools respectively used for turning and 
carpentry ........ 508 

SECT. 2. Turning tool* for toft wood Gouge, chisel, hook tools ; underhand 
tools, broads, side-cutting, screw-cutting and parting tools for soft 
woods . 512 



Xll TABLE OF CONTENTS. 

PAGE 

SECT. 3. Turning tools for hard wood and ivory Gouge, side-cutting, flat, 
point, bevil and parting tools Curvilinear tools, simple and complex, 
for mouldings both external and internal Screw-cutting tools . 517 

SECT. 4. Turning tool* for brass Round or rough-out tool, square tool, planish- 
ing tools, the last sometimes burnished on their edges and held in a 
restless manner Many of the other tools for brass nearly resemble 
those used for ivory. The arm-rest and its employment . . 520 

SECT. 5. Turning tools for iron and steel Triangular tool, graver, flat chisel ; 

heel ancl hook tools nail-head tools cranked or hanging tools . 523 

SECT. 6. Fixed or machine tools for turning and planing By comparison with 
hand toolstheirformsrequire more rigid observance of principle Fixed 
tools for soft wood for hard wood and ivory for brass for iron 
general principles Nasmyth's tool-gage Cutter-bars or tool-holders 
with small changeable cutters finishing, hanging, or springing tools . 527 



CHAP. XXV. BORING TOOLS. 

SECT. 1. Soring bits for wood Various kinds of awls fluted or semi-tubular 
bits center bits English, American and German screw augers or- 
dinary braces and angle braces for wood . 539 

SECT. 2. Drills for metal used by hand Small double cutting drills used with 
the drill-bow larger single cutting drills used in the hand-brace and 
in boring machines including pin-drills, and also square and cone 
countersinks of each kind . . . . . . 646 

SECT. 3. Methods of working drills by hand-power Watch-drills, various 
drill-bows and drill-stocks Smith's old press-drill ; outline of modern 
contrivances for the same purpose Ratchet and lever-drills Corner- 
drill with bevil pinions Shanks' a differential screw-drill . . 553 

SECT. 4. Drilling and boring machines The lathe very much used for boring 
with fixed drills of numerous kinds Sketch of the general characters 
of drilling machines for small holes and also of boring machines, with 
revolving and sliding cutter-bars, such as are uaed for the largest 
steam cylinders . . . . . . . 563 

SECT. 5. Broaches for making taper holes Broaches and rimers of various trans- 
verse sections, for making taper and cylindrical holes, both in woods 
and metals Comparison between the actions of drills and broaches . 572 



CHAP. XXVI. SCREW CUTTING TOOLS. 

SECT. 1. Introductory remarks Observations on the screw both elementary 

and descriptive Division of the subject of screw cutting . . 577 

SECT. 2. On originating screws Simple methods invented by Pappus, (see foot 

note, page 635,) by Plumier, Robinson, Maudslay, Allan, Walsh, etc. . 579 

SECT. 8. On cutting internal screws with screw-taps Old and modern taps 
of numerous transverse sections ; on their longitudinal sections ; and 
their general applications Taps with loose cutters Original taps and 
cutters, for cutting the dies of diestocks, the teeth of worm wheels, 
and screw tools. Screw taps and cutters for wood . . . 583 



TABLE OP CONTENTS. Mil 






SICT. 4. On cutting crtsriMtl ttnm with tertw dm, tie. Screw-box for cutting 
wood screws Screw plaU* for small metal screws Old and modern 
crewstocks or diestocka Proportions of original or master Up* ustd 
for cutting the dies of dieetoeks Various forms of dies considered ; 
far John Robiaon's dice, also Heir's and Jones's dies, with detached 
cutters On producing left-band screws from right-hand apparatus 
W hit worth's, and Bodmer's, patent sorew-stocks screwing machines 
concluding remarks . . . . . . . 693 

Sicr. 5. On cutting scnwt by hand in ike common lathe Explanation of the 

causes of failure in cutting screws flying, or in striking threads by hand rt J 1 

SlCT. 6. On cutting icrnct in lathet with trarrrtiny mandrels Sketch of old 

and modern apparatus for this purpose, and their applications . 012 

SECT. 7. O cutting screw in lathe* i'M trarcrtiny tool* Various simple 
contrivances for cutting short screws, invented by Besaon, Grandjean, 
Thiout, Henley, and Varley Machinery for cutting long and accurate 
screws by the modern syntem of guide-screws and change-wheels the 
smaller application used as an addition to the ordinary slide-rest the 
larger constitutes the screw-cutting or slide-lathe Mode of computing 
the pitches of screws from the wheels and guide-screws employed Screw 
tools or chasing tools of ordinary kinds used in slide-rests and nlide- 
lathes ; those by Clement, Bodmer, and the Author Roberta's tool- 
slide Shanks'* tool-slide for cutting both in the to-and-fro movement 
Backstay for supporting long and slender screws whilst being cut . 615 

SECT. 8. Various modesof originating and improving screws,etc. First as regards 
screw tackle for ordinary and general purposes Secondly, the appa- 
ratus for regulating and micrometrical screws, required to agree in pitch 
with Standard Measure Method of originating screws with theinclined 
plane, used in some fusee cutting engines, and improved by Reid. 

Modes of perfecting the screw, introduced by Ramsden, Maudalay, 
Barton, Allan, and Clement, fully explained Account of the con- 
struction of Mr. Donkin's rectilinear dividing engine, in which the 
micrometrical errors in the best screws, due principally to the want of 
homogeneity in the materials, may be discovered and compensated for 635 

SECT. 9. Screw threads considered m respect to their proportions, forms, and 
general characters Relative strengths of screws and nuta ; comparison 
of square and angular threads ; split nuts to compensate for wear ; 
different sections of screw threads, and their purposes Inconvenience 
experienced from the dissimilarity of screws System of screws to 
agree with Standard Measure, proposed by Mr. Whit worth for universal 
adoption ; this proposal surrounded by various and almoot insurmount- 
able difficulties Modes of formingscrews, differing from all those before 
noticed ; namely by Wilks, Warren, Perkins, Scott, and Rand . 656 

CHAP, xxvn. s.\ 

SECT. 1. Division of the sufyect ; forms of saw teeth Introduction; descriptions 

of the teeth used in various kinds of saws, and their several purposes 682 

SECT. 2. Marymiay and setting tout Fully explained as regards the five 
usual modes employed. The tools used, namely, the horses, files, 
stakes, and set hammers; the ordinary saw-net, plier saw-set, and saw- 
set for circular saws . . . <88 






XIV TABLE OF CONTENTS. 

PAGE 

SECT. 3. Rectilinear saws used by hand Table of the dimensions of rectilinear 
saws in three divisions. Pint division Taper saws mostly without 
frames Felling saws, cross cutting saws, various pit saws, some of 
them with frames Instructions for marking out and sawing round 
and squared timber Hand saws, panel saws, compass, keyhole and 
pruning caws, and directions for their use. Second division Parallel 
saws with backs Tenon, sash, carcase, and dovetail saws; sawing 
block ; cutting tenons and mortises, and also dovetails of all kinds 
Smith's screw-head saw, comb-makers' saw, double saws for cutting 
racks. Third division Parallel saws used in frames; and instructions 
for their application Mill saw blades, pit veneer saw, chair-maker's 
saw, wood-cutter's saw, Continental frame saw, turning or sweep saw 
The smith's frame saw, side frame saw, piercing saw, buhl saw ; the 
practice of buhl and marquetry work fully explained . . 698 

SKCT. 4. Rectilinear or reciprocating saw machines Those at the Govern- 
ment and City saw-mills American and Continental fire-wood saw 
machine Vertical saw mills for deals; also those for square and 
round timber Small vertical machine from the Manuel du Tourneur. 
Mac Duff's, Lunds", and Professor Willis's vertical sawing machines 
for small purposes, including buhl works .... 739 

SECT. 5. Common applications of the circular saw to small worlcs Smallest 
circular saws mounted on the lathe for telescope tubes, screw heads, 
making joints, &c. Small saw spindle; platforms of wood and iron; 
saw stops, parallel and angular guides Sawing rectangular pieces ; 
grooves; rebates; cross-cutting the ends of pieces square or bevil. 
Sawing bevilled edges, and oblique prisms, fully exemplified by 
the formation of the various Mosaic works of the Tunbridge turner. 

Sawing regular and irregular prisms ; also regular, irregular, single, 
double and mackled pyramids The subject minutely illustrated by 
the formation, with the circular saw. of the five regular bodies, or 
platouic solids, and a variety of other solids that occur in mineralogy 
and crystallography ; with all the angles critically given . . 751 

SECT. 6. Common applications of circular saws to large works Table of 
dimensions of circular saws, given in three divisions, with the speed 
and power severally required for them Various general conditions 
Spindles for large saws; benches and platforms; stops and parallel 
guides for the same Sawing rectangular pieces . . . 783 

SECT. 7. Lea common or specific applications of circular saws to large works 
Sawing grooves, rebates and tenons Pow & Lyne's sawing machine 
for combs Cross cutting the ends of pieces square or at angles 
Sawing works with bevilled edges; Eastman's machine for feather 
edged boards; sawing hexagonal and other wood pavement Professor 
Willis's mode of blocking out architectural mouldings Sawing works 
bevilled in both planes, Mr. Donkin's saw bench Curvilinear saving 
Trephine saw and various others used in surgery; cylindrical or 
drum saws, used for felloes of wheel?, backs of chairs, brushes, &c. 
Smart's machinery for sawing the curvilinear staves of casks . 792 

SECT. 8. Circular tawt and machinery for cutting veneers Veneers known to 
the Roman*, and until recently cut by the pit sawyers Brunei's split- 
ting machine for veneers Modern veneer paws Thesmallerapplication 
with single plate*, for leaves of ivory and small veneers of wood The 



TAB1 oNTENTS. 

r*ot 

larger application, or the modem veneer mill ; iu action fully 
plained wad figured Conclusion of the chapter Additional illutra- 
lioim of circular saw* ; for cutting off pile* under water; sawing (late; 
and Hawing eiuU of railway ban whilst rod hot . . . 805 



CHAP. XXV11L FILES. 

SECT. 1. General and dttcriptive view of Jilts of untal kindt Explanation of 
the rix principal features in filea Description and purpose* of the 
files principally used ; namely, taper, hand, cotter, pillar, half-round, 
triangular, cross, round, square, equalling, knife, and slitting files. 

Description of other files less frequently used Sketch of the manu- 
facture of files and rasps Different means of grasping the file to adapt 
it to various specific uses ...... 817 

SECT. 2. General und detcriptivi: view of filet of let tuual kindt Rioters for 
sculptors and others Float* or single cut files u&ed for ivory, horn, 
and tortoiscahell ; the quauuett White's perpetual file Raoul's and 
Ericcson's machines used for cutting the teeth of files Sir John 
Robison's concave half-round files, and also hia project for file cutting 837 
SECT. 3. Preliminary remark* on uting filet and on holding workt that are to 
be filed The three positions of the individual, corresponding mode* 
of holding the file, and general observations on filing Chipping, 
pickling, or grinding works preparatory to filing On cleaning files. 

Modes of grasping works to be filed, the taper vice, tail vice, vice 
benches, tripod vice stand, table and parallel vices, wood and metal 
vice clamps Pin vice and sliding tongs, used for small works, espe- 
cially those of cylindrical forms Filing boards, and Sheffield flatting 
vice, used for thin plates ...... 844 

SECT. 4. I Httructiont for filing a fiat turface under the guidance of the tlraiyht 
edge, and of the trial plate, or planometer The concluding steps to be 
accomplished by scraping and not by grinding Same care partially 
necessary in works that require less accuracy ; chipping chisel now 
less used than formerly Impolicy of finishing metallic surfaces by 
grinding them together ...... 865 

SECT. 5. fnttructions for originating ttraight tdgtt and trial platet or piano- 
mttert Joiner's method of preparing wooden straight edges ; these 
employed in commencing steel straight edges ; which latter are after- 
wards delicately corrected by working on a series of three On origi- 
nating plane surfaces in iron, or planometers . . . 872 
SCOT. 6. Inttructiont for filing rectilinear workt in uhicft ttveral or all the 
tuperficiet have to be wrought Works with plane surfaces and square 
edges; works with bevilled edges ; works with rebates and grooves, some 
these filed up in different pieces for the facility of manipulation. 

:ug mortises and aperture* Drifts or punches used in combina- 
. with files, in completing square and other mortises and holes, the 
key ways in wheels, Ac. ...... 873 

SECT. 7. Instruction! for filing cutvUinear workt according to the three ordi- 
nary modt The operation lew difficult than filing flat surfaces ; the 
file often nearly a counterpart of the work ; its position incessantly 



XVI TABLE OF CONTENTS. 

PAGE 

changed Filing curved works, that are moulded or formed, prior to 
the application of the file Filing curved works, that are moulded or 
formed almost entirely with the file Filing curved works that are 
shaped with the file, under the guidance of templets or pattern plates 
of hardened steel ; including the making of joints of various kinds . 886 
SECT. 8. Comparative sketch of the application* of the file, and of the engineer's 
planing machine, <tc. Intended to show, by way of contrast, how 
several of the pieces advanced in sections 4 to 7, in illustration of 
works executed with files, are produced in the engineer's planing 
machine, key groove machine, slotting and paring machines, shaping 
machines, &c. ........ 896 

CHAP. XXIX. SHEARS. 

SECT. 1. Introduction Cutting nippers and pliers of various kinds for cutting 

wires Bursill's cutting nippers with removable cutters . . . 904 

SECT. 2. Scissors and shears for soft flexible materials Principles upon which 
they act, their blades always curved and elastic, importance of the 
riding parts Scissors of various peculiar forms, explained Pruning 
scissors and shears Sliding shears Card-maker's shears Revolving 
shears for cloth, and for grass lawns ..... 907 

SECT. 3. Shears for metal worked by manual power Hand shears, bench 
shears ; purchase shears with secondary lever ; modes of using them 
Collett's tag shears Shears for making stationer's ruling pens 
Chisel and hammer used instead of shears for curved and some 
straight works ...... . . 914 

SECT. 4. Engineer's shearing tools generally worked by steam power These 
may be considered as massive copies of the foregoing tools, but are 
moved by eccentrics and cams Barton's double shears Roberts' 
shearing and punching engines for boiler-makers, the one with lever, 
the other with slide Thorneycraft's shearing machine for cutting 
wide plates of iron Nasmyth & Co's cutting vice for wide plates 
Renton's hydraulic machine for cutting off copper bolts Rotary 
shears for cutting thin metal, in straight and curved lines . . 919 

CHAP. XXX. PUNCHES. 

SECT. 1. Introduction, punches used without guides Single hollow punches 
for gun-wadding, pasteboard, wafers, confectioners' lozenges ; double 
punches for leather washers; figured punches Solid and hollow 
punches for thin iron, tinned plate, copper, &c. used upon lead. 

Smith's punches for red-hot iron, used with counterparts or bottom 
tools, known as bolsters Harpmaker's punch for cutting mortises . 926 

SECT. 2. Punches, used with simple guides Plier punches for leather straps 
Instrument for making quill pens Hammer press for holes, circular 
mortises, &c. Portable screw press or clamp, for the leather straps 
of machinery ; a similar portable instrument on a larger scale used 
for punching boiler plate ... . 930 

SECT. 3. Punches used t fly presses, and miscellaneous examples of their pro- 
ducts General characters of the fly press Some peculiarities in fly 
presses, and machinery of analogous kinds Productions of presses 






TAIU \\11 

MM 

I Juki fur coin, ingenious compensatory method of ensuring thoir critical 

quality of weight Punching disks for button* ; wiuhen with ruuml 
and square holes. The link* fur chain* of various kind* for machinery, 
including chain* for pin wheels, and Oldham's chain fur oommon spur 
wheels, intended to act M leather bands. Peculiar punching tool* used 
for making watch chain* Punching the teeth of straight and circular 
saw* Punching copper caps and steel pens Lariviere's perforated 
motals for colanders, and various domestic purposes Punches used in 
the manufacture of Jeffrey's patent respirators Buhl work made by 
punching or stamping Sketch of the mode uf cutting brads, tacks, and 
nails by punching or shearing tools ..... 984 
Sect. 4. Punching machinery uted by engineer* Nearly the same iu general 
arrangement M the shearing tools The punching engine commonly 
used for cutting curvilinear liuos in thick plates Colthurst's,and Hick's 
comparative experiments on the force required in using punches . 950 



APPENDIX. 

NOTES REFERRING TO THE FIRST VOLUME. 
RdentoVol. I. 
Not*. Page. 

II Payne's Patent process for preserving timber from decay . . 953 

I 25. The bassCClah or Indian adze (by the late Sir J. RobUon). . 953 

J 46. Irving's Patent carving machine, principally applicable to mouldings 954 

K 46. Jordan's patent carving machine, principally applicable to figures 954 

L 46. Tomes's patent dentifactor, for carving artificial teeth and gums . 955 

M 121. Straightening stag horn and buck horn for knife handles . 957 

N 155. Making isinglass glue (by the late Sir J. Robison) . . . 957 

O 160. Prosser's patent process for works made of dry clay with dies . 957 

P 191. Clay's patent process for manufacturing wrought iron . . 953 

Q 196. Nasmyth's patent direct action steam hammer (by the Patentee). 958 

R 196. Nasmyth's patent steam pile driving engine (by the Patentee) . 961 

202. The "Oliver" or small lift hammer worked by the foot . . 962 
T 226. The manufacture of wrought iron tubes (explained by Mr. Pros- 
ser's Synoptical table followed by brief professional notices of 
the several patents) . . . . . .963 

U 256. Remarks on Sir J. Robisoo's workshop blowpipe (by the Inventor) 970 

V 283. Amalgams used by dentists for stopping teeth . . . 970 

W 323. Babbett's patent anti-friction metal for bearings of machinery . 970 

802. Craufurd's patent process for making galvanised iron . .971 

V 802. Morewood 4 Rogers's patent for making galvanized tinned-iron . 972 

Z 808. Portable brass furnace by HolUapffel & Co. . . . . 978 

AA 374. Berlin method of moulding delicate and complicated objects . 974 

AB 424. Fluid employed in India for lubricating draw-plates . . . '.'71 

AC 410. Foxall's patent method of raising vessels in sheet metal . . 974 

AD 431. Drawing taper brass tubes for locomotive engines . - . 976 

431. Rand's patent method of making collapsable tubes for oil colors . 977 

AF 433. Clay prup* used by the Asiatic* instead of binding wire in soldering 977 

AG 444. Pumice stone used by dentuts, instead of charcoal in soldering . 978 



XV111 TABLE OF CONTENTS. 

NOTES REFERRING TO THE SECOND VOLUME. 
Refers to VoL II. 

Note. Page. PAGE 

All 482. Silcock & Lowe's patent planes for joiners and cabinet-makers . 978 
AI 487- Lund's screw router plane for working recesses in cabinet work . 979 
AJ 488. Falconer's improved circular plough for joiners . . . 979 

AK 495. Franklin's screw bench hook for carpenters . . . 979 

AL 495. De Beaufort's vice, or atop for joiner's benches . . . 979 

AM 495. S. Nicholl's stop or clamp for joiner's benches . . . 980 

AN 504. Esdaile & Margrave's machine for cutting scale boards for boxes 981 
AO 505. On machines for planing wood, by Paxton, and by Burnett &Poyer 981 
AP 505. Mayer's patent machine for cutting splints for chemical matches 982 
AQ 533. Side cutting tool for iron to be used in the slide rest . . 983 

AR 538. On lubricating metal turning tools with water . . . 983 

AS 538. Paper on the principles of tools for turning and planing metals (by 

Charles Babbage, Esq., F.R.S., &c.) . . . . 984 

AT 538. The author's description of tools and tool holders for turning and 

planing metals, constructed by C. Babbage, Esq. . . 987 

AU 538. Paper on the principles of tools for turning and planing metals (by 

the Rev. Prof. Willis, of Cambridge, A.M., F.R.S., &c.) . . 991 
AV 538. Paper on a new form of tool holder, with detached blades for 

turning or planing metals, and on a new mode of fixing tools 

upon the slide rest (by Prof. Willis) . . . 996 

AW 542. Franklin's expanding center bits for holes of various diameters . 1001 
AX 544. The American screw auger, patented by Mr. Ash . . . 1002 

AY 554. Freeman's registered drill tool, for actuating small drills . 1002 

AZ 557. Mac Dowall's Archimedean screw drill stock . . . 1003 

BA 557. MacDo wall's rectangular Archimedean drill stock for dental surgery 1003 
BB 557. Capt D. Davidson's rectangular drill stock for dental surgery . 1004 
BC 563. G. Scott's apparatus for boring and tapping cast iron main pipes 1004 
BD 567- Collas' lathe drill for boring holes out of the solid . . 1006 

BE 567. C. Holtzapffel's boring bit with changeable cutters, for the lathe . 1006 
BF 567. The Cornish boring bit with loose cutters, for the lathe . 1007 

BG 567. Maudulay's boring bit with loose cutters, for the lathe . . 1008 

BH 567. Stiven's registered lathe drill . . . . 1008 

BI 567. Kittoe's expanding half round bit, for the lathe . . . 1009 

BJ 572. G. Wright inventor of the modern system of boring large cylinders 1010 
BK 580. Mallett's method of describing regular and irregular spirals . 1010 
BL 696. On sharpening the teeth of saws by means of grindstones . . 1011 
BM 789. On the gages at present used for measuring the thicknesses of 

shet metals and wires and proposals for anew system of gages 

founded on the decimal subdivision of the standard inch . 1011 
UN 751. Bodmer's patent for making the tires of locomotive wheels . lu_M 
BO 803. Harvey 'a patent curvilinear saws for long or short works . 1022 

BP 827. Cutting the teeth at the ends of files . . . . 1022 

BQ 839. Michael Kelly's Quauuett for tortoiseshell, used also for zinc . 1023 
BB 841. Inventors of various file cutting machines . . . 1023 

BS VoL L 299. Table of decimal proportions of the pound avoirdupois . 1023 
BT Vol. I. 46. Gibb's Carving Machine patented 1829 . . . 1025 

THE KND OF THE TABLE OF CONTENTS. 



TURNING 



MECHANICAL MANIPULATION. 



VOL. II. 

THE PRINCIPLES OF CONSTRUCTION, ACTION, AND APPLICATION 

OF CUTTING TOOLS USED BY HAND; AND ALSO OP 

MACHINES DERIVED FROM THE HAND TOOLS. 



CHAPTER XXII. 

GENERAL REMARKS UPON CUTTING TOOLS. 

INTRODUCTION. 

THE title of the present volume appears to be sufficiently 
descriptive without additional explanation, consequently the 
author will alone offer a few words on the notions which led to 
the division of the volume into the eight chapters enumerated 
in the table of contents, and on their particular arrangement. 

The chisel was selected as the subject of the first chapter, as 
from the simplicity of its form and action, it may be viewed as a 
keen wedge, sometimes employed with quiet pressure, at other 
times used with percussion, as in tools of the character of axes 
and adzes ; and the straight chisel mounted in a stock for its 
guidance becomes the plane. Further, the carpenter's chisel may 
be ii-ril as a turning tool, and many tools of this kind, the second 
in the classification, follow the condition of chisels and planes, if 
we imagine the tool to be held at rest, and the work to revolve 
against it, on a fixed axis. The practice of turning is naturally 
associated with that of boring holes, although in most cases, the 
boring tool revolves whilst the work remains at rest. Turning 
and boring, each circulatory processes, led to the selection of the 
screw as the subject of the next chapter, for revolution combined 

\ul.. II. II II 



458 THE ANGLES AND POSITIONS OF TOOLS. 

with rectilinear advance, are exhibited in all the numerous modes 
of producing screws. 

Saws were ideally compared with some of the scraping chisels, 
but with a multiplication of points, and these sometimes arranged 
in continuous order as in the circular saw. The file from its vast 
assemblage of scraping teeth, was likened to a multiplication of 
the saw ; but unfortunately the file has not been engrafted upon 
any machine, embodying the manipulation of the unassisted 
instrument. Shears and punches are next considered in great 
measure as parallel subjects, and the rectilinear edges of shears 
although mostly duplicated, nevertheless bear some resemblance 
to simple chisels, although from their duplication they act on 
both sides of the material; and lastly the ordinary punch is 
comparable with the rectilinear edges of the shears and chisels, 
if we do but conceive these to be bent into the circular form. 

Should these grounds for the arrangement adopted be deemed 
fanciful or visionary, it may be added that some order or selec- 
tion was imperative, and it is hoped the present will serve as 
efficiently as any other that could be selected. 

SECT. I. THE ANGLES AND POSITIONS OF TOOLS, AS REGARDS 

THE ACT OF CUTTING. 

THE section now to be commenced, refers exclusively to the 
principles and construction of cutting tools, which will be 
considered in a general manner, and without reference to any 
particular branches of mechanical art, the tools and applications 
being selected by their characters and principles alone. 

All edged tools may be considered to be wedges formed by 
the meeting of two straight, or of two curvilinear surfaces, or 
of one of each kind, meeting at angles varying from about 20 
to 120 degrees. 

Some few tools are pointed, from the meeting of three or 
more planes or surfaces. 

Occasionally, as in the hatchet, the chipping chisel, and the 
turner's chisel for soft wood, the tool is ground from both sides, 
or with two bevils or chamfers; at other times, as in the 
carpenter's chisels and plane irons, the tool is ground from one 
side only, and in such cases, the general surface or shaft of the 
tool constitutes the second plane of the wedge ; this difference 
does not affect the principle. 












DIVISION INTO rviUNG, SCRAPING, AND .SHEARING TOOL*. I.V.t 

general characters of cutting tools, namely, the -ir angles, 

and their relations to the surfaces to be produced, depend upon 

the hardness of the opposed substances, and the direction and 

naturv <>f their fibres ; these primary characters require especial 

Moderation. 

The particular or specific characters of cutting tools, namely, 
tin forms of their blades, stocks, or handles, are adapted to the 
convenience of the individual, or the structure of the machine 
by which they are guided; these secondary characters, the less 
require or admit of generalization. 

It will be now attempted to be shown that, granting the 
latitude usual in all classifications, cutting tools may be included 
in three groups, namely, Paring Tools, Scraping Tools, and 

ring Tools. 

First Paring or splitting tools, with thin edges, the angles of 
which do not exceed sixty degrees ; one plane of the edge being 
: ly coincident with the plane of the work produced (or with 
the tangent, in circular work). These tools remove the fibres 
principally in the direction of their length, or longitudinally; 
and they produce large coarse chips or shavings, by acting like 
the common wedge applied as a mechanical power. 

Secondly Scraping tools with thick edges that measure from 

sixty to one hundred and twenty degrees. The planes of the 

edges form nearly equal angles with the surface produced ; or else 

the one plane is nearly or quite perpendicular to the face of the 

work (or becomes as a radius to the circle). These tools 

remove the fibres in all directions with nearly equal facility, 

and they produce fine dust-like shavings by acting superficially. 

Tlilrilly Shearing, or separating tools, with edges of from 

to ninety degrees, generally duplex, and then applied on 

opposite sides of the substances. One plane of each tool, or of 

ngle tool, coincident with the plane produced. 

4>lanation of these views, the diagram, fi g. 3 16, is supposed 
to represent seven different tools, the bevils or edges of which 
are all at the angle of sixty degrees, this may be considered as 
the medium angle of the paring, scraping, and shearing tools. 

:md scraping tools are supposed to be moving 
which line represents the face of the work; or the 
may be considered to be at rest, and the work to be moving 
from B to A. 

n H 2 



460 



DIVISION INTO PARING, SCRAPING, AND 



Or, in turning, the tool may be supposed to remain fixed, and 
the circle to represent the moving surface of the work ; one 
plane of the tool then becomes a tangent or radius. 

The shearing tools, if in pairs, are proceeding towards each 
other on the line C D, whilst A B still represents the face of the 
work. The single tools act on the same principle, but the body 
of the material, or the surface of the bench or support, supplies 
the resistance otherwise offered by the second tool. 

The tools a, c, f, are bevilled or chamfered on both sides, the 
others from one side only; in these latter, the general face of the 
tool forms the second side of the angle, and allowing for exag- 
geration, both as to excess and deficiency, the diagram may be 
considered to represent the edges of the following tools. 

[a, b, c, d, Splitting and Paring Tools, proceeding from A to B.] 

a The axe, or the cleaver for splitting. 

b The side hatchet, adze, paring and drawing knives, paring 
chisels, and gouges, the razor, pen-knife, spokeshave, the engra- 
ver's graver, and most of the engineer's cutting, turning and 
planing tools for metal. 

Fig. 316. 




c The turning chisel, for soft wood ; the chipping chisels, for 
iron, stone, &c. 

d The joiner's chisels, and carving tools, used with the bevils 
downwards, the joiner's planes, the cross-cut chisel for metal, 
and some other metal tools. 

[e, f, Scraping Tools, proceeding from A to B.] 
e When single, the scraping tools for turning the hardwoods, 

ivory, and brass, the hand-plane for metal, and when multiplied, 

the various saws, and files. 
/ When single, a triangular scraper for metal, and when 



8IIEAUIN NOLES Of THE EDGES. II 

n.ultiplied, the cross-cut saw for wood, and also polygonal 
lies or rimers with any number of sides, for metal. 

[e,f, Shearing Tools, proceeding from C to D.] 
e "When duplex, shears \uth edges from eighty to ninety 
i ccs, commencing with delicate lace scissors for single threads, 
and ending with the engineer's shears for cutting iron bars and 
plates upwards of two inches thick ; also duplex punches with 
rectangular edges, for punching engines and fly-presses. 

e When single, the carpenter's firmer and mortise-chisels, 
the paring-knife moving on a hinge, and cutting punches for 
gnu wadding and thin materials. 

/When duplex, common nippers for wire; more generally, 
however, the blades are inclined, so that one bevil of each blade 
in one and the same plane, and which is vertical to A B, as 
at g //. 
/When single, the smith's cutting-off chisel. 



In practice, the tools differ from the constant angle of sixty 
degrees assumed in the diagram for the convenience of explana- 
tion, as the angles of all tools are determined by the hardness, 
and the peculiarity of fibre or structure, of the several substances 
upon which they are employed. The woods and soft fibrous 
materials, require more acute angles than the metals and hard 
bodies ; and the greater or less degree of violence to which the 
tools are subjected, greatly influences likewise the angles adopted 
for them. 

Thus, under the guidance of a little mechanism, the thin edge 
of a razor, which is sharpened at an angle of about 15 degrees, 
i - used to cut minute slices or sections of woods, in all directions 
of the grain, for the purpose of the microscope. But the car- 
penter and others require more expeditious practice, and the 
change is to thicken the edges of the tools to range from 
about 20 to 45 degrees, to meet the rough usage to which they 
re then exposed, whether arising from the knots and hard places 
in the woods, or the violence applied. 

In tools for iron and steel from 60 to 70 will be found a very 
common angle, in those for brass 80 to 90, in hexagonal broaches 
for metal it increases to 120, and in the octagonal broach some- 
times employed the angle is still greater ; in the circular broach 



462 POSITIONS OF THE EDGES OF TOOLS. 

required by clock and watchmakers, the angle disappears and 
the tool ceases either to cut or scrape, it resolves itself into 
an instrument acting by pressure, or becomes a burnisher. 

To a certain extent, every different material may be considered 
to demand tools of a particular angle, and again the angle is 
somewhat modified by the specific mode of employment : these 
conditions jointly determine the practical angles suited to every 
case, or the angles of greatest economy, or most productive effect. 

The diagram shows that, independently of the measure of the 
angle of the tool, we have to consider its position as regards the 
surface of the work, the broad distinction being that, in the 
paring tools, the one face of the wedge or tool, is applied nearly 
parallel with the face of the work ; and in the scraping tools, it 
is applied nearly at right angles, as explained in the foregoing 
definitions. Indeed the paring tools, if left to themselves, will 
in some cases assume the position named ; thus, for example, if 
we place a penknife at an elevated angle upon a cedar pencil, 
and attempt to carry it along as a carpenter's plane, the pen- 
knife if held stiffly will follow the line of its lower side and dig 
into the wood ; but if it be held slenderly, it will swing round in 
the hand until its blade lies flat on the pencil, and it will even 
require a little twisting or raising to cause it to penetrate the 
wood at all. This disposition appears to be equally true, in the 
thin edges of the penknife or razor, and in the thick edges of 
the strong paring tools for metal. 

The action of a cutting tool in motion is twofold. The moving 
force is first exerted on the point of the wedge, to sever or divide 
the substance particle from particle ; the cohesion of the mass 
now directly opposes the entry of the tool, and keeps it back. 
But the primary motion impressed on the tool having severed a 
shaving, proceeds to bend or curl it out of the way ; the shaving 
ascends the slope of the wedge, and the elasticity of the shar'uiy 
confines the tool in the cleft, presses it against the lower side, 
disposes it to pursue that line, and therefore to dig into the 
substance. 



In pursuing the more detailed examination of different cutting 
tools employed in the mechanical arts, amongst the several classi- 
fications which might be adopted, it appears to the author to be 
the more generally useful to consider the various tools in separate 






FORMS AND MOTIONS OP TOOLS. 

chapters under the f..llo\\ in heads, nnmcly, Chisels and Planes 
Turning tools Boring tools Screw-cutting tools Saws 
- Shears and Punches as some of all these kinds of tools 
may be found in e\ery work-room. 

The several chapters and sections will be commenced with the 
tools for the woods, which are perhaps the more commonly used 
by the amateur, the corresponding tools for metal will generally 
lie then considered, and lastly some illustrations will be given <>f 
the same tools applied to various machines, still further to prove 
the uniformity of principle upon which they act, throughout 
these several circumstances. 

e comparative views may serve to show the similitude of 
principle in tools for like purposes, whether the tools be large or 
small, whether they be used for wood or metal, and either by 
hand or machinery ; and in cases of indecision or difficulty, a 
glance through any one section or chapter may denote, either 
the most appropriate of the ordinary tools, or may occasionally 
suggest some new modification to suit a particular case, in imita- 
tion of the numerous conversions which will be already found to 
exist amongst the tools used in the constructive arts. 

SECT. II. THE FORMS AND MOTIONS OF TOOLS, AS REGARDS Tin: 
PRODUCTION OF LINES, SUPERFICIES, AND SOLIDS. 

THE principles of action of all cutting tools, and of some 
others, whether guided by hand or by machinery, resolve them- 
selves into the simple condition, that the work is the combined 
copy of the form of the tool, and of the motion employed. Or 
in other words, that we exactly put into practice the geometrical 
definitions employed to convey to us the primary ideas of lines, 
superficies, and solids ; namely, that the line results from the 
ion of a point, the superficies from the motion of a line, 
and the solid from the motion of a superficies. 

It therefore follows, as will be shown, that when the tool is a 
point having no measurable magnitude, that two motions must 
he impressed upon it, one equivalent to the breadth, and another 
equivalent to the length of the superficies. When the tool is 
wide, so as to represent the one dimension of the superfi 

its breadth, then only one motion is to be impressed, say a 
motion equivalent to the length of the superficies ; and these two 
are either rectilinear or curvilinear, accordingly as straight or 
curved superficies are to be produced. 



464 MOTIONS REQUIRED FOR THE PRODUCTION 

To illustrate this in a more familiar way than by the ideal 
mathematical conceptions, that a point is without magnitude, 
a line is without breadth, aud a superficies without thickness ; 
we will suppose these to be materialised, and to become pieces 
of wood, and that the several results are formed through their 
agency on soft clay. 

Fig. 317. 

tp 




Thus supposing g g, to be two boards, the edges of which are 
parallel and exactly in one plane, and that the interval between 
them is filled with clay ; by sliding the board p, along the edges 
of g g, the point in p, would produce a line, and if so many lines 
were ploughed, that every part of the clay were acted upon by 
the point, a level surface would at length result. The line I, such 
as a string or wire, carried along g g, would at one process 
reduce the clay to the level of the edges of the box. 

Either the point or the line, might be applied in any direction 
whatever, and still they would equally produce the plane, pro- 
vided that every part of the material were acted upon ; and this, 
because the section of a plane is everywhere a right line, and 
which conditions are fulfilled in the elementary apparatus, as the 
edges of g g are straight and give in every case the longitudinal 
guide ; and with /, the second line is formed at once, either with 
a string, a wire, or a straight board ; but in p, the point requires 
a second or transverse guide, and which is furnished by the 
straight parts of the board p, rubbing on the edges of g g, and 
therefore the point obtains both a longitudinal and a transverse 
guide, which were stated to be essential. 

The board c, with a circular edge, and m, with a moulding, 
would respectively produce circular and moulded pieces, which 



LINKS, SUPERFICIES, AND SOLIDS. I' 

would be straight in point of length in virtue ..!'// //, the line of 

; in, and curved in width in \irtue of c or m, the lines of tin; 
c, and m, must always advance parallel with 
their Mailing positions, or tin- \\iiltli of tin; moulding would \;i 
and this is true, \\hetic\cr curved guides or curved tools 
mi ployed, as the angular relation of the tool must be then 

-tantly maintained, \\hiehitis supposed to be by the external 
piece or guide attached to m. 

Supposing g g, each to have circular edges, as represented 
by the dotted arc a a, or to be curved into any arbitrary mould- 
ing, the same boards p t /, c, m, wonld produce results of the 
former transverse sections, but the clay would in each case pre- 
sent, longitudinally, the curved figure of the. curved longitudinal 
boanls n a ; here also the line of the tool and the line of the 
motion would obtain in the result. 

If, to carry out the supposition, we conceive the board a a, to 
be continued until it produced the entire circle, we should obtain 
a cylinder at one single sweep, if the wire /, were carried round 
at ritjht angles to a a. But to produce the same result with the 
point j>, it must be done either by sweeping it round to make 
circular furrows very near together, or by traversing the point 
from side to side, to make a multitude of contiguous lines, 
parallel with the axis of the cylinder. In either case we should 
apply the point to every part of the surface of the cylinder, 
which is the object to be obtained, as we copy the circle of a a, 
(which is supposed to be complete,) and the line /; or the trans- 
verse motion of /), which is equivalent to a line. 

Hut it is obvious that, in every case referred to, there is the 

ce of moving either the clay or the tool, without variation 
in the ell'eet. If iii respect to the circular guide a a, we set tin- 
to rotate upon its center, we should produce all the results 
without the necessity for the guide boards a a, as the axis bein^ 
fixed, and the tool also fixed, the distance from the circuin- 
to the center \\ould be everywhere alike, and we should 
obtain the condition of the circle by motion alone, instead of by 

;iiiil<' : and uch. in cH'eet, is turning. 

An r\ cry-day Example of this identical supposition is seen in 
tht- potter's wheel; and the potter also, instead of always 

nbini; the lines of hi> \\ orks with his hands, as in sketchini:, 
occasionally resorts to curved boards or templets, as for making 

n n 



406 MOTIONS REQUIRED FOR THE PRODUCTION 

the mouldings for the base of a column, or any other circular 
ornament. But here, as also in ordinary turning, we have choice, 
either to employ a figured tool, or to impress on a pointed tool 
a path identical with the one section ; for example, the sphere 
is turned either by a semicircular tool applied parallel with the 
axis, or else by sweeping a narrow or pointed tool around the 
sphere, in the same semicircular path. 

Having shown that in every case, the superficies is a copy of 
the tool and of the one motion, or of the point and the two 
motions, it will be easily conceived that the numerous super- 
ficies and solids, emanating from the diagonal, spiral, oval, 
cycloid, epicycloid, and other acknowledged lines, which are 
mostly themselves the compositions of right lines and of circles, 
may be often mechanically produced in three different ways. 

First, by the employment of tools figured to the various shapes, 
and used with only one motion or traverse; secondly, by the use 
of figured guides, cams, or shaper-plates, by which the motion 
is constrained, just the same as p makes a right or a curved 
line, in virtue of its straight or curved guide ; and thirdly, by 
the employment of a point actuated by two motions, by the 
composition of which most geometric lines are expressed. 

Thus when uniform motions are employed, two rectilinear 
motions produce a diagonal to themselves ; one circular and one 
continued right-line motion, give the spiral, the screw, and the 
cycloid ; also if during one circular revolution, either the circle 
or the point make one oscillation in a right line, we obtain the 
oval ; by two circular movements we obtain the epicycloid, by 
three motions the compound or double epicycloid, and so on. 
And when one or both of the rectilinear or circular generating 
motions, are variable as to velocity, we obtain many different 
kinds of curves, as the parabola, hyperbola, and others; and 
thence the solids, arising from the revolutions of some of these 
curves upon an axis. 

produce the practical composition of any two lines or 
movements, whether regular or irregular, by impressing these 
movements on the opposite extremities of an inflexible line or 
rod ; from which rod we obtain a compounded*/?';*?, if \ve trace 
tin- motion of a point inserted in any part of the rod, and we 
obtain a compounded superficies, if we copy the motion of the 
entire line. This may need explanation. 



Or LINES, SUPERFICIES, AND SOLIDS. !'.? 

Supposing that i: !, guide ff g, to rcmuin :i 

;-lt line, tin- front t. : iivular arc a a, the board 

/<, In in- now traversed in contact both with the- straight and 
cm\ ;nt i> would describe a line if it were el 

against tlu- line // // , or an arc it' close against the arc a a; mid- 
way it would iK scribe an arcof about half the original curvature. 
On the other hand, the line b would cut off the clay in a super- 
fines possessing at the three parts these same conditions, and 
merging gradually from the right line to the arc a a. 

Hut a similar composition of the two lines or motions would 
ir, were the lines ff ff, a a, to be exchanged for any others, 
similar or dissimilar, parallel or oblique, or irregular in two 
directions; and in mechanical practice we combine, in like 
manner, two motions to produce a compound line or a com- 
pound superficies. Indeed in many cases there is no alternative 
but to impart to two edges ff a of a block, the marginal outlines 
of the superficies, and then, generally by hand-labour, to reduce 
all the intermediate portions under the guidance of a straight 
edge applied at short intervals upon the two edges, which thus 
become compounded or melted together in the superficies. Num- 
bers of irregular surfaces can be produced by this mode alone. 

lu fine, in mechanical processes, we translate the mathe- 
matical conceptions vf the rectilinear, circular, and mixed motion*. 
of points and lines, into the mechanical realities of rectilinear, 
circular, and mixed motions of pointed or linear tools. 

not imperative, however, that the tools should have but 
1 point or edge, as without change of principle a succcs- 
ot' similar points may be arranged in a circle, to constitute 
\ol\ing cutter, which by its motions will continually present 
a new point, and multiply the rapidity of the effect. In most 
introduction of a tool with a figured outline, cancels 
tor the means otherwise required to generate such 
line by the motion of a point; and a tool with a figured 
B8, cancels also the remaining motion required to pro- 
duce tin superficies, and the tool is simply impressed as a stamp 



In tracing the method of applying these theoretical views 

the explanation of the general employment of cutting tools, 
or the practice of the workshop, we may safely abandon all 

n i 






468 GENERAL METHODS OF PRODUCING 

apprehension of complexity, notwithstanding the almost bound- 
less variety of the elements of machinery, and other works ot 
cutting tools. For although all the regular figures and solids 
referred to, are in reality met -with, besides a still greater 
number of others of an irregular or arbitrary character, still 
by far the greater majority of pieces resolve themselves into 
very few and simple parts, namely, solids with plane superficies, 
such as prisms, pyramids, and wedges, and solids with circular 
superficies, such as cylinders, cones, and spheres. These are 
frequently as it were strung together in groups, either in their 
entire or dissected states ; but as they are only wrought one 
surface at a time, the whole inquiry may be considered to resolve 
itself into the production of superficies. 

And it may be further stated that, the difference between 
the modes of accomplishing the same results, by hand tools 
or by machinery, bears a very close resemblance to the difference 
between the practices, of the artist who draws the right line and 
circle by aid of the unassisted hand, and of the mechanical 
draftsman, who obtains the same lines with more defined exact- 
ness, under the guidance of the rule and compasses. 

The guide principle is to be traced in most of our tools. In 
the joiner's plane it exists in the form of the stock or sole of 
the plane, which commonly possesses the same superficies as it is 
desired to produce. For instance, the carpenter's plane used for 
flat surfaces is itself flat, both in length and width, and there- 
fore furnishes a double guide. The flat file is somewhat under 
the same circumstances, but as it cuts at every part of its 
surface, from thousands of points being grouped together, it is 
more treacherous than the plane, as regards the surface from 
which it derives its guidance, and from this and other reasons, 
it is far more difficult to manage than the carpenter's plane. 

In many other cases the cutting instrument and the guide 
are entirely detached; this is strictly the case in ordinary 
turning, in which the circular guide is given by the revolution of 
the lathe mandrel which carries the work, the surface of which 
becomes the copy of the tool, or of the motion impressed upon 
the tool, either by the hand of the workman under the guidance 
of his eye alone, or by appropriate mechanism. 

AVhcn the lathe is cm ployed under the most advantageous 
circumstances to produce the various geometrical solids or 



1. 1 MS, -i i-i iu ;< IBS, AND SOLIDS. l''-'.l 

figures, the tool is placed under the guidance of a ruler Of 
rati -lide. by \\hieh its path is strictly limited to a recti- 

linear motion. Thus for a cylinder, the slide is placed exactly 
parallel with the rotary axis of the mandrel, and tor a plain flat 
thfl to . .1 is in, >\ i'd on a slide at right angles to the axis. 
rally two slides fixed in these positions are attached to the 
lathe to cany and guide the tool, the machine being knowu 
as the sliding rest; hut mostly the one slide only is used as a 
traversing or directional slide for guiding the tool, the other as 
an adjusting or position slide, for regulating the penetration of 
the tool into the work. 

Sometimes the two slides are moved simultaneously for the 
production of cones, but more generally the one slide is placed 
oblique and used alone. The lathe is employed with great effect 
in producing plane surfaces, but the more modern engine, the 
pianino-machine, the offspring of the slide or traversing lathe 
iitly adverted to, is now also very much employed for all 
kinds of rectilinear works. 

The planing-machiue being intended principally for rectilinear 
solids of all kinds, its movements are all rectilinear, and these 
are in general restricted to three, which are in the same relation 
to each other as the sides of a cube ; namely, two are horizon- 
tal and at right angles to each other, and the third is vertical, 
and therefore perpendicular to the other two. The general 
outline of the machine will be conceived by imagining a 
horizontal railway to take the place of the revolving axis of the 
lathe, and the slide rest of the lathe to be fixed vertically 

.st the face of a bridge stretching over the railway. 

In the general .structure of this most invaluable machine, the 

railway is the cutting slide, upon which the work is slid to and 

r producing a horizontal surface, the horizontal slide 

;'.)! traversing the tool across the face of the work', 

which is thus reduced by ploughing a series of parallel grooves, 

not exceeding in distance the width of the pointed tool, so that 

the line, and then the surface arise, exactly as in the geome- 

1 suppositions. For vertical planes, the vertical is the 

traversing slide, the hori/.ontal the adjusting; and for oblique 

planes, th.- vertical slide is swivelled round to the assigned 

angle, the imaginary railway being employed in all cases to 

ion. 



170 GENERAL METHODS OF PRODUCING 

To advance into greater detail would be to encroach on the 
subject of the succeeding chapters ; although it may be added, 
that when we examine into almost any machine employed in 
cutting, it will be found that the end to be obtained is always a 
superficies, either plane or curved, and which superficies reduced 
to its elementary condition, presents length and breadth. 

When, therefore, we have put on one side the mechanism 
required for connecting and disconnecting the engine with the 
prime mover, whether animal, steam, or other power ; it will be 
found that when the superficies is produced by a pointed tool, 
the primary motions resolve themselves into two, which may be 
considered representative of length and breadth. The velocity 
of the one primary motion, is suited to the speed proper for 
cutting the material with the most productive effect, which for 
the metals is sometimes as low as ten or twenty feet per minute, 
measured at the tool, and for the woods, the speed is above ten 
or twenty times as great.* The velocity of the other primary 
motion is generally very small, and often intermittent ; and it 
becomes a mere creep or traverse motion, by which the pointed 
tool is gradually moved in the second direction of the superficies, 
under formation. 

In producing circular bodies, one of these primary motions 
becomes circulating or rotary, and in complex or irregular forms, 
an additional movement, making in all three, or sometimes four 
are compounded ; and lastly, when linear or figured tools are 
employed, one of the motions is generally expunged. 

* The principal limit of velocity in cutting machines, appears to be the greatest 
speed the tool will safely endure, without becoming so heated by the friction of 
separating the fibres, as to lose its temper or proper degree of hardness. 

The cohesion of iron being very considerable, a velocity materially exceeding 
ten to twenty feet per minute, would soften and discolour the tool, whereas in 
general the tools for iron are left nearly or quite hard. Brass having much less 
cohesion than iron, allows a greater velocity to bo used, lead and tin admit of still 
more speed, and the fibrous cohesion of the soft woods is so small, that when the 
angles of the tools are favourable, there is hardly a limit to the velocity which may 
bo used. Water, soap and water, oil, milk, and other fluids, are in many cases 
employed, and especially with the more fibrous metals, for the purpose of lubri- 
cating the cutting edges of the tools to keep down the temperature, the fluids 
reduce the friction of separating the fibres, and cool both the tool and work, 
thereby allowing an increase of velocity ; and at the same time they lessen the 
deterioration of the instrument, and which when blunted, excites far more friction, 
and is likewise more exposed to being softened, than when keen and in perfect 
working order. There are, however, various objections to the constant use of 
lubricating fluids with cutting tools. 



I INKS, SUPERFICIES, AND SOLIDS. 171 

The utlu T movements of cutting machines may be considered 
M secondary, and introduced cither to effect the adjustment of 
position nt starting, or the changes of position during the 
_ r ress of the work; or the resetting* by which the same 
superficies is repeated, as in the respective sides of a prism, or 
the teeth of a spur wheel, which may be viewed as a complex 
prism. 

The above two or three movements may in general be im- 
pressed wholly upon the tool, wholly upon the work, or partly 
upon each ; and which explains the very many ways which, 
in cases of simple forms, may be adopted to attain the same 
result. 

In numerous instances likewise, all the movements arc as it 
were linked together in a chain, so that they may recur at 
proper intervals, without the necessity for any other adjustment 
than that \\hich is done prior to the first starting, such are very 
appropriately called self-acting machines, and these, in many 
cases, give rise to very curious arrangements and combinations 
of parts, quite distinct from the movements abstractedly required 
to produce the various superficies and solids, in which the 
mathematician and mechanician from necessity exactly agree, 
when their respective speculations are sifted to their elementary 
or primary laws, which are few, simple, and alike for all. 

Mr. Nasniyth has written an interesting paper, entitled, 
" Remarks on the Introduction of the Slide Principle, in Tools 
and Machines employed in the production of Machinery." * 

This principle, although known for a far greater period, has 
within less than half a century, and in many respects even within 
1< H than the fourth of a century, wrought most wonderful 
changes in the means of constructing mechanism, possessed of 
nearly mathematical accuracy. The whole of this is traced to 
the employment of the two, or the three slide movements, to 
which method Mr. Nasmyth has judiciously applied the term 
</r I'rinciple," but the object in this place is rather to 
examine in detail the principles and practices, than to refer to 
the influence these have had on manufacturing industry, and 
thence on the general condition of mankind, and upon our own 
n in particular. 

See Buchanau'a Mill Work, by O. Rennio, F.R.& 1841. Page 398. 



472 



CHAPTER XXIII. 

CHISELS AND PLANES. 



SECT. i. INTRODUCTION; BENCH PLANES. 

IF we drive au axe, or a thin wedge, into the center of a 
block of wood, as at a, fig. 318, it will split the same into two 
parts through the natural line of the fibres, leaving rough 
uneven surfaces, aud the rigidity of the mass will cause the rent 
to precede the edge of the tool. The same effect will partially 
occur, when we attempt to remove a stout chip from off the side 
of a block of wood with the hatchet, adze, pariug or drawing 
knife, the paring chisel, or any similar tool. So long as the chip 
is too rigid to bend to the edge of the tool, the rent will precede 
the edge ; and with a naked tool, the splitting will only finally 
cease when the instrument is so thin and sharp, and it is applied 
to so small a quantity of the material, that the shaving can bend 
or ply to the tool, and then only will the work be cut or will 
exhibit a true copy of the smooth edge of the instrument, in 
opposition to its being split or rent, and consequently sho\viug 
the natural disruption or tearing asunder of the fibres. 

In fig. 318 are drawn to one scale several very different paring- 
tools, which agree however in similitude with the type, b, fig. 
81 G, page 460, and also corroborate the remark on page 462, 
that " in the paring-tools, the one face of the wedge or tool is 
applied nearly parallel with the face of the work." In tools 
ground with only one chamfer, this position not only assists in 
giving direction to the tool, but it also places the strongest line 
of the tool exactly in the line of resistance, or of the work to 
be done. 

For example, the axe or hatchet with two bevils, a, fig. 318, 
which is intended for hewing and splitting, when applied to 
pariny the surface of a block, must be directed at the angle a 
uliich would be a much less convenient and less strong position 
than b, that of the side hatchet with only one chamfer; but for 
paring either a very large or a nearly horizontal surface, the side 



MOIM > OK III I 









;;;-. 



'net in it> turn is greatly inferior to the adze C, in which the 
haiullc i> clt-\atcd like a ladder, at some (50 or 70 degrees from 
the -round, th.- preference being grtcn to the hon/.>nt:il portion 
for tlu- surface to In- wrought. 
Tin- iiistruuiriit is lii-lil in both 
hands,whibttheo] unK 

upon h;s \\ork in a stooping 

:on, the handle being from 
twenty-four to thirty inches 
long, ami the weight of the 
blade from two to four pounds. 
Th'- ad/e i> swung iu u cir- 
enlar path almost of the same 
rnrvature as the blade, the 
shoulder-joint being the center 

.otion, and the eutire arm 
and tool forming as it were one 
indexible radius; the tool there- 
ton- makes a succession of small 
are-, and in each blow the arm 
of the workman is brought in 
contact with the thigh, which thus serves as a stop to prevent 

lent. In coar>e preparatory works, the workman din 
the ad/.e through the space between his two feet, he thus sur- 
priM-s us by the quantity of wood removed; in tine works, he 
frequently places his toes over the spot to be wrought, and the 
adze penetrates two or three inches beneath the sole of the 

, and he thus surprises us by the apparent danger 
pei feet working of the instrument, which in the hands of the 
shipwright in particular, almost rivals the joiner's plane; i 
with him the nearly universal paring instrument, and is i 
upon work> in all positions. 

The small Indian adze OrBanMlXh d, fig. 3 18, in place of being 
circular like the Kuropcan ad/e, is formed at a direct angle of 
aboi Mi degrees; its handle is very short, and it is i. 

with givat precision bj thfl marly cxchiMve motion of the elbow 
joint.* In nnl.T to ^lind either of these adzes, or percussive 




" TLi very tuvful iuatr umuut (says Sir Jolm liubioou), v*rie a little iu different 

i weight and iu the angle which the cutting face forma with the line of 

tin- handle, but the funn ahown is the most gcueral, and the weight averages abuut 






-471 MODIFICATIONS OF THE CHISEL. 

chisels, it is necessary to remove the handle, which is easily 
accomplished as the eye of the tool is larger externally as in the 
common pickaxe, so that the tool cannot fly off when in use, 
but a blow on the end of the handle easily removes it. 

The chisel e, admits of being very carefully placed, as to posi- 
tion, and when the tool is strong, -very flat, and not tilted up, it 
produces very true surfaces as seen in the mouths of planes. The 
chisel when applied with percussion, is struck with a wooden 
mallet, but in many cases it is merely thrust forward by its 
handle. It will shortly be shown that various other forms of the 
handle or stock of the chisel, enable it to receive a far more 
defined and effective thrust, which give it a different and most 
important character. The paring-knife, fig. 8, p. 26, Vol. I, exhibits 
also a peculiar but most valuable arrangement of the chisel, in 
which the thrust obtains a great increase of power and control ; 
and in the drawing-knife, the narrow transverse blade and its 
two handles form three sides of a rectangle, so that it is actuated 
by traction, instead of by violent percussion or steady thrust. 

The most efficient and common paring-tool for metal, namely/, 
has been added to fig. 318 for comparison with the paring-tools 
for wood ; its relations to the surface to be wrought are exactly 
the same as the rest of the group, notwithstanding that the angle 
of its edge is doubled on account of the hardness of the material, 
and that its shaft is mostly at right angles, to meet the construc- 
tion of the slide rest of the lathe or planing machine. 

The chisel, when inserted in one of the several forms of stocks 
or guides, becomes the plane, the general objects being, to limit 
the extent to which the blade can penetrate the wood, to provide 
a definitive guide to its path or direction, and to restrain the 
splitting in favour of the cutting action. 

In general, the sole or stock of the plane is in all respects an 

1 lb. 12oz. The length of handle is about twelve or thirteen inches, and in use 
it is grasped so near the head, that the forefinger rests on the metal, the thumb 
nearly on the back of the handle, the other fingers grasp the front of it, the nails 
approaching the ball of the thumb. The wrist is held firmly, the stroke being 
made principally from the elbow, the inclination of the cutting face being nearly 
a tangent to the circle described by the instrument round the elbow joint as a 
center, the exact adjustment being made by the grasp and the inclination of the 
wrist, which is soon acquired by a little practice. In this way very hard woods 
may be dressed for the lathe with a degree of ease and accuracy not attainable 
with the small axe used in this country." 



(iKNKRAL KORM8 OK r: 



475 



counterpart of the form it is intended to produce, and 
it therefore combine* in itself tin- longitudinal and the transvene 
ecti 'hi- two guides referred to in the theoretical diagram, 

page 4<>1, and the annexed figure :;!'.", the parts of which are 
all drawn to one scale, may he considered a parallel diagram to 
')!?, page 404, so far as regards planes. 




Thus, although convex surfaces, such as the outside of a hoop, 
may be wrought by any of the straight planes, applied in the 
direction of a tangent as at a, it is obvious the concave plane, 
//, would be more convenient. For the inside of the hoop, the 
radius of curvature of the plane must not exceed the radius of 
the work : thus c, the compass plane, would exactly suit the 
curve, and it might be used for larger diameters, although in a 
lc-s perfect manner. For the convenience of applying planes to 
very small circles, some are made very narrow or short, and 
uith transverse handles such as d, the plane for the hand-rails 
of staircases, the radius of its curvature being three inches ; it 
resembles the spokcshave e, as respects the transverse handles, 
although the hand-rail plane has an iron, wedge, and stop, much 
like those of other planes. 

sections of planes, are also either straight, concave, 
com i A. or mixed lines, and suited to all kinds of specific 
mouldings, but we have principally to consider their more 
common to;: :nely, the circumstances of their edges and 

guides ; first, of those used for flat surfaces, called by the 
join | secondly, the growiny planes; and thirdly, 

the innnldinii planes. 



476 SURFACING, OR BENCH PLANES. 

The various surfacing planes are nearly alike, as regards the 
arrangement of the iron, the principal differences being in their 
magnitudes. Thus the maximum width is determined by the 
a vi 1 rage strength of the individual, and the difficulty of main- 
taining with accuracy the rectilinear edge. In the ordinary 
bench planes the width of the iron ranges from about 2 to 2 
inches.* 

The lengths of planes are principally determined by the degree 
of straightuess that is required in the work, and which may be 
thus explained. The joiner's plane is always either balanced 
upon one point beneath its sole, or it rests upon two points at 
the same time, and acts by cropping off these two points, with- 
out descending to the hollow intermediate between them. It is 
therefore clear, that by supposing the work to be full of small 
undulations, the spokeshave, which is essentially a very short 
plane, would descend into all the hollows whose lengths were 
greater than that of the plane, and the instrument is therefore 
commonly used for curved lines. But the greater the length of 
the plane, the more nearly would its position assimilate to the 
general line of the work, and it would successively obliterate the 
minor errors or undulations ; and provided the instrument were 
itself rectilinear, it would soon impart that character to the edge 
or superficies submitted to its action. The following table may 
be considered to contain the ordinary measures of surfacing 
planes. 

Names of Planes. Lengths, Widths, Widths 

in inches. in inches. of Irons. 

Modelling Planes, like Smoothing Planes . 1 to 5 ^ to 2 TV t H 

Ordinary Smoothing Planes . . . 64 to 8 --2|to3J If to2| 

lie-bate Planes 94 - - f to 2 - - j| to 2 

Jack Planes 12 to 17 - 2J to 3 2 to 2$ 

Panel Planes 14J -34 - 2J 

Trying Planes 20 to 22 3} to 3| 2| to 24 

Long Planes 24 to 26 -- 3| - 2$ 

Jointer Plauea 28 to 30 3j 2} 

Cooper's Jointer Planes . . .. 60 to 72 -- 5 to 5$ 34 to 3J 

The succession in which they are generally used, is the jack 
plane for the coarser work, the trying plane for finer work and 
trying its accuracy, and the smoothing plane for finishing. 



* The " iron," u scarcely a proper name for the plane-iron, which is a cutter 
or blade, composed partly of iron and steel ; but no confusion can arise from the 
indiscriminate use of any of these terms. 



GENERAL STRUCTURE or ri . \M. 






diagram, iig. ">-<), is one quarter the full size, and may 
be considered to represent the ordinary surfacing planes, tin- 
mouths of which arc alike, generally about one-third from tin- 
front <>f the plane, and t Ims const it uted. The line a, b, is culled 
the tolt : ' . '/, upon which the hlnde is supported, is the bed, and 
this, in planes of common pitch, is usually at an angle of 45 
with the perpendicular. 

Fig. 320. 




The month of the plane is the narrow aperture between the 
fare of the iron, and the line c, f, which latter is railed the >'< 
the anu'lc between these should be as small as possible, in order 
that the wearing away of the sole, or its occasional correction, 
may cause but little enlargement of the mouth of the plane ; at 
the same time the angle must be sufficient to allow free egress 

he shavings, otherwise the plane is said to choke. The line 
//. is called the front, its angle is unimportant, and in pra> 
it is usually set out one quarter of an inch wider on the upper 
surface than the width of the iron. 

'?/< of the plane which fixes the iron is commonly at 
an angle of 10, and it is slightly driven between the face of the 

. and the shoulder or nhiitment, C, e. It is shown by the two 
detached views, that t he wedge w, is cutaway at the central part, 
both to clear the screw which connects the double iron, and to 
allow room for the escape of the shavings. The wedge is loosened 
by a moderate blow, either on the end of the plane at h, on the 



478 GENERAL STRUCTURE OF PLANES. 

top at i, or by tapping the side of the wedge, which maybe then 
pulled out with the fingers ; a blow on the front of the plane 
at jt sets the iron forward or deeper, but it is not resorted to. 

In all the bench planes, the iron is somewhat narrower than 
the stock, and the mouth is a wedge-formed cavity; in some of 
the narrow planes the Cutting edge of the iron extends the full 
width of the sole, as in the rebate plane/, fig. 319, page 475 ; in 
these and others, the narrow shaft of the iron and the thin wedge 
alone proceed through the stock, and there is a curvilinear mouth 
extending through the plane ; the mouth is taper, to turn the 
shavings out on the more convenient side. When the planes 
only cut on the one part of the sole, as in fig. 332, page 485, the 
angular mouth extends only part way through the plane, and the 
curvilinear perforation is uncalled for. 

In the diagram, fig. 320, when the stock terminates at the 
clotted line, *, *, it represents the smoothing plane ; when it is 
of the full length, and furnished with the handle or toat, it is 
the jack plane or panel plane ; the still longer planes have the 
toat further removed from the iron, and it is then of the form 
shown in fig. 330, page 483. 

Fig. 321 represents, one-eighth the full size, a very effective 
plane, which is commonly used on the continent for roughing 
out, or as our jack plane, the horn h, being 
intended for the left hand, whilst the right 
is placed on the back of the stock. The 
Indians and Chinese bore a hole through 
the front of the plane for a transverse 
stick, by which a boy assists in pulling 
the plane across the work. When the 
plane is very large, it is by the Chinese, 
and others, placed at the end of the bench at an angle, and 
allowed to rest on the ground, whilst the work is slid down its 
face ; and a similar position is employed by the coopers in our 
own country, for planing the staves of casks, the plane being in 
such cases, five or six feet long and very unwieldy, the upper 
part is supported on a prop, and the lower rests on a transverse 
piece of wood or sleeper. 

The amount of force required to work each plane is dependent 
on the angle and relation of the edge, on the hardness of the 
material, and on the magnitude of the shaving ; but the required 




( Ol I UK PLANE-IKON. 



479 



force is in addition greatly influenced by tin- degree in which 
the -having \* l>i-iit for its n-moval in tlir most ; tanner. 

I :',-2-2 to .".Jil represent, of their full size, parts of 
the irons and mouths of various plant -s, each in the act of rc- 
;nu' a >hav in:;. Tin 1 sole or surface of the plane rests upon 
the face of tin- work, and the cutter stands as much in advance 
of the sole of tin- plane, a.s the thickness of the shaving, which 
U in each cax- so In nt as to enable it to creep up the face of 
the inclined iron, through the narrow slit of the plane, called its 
mouth, tin- width of which determines the extent to which the 
fibre of the wood can tear up or split with the jjrain. 

The spokeshave, fig. 322, cuts perhaps the most easily of all 
the planes, and it closely assimilates to the penknife; the angle 
of the blade is about 25 degrees, one of its planes lies almost in 
contact with the work, the inclination of the shaving is slight, 
and the mouth is very contracted. The spokeshave works very 
easily in the direction of the grain, but it is only applicable 
to small and rounded surfaces and cannot be extended to suit 
larire tlat superficies, as the sole of the plane cannot be cut away 
for such an iron, and the perfection of the mouth is compara- 
tively soon lost in grinding the blade. 



. 



Fig. 323. 




The diagrams, figs. 323, 4, and 5, suppose the plane irons to 
be ground at the anirle of 25, and to be sharpened on the more 
refined oilstone at 35, so as to make a second bcvil or slight facet, 
as shown by the dotted lines a, in each of the figures ; the irons 
O ground are placed at the an^lc of 45, or that of common pitch ,- 
it t i : -llovv ^. that the ultimate bev il which should be \ 

nai elevation of 10 from the surface to be planed. 

its the mouth of an old jack plane, from the 
sole of which about half an inch of wood has been lost by wear 



480 



ACTION OF THE PLANE-IRON. 



and correction, which is no uncommon case. The wide mouth 
allows a partial splitting of the fibres before they creep up the 
face of the single iron ; this plane works easily, and does not 
greatly alter the shavings, which come off in spiral curls, but 
the work is left rough and torn. 



Fig. 324. 



Fig. 325. 



Fig. 326. 




Fig. 324, a similar but less worn plane with a closer mouth, 
allows less of the splitting to occur, as the shaving is more sud- 
denly bent in passing its narrower mouth, so that the cutting 
now begins to exceed the splitting, as the wood is held down by 
the closer mouth : the shaving is more broken and polygonal, 
but the work is left smoother. 

The same effects are obtained in a much superior manner in 
the planes with double irons, such as in fig. 325, the top iron is 
not intended to cut, but to present a more nearly perpendicular 
wall for the ascent of the shavings, the top iron more effectually 
breaks the shavings, and is thence sometimes called the break 
iron. 

Now therefore, the shaving being very thin, and constrained 
between two approximate edges, it is as it were bent out of the 
way to make room for the cutting edge, so that, the shaving is 
removed by absolute cutting, and without being in any degree 
split or rent off. 

The compound or double iron is represented detached, and 
of half size in fig. 327 : in this figure the lower piece e, is the one 



Fig. 327. 




used for cutting, the upper piece t or the top iron, has a true 



of THE PLANB-IK I M 

edge, which is also moderately sharp, the top iron is placed 
from one.sKteenth to oiir-tini. th of an inch from the edge of 
the cutter, the two are held together so closely by the screw 
which passes through a lm- mortise in C, and tits in a taj 
hole in /, that no shaving can tret l)et\veen tliein. 

The constant employment of the top iron in all available cases, 
shows the value of the improvement; and the circumstance 
the plane working the smoother, hut harder, when it is added. 
and the more so the closer it is down, demonstrate that its 
action is to break or bend the fibres. This is particularly 
rvablc in the coarse thick shavings of a double-iron jack 
<, compared with those of the same thickness from a single- 
iron plane; the latter are simply spiral and in easy curves, 
whereas those from the double-iron are broken across at short 
intervals, making their character more nearly polygonal ; and 
the same difference is equally seen in thinner shavings, although 
of course less in degree. 

represents the iron of a plane intended " for the use 
of cabinet-makers and others, who require to cut either hard 
or coarse-grained wood," the upper bevil given to the iron, 
being considered to dispense with the necessity for the top-iron ; 
but it is obviously much more difficult to produce a true right- 
lined edge, by the meeting of two planes, each subject to error 
in .sharpening, than when one exists permanently flat as in the 
broad surface of the blade. 

same edge may be obtained by a blade with a single 

chamfer, the flat side of which is placed in either of the dotted 

tions of fig. -'5 2'.. The first, or b, is that previously in common 

in the ordinary moulding planes for mahogany, and c is almost 

the position of the bed for the iron of the mitre-plane, also pre- 

\ iou>l\ e Miimon : in all three planes, the ultimate angle of the 

face of the cutter is just GO degrees from the horizontal. 

its the mouth of the mitre plane full size, 

and the entire instrument one-eighth size. The stock 

is much less in height than in ordinary planes, and the iron lies 

at an angle of about 2~), and is sharpened at about the ordinary 

, making a total elevation of 60, which, together 

the delicate metallic mouth, render the absence of the top 

Soe Tntn artioiw of tl.e Society of Arts, 1825, rol. zliiL p. 85. 
I I 



MITKi: PLANE. ANGLES OF PITCH. 

iron unimportant, even when the plane is used lengthways of the 
fibres, although its ostensible purpose is to plane obliquely 
across their ends, as in the formation of mitre joints. 



r 




329. 




In all ordinary planes the mouth gets wider as the iron is 
ground away, because of the unequal thickness or taper form of 
the blade as seen at c, fig. 327. In the mitre plane this is avoided 
by placing the chamfer upwards, now therefore the position of 
the blade is determined by its broad flat face which rests on the 
bed of the instrument d, and maintains one constant position as 
regards the mouth, uninfluenced by the gradual loss of thickness 
in the iron. 

The smoothing and trying planes are also made with metal 
soles, and with single irons of ordinary angles, as one great pur- 
pose of the top iron is to compensate for the enlargement of 
the mouth of the plane by wear, this defect is almost expunged 
from those with iron soles, and which are gradually becoming 
common, both with single and with double irons. See Appendix, 
Note A.H., page 978. 



Some variation is made in the angles at which plane irons are 
inserted in their stocks. The spokeshave is the lowest of the 
series, and commences with the small inclination of 25 to 30 
degrees; and the general angles, and purposes of ordinary planes, 
are nearly as follows. Common pitch, or 45 degrees from the 
horizontal line is used for all the bench planes for deal, and 
similar soft woods. York pitch, or 50 degrees from the hori- 
zontal, for the bench planes for mahogany, wainscot, and hard 
or stringy woods. Middle pilch, or 55 degrees, for moulding 
planes for deal, and smoothing planes for mahogany, and similar 
woods. Half pitch, or 60 degrees, for moulding planes for 
mahogany, and woods difficult to work, of which bird's-eye 
maple is considered one of the worst. 



. PI It II. 

Mxxl, mid other close hard woods, may be smoothly 
il, if not cut, in any direction of the grain, when the angle 
mi: the pitch entirely disappears ; or with a common 
tiling-plane, in which the cutter is perpendicular, or 
Ell slightly forward; this tool is railed a scrnjiiiiy ji/ane, and 
is used for scraping the i\ory keys of piano-fortes, and works 
inlaid with ivory, brass, and hardwoods; this is quite analogous 
lie process of turning the hardwoods. 

cabinet-maker also employs a scraping-plane, with a 
perpendicular iron, which is grooved on the face, to present a 
es of fine teeth instead of a continuous edge; this, which is 
called a tool/iiny plane, is employed for roughing and scratc/iint/ 
veneers, and the surfaces to which they are to be attached, to 
make a tooth for the better hold of the glue. 

The smirh's-plane for brass, iron, and steel, fig. 330, has 

likewise a perpendicular cutter, ground to 70 or 80 degrees; it 

justed by a vertical screw, and the wedge is replaced by an 

end screw and block, as shown in the figure, which is one-eighth 

In the planes with vertical irons, the necessity for the 

narrow mouth ceases ; and in the smith's plane some of the 

irons, or more properly cutte; 

No grooved on the faces, by Fig 330. 

which their edjres are virtually 
divided into several narrow 
pieces; this the instru- 

ment to be more easily employed "yUj 
in rou^hin^-out works, by abs- I 

in:; so much of the width 

of the iron, and by giving it a greater degree of penetration, but 
the finishing is done with smooth-edged cutters, and those not 
exceeding from five-eighths of an inch to one inch wide. 




well known that most pieces of wood will plane better 

from the one end than from the other, and that when such 

: in ued over, they must be changed end for end 

likewise; the necessity for this will immediately appear, if we 

the shade-lines under the pi:,. . 331, to 

repiv-rii! the natural til ires of the wood, which are rarely parallel 

with the face of the work. The pi. me a, working triM t/ie ff 

i ' 



484 



SCRAPER. GROOVING PLANES. 



would cut smoothly, as it would rather press down the fibres 
than otherwise; whereas b would work against the grain, or 
would meet the fibres cropping out, and be liable to tear them up. 

It was explained in 
Fig. 331. Chap. IV., Vol. I., that 

\ >-"" / / / the handsome characters 
,/...-' / / / of showy Avoods, greatly 
: 




6 depend on all kinds of ir- 
regularities in the fibres: 



so that the conditions a 
and b, fig. 331, continually 

occur in the same piece of wood, and in which we can therefore 
scarcely produce one straight and smooth cut in any direction. 
Even the most experienced workman will apply the smoothing- 
plane at various angles across the different parts of such wood 
according to his judgment ; in extreme cases, where the wood 
is very curly, knotty, and cross-grained, the plane can scarcely 
be used at all, and such pieces are finished with the steel scraper. 
This simple tool was originally a piece of broken Avindow-glass, 
and such it still remains in the hands of some of the gun-stock 
makers ; but as the cabinet-maker requires the rectilinear edge, 
he employs a thin piece of saw-plate, which is represented black 
and highly magnified at *, fig. 331. The edge is first sharpened 
at right angles upon the oilstone, and it is then mostly bur- 
nished, either square or at a small angle, so as to throw up a 
trifling burr, or wire-edge. The scraper is held on the wood at 
about 60, and as the minute edge takes a much slighter hold, 
it may be used where planes cannot be well applied. The 
scraper does not work so smoothly as a plane in perfect order 
upon ordinary wood, and as its edge is rougher and less keen, 
it drags up some of the fibres, and leaves a minute roughness, 
interspersed with a few longer fibres. 

SECT. II. GROOVING PLANES. 

We may plane across the grain of hard mahogany and box- 
wood with comparative facility, as the fibres are packed so 
closely, like the loose leaves of a book when squeezed in a press, 
that they may be cut in all directions of the grain with nezirly 
equal facility, both with the flat atid moulding planes. But 
the weaker and more open fibres of deal and other soft woods, 



IDB-riLUtTKR. 



i-r, 



cannot withstand ;i cutting edge applied to them /iarallrl with 
thfiHselvet, or lat > they are torn up, ami ha\earough 

unfuii.hcd n 1 he jnim-r UM-> then.- fore, for deal and soft 

/.v. a very keen plane of low pitch, and slides it across 
obliquely, so as to attack the fibre from the one end, and 
virtually to remove it in the direction of its length; so that 
the force is divided :uul applied to each part of the fibre in 
succession. 

Tin 1 moulding planes cannot be thus used, and all mouldings 
le in deal, and woods of similar open soft grain, are con- 
sequently always planed lengthways of the grain, and added 
as separate pieces. As however many cases occur in carpentry, 
in which rebates and grooves are required directly across the 
u of deal, the obliquity is then given to the iron, which is 
rtnl at an angle, as in the skew-rebate and fillister, and the 
stock of the plane is used in various ways to guide its transit. 

.Many of these planes present much ingenuity and adaptation 
to their particular cases : for example fig. 332 is the side view, 
and ti;:. -i-i-i the back of the side-fillister, which is intended to 
Figs. 332. 333. 334. 

n 

a 6 








plane buth with and across the grain, as in planing a re! 
around the margin of a panel. The loose slip, or the fence./) is 
adjusted to expose so much of the oblique iron as the width 
of the rebate; the screw-stop *, at the side, is raised as much 
above the sole of the plane as the depth of the rebate, and the 
little tooth t, or scoring point (shown detached, in two views a, b], 
cdes the bevelled iron, so as to shear or divide the fibres as 
with the point of a penknife, to make the perpendicular edge 
i and square. This plane is then-fore a four-fold combina- 
tion of two measures and two cutters. The oblique iron, and 
the tooth or cutter, are pretty constantly met with in the p!:i 

kfl jrrain. 
Others of these planes have less power of adjustment; for 



486 



GROOVING PLANES; PLOUGH, ETC. 



instance the grooviug-plane fig. 334, for planing across the 
grain, has two separate teeth, or else a single tooth with two 
points c, in addition to the cutting-iron which is commonly 
placed square across the face of the plane ; the groove is only 
used for the reception of a shelf, its sides are therefore the more 
important parts, and the obliquity of the iron maybe safely 
omitted. The fence can no longer be a part of the instrument, 
as it is often used in the middle of a long piece, a wooden 
straight-edge s, is therefore temporarily nailed down to guide 
the plane ; and the stop is sometimes a piece of boxwood fitted 
stiffly in a mortise through the stock, at other times it is 
adjusted by a thumb- screw, as in the figure 334. 

The plough, fig. 335, is a grooving-plane, to work with the 
grain ; it has similar powers to the fillister, but with a greater 
horizontal range. The width of the groove is determined by 
that of the blade, of which each plough has several ; they are 
retained in the perpendicular position by a thin iron plate, 
which enters a central angular groove in the back of the biade. 
The teeth or scoring points are now uncalled for, as the iron 
works perfectly well the lengthway of the fibre. The screw-stop 
is the same as before; but the fence f, is built upon two trans- 
verse stems s s, one only seen, passing through mortises in the 
body of the plane, and fixed by wedges. In the German plough 
the position of the fence/, is determined and maintained by two 
wooden screws, instead of the stems s s, and there are two wooden 
nuts to each screw, one on each side of the stock of the plough. 
Figs. 335. 336. 337. 338. 




Other grooving-planes for working with the grain are also 
made without teeth, examples of which may be seen in the 
(Irawrr-hottom plane 330, and the slit deal planes, of which \\-\7 
tin- gi-.Mivr, ;iiid 338 the tongue, used for connecting 



, lint I I 1C, < UU'KNTERH ' 






boards for partitions and other purposes, with the groove and 

oint MO. The- planes of this class bcin^ generally used 

for out* specific purpose and measure, arc nnprmided with loose 

parts, as they arc worked until the sole of the plane, or some of 

dges come in contact with the wood, and stop the further 

pn>t;rcsx of the .utter. 

Fig. o in, the re-let plane, is of this kind, it derives its name 
from being employed in making the parallel slips of wood, or 
i\f//i 7. used by the printer for the wide separation of the lines of 
metal type, the adjustable fences are screwed fast, as much in 
aihance of the sole of the plane as the required thickness of the 
re-lets or rules, which are then planed away until, from the slips 
j on the bench, the tool will cut no Ion 



Fig*. 340. 











11 is a router plane ; it has a broad surface carrying in 

its centre one of the cutters belonging to the plough, it is n> d 

for levelling the bottoms of cavities, the stock must be more than 

the \\idth of the recess, and the projection of the iron 

determines the depth, the sides of the cavities are prepared 

before-hand with the chisel and mallet. The ordinary name for 

this plane is not remarkable for its propriety or elegance, it is 

ally called the " old woman's tooth." See Appendix, 

Note A. I., page 979. 

The carpenters' gages, for setting out lines and grooves parallel 

\\ith the margin of the work, are closely associated with the 

ui of fences or rails. The stem of the gage, fig. 3t2, is 

retained in the head, or stock, l>y means of a small wedge, and 

the cutter is fixed in a hole at right angles to the face of tin- 

stem, by another wedge. The warkiny-gage, for setting out 

lines, has a simple conical point ; the cut tiny -gage, for cutting 

and thin wood, has a lancet--ha:>ed knit. . and is a 



488 GAGES, BANDING PLANE, AND ROUNDER. 

very effective tool ; the router-gage, for inlaying small lines of 
wood and brass, has a tooth like a narrow chisel. 

There are other forms of gages, some of these have screw 
adjustments ; in the most simple, the stem is a wooden screw, 
flattened on one side, and the head of the gage consists of two 
wooden nuts, which become fixed when screwed fast against 
each other. The mortise-gage, which is much used, has two 
points that may be adjusted to scribe the widths of mortises and 
tenons. In the bisecting gage there are two sliding pieces or 
heads, which are made to embrace the object to be bisected, and 
the scribing point is in the center of two equal arms jointed 
respectively to the two sliding heads.* 

The cooper's croze is used for making the grooves for the 
heading of casks, after the ends of the staves have been levelled by 
a tool called a sun plane, like a jack-plane, but of a circular plan. 
The croze is similar to the gages, except that it is very much 
larger; the head is now nearly semicircular, and terminates 
in two handles; the stem, which is proportionally large, is also 
secured by a wedge, but the cutter is composed of three or four 
saw-teeth, closely followed by a hooked router, which sweeps 
out the bottom of the groove. 

The banding -plane-f is allied to the gages, and is intended for 
cutting out grooves, and inlaying strings and bands in straight 
and circular works, as in the rounded corners of piano-fortes 
and similar objects. It bears a general resemblance to the 
plough, fig. 335, but it is furnished in addition with the double 
tooth c, of the grooving plane, fig. 334. In the banding plane, 
the central plate of the plough is retained as a guide for the 
central positions of the router and cutter, which are inserted, so 
as to meet in an angle of about 80 degrees, between two short 
projections of the central plate ; the whole of the parts ent jring 
the groove are compressed within the length of one inch, to 
> through curvatures of small radius ; there are various 
cutters and fences, both straight and circular, according to the 
nature of the work. See Appendix, Note A.J., page 979. 

Fig. 343 is a plane which is the link betwixt carpentryand 



* Seo H. It. Palmer's ga-e for marking center Hues. Trails. Soc. of Arts, 1813, 
vol. xxxi. p. 248. 

t Mr. It. Ouwin'a Landing plane. Trans. Soc. of Arts, 1817, vol. xxxv. p. 122. 



Mo II . \M>, AM) Til Kill IMPERKEITIONS. 

turning; the conical hole in the plain- is furni-hed w iih a cutter 
placed as a tangent to tin- circle, so that the \\ootl enters in the 
:h octagonal form, and lea uuled, lit for a broom, an 

umbrella handle, or an oilier rnlcr; sometimes either the work 
or plane i by machinery, with the addition of one or two 

preparatory gouges, for removing the rougher parts. 

SECT. III. MOULDING PLANES. 

All the planes hitherto considered, whether used parallel with 
the Mirt'aco, as in straight works, or as tangents to the cui 
as in curved works, are applied under precisely the same circum- 
stances, as regards the angular relation of the mouth, because 
the edge of the blade is a right line parallel with the sole of the 
plane; but when the outline of the blade is curved, some new 
conditions arise which interfere with the perfect action of the 
instrument. It is now proposed to examine these conditions in 
respect to the semicircle, from which the generality of mould- 
ing may be considered to be derived. 

In the astragal, a, b, c, d, e, fig. 844-, a small central portion 

at c, may be considered to be a horizontal line; two other 

small portions at b, and d, may be considered as parts of the 

ical dotted lines, b,f, and d, g ; and the intermediate parts 

of the semicircle are seen to merge from the horizontal to the 

al line. 

The reason why one moulding plane figured to the astragal 
cannot, under the usual construction, be made to work the \ei- 
tical parts of the moulding with the same perfection as the hori- 
zontal, consists in the fact, that whereas the ordinary plane iron 
PIVM ut> an angle of some 15 to 60 degrees to the sole of the 
plane, which part is meant to cut, it presents a right angle to 
the side of the plane, which part is not meant to cut. Thus if 
the parts of the iron of the square rebate plane, which protrude 
thronirh the sides of the stock, were sharpened ever so keenly, 
they would only scrape and not cut, just the same as the scraping 
plane with a perpendicular iron. 

\Vhen, however, the rebate plane is meant to cut at the side, 

it is called the si <lt -rebate plain-, and its construction is then. 

. as >ho\vu in the three views, fig. 346 j that is, the 

iron is ins-Tit d perpendicularly to the sole of the plane, but ait 

a hoi i/ontal angle x x, or obliquely to the tide of the plane, so 



IMPERFECTIONS OF 



that the cut is now only on the one side z z, of the plane, and 
which side virtually becomes the sole. A second plane sloped 




the opposite way, is required for the opposite side, or the planes 
are made in pairs, and are used for the sides of grooves, and 
places inaccessible to the ordinary rebate plane. 

In the figures 344 and 345, the square rebate planes 1 and 2, 
will cut the horizontal surfaces a, b, and c, perfectly, because the 
irons present the proper slopes to these surfaces ; but in attempt- 
ing to plane the vertical line b f, with the side of 1, we should 
fail, because the cutter is at right angles to that superficies, and 
it would only scrape, or be said to drag. The plane 3, when laid 
on its side, would act perfectly on the vertical face, but now it 
would be ineffective as regards the horizontal. The square 
rebate plane, if applied all around the semicircle, would be 
everywhere effective so long as its shaft stood as a radius to the 
curve, in fact as at 2, and 3, as then the angle of the iron would 
be in the right direction in each of its temporary situations. 
But in this mode ;i plane to be effective throughout, demands 



M<il I.I.I 

cither numerous positions of the plane, or mi iron of sin 
kind as to combine these several position 

rctically speaking then fore, the face of the cutter suit- 
able to working the entire semicircle or bead, would become ;i 
cone, or like a tube of steel bored with a hole of the same dia- 
meter as the bead, turned at one end externally like a cone, ami 
split in two p.u:-. Fig. 317 would represent such a cutter, and 
which just resembles a half round gouge applied horizontally and 
sharpened externally. But this theoretical cutter would present 
all the difficulties of the spokcshave iron ; as to the trouble of 
tixiiiir if, its interference with the sole of the plane, and the dilli- 
culty of maintaining the form of the mouth of the instrun. 
it* made as a spokcshave, owing to the reduction of the cutter in 
.sharpening.* 

Hut as the iron 3, and also the side-rebate, fig. 31G, work 
perfectly well in their respective positions, or when the cutters 
are inclined horizontally, whilst the central iron 2, only requi 
to be inclined vertically, it occurred to me that by employing a 
cutter in all respects as usual, except that its face should be 

I'd as in the arc coiuu'dini/ the three irons in fig. 315, the one 
tool would cut equally well at every point of the curve ; and 

rieuce proved the truth of the supposition. The precise 
form of the iron will be readily arrived at, by cutting out in card 
the diagram, fig. 318, and bending it to a circular sweep, until 
the parts exterior to the dotted lines bf, d g, just meet the 
spring of the bead, at about the angle of half or middle pitch, or 
30 or 35 degrees from the right angle, and it will be then found 
necessary to cut away the corners to the lines b s, d 9, or so 
much of them as dip below the straight surface of the fillet, as 
seen in fiir. -'519. 

author had a plane constructed exactly in agreement with 
the above particulars, that is, with an iron curved to about the 
third of a circle, the mouth of the plane was curved to cor- 

nd, and in every other respect the instrument was as usual; 
it \\as found entirely successful. 

inclination of the tool to each part of the work is \ery 

The cutter 347, i uwxl fur making the cylindrical rollers upon which ribbon* 

arc wound ; tho cutter is fixed at the end of a slide, and is worked by a lorcr, 

.linden are made at two cuts in length* of 8 or 10 inches, and afterward* 



492 IMPERFECTIONS OF 

nearly alike, and it assimilates at different parts to each of the 
ordinary rebate planes, all of which work well. Namely, at the 
crown of the moulding c, to the square rebate plane ; at the 
spring b and d, to the side rebate planes ; and at the fillets a b, 
d e, to the skew rebate. And notwithstanding the fluted form 
of the iron, no greater difficulty is experienced in sharpening the 
iron in the new form like a gouge, than in the old like a chisel, 
the figure of the end being nearly alike in each case.* 

As all the imperfections in the actions of moulding-planes occur 
at the vertical parts, there is a general attempt to avoid these 
difficulties by keeping the mouldings flat or nearly without ver- 
tical lines. For example, concave and convex planes, called hol- 
Ifjivs and rounds, include generally the fifth or sixth, sometimes 
about the third of the circle ; and it is principally in the part 
between the third and the semicircle that the dragging is found 
to exist ; and therefore, when a large part of the circle is wanted, 
the plane is applied at two or more positions in succession. 

In a similar manner large complex mouldings often require to 
be worked from two or more positions with different planes, even 
when none of their parts are undercut, but in which latter case 
this is of course indispensable. And in nearly all mouldings the 
plane is not placed perpendicularly to the moulding, but at an 
angle so as to remove all the nearly vertical parts, as far towards 
the horizontal position as circumstances will admit. 

* The above forms of cutters suggested for mouldings, are each applicable to 
most mouldings, but from their nature they are too troublesome for ordinary use. 

For instance, we may employ a cutter such as 347, the lower surface of which, 
as in 350, is the astragal or any other moulding, \he general slope or chamfer, 
will cause the tool to cut at the fillets and at c, which parts are horizontal ; but 
the lines of the mouldings, which are vertical, require the tool to be fluted to 
obtain the horizontal angle, x, shown in dotted lines in 351, and there is all the 
inconvenience of the nearly horizontal position of the spokeshave iron. 

The iron, when sloped at the accustomed angle of pitch, requires to be convex 
for a convex moulding, and to be sharpened behind ; and by the converse, for a 
concave moulding the tool must be also concave and sharpened in front, and all 
vertical lines in the moulding require the cutter to be fluted as in fig. 351, at x. 
Mixed or flowing mouldings will require, on the same principle, the cutter to have 
nearly the sections of the mouldings, and to be sharpened always in front, in the 
apokeahave form of iron ; but partly in front and partly behind in the sloping 
irons ; but these conditions are far too complex except in some favourable cases. 
The cutters are always made flat on the face, and to lessen the difficulty, the 
mouldings are drawn shallow, with but few or no vertical parts, or else they are 
wrought by two or more different planes. 




Mot . RS. | '.:', 

Tims the pl-me for the moulding, fig. 852, would Imvc it* stock 
perptBcBadat to the dotted line //. eonm -ctiiii: tin- extreme parts 
of the moulding, the angular 

deviation being generally called f \ 

the 'I'he spring is al>o 

partly determined by the position 
which is in irahle to the 

maintenance of the form of the 
cutter in sharpening it; as the 
obliquity of the sole of the plane 
causes the cutter, when advanced 
through it, also to shift sideways, 
and cause a disagreement betv 
their figures. 

In the act of working, or as it is called in sticking the mould- 
ing, the wood is always first accurately squared to its dimensions 
to serve as a guide, and it is then sometimes roughly bevelled 
nearly to the line a b ; the plane is applied in the dotted posi- 
tion, the blank edge o, of the plane, rests against the edge of 
the prepared wood, and determines what is called the "on" of 
the moulding, that is, how far the plane can proceed upon the 
wood; and the planing is continued vertically until the blank 
edge d stops the further action, or determines the " down," by 
resting upon the solid wood beneath it. In some cases where 
the planes are unprovided with fences or blank edges, or that 
they are applied in places where fences in the ordinary form 
are inapplicable, a slip of wood is nailed down for their guid- 
as in fig. -'1-5-t, page 485. 

Wide moulding planes have been occasionally worked by two 
individuals, one to guide and thrust as usual, the other to pull 
with a rope. The top iron is however absent from the whole of 
the group, if we except the c<ij>/)i/it/ jtfane used for the upper 
surfaces of staircase rails, which are faintly rounded. The 
absence of the top iron is partly compensated forj by the pitch 
of moulding planes being as stated on page 482, about 10 
degrees more upright than in bench planes for the same m; 

nirle.s and edges of many of the small planes are 
box slipped, that is, slips of boxwood arc inlaid in the beech- 
wood, in order that the projecting edges or the quirks may 
possess greater durability. 



494 



CABINET-MAKER'S BENCH. 



SECT. IV. REMARKS ON THE BENCH, AND USE OF THE PLANE. 

It is not the present intention to resume the consideration of 
the joiner's planes in this work, it therefore appears desirable 
before quitting the subject to add a few instructions respecting the 
modes of keeping them in order, and of using them, in which 
some kind of bench or support for the work is always required. 

The benches are made in various Avays, from a few rough 
boards nailed together, to the structure shown in fig. 353, which 
represents one of the most complete kind of cabinet-makers' 
benches, carefully connected by screw-bolts and nuts : its surface 
is a thick plank planed very flat and true, with a trough to 
receive small tools, without interfering with the surface of the 
bench. 



353. 




The wood to be planed is laid on the bench, and is stayed by 
an iron bench-hook a, which is fitted in a mortise, so that it 
may be placed at any required elevation, or flush with the sur- 
face of the bench. The bench-hook has teeth projecting from its 
face, intended to stick into the wood, and retain it from moving 
ideways ; but to avoid the injury which would be inflicted by 
the teeth on nearly finished works, there is also a square wooden 
stop b, fitted tight into a square mortise. These are shown 



c \niSKi-.MAKi:u's HKNCII. !'.'.' 



removed, and OB a much larger scale, sit the toot of the 
the same letters of reference hcin^ repeated. 

The two Bide screws c, d, constitute with the chope, n kind of 

; the screw r, simply compresses, the .screw d, has a pit< 
called a //<///</ (shown detached), which enters a groove in the 
cylindrical neck of the screw d, so that when the screws are both 
opened. <o hriii^ the chop e outwards. The chops are 

greatly used for fixing work by the sides or cdL r '-s and as they 
open many inches, small boxes, drawers, and other works, may 
be pinched between them. 

There arc other constructions of benches which it is unneces- 
sary to describe ; some have only one of the screws c, d, the 
other being replaced by a square bar fixed in e, and many are 
not furnished with the end screw g, which draws out the sliding 
/i, that i> \. TV carefully fitted. The end screw serves also 
as a vice for thin works which are more conveniently held at 
i -i^ht angles to the position of the side screws ; but its more 
valuable purpose is for holding work by the two ends, which 
mode is exceedingly convenient, especially in making grooves, 
rebates, and mouldings, as the work is in no danger of slipping 
away from the tools. There are several square holes along the 
front of the bench, for an iron stop i, which has a perpendicular 
and slightly roughened face, and a similar stop j, is also placed 
in //, and as the latter slides a quantity not less than the interval 
ecu the holes, pieces of any length below the longest may 
be securely held. 

For holding squared pieces of wood upon the bench, as in 
making mortises or dovetails, the holdfast k, is used in the 
manner shown, it is an L formed iron, the straight arm of which 
fits loosely in a hole in the bench; the work is fixed by driving 
on the top at k. and it is released by a blow on the back at /. 
Sometimes also the holdfast is made in two parts jointed toge- 
ther like the letter T, with a screw at the one end of the 
transuTM- piece, by which the work can be fixed without the 
hammer, but tin mode is far more common and is suf- 

ficiently manageable. And /// is a pin which is placed in any 
of the holes in the leg of the bench, to support the end of long 
boards, win. d at their other extremity by the screws, /, </. 

\\ V iriH n m proceed to the manairement of the planes. See 
Appendix, notes A K, A L, and A Iff, ] 'MS and 980. 



496 SHARPENING AND ADJUSTING. 

Of the bench planes enumerated in the list on page 476, the 
following are most generally used, namely, the jack plane for 
the coarser work, the trying plane for giving the work a better 
figure or trying its straightuess and accuracy, and the smooth- 
ing plane for finishing the surface, without detracting from the 
truth obtained by the trying plane. Sometimes when the wood 
is very rough and dirty, two jack planes are used still more to 
divide the work, and these instruments are managed in the 
following manner. 

The remarks on pages 477-8 explain that, for long planes, the 
iron is released by a blow of the hammer on the top of the plane 
at the front ; the smoothing, and all short planes, are struck at 
the back of the plane, and never on the top, or the wedge may 
be tapped sideways, and pulled out with the fingers. 

The top iron is then removed, by loosening the screw, and 
sliding it up the mortise, until its head can pass through the 
circular hole in the cutting iron. 

The plane iron having been ground to an angle of some 25 
degrees, with the stone running towards the edge, it is next 
sharpened at an angle of about 35 degrees on the oilstone. The 
iron is first grasped in the right hand, with the fore finger only 
above and near the side of the iron, and with the thumb below; 
the left hand is then applied with the left thumb lapping over 
the right, and the whole of the fingers of that hand on the sur- 
face of the iron ; the edge should be kept nearly square across 
the oilstone, as when one corner precedes the other the foremost 
angle is the more worn. 

When the iron is required to be very flat, as for the finishing 
planes, the surface of the oilstone should be kept quite level, and 
the blade must be held at one constant angle ; but when it is 
required to be round on the edge, a slight roll of the blade is 
required edgeways ; lastly, the flat face of the iron is laid quite 
flat on the oilstone, to remove the wire edge, and if required, 
the edge is drawn through a piece of wood to tear off this film, 
after which the iron is again touched on the oilstone, both on 
the chamfer and flat surface, as the edge when finished should 
be perfectly keen and acute. 

The iron is frequently held too high to expedite the sharpen- 
ing ; it is clear, that should it be elevated above 45, or the pitch 
of the plane, the bevil would be in effect reversed, and it could only 



TII IKONS. 497 

act as a burnish' ly at i:> the keen (<!;;< \\ould be soon 

worn away, :uul tin condition of tin- hurnishi r would remain ; 
and, within certain limits, the lower or thinner the edge is sharp- 
i the better. lYrhaps the an^le of ''>'>' which is assumed, is 
as favourable as any, a> if the edge be too acute the durability 
greatly decreases, and therefore some regard is also shown to the 
degree of wear and fatigue the iron is called upon to endure.* 

The edge of the iron is likewise ground to different forms ac- 
cording to the work ; thus, the jack plane is found to work n 
easily when the iron is rounded as an arc, so that whether it 
project in the center more or less than one-sixteenth of an inch, 
the common measure, the angles of the iron should sink down 
to the sole of the plane at the corners of the month. 

The ease thus afforded appears more or less due to three causes. 
The rounded iron makes its first penetration more easily, a 
commences as it were with a point, or very narrow edjre : the 
iron has to penetrate the wood as a wedge, first to cut and then to 
/ the shaving; and it is likely that the reduction of labour in 
the cut tiny, by the narrow portion of the edge being employed, 
is greater than the increase, in hcml'iny a thicker but narrower 
shavinir; and lastly, the curved iron di.-tantly approaches the 
condition of the skew-iron, and in all inclined blades there is a 
partial sliding or saw-like motion, which is highly favourabl 
cutting. The irons for the finishing planes, although sharpened 
as flat as possible at other parts, arc faintly rounded at the 
corners to prevent their having marks upon the wood. 

The cutting iron having been sharpened, the top-iron is 
screwed fast at the required distance from the edge, say for 
se works one-sixteenth, and for fine work, one fortieth or 
fiftieth of an inch. The compound iron is placed in the mouth 
of the plane, and the eye is directed from the front along the 
sole, to see that it projects uniformly and the required quantity ; 
the wedge is then put in with the right hand, and slightly tapped 
with the hammer. If this should by chance carry forward the 
iron also, a blow on the back of the plane at h, fig. 320, p. 477, 



* When the minute chamfer of the plane-iron w a I moat parallel with the sole 

of the plane, it will for a short time be entirely effective. Thus, as an experiment. 

the iron a very small quantity through the aole, and aharpen it by allowing 

the oilstone to rub both on the edge and on the wood behind ; this will produce a 

very accurate edge, and the iron when set back, will cut beautifully. 

K K 






498 MODIFICATIONS OF THE DOUBLE IRON. 

or on the upper surface of the long planes at i, partially with- 
draws the iron, and in this manner, by a few slight hlows on the 
end or either edge of the iron, and on the end of the wedge, the 
adjustment is readily effected. Violence should be avoided, as 
the wedge if overdriven might split the plane, and long before 
that it would distort the sole and drive the back wood up, which 
means, that the wood behind the iron would be driven so as to 
stand slightly in advance of that before the iron, the two parts 
of the sole becoming slightly discontinuous or out of line. The 
iron should be always so slenderly held, that one or two mode- 
rate blows would release the iron and wedge. 

There is a very ingenious modification of the double iron 
plane,* in which the cutter is a thin unperforated blade of steel 
placed between a brass bed and an iron top-piece ; the cutter, 
instead of being fixed and adjusted in the ordinary manner by 
taps of the hammer, is managed by the quiet action of various 
screws. 

In a plane patented in America, in 1832, the bottom or cutting 
iron is made as usual, but without any mortise ; the top iron has 
a thumb-screw at its upper end, and moves on two lateral pins or 
fulcrums f -inch from its lower edge ; the pins fit into two grooved 
pieces of metal let into the sides of the plane, the lengths of the 
grooves exactly determine the situation of the top iron. When 
therefore the cutter is placed in its required position, the thumb- 
screw is turned, it bears on the upper part of the cutter, and 
tilts the top iron, until its lower edge also bears hard against the 
usual part of the cutter, and thereby fixes it without a wedge. 

The main hindrances to the general employment of these 
constructions appear to be their increased cost, and the great 
dexterity with which the required adjustments are accomplished 
by the accustomed hand with the apparently rude, yet sufficient, 
means of the haminer.f 



The planes being respectively in good working condition, the 
board to be planed is laid on the bench, and if it should be 
obviously higher, either at the opposite corners from being "in 
iri a ili ay" or in the middle, or at the edges from being "cast and 

Invented by Mr. H. Bellingham. See Trans. Soc. of Arts, 1836, vol. li. 
t The same remark applies to Mr. F. E. Franklin's Screw Bench Hook, (idem, 
vol. liii,) intended to supersede a orj, fig. 353, page 494. 



PLANING A PLAT SURFACE. 499 

roum/in>/," these partial prominences arc first removed with the 
jack plane; hut in general the shavings should be of the full 
ii of the work, or at any rate a yard long. 

toat of the plane is held in the right hand, the front 
ig grasped with the left hand, the thumb towards the work- 
man ; the planes require to he pressed down on the work during 
the cut, this is done 1. -ss by an exertion of the muscles, than by 
slightly inclining tin: body, to cause its weight to rest partly 
upon the plane. During the return stroke, the pressure should 
he discontinued to avoid friction on the edge, which would be 
thereby rounded, and there is just an approximation to lifting 
the heel of the plane off the work: or in short pieces it is 
entirely lifted. The general attempt should be to plane the 
ork somewhat hollow, an effect which cannot however really 
occur, when the plane is proportionally long and quite straight. 

The sole of a long plane is in a great measure the test of the 
straightness of the work ; thus when the rough outside has 
:i removed with the jack-plane, the trying-plane is employed, 
which is set with a much finer cut, and the workman will in a 
great measure tell the condition of the surface by the continuity 
and equality of the shavings. It is however also needful to 
nine its accuracy with a straight-edge; the edge of the 
plane applied obliquely across the board is in general the 
primary test, but as the work approaches to perfection, the 
straight-edge is laid parallel with the sides of the work, and also 
diagonally across it; and towards the last, the work if small is 
raised to the level of the eye, or in large pieces, the workman 
stoops to attain the same relative position. 

In using the straight-edge the workman is partly guided by the 
eye, or the line of light that is observable between the instru- 
ment and the work, and partly by the sense of touch, as he 
s whether the straight-edge, when it is very slightly rotated 
as on a center, bears hardest at the ends or in the middle, and 
he applies the plane accordingly.* 

* The straight-edge U simply a wide thin bar of wood or nieUl, made aa accu- 
rately straight aa possible ; the tnith of a straight-edge can be only proved by the 
examination of a series of at least three. Thus, supposing A to be perfect, B to 
be slightly concave, and C to be slightly convex ; it might happen that B and C 
exactly agreed, but .1 could not agree with either of them. 

Or supposing A to be concave exactly like B, or to become If, then B and C 

K K 2 



500 WINDING STICKS. 

The foregoing mode refers to surfaces of moderate width, but 
when the pieces are narrow, or two or more distant parts alone 
are required to be in one level, the winding sticks are employed. 
These are two straight-edges, say twenty to thirty inches long, 
which are placed transversely upon the ends of the work and 
parallel with each other, they receive their direction from the 
respective ends or transverse sections, and should these be 
inclined to each other, or in winding instead of parallel, the 
winding sticks would magnify the error. This is explained by 
the diagram fig. 354, the eye placed on the level of the imagi- 
nary plane, bounded by the edges a b, c d, of the winding sticks, 
would find the edge of a b exactly parallel with that of c d, but 
if c d were situated as in the dotted lines, the disagreement of 
position arising from the twist or inclination of the edge would 
be immediately apparent. It is important that the winding 
sticks should be parallel, as then the eye may be directed to 
their upper edges, thereby avoiding the interference of the work 
itself. If the work be perfect, the two sticks appear in exact 
parallelism, when from the foreshortening, c d, is nearly eclipsed. 

Figs. 354. 355. 

^1 / 

ll d A A 




7 



/ 



Nearly all the works in carpentry are first prepared as paral- 
lelograms of various proportions, whether they are to be subse- 
quently used in that simple form, or to be worked with grooves, 
rebates, or mouldings ; or to be connected by joints of various 
kinds. We will now follow up the formation of one flat surface, 
by explaining the order in which to produce the three pairs of 
parallel rectangular surfaces in fig. 355, namely, A a, the two 
faces, B b, the two sides, and C c, the two ends ; and in this 
and every work possessing flat surfaces, it is of the utmost 
consequence that one face A, should be first wrought in the 
most careful and exact manner as above described, to serve 

would also agree, but B and B' would disagree ; therefore the rectilinear form can 
only be proved to exist when A, B, and C will bear a strict comparison in i-ach 
binary combination. 



MCI \.. I Itll k AM ll IN WORKS. 

aa tlu- foundation or Imse, from which all the other measures 
are to be successively derived. 

Tin- works are generally sawn out a trifle above the required 
sixes, aild tlic Mil-<-.|Ui-nt modes of proeeedmg, depend upon 
the proportions of the pieces, or whether they are thick as in 
rarpentry, or thin as in joinery and cabinet making. In thick 
pieces, after the face A, has l)t en planed quite flat, the side B is 
next wrought, and a short square is used to examine whether 
the two are exactly at right angles, for this purpose the stock 
of tin- square is rested against A, and the blade on B ut various 
parts of the work ; or indeed the square is slowly traversed to 
ascertain that the angle is everywhere in agreement with the 
square. The angle A B, is then marked with pencil lines 
extending on the face and side, to denote that this angle is to 
as the foundation for the subsequent measures. 

Before proceeding to plane the second face a, the marking 
gage, fig. 342, p. 487, is adjusted until its point stands exactly 
as far from the head of the gage as the intended thickness of 
the work. The gage is then rubbed forcibly against the finished 
face A, so as to scratch a line on the edges of B b, indicative of 
the intended new surface a, and which is then worked with the 
same care and precaution as its companion A^ After this b, is 
similarly worked, when the width of the faces A a, have been 
also scored by the marking gage applied against the true side B. 
In planing a and b, the square is applied from B and A respec- 
tively, to ensure the rectangular forms of the edges, and the 
gage is also used together with the square to test the parallelism 
of the work ; and lastly, the ends C c are marked on all four 
I with the square, preparatory to the use of the saw, or the 
formation of the tenons, mortises, or dovetails by which the parts 
are attached. When the works are planed with rebates, grooves, 
or moulding, the squaring up of the four sides is always the 
preliminary step, although in some cases the principal attention 
d to the two surfaces A B, especially when they are only 
required to serve for the attachment of other parts of the work. 
juariu^ up works cut out of thin plank, the mode is dif- 
ferent, the pit-saw leaves the hoard nearly parallel, and when 
the piece has been cut out with the hand-saw, the face A is first 
/ mi, that is, corrected with the trying plane, the piece is 
next gaged to thicknets, either at the ends only, or on all four 



502 



SHOOTING BOARDS. 



edges, and the second face a, is planed up. The rectangular 
piece is next fixed in the screw clamp of the bench, with the 
edge B upwards, and which is made quite straight with the 
trying plane in its ordinary position, and tested with the square ; 
the two ends C c, are next marked off with the square, and 
planed from the corrected edge B, and lastly b is gaged and shot 
down to the width. By these means, should the fibres have 
been split, or spoiled off in shooting the ends, the removal of 
the edge b, as the last process would correct the evil. There 
are some very useful contrivances employed in planing the edges 
of thin works, and which will be next adverted to. 

In squaring or shooting the edges of boards, the shooting board 
drawn in figs. 356 and 357, is very much used; it is a contriv- 
ance to enable the side A, of the work (the ends of which are 
shaded in each of these views), to be laid flat on a bed e, whilst 
the plane lies on its side, either on the bench, or upon the 
additional piece /; and provided the shooting board is parallel 
and straight, and that the sole of the plane is at right angles to 
its side, the rectangular forms of the edges are much more 
readily attained. The work is, nevertheless, examined with the 
square, as if the set of the iron be imperfect it will introduce a 
little error, and which is corrected by tapping the iron sideways, 
to correct its position. 



357. 




In squaring the ends C c, the transverse block g of the shooting 
board, is the rectangular gage, and the cross piece also partly 
supports the fibres from tearing away ; for bevils, corresponding 
blocks are fitted to it as represented at /*, but the mitre, or the 



I'l. \\l\ti MVCII1NE8 FOR WOOD HKNTIIAX's. 

angle of forty-five degrees there shown is the on .illy 

required. To plane tin- edges, B or C, to the mitre or other 
angle, the respective heds upon wliieii the work and plane are 
supported, are reijuireil to be to each other in that particular 
angular relation, :i* in ti^s. :i:>^ and Ji59 which represent the 
mitre block tor angles of forty-live degrees. 

s of external fences materially assist in pieces 
much narrower than the face of the plane, and the order in which 
the six faces are dressed, is very closely followed, although with 
ilitti rent tools, in other arts, in which the works consist of like 
surfaces requiring a similarly strict relation to each other. 

SECT. V. PLANING MACHINES FOR WOOD. 

In nsinu' hand-tools the instrument rests immediately upon 
the face of the work under formation; and in repeating any one 
ilt, the same careful attention is again required in every 
successive piece. But it was explained in the last chapter, that 
in the machines acting by cutting, the accuracy is ensured far 
more readily, by running either the work or the tool, upon a 
straight slide, an axis, or other guide, the perfection of which has 
In t-n carefully adjusted in the first formation of the machine; and 
the slide or movement copies upon the work, its own relative 
degree of perfection. The economy of these applications is there- 
fore generally very great, and they are frequently most interesting, 
on account of the curious transitions to be observed from the 
hand-processes to the machines, in some cases with but little, in 
others with considerable change in the general mode of procedure. 

The first planing machine for wood is supposed to have been 
that invented by General Bentham, who took out a patent for 
it in 1701 ; it was based on the action of the ordinary plane, 
the movements of which it closely followed. This contrivance 
reduced the amount of skill required in the workman, but not 
that of the labour; it appears to have been but little used. 
hoard to he planed was sometimes laid on a bench, at other 
times fixed by long cheeks having teeth which penetrated its 
edges, the iron of the plane extended the full width of the board, 
and the stock of the plane had slips to rest on the bench and 
check the cutting action, when the board was reduced to the 
intended thickness, muchthe same as in the reglet plane, fig. 8 HI. 
-edged boards, the two slips were of unequal 



501 BRAMAH'S PLANING MACHINE. 

thicknesses; for those intended to be taper in their length, the 
guide rails had a corresponding obliquity, and were fixed to the 
bench. The plane was moved to and fro by a crank, it was 
held down to its work by weights, and the plane was lifted up in 
the back stroke to remove the friction against the cutter.* 

The scale-board plane, abbreviated into scabbard-plane, for 
cutting off the wide chips used for making hat and bonnet boxes, 
is, in like manner, a plane exceeding the width of the board ; it 
is loaded with weights, and dragged along by a rope and wind- 
lass, the projection of the iron determines the thickness of each 
shaving or scale-board. This construction is also reversed, by 
employing a fixed iron, drawing the wood over it, and letting the 
scale-board descend through an aperture in the bench ; each of 
these modes is distinctly based on the common plane. See 
Appendix, Note A. N., page 981. 

The late Mr. Joseph Bramah took out a patent in 1802 for 
a planing machine for wood ; one of which may be seen in the 
Gun Carriage Department, Woolwich Arsenal. The timber is 
passed under a large horizontal wheel, driven by the steam- 
engine at about ninety revolutions per minute ; the face of the 
wheel is armed with a series of twenty-eight gouges, placed hori- 
zontally and in succession around it ; the first gouge is a little 
more distant from the center, and a little more elevated than the 
next, and so on. The finishing tools are two double irons, just like 
those of the joiner, but without the advantage of the mouth. 

Mr. Bramah employed the principle of his famous hydrostatic 
press (patented in 1791), both for raising the cutter wheel to suit 
the different thicknesses of wood, and also for traversing the 
timber under the cutters upon guide rails ; the latter, by means 
of an endless chain connected with the piston of the pump, by a 
rack, pinion, and drum. The bottom of the axis of the cutter 
wheel is cylindrical to the extent of its vertical adjustment, and 
is fitted in a tube terminating at its upper part, in a cupped 
leather collar, impervious to oil or water, as in the hydrostatic 
press. The injection of water into the tube by a small force- 
pump, lengthens the column of fluid, upon which the wheel is 
supported as on a solid post ; the descent of the wheel is effected 
by allowing a portion of water to escape by a valve.f 

* See the Encyclopedia Metropolitans, &c. &c. 
t Mr. Bramah's patent includeR tnnny modifications of fixed and revolving 



Ml Ill's 1M. \ M M. M \t III 

A more recent machine tor planing flooring hoards, and other 
wood works, consists of a M in ^ of knives placed parallel with, 
and around the axis of, a small cylinder ; the hoard is passed 
underneath the cutter ulul>t it is in rapid motion ; this may be 
called an adzing machine, and the Unives arc of the full width 
of the Ix . 

In Mr. Mnir's patent planing machine for flooring boards, a 
i y adze roughly planes the bottom, another operates on the 
top of the board ; afterwards, two oblique fixed cutters, like the 
skew-n bate irons, but with top irons, remove each a shaving of 
the full length and width of the deal; two cutters make the 
sides parallel, and two others groove the edges for the tongues, 
or in fact, these are four revolving planes or saws in order to 
expedite their effect. The board enters the machine as left from 
the saw-mill, it is thrust forward by the engine, and comes out 
\ery speedily in a condition nearly ready for fixing, the eight 
operations being simultaneous ; but sometimes a little finishing 
with the hand-smoothing plane is required at those parts where 
the grain is unfavourable to smooth cutting. Other machines, 
by Paxton, by Burnett and Poyer, and others, are used for 
preparing sash-bars, and similar works.* See Appendix, Notes 
A.O., & A.P., pages 981 & 9^ 

The preceding machines are mostly intended to work irith the 
grain ; and I am only acquainted with one rectilinear planing 
machine that is exclusively intended for cutting across the grain, 
namely, the mortising engine, one of the series of machines 
erected at Portsmouth in 1807, by Mr. Brunei, for the manu- 
facture of ships' blocks.f 

A hole is first bored through the block at the commencement 
of the intended groove for the sheave, and it is extended by the 
successive action of a mortising or paring tool, which rides 

cutter*, for planing and cutting wood and metal works ; also a machine for turning 
spheres, and for cutting wooden bowla one out of the other, and likewise other 
mechanical contrivances. See Specification, Gregory's Mechanics, vol. ii. p. 415. 

* See tho description of Paxton's machine, Trans. Soc. of Arts, voL liii. p. 97 ; 
see also specification of Burnett and Foyer's patent 

The reader is likewise referred to tho foot-note, page 32, voL i, on Taylor's 
patent machine for chopping out the staves for casks ; a similar mode was pre- 
viously employed for chipping into fragments the dye-woods, the logs of which 
fell against the revolving disk through an inclined shoot 

+ Now Sir Mark Isambard Brunei. 



506 BRUNEL'S MORTISING AND SCORING ENGINES. 

perpendicularly up and down ; just before the tool descends, the 
block is traversed a quantity equal to each cut or shaving. 

The cutter is made cylindrical, and is formed just like a 
quill pen, but solid and with an elliptical cutting edge instead of 
the points. " The chisels are provided with small teeth, which 
are fitted into dove-tailed notches formed in the blade of the 
chisel. These are called scribers, they have a sharp edge pro- 
jecting a short distance beyond the inside edge of the chisel, 
and therefore in descending through the mortise, the scribers cut 
the sides of the mortise fair, and make two clefts which separate 
the chip (which will be cut out at the next stroke), at its edges 
from the inside of the mortise, so that the chip comes out clean 
without splitting at the edges, and this makes the inside of the 
mortise as clean and smooth as possible."* A hole is drilled 
nearly in the axis of the cylinder, for the insertion of a pin, by 
which the shavings are thrust out when they happen to clog 
the hole. 

By forming the tool of a semicircular section and with two 
small fins, or edges projecting at right angles from the ends of 
the diameter, and then sharpening it so that the diameter 
becomes a straight chisel-edge, the scribing points are formed 
in the solid with the chisel, and are continually restored as the 
tool is sharpened. The tool is then perfectly analogous to fig. 334, 
page 485, if we suppose the plane condensed into a long chisel 
of semicircular section, equal to the diameter of the hole, the 
progressive elongation of which it has to effect. 

There are many useful applications of revolving figured planes, 
moving through curved paths, by which we obtain figures of 
double curvature, as explained in the theoretical diagram, 
fig. 317, page 464. Mr. Brunei introduced an example of this 
in the scoring engine, one of the machines recently adverted 
to, for the manufacture of ships' blocks. 

It is intended to form the groove around the block, for the 
rope by which it is attached to the rigging. The revolving plane 
is a disk of brass with a round edge and two cutters, inserted 
at an angle of about 30 with the radius; it traverses around 
the one side of the block, and receives its direction from a 
shaper plate or pattern placed parallel with the block, by which 

* Rees'a Cyclopedia, article " Machinery for manufacturing Ships' Blocks." 



COMPARISON OP HAND AND MACHINE PLANING. 507 

11-,'finciit tin- ruth i ma ,cs the groove deep at the ends, but 
-!i:i!l,.u win ! it passes the pin or axis of the sheave. Thcsame 
method has been subsequently extended to shaping the entire 
block with cutters of the full width, applied at four times.* 



These several machines are compounds of slides and guides, 
and of fixed or revolving planes : the relative degrees of perfec- 
tion :itt:iim-il, depend on the stability of the machines, and their 
respective agreement with the principles of the ordinary hand 
tools, which are generally themselves, the last stages of a long 
series of gradual improvements. 

But the absence of some of the true characters of the plane, 
iu nearly the whole of the machines for wood, namely, the proper 
obliquities of the iron, the frequent want of the mouth of the 
plane, and of the top or breaker iron, which so greatly restrains 
the splitting and tearing up of the fibres, prevent the machines 
from producing, in the softer woods, the smooth finished work 
of hand tools, in the management of which the judgment of the 
operator can be employed to combat the peculiarities of fibre. 
But the enormous productive powers of such machines, out- 
Ji these drawbacks, and the more especially so, as the 
general forms or outlines are repeated by them in a most exact 
manner, and a little after-trimming by hand imparts the neces- 
sary finish. 

In speaking of the apparatus for ornamental turning, there 
will be occasion to show that these same principles arc strictly 
embodied in miniature, in the various parts of the complex lathe 
for ornamental turning; but as the hardwood and ivory therein 
generally used, admit of the employment of scraping-tools, not 
requiring either the obliquity of the cutter, or the mouth of the 
plane, the above objections do not apply to them, and their several 
results exhibit a much nearer approach to perfection. 

* Iu revolving planes for wood, the cutters should always present an obliquity 
of about 80 to the radius, otherwise, or when the cutters are placed radially, they 
only scrape, or act like saws. Some of these planes are made of one disk of steel, 
in which oa*e there are four, five, or six openings, like the mouths of rebate 
planes; the one ai<le of each wedge or cutter is now a part of the circumference, 
the other is elevated some 20 or 30 degrees, thereby resembling the spokeshave 
iron. This form of cutter, although nearly perfect, is very expensive, and difficult 
to maintain in order. 



508 



CHAPTER XXIV. 

TURNING-TOOLS. 



SECT. I. FACILITY OF TURNING COMPARED WITH CARPENTRY. 

THE process of turning is accomplished with considerably 
more facility, truth, and expedition, than any other process 
requiring cutting tools, because in the most simple application 
of the art, the guide principle is always present, namely, that of 
rotation. The expedition of the process is due to its being un- 
interrupted or continuous, except as regards the progressive 
changes of the tool, and which is slowly traversed from part to 
part, so as to be nearly always in action. 

To choose the most simple condition, let us suppose the 
material to be in rotation upon a fixed axis, and that a cutting 
tool is applied to its surface at fifty places. Provided the tool 
remain quiescent at one place, for the period of one revolution of 
the material, the parts acted upon will each become one circle ; 
because the space between the tool and the axis is for a period 
constant, and the revolution of the material converts the distance 
of the tool from the center, into the radius of one circle ; and the 
same is equally true of the fifty positions. 

The fifty circles will be concentric, or parallel with each other, 
because the same axis extended, or continued as a line, remains 
constant, or is employed for each of them, arid therefore con- 
ceiving the fifty circles to be as many parts of the outline of a 
vase or other object, simple or complex, it will be strictly 
symmetrical, or equidistant from the central line at correspond- 
ing parts. 

Each of the fifty circles will also become the margin of a 
plane at right angles to the axis, and which axis being a straight 
line, the whole of the circles will be parallel, and therefore the 
top and bottom of the vase will be also exactly parallel. And yet 
all these accurate results must inevitably occur, and that without 
any measurement, provided the material revolve on one fixed 



FACILITY <T M UMNO COMPARED WITH CARPENTRY. 509 

axis, and t hut t he tool is for a short period constant or stationary 
.ich part of tin- surface; conditions inseparable from the 
tunii -r'> 

Tin- principle of rotation upon a fixed axis, removes the 
necessity for many of the steps and measurements required to 
.:!( with accuracy the various angular solids employed in 
carpi -ntry and many other arts. For example, at page 501 the 
methods were explained by which the joiner produces the three 
pairs of parallel surfaces A a, B b, C c, of fig. 855, and which 
-enerally required in each separate piece of his work. And 
in making a box he has to combine six such pieces with the 
same relations of parallelism, and therefore thirty-six various 
surfaces have to be operated upon, to obtain the hollow cube, or 
the carpenter's box. 

The turner's box consists of two pieces, in place of six ; as the 
bottom and its four sides are resolved into one piece ; when of 
wood, by nature in the forest; when of metal, by man in the 
crucible. The surfaces are therefore reduced from thirty-six to 
eight, namely, the inner and outer surfaces of the bottom and 
lid amounting to four, and the inner and outer sides or margins, 
amounting to four also, and the revolution of the work upon one 
axis, places the eight in exact and true relation with extreme 
rapidity. 

For example, the ends or terminal planes of the box, are from 
necessity at right angles to the axis of rotation, and parallel 
with each other. In each of these superficies the question of 
being in or out of winding ceases; as if straight, they can only 
be planes or coucs, and which the one straight-edge immediately 
points out. 

The principle of rotation ensures circularity in the work, and 
perpendicularity or equality as regards the central line ; it only 
remains, therefore, to attend to the outline or contour. The 
riu'lit line serves to produce the cylinder, which is a common 
outline for a box ; and the employment of mixed, flowing, and 
arbitrary lines, produces vase* and ornaments of all kinds, the 
beaut \ of which demands attention alone to one single element, 
or i 11, namely, that of form; and in the choice and 

production of \\hich a just appreciation of drawing and propor- 
tion greatly assist. 

In the art of drawing, it is almost essential to the freedom of 



510 PRACTICE OF TURNING, 

the result, that the lines should be delineated at once, and 
almost without after correction; in the art of turning, it is 
always desirable to copy a drawing or a sketch, but having 
nearly attained the end, the tool may be continually re-applied, 
partially to remove any portions which may appear redundant, 
until the most scrupulous eye is satisfied. 

The combining of the several parts of turned objects, as the 
separate blocks of which a column or other work is composed, 
is greatly facilitated from the respective parallelism of the ends 
of the pieces of which turned objects consist ; and the circular 
tenons and mortises, whether plain or screwed, place the differ- 
ent pieces perpendicular and central with very little trouble. 

These several, and most important facilities in the art of 
turning, are some amongst the many reasons, for its having 
obtained so extensive and valuable an employment in the more 
indispensable arts of life, as well as in its elegances. 



The relative advantages of the different sections of the tree, 
as regards the works of the turner and carpenter, were explained 
with figures in the fifth chapter of Vol. I., at pages 49 and 50, 
where it is shown that, from various reasons, the transverse 
section of the entire tree or branch is the most generally proper 
for the lathe ; and therefore, in turning the tops and bottoms of 
works, as in figs. 13 and 14, page 49, Vol. I., we are cutting 
across the ends of the fibres, and in turning the sides of the 
same we are, as it were, proceeding across the width of a plank 
or board. 

The tools used in turning the woods act much in the manner 
of the blades of the carpenter's planes ; but as we have now, at 
all times, a circular guide in the lathe-mandrel, we do not 
require the stock of the plane or its rectilinear guide. Although 
if we conceive the sole of the plane applied as the tangent to 
the circle, the position it would give is nearly retained, but we 
are no longer encumbered with the stock or guide. In turning- 
tools for soft woods, the elevation of the tool, and the angle of 
its edge, are each of them less than in ordinary planes, and in 
those for the hard woods both angles are greater. 

For example, the softest woods are turned with tools the 
acute edges of which measure about 20 to 30 degrees, and are 
applied nearly in coincidence with the tangent, as in fig. 360. 



\\llll CARPENTRY. Ml 

These tools closely assimilate to the spokcshaxc, which 1-, the 
plant- of tlir lowest pitch and keenest edge. Oil tlu; nmtran, 
the hardest woods may he turned with the above soft-wood tools., 
applied just as usual; but on the score of economy and general 




convenience, the edges are thickened to from 60 to 80 degrees, 
and the face of the tool is applied almost horizontally on the 
lathe-rest, or as a radius to the circle, as in fig. 361, thus 
agreeing with the opposite extreme of the planes, in which the 
cutter is perpendicular and much less acute, as in the scraping 
and toothing-planes, which are only intended to scrape and not 
to cut. 

The hard-wood tools may be figured, and employed as scrapers 
in turning the members of the capital or the base of a column, 
or Minilar object in hard word or ivory; but if we try the same 
tools on deal, ash, and other soft woods, we shall in vain attempt 
to produce the capital of a column, or even its cylindrical shaft, 
with a thick horizontal tool as in hard wood; for the fibres would 
not he cut, but forcibly turn asunder, and the surface would be 
left coarse and ragged. 

But a reference to the planes with which the joiner proceeds 

>ss the fibres of deal, will convey the particulars suited to the 

present case; the iron is always thin and sharp, and applied in 

an oblique manner, so as to attack the fibre from the one end, 

and \irtually to remove it in the direction of its length. 

It is proposed now to describe some of the more important of 



512 TURNING TOOLS FOR SOFT WOOD. 

the turning-tools, commencing with those employed on the soft 
grained woods, but it would be both hopeless and unnecessary 
to attempt the notice of all the varieties which are to beVmet 
with in the hands of different individuals; and as their prac- 
tical applications will be entered upon in detail in the suc- 
ceeding volume, only so much will be here advanced as, it is 
hoped, may serve to explain the modifications of the general 
principles of cutting tools, to some of the more usual purposes 
of turning. To avoid repetition, it may be observed, that in 
general the position of the tool for turning the cylinder, and 
secondly that for the flat surface or plane, will be alone de- 
scribed. For works of intermediate angles, whether curves or 
flowing lines, the position of the tool slides from that for the 
cylinder to that for the plane, or the reverse ; and these changes 
will be readily made apparent, when the reader gradually moves 
either a tool or even a rod of wood, from the one to the other 
of the described positions. 

It may be added, that most of the tools for metal are applied 
direct from the grindstone, the oilstone being used for such tools 
only as are employed for the more delicate metal works, or for 
the last finish of those of stronger kinds ; all the tools for wood, 
ivory, and similar materials, are invariably sharpened on the 
oilstone. It may be desirable to remark, in addition, that the 
rough exterior faces of all works should be turned with narrow 
or pointed tools, and only a narrow portion at a time, until 
the surfaces are perfectly true or concentric ; as wide flat tools, 
applied to rough irregular surfaces, especially of metal, would 
receive a vibratory, or rather an endlong motion, quite incom- 
patible with truth of work. 

SECT. II. TURNING TOOLS FOR SOFT WOOD. 

Angle 20 to 30. Figures generally half-size. 

The tools most generally used for turning the soft woods, are 
the gouge and chisel, figs. 3(52 to 365, wherein they are shown 
of one-fourth their medium size; they vary from one-eighth to 
t\\<> inches wide; and as they are never driven with the mallet, 
they do not require the shoulders of the carpenter's tools, they 
an: also ground differently. The turning-gouge is ground exter- 
nally and obliquely, so as to make the edge elliptical, and it is 



M aXINU OOfGE AND CHISEL. 



511 



l>rincijmlly the inidillc portion of the edge which is used; the 
clusrl is ground from both sides, and with an oblique edge, 
and figs. 366 and 367 represent the full thickness of the chisel 
and its. ordinary angles, namely, about 25 to 30 degrees for soft, 
and HI fur hard woods. The gouges and chisels wider than one 
inch an- almost invariably fixed in long handles, measuring with 
tin- blades from 1 :> to 24 inches; the smaller tools have short 
handles, in all from 8 to 12 inches long. 

Fig. 860 shows the position of the gouge in turning the 
cylinder; the bevil lies at a tangent, and the tool generally 



863. 



Mi 



Mft 



367 



rests on the middle of the back, or with the concave side 
upwards, the extremity of the handle is held in the right hand 

L L 



514 



TURNING GOUGE, HOOK-TOOLS FOR SOFT WOOD. 



close to the person, and the left hand grasps the blade, with the 
fingers folded beneath it, and in this manner the gouge is 
traversed along the cylinder. 

For turning the flat surface, the gouge is supported on its 
edge, that is, with the convex side towards the plane of the 
work, and with the handle nearly horizontal, to bring the center 
of the chamfered edge in near coincidence with the plane; the 
tool is inclined rather more than the angle at which its chamfer 
is ground, and it is gradually thrust from the margin to the 
center of the work. 

The gouge is also used for hollow works, but this application 
is somewhat more difficult. For the internal plane, the position 
is almost the same as for the external, except that the blade is 
more inclined horizontally, that it may be first applied in the 
center, to bore a shallow hole, after which the tool is traversed 
across the plane, by the depression of the hand which moves 
the tool as on a fulcrum, and it is also rotated in the hand 
about the fourth of a circle, so that in completing the margin, 
or the internal cylinder, the tool may lie as in fig. 360, but with 
the convex instead of the concave side upwards as there shown. 

In figs. 368 and 370 are represented the plans, and in 369 
and 371 the elevations, of the hook-tools for soft wood, 

which may be called internal 
Figs. 368. 3fi9. 

ri 



370. 



371. 



gouges; they differ some- 
what in size and form, the 
blades are from 6 to 12 
inches long, the handles 12 
to 15. They are sharpened 
from the point around the 
hook as far as the dotted 
lines, mostly on one, some- 
times on both sides, as seen 
by the sections. The hook 
tools follow very nearly the 
motion of the gouge in hol- 
lowing, the rest is placed 

rather distant and oblique; the tool is moved upon it as a 
fulcrum, and it is also rotated in the hand, so as always to place 
the bevil of the tool at a very small inclination to the tangent. 
The finishing tools used subsequently to the gouges or hook- 




I Mi CHISEL, BROADS POR 8OPT \v 



516 



tools ha\c straight edges; tin- chisel, fi^. ;;m, is the most 

position closely resembles that of the gouge, Mih- 
to the modifications called for by its rectilinear edge. If, 
pie, the edge of the chisel were JIM parallel with tin- 
axis of the cylinder, it \vould take too wide a hold; there would 
In- risk of one or other corner digging into the work, and the 
edge, from its parallelism with the fihres, would he apt to tear 
them out. All these inconveniences are avoided by placing the 
edge oblique, as in fig. 3t>t, in which the tool may be supposed 
to be seen in plan, and proceeding from right to left, fig. 860 
being still true for the other view; the tool is turned over to 
proceed from left to right, and both corners of the tool are 
oved from the work, by the obliquity of the edge. The tool 
may he ground square across, but it must be then held in a 
more .sloping position, which is less convenient. 

Turning a flat surface with the chisel is much more difficult. 
The blade is placed quite on edge, and with the chamfer in agree- 
ment with the supposed plane a, b, c, fig. 366; the point of the 
chisel then cuts through the fibres, and removes a thin slice 
which becomes dished in creeping up a, d, the bevil of the tool; 
it then acts something like the scoring point of the planes, or the 
point of a penknife. Flat surfaces, especially those sunk beneath 
the surface, as the insides of boxes, are frequently smoothed 
with an ordinary firmer chi- 
sel, which is ground and 
sharpened with one bevil, 
but rather thicker than for 
carpentry. The edge is then 
burnished like the scraper, 
p. 484, and it is applied 
horizontally like a hard- 
wood tool, as in liu -'Ml, but 
against the face or plane 
surface. The wire edp- then 
:i the required position, 
but it must be frequently 
rein 

The broad, represented in 

riewl in tL p . -">7- endures much longer, but it requires to 
be held downwards or underhand, at about an angle of 40 to 50 

L L 2 



373. 



Fig*. 872. 





516 



SIDE-TOOLS AND SCREW- TOOLS FOR SOFT WOOD. 



degrees from the horizontal, in order to bring its edge into the 
proper relation to the plane to be turned. Another form of the 
broad is also represented in fig. 373, it is a cylindrical stem, 
upon the end of which is screwed a triangular disk of steel, 
sometimes measuring 3 inches on the sides, and sharpened exter- 
nally on each edge, this tool requires the same position as the 
last. Broads of the forms b, c, are also used, but principally for 
large works, the plank way of the grain.* 

For the insides of cylinders, the side-tool, fig. 374, which is 
represented in three views, is sometimes used ; it is sharpened 
on both edges, and applied horizontally. The tool fig. 375, also 
shown in three views, serves both for the sides and the bottoms 
of deep works, but it does not admit of being turned over; and 
376 is another form of the same tool for shallower works, the 
cranked form of which is considered to give it a better purchase. 



Figs. 374. 



375. 



376. 





The tools used for cutting screws in soft wood, by aid of the 
traversing or screw mandrel lathe, partake of the same general 
characters as the others, and are represented in their relative 
positions; fig. 377 is for the outside, and 378 for the inside 



* Similar tools are also used for turning pewter wares. 



PARTING TOOL. TOOLS FOR HARD WOOD AND IVORY. 

screw. To conclude the notice of tools of this class, the pnrtint: 
tool, ti_'. 379, has an angular notch or groove on its upper 
surface, from which it results that u hen the tool is sharpened 
on the hevil />, the upper face/, presents two points, which sepa- 
rate the films by a double incision. This method wastes only 
as much wood as equals the thickness of the tool, and it leaves 
the work smooth and flat; whereas, when the angle of the 
chisel is used for the same purpose, several cuts are required, 
and the gap must present a greater angle than the bevil of the 
tool, and which consumes both time and wood. 

The various turning tools for soft woods which have been 
described are, with the exception of the gouge and chisel, nearly 
restricted to the makers of Tunbridge-ware, toys, and common 
turnery ; with them they are exceedingly effective, but to others 
somewhat difficult. The amateur turner scarcely uses more than 
the common gouge and chisel, and even these but insufficiently, 
as much may be done with them ; it has been shown, for in- 
stance, that moulding tools cannot be used for the soft woods, 
but they are efficiently replaced by the gouge for the concave, 
and the chisel for the convex mouldings, which proceedings will, 
however, be detailed in the fourth volume. 

A good fair practice on the soft woods would be found very 

ally to facilitate the general manipulation of tools, as all 

those for the soft woods, demand considerably more care as to 

their positions and management than those next to be described. 

SECT. III. TURNING TOOLS FOR HARD WOOD AND IVORY. 

Angle 40 to 80. Figure* generally half -size. 

The gouge is the preparatory tool for the hard as well as for 
the soft woods, but it is then ground less acutely; the soft-wood 
chi-el may indeed be employed upon the hardest woods, but 
this is seldom done, because the tools with single bevils, held in 
a horizontal position, as in fig. 861, page 511, are much more 
manageable, and on account of the different natures of the 
Figs. 380. 831. 



materia are thoroughly suitable, notwithstanding that 

their edges are marly as thick again as those of soft-wood tools. 



518 RECTILINEAR TOOLS FOR HARD WOOD AND IVORY. 



In general, also, the long handles of the latter are replaced by 
shorter ones, as in figs. 380 and 381, measuring with the tools 
from 8 to 12 inches; but these give in general an abundant 
purchase, as from the nearly horizontal position of the tool, the 
lathe rest or support can be placed much nearer the work. 

The hard-wood tools are often applied to a considerable extent 
of the work at one time, and the finishing processes are much 
facilitated by selecting instruments the most nearly in corres- 
pondence with the required shapes. Rectilinear surfaces, such 
as cylinders, cones, and planes, whether external or internal, 
necessarily require tools also with rectilinear edges, which are 
sloped in various ways as regards their shafts ; they are made 
both large and small, and of proportionate degrees of strength 
to suit works of different magnitudes : the following are some 
of the most usual kinds. 



Figa. 382. 383. 384. 










385. 386. 387. 388. 389. 
\ 



390. 



391. 




The right side tool, fig. 382, cuts on the side and end, the dotted 
lines being intended to indicate the undercut bevil of the edge ; 
it is thus named because it cuts/rom the right hand towards the 
left. The left side tool, fig. 383, is just the reverse. The flat-tool, 
fig. 384-, cuts on both sides, and on the end likewise; and in all 
three tools the angle seen in plan, is less than a right angle, to 
allow them to be applied in rectangular corners. The point-tool, 
fig. 385, is also very convenient; and bevil-tools, figs. 386 and 
387, the halves of the former, are likewise employed ; figs. 388 
show the general thicknesses of these tools. When any of them 
are very narrow they are made proportionally deep to give suffi- 
cient strength, the extreme case being the parting-tool, fig. 389, 



tllt\IIINEAR TOOLS FOR HARD WOOD A\l IVORY. 



519 



\\ hii-li is no longer required to be tinted, ns m the corresponding 
tool for soft wood ; but the side tools, when used for small and 
deep holes, necessarily require to be small in both respects, as 
in tig. 890. Tin- application of the inside parting-tool, fig. 391, 
has been previously slmvvn on paire I :> I , Vol. I., in respect to 
the removal of rings of ivory from the interior of solid works, 
in preference to turning the materials into shavings; it is also 
"ill in some other undercut works. 

Some of the curvilinear tools for hard wood are represented 
in the annexed group; the semicircular or round tool, fig. 392, 



Figs. 393. 93. 394. 395. 396. 397. 898. 399. 








f 


^ 




w 




J 




V 


1 


llll 


























r^ 


















r 






i 


Jr V 


















vvAVWW 


404. 




405. 



402. 



403. 




is the most general, as concave mouldings cannot be made 
without it, and it is frequently divided, as in the quarter round 
tools, figs. 3Uo and '>'.' I ; it is convenient that these should be 
exact counterparts of the mouldings, but they may also be used 
for works larger than themselves, by sweeping the tools around 
the curves. Convex mouldings are frequently made by recti- 
linear tools, which arc carried round in a similar manner, so as 
to place the edge as a tangent to the curve, but the bead, 

. the astragal, fig. 390, or the ijmirter hollows, figs. 397 
and V. 1 ", facilitate the processes, and complete the one member 
of the moulding at one sweep, and enable it to be repeated any 
number of times with exact uniformity. 

uently the tools are made to include several members, as 
the entire base or capital of a column, as in fig. 399. Similar 
figured tools, have been applied to turning profiles of about one 
or one and a half inches high, by employing four different tools, 



520 PROFILE TOOLS ; TOOLS FOR BRASS. 

embracing each about a quarter of the profile, and applied at 
four radial positions, around a ring of some three to five inches 
diameter; the rings are cut up into radial slices, and turned 
flat on each face prior to being glued upon tablets. Profiles 
have been likewise successfully and more skilfully turned, by 
the ordinary round, point, and flat tools, which processes will be 
proposed as examples in the practical part of the fourth volume. 

Figs. 400 to 403 represent some of the various kinds of inside 
tools, which are required for hollowing vases and undercut works; 
and 404 the inside screw tool, and 405 the outside screw tool 
for hard wood, ivory, and the metals, these tools are made with 
many points, and are bevilled like the rest of the group, they 
will be further noticed in the chapter on screw-cutting tools. 

The hollow tools, figs. 395 to 398, may be sharpened with a 
narrow slip of oilstone used almost as a file ; but their sweeps are 
more accurately sharpened by conical metal grinders, supplied 
with emery, as will be explained ; most other moulding tools, 
and the screw tools, are only sharpened upon the face. The 
ends of these tools may be whetted at a slope, if it be more 
gradual, than in fig. 406, this however, increases the angle of the 
edge; but by nicking in the tools, as in fig. 407, by applying 
them transversely on the grindstone, the original angle is main- 
tained, and which is the better mode for screw tools more 
especially. 

SECT. IV. TURNING TOOLS FOR BRASS. 

A ngles 70 to 90. Figures generally the same as (he tools for hard wood. 

The turning-tools for brass are in general simple, and nearly 
restricted to round, point, flat, right and left side tools, parting 
tools, and screw tools ; they closely resemble the hard-wood tools, 
except that they are generally ground at angles of about 60 or 
70, and when sharpened it is at an angle of 80 or 90; some 
few of the finishing or planishing tools, are ground exactly at 
90, upon metal laps or emery wheels, so as to present a cutting 
edge at every angle and on both sides of the tools. 

It is not a little curious that the angles which are respec- 
tively suitable to brass and to iron, are definitively shown to 
be about 90 and 60 degrees. For turning brass, a worn-out 
square file is occasionally ground on all sides to deprive it of its 
teeth, it is used as a side tool, and is slightly tilted, as in 



IIM-HIM, [-OOL8 FOR BRASS. .V.'l 

l |ls , just to give one of the edges of the prism sufficient 
pen. hut applied to iron, steel, or copper, it only scrapes 

with inconsiderable effect. A triangular file, fig. 409, similarly 
ground, cuts iron with great avidity and effect, but is far less 

Fig*. 408. 409. 410. 

r~*>y 




suited to brass; it is too penetrative, and is disposed to dig 
into the work. It appears indeed, that each different substance 
requires its own particular angle, from some circumstances of 
internal arrangement as to fibre or crystallization not easily 
accounted for. 

A stout narrow round tool, fig. 392, in a long handle, serves 
as the gouge or roughing out tool for brass-work, others prefer 
the point, fiL' '-'<^~>. with its end slightly rounded, which com- 
bines, as it were, the two tools with increased strength ; a small 
but strong right side tool 382, is also used in rough-turning; 
the graver, figs. 411 and 412, although occasionally employed 
for brass, is more proper for iron, and is therefore described in 
the next section. 

The wide finishing tools should not be resorted to under any 
circumstances until the work is roughed out nearly to the shape, 
and reduced to perfect concentricity or truth, with narrow tools 
which only embrace a very small extent of the work. 

It is the general impression that in taking the finishing cuts 
on brass it is impolitic, either to employ wide tools, or to support 
th'-m in a rigid solid manner upon the rest, as it is apt to make 
the work full of fine lines or striae. This effect is perhaps jointly 
attributable to the facility of vibration which exists in brass and 
similar alloys, to the circumstance of their being frequently 
used in thin pieces on the score of economy, and to their being 
ted more rapidly in the lathe than iron and steel, to expedite 
the progress of the work. 

\Yhen a wide flat tool is laid close down on the rest, and 
made to cut with equal eH'ect throughout its width, lines are 
vrrv likely to appear on the metal, and which if thin, rings like 
a bell from the vibration into which it is put ; but if the one 



522 FINISHING TOOLS FOR BRASS. 

corner of the tool penetrate the work to the extent of the thick- 
ness of the shaving, whilst the other is just flush with the 
surface, or out of work, the vibration is lessened, and that 
whether the penetrating angle or the other move in advance. 

The brass turner frequently supports the smoothing tool 
upon the one edge only, and keeps the other slightly elevated 
from the rest by the twist of the hand, which thus appears to 
serve as a cushion or spring to annul the vibrations, fig. 410 
shows about the greatest inclination of the tool. Some work- 
men with the same view interpose the finger between the tool 
and the rest, in taking very light finishing cuts. The general 
practice, however, is to give the tool a constant rotative shuffling 
motion upon the supported edge, never allowing it to remain 
strictly quiet, by which the direction of the edge of the tool is 
continually changed, so as not to meet in parallelism any former 
striae which may have been formed, as that would tend to keep 
up the exciting cause, namely, the vibration of the metal. The 
more the inclination of the tool, the greater is the disposition 
to turn the cylinder into small hollows. 

Some workmen burnish the edges of the finishing tools for 
brass, like the joiner's scraper, or the firmer chisel used in soft- 
wood turning. On account of the greater hardness and thick- 
ness of the edge of the tool, it cannot be supposed that in these 
cases any very sensible amount of burr or wire edge is thrown 
up. The act appears chiefly to impart to the tool the smooth- 
ness and gloss of the burnisher, and to cause it, in its turn, to 
burnish rather than cut the work; the gas-fitters call it a 
planishing tool, but such tools should never be used for accu- 
rate works until the surface is perfectly true and smooth. 

The hard-wood and brass turners avoid the continual neces- 
sity for twisting the lathe rest in its socket to various angular 
positions, as they mostly retain it parallel with the mandrel, and 
in turning hollow works they support the tool upon an arm- 
rest; this is a straight bar of iron, which resembles a long- 
handled tool, but it has a rectangular stud at the end, to 
prevent the cutting tool from sliding off. 

The position of the arm-rest and tool, as seen in plan, are 
therefore nearly that of a right angle ; the former is held under 
the left arm, the latter in the right hand of the workman, the 
fore-fingers of each hand being stretched out to meet near the 



TOOI.8 Kill IK<>\. I HI \ \.l I \ll Midi.. (,K\\ .',:].', 

cud of the tool. This may appear a diHienlt method, but it is 
in all respects exceedingly commodious, and gives considerable 
iom and choice of position in managing the tool, the advan- 
tage of which is particularly t'dt in guiding the first entry of 
the drill, or the path of the screw-tool; and iu brass work it 
likewise renders the additional service of associating the tool 
with the elastic frame of the man. Hut when particular firm- 
ness and accuracy are required the tool should be supported 
upon the solid rest as usual. 

SECT. V. TURNING TOOLS FOR IRON, STEEL, ETC. 
Anyttt 60* to 9<f.Pi<juru generally onetixth the full tizt. 

The triangular tool is one of the most effective in turning 
these metals, as was adverted to at page 521; the triangular 
tool is also used by the engravers and others for scraping 
the surfaces of the metals, and it is then applied nearly perpen- 
dicular, or ns a penknife in erasing; but when the triangular 
tool is placed nearly as a tangent against the inner or outer edge 
of a ring or cylinder, as in fig. 409, it seems almost to devour 
the metal, and instead of scratching, it brings off coarse long 
shavings. In turning the flat sides of the ring, the face of the 
tool is placed almost in agreement with the plane to be turned. 

The yrarer, which is also an exceedingly general tool, is 
a square bar of steel ground off at the end, diagonally and 
obliquely, generally at an angle of from 80 to 50 degrees. The 
parts principally used are the two last portions of the edge close 
to the point, and to strengthen the end of the tool a minute 
facet is sometimes ground off, nearly at right angles to the broad 
chamfer, or principal f 

The proper position of the tool, in turning a cylinder, will be 
most readily pointed out by laying the chamfer of the tool in 
exact contact with the flat end of such cylinder ; it will be then 
found that one of the lateral angles of the tool will touch the 
. and the obliquity in the shaft of the tool, would be the 
angle, at which the Braver is ground, instead of which it is 1 

ire and slightly elevated above the horizontal position, as- 
shown in ti;:. 111. The graver is rotated upon the supporting 
angle, which sticks into the rest, much the same as the edge of 
the triangular tool ; in fact, the two tools, although different in 
form, remove the shaving in a very similar manner. 



524. 



GRAVER AND FLAT CHISEL. 



In using the graver and other tools for the metals, it is the 
aim to avoid exposing the end of the tool to the rough gritty sur- 
face of the material. This is done by cleaning the surface, espe- 



412. 



413. 



414. 




cially the extreme edge, with an old file, and beginning at that 
edge, the work is at one sweep reduced nearly to its required 
diameter by a wide thin cut, which may be compared with a 
chamfer, or a conical fillet, connecting the rough external surface 
with the smooth reduced cylinder. Therefore after the first 
entry, the point of the tool is buried in the clean metal below 
the crust, and works laterally, which is indeed the general path 
of pointed tools for metal. 

When the graver is used in the turn-bench with intermittent 
motion, as for the pivots of watches, the axes for sextants, and 
other delicate works ; it is applied overhand or inverted, as in 
fig. 412, but it is then necessary to withdraw the tool during 
each back stroke of the bow, to avoid the destruction of the 
acute point, and which alone is used. The graver, when thus 
applied in lathes with continuous motion, is only moved on the 
rest as on a fulcrum, and in the plane in which it lies, rather as 
a test of work done, than as an active instrument. 

The edge of the graver is afterwards used for smoothing the 
stronger kinds of work, it is then necessary to incline the tool 
horizontally, to near the angle at which it is ground, in order 
to bring the sloping edge parallel with the surface. But the 
smoothing is better done by a thick narrow flat tool, ground 
at about sixty degrees, the handle of which is raised slightly 
above the horizontal, as in fig. 413, in order that its edge may 
approach the tangential position ; here also the tool is rotated 
on one edge, after the manner of the brass tools or the graver. 

For many slight purposes requiring rather delicacy than 
strength, as in finishing the rounded edge of a washer, the flat 
tool is inverted or placed bevil upwards, as in fig. 414 ; the 



HEEL-TOOLS POR IRON. 



528 



lower side then heeoiues the tangent, and the edge the axis of 
ion of the tool, the same as in turning convex mouldings with 
t lie soft-wood chisel. Indeed, many analogies may be traced be- 
t \\een the loth respectively used for soft woods and iron, except 
that the latter are ground at about twice the angle to meet the 
increased resistance of the hard metal, and the tools are mostly 
sustained by the direct support of the rest, instead of resting in 
great measure against the hands of the individual. 

For instance, the heel-tool, which is used for rough turning the 
metals, is represented of the full size in the side-view, fig. 415, 
and the front-view, fig. 416, and also on a smaller scale in figs. 
417 and 418. The dotted lines a, fig. 417, denote the relative 



Figs. 415. 



416. 







position of the fluted gouge, and although the heel or hook-tool 
occupies nearly the same spot, its edge is of double the thickness, 
ami the entire resistance of the cut is sustained by the heel of 
the tool, which is poised upon the flat horizontal surface of the 
it> of the tool is bent nearly at right angles, that it 
may he held either above or below the shoulder of the workman 
as preferred. Some variation is made in the form and size of 



526 HEEL-TOOLS, NAIL-HEAD TOOLS FOR IRON. 

the heel-tools, aud they are occasionally pointed instead of round 
upon the cutting edge. 

The heel-tool is slightly rotated upon its heel in its course 
along the work, so that, as seen at b, its edge travels in short 
arcs, and when its position becomes too inclined, a fresh footing 
is taken ; on this account the straight handle, employed in ordi- 
nary tools, is exchanged for the transverse handle represented. 
In the best form of heel-tools the square shaft lies in a groove 
in the long handle, and is fixed by an eye-bolt and nut, passing 
through the transverse handle, as seen in the section 418. 
Notwithstanding the great difference between the materials 
upon which the gouge and heel-tool are employed, their manage- 
ment is equally easy, as in the latter the rest sustains the great 
pressure, leaving the guidance alone to the individual. 

Fig. 419 represents another kind of hook-tool for iron, which is 
curiously like the tools, figs. 368 to 371, p. 514, used for soft 
wood, the common differences being here also observable, namely 
the increased strength of edge, and that the one edge is placed 
upon the rest to secure a firm footing or hold. 

Nail-head tools are made much on the same principle, one of 
these, fig. 420, is like a cylinder, terminating in a chamfered 
overhanging disk, to be rolled along so as to follow the course 
of the work, but it is rather a theoretical than practical instru- 
ment. When, however, the tool is made of a square or 
rectangular bar, and with two edges as at fig. 421, it is excel- 
lent, and its flat termination greatly assists in imparting the 
rectilinear form to the work. Occasionally the bar is simply 
bent up at the end to present only one edge, as in fig. 422, it is 
then necessary the curved part should be jagged as a file to cause 
it to dig into the rest like the others of its class, and which 
present some analogy to the soft-M r ood tools, figs. 372 and 373, 
p. 515. 

The cranked or hanging tools, fig. 423, are made to embrace 
the rest, by which they are prevented from sliding away, with- 
out the necessity for the points and edges of the heel-tools ; 
the escape of the cranked tool sideways is prevented by the pin 
inserted in one of the several holes of the rest. The direct 
penetration is caused by the depression of the hand ; the side- 
way motion by rotating the tool by its transverse handle, which 
is frequently a hand-vice temporarily screwed upon the shaft. 



CRANKED oil 1I\\(,IM. TOOLS. FIXED TOOLS. 527 

To save the trouble of continually shifting tin- lathe-rest, an iron 

ally introduced at a, between 

rest .-111.1 the hack of the tool ; when the wedge is advanced 
at intervals it sets tin- tool deeper into the work, when it is 
withdrawn it allows more room for the removal of the tool. 



I' - 




The succeeding figure, 1.1, represents a tool of nearly similar 
kind, the stock is of iron, and it carries a piece of steel, about 
three or four inches long, and one inch square, which is forged 
hollow on the faces by means of the fuller, to leave less to be 
ground away on the stone. The rectilinear edges of this tool 
are used for smoothing irou rollers, iron ordnance, and other 
works tunied by hand, and to preserve the edge of the tool, thin 
spills of hard wood are sometimes placed between the cutter and 
the bar. Under favourable arrangements these tools also are 
managed with great facility ; indeed it occasionally happens that 
tin- weight of the handle just supplies the necessary pressure to 
advance the tool, so that they will rest in proper action without 
being touched by the hand; a tolerable proof of the trifling 
muscular effort occasionally required, when the tools are judi- 
eion-ly moulded and well applied. 

Tin >e hand tools and various others of the same kinds, 
although formerly much used by the millwrights, are now in a 
: measure replaced by the fixed tools applied in the sliding 
rest, some account of which will be given in the next section. 

SECT. VI. FIXED OR MACHINE TOOLS FOR TURNING AND PLANING. 

Angltt at in the kaitd-toolt. Piywet generally one-fourth to o*+cigktk 



The performance of fixed tools is, in general, much more 
etKetive than that of hand tools; as the rigid guides and slides 
now employed, do not suffer the muscular fatigue of the man, 

'hose fluctuations of position to which 

his hand is liable. Therefore, as the tool pursues one constant 
nnde\iating course, the corresponding results are obtained both 



528 



FIXED TOOLS, GENERAL REMARKS. 



more economically and more accurately by the intervention of 
the guide -principle, or the slide-rest) from which we derive the 
slide-lathe, and thence the pianino-machine, and many other 
most invaluable tools. 

The cutting edges of machine tools mostly follow the same 
circumstances as those of hand tools, but additional care is 
required in forming them upon principle ; because the shafts of 
the fixed tools are generally placed, with little power of deviation, 
either at right angles to, or parallel with, the surfaces to be 
wrought ; the tools are then held in the iron grasp of screws 
and clamps, in mortises, staples, and grooves. The^tools do not, 
therefore, admit of the same accommodation of position to 
compensate for erroneous construction, or subsequent deteriora- 
tion from wear, as when they are held in the hand of the work- 
man, and directed by his judgment. 

It must also be additionally borne in mind that, however 
ponderous, elaborate, or costly the machine may be, its effective- 
ness entirely depends upon the proper adaptation and endurance 
of the cutting-tool, through the agency of which it produces its 
results. 



The usual position of the fixed turning tools is the horizontal 
Fig. 425. d e f line,as at a,fig.425; and unless the 

tools always lie on the radius, (or 
any other predetermined line,) 
various interferences occur. For 
instance, the tool proceeding in 
either of the lines b or c, could not 
reach the center of the work, and 
a portion would then escape being 
wrought; the curvature of the 
circle at b, would sacrifice the pro- 
per angle, and expose the tool to 
fracture from the obliquity of the 
strain ; and at c, the edge would 
be altogether out of contact, and 
the tool could only rub and not 
cut. These evils increase with 
the diminution of the circle ; and 
although the diagram is greatly 
exaggerated for illustration, the want of centrality is in truth 




FIXED TOOLS FOR SOFT WOOD. 

an e\ il of Midi magnitude that various contrivances are resorted 
iv which cither tin; entire slide-rest, or the cutter alone, 
niav he adjusted for height of center. 

The pinning tools for metal arc in general fixed vertically, and 
the path of the work bein:r, in the majority of planing machines, 
rectilinear and horizontal, the tool may be placed at d, e, or/, 
indifferently, then- hi-ing no interference from curvature as in 
tnrnint:. 

In those modifications of the planing machine, in which as in 
MrumTs mortising enjrino, the cutter travels perpendicularly, 
and is also fixed perpendicularly, as in the key groove or slotting 
engines, and the paring engines, the general form of the tool /, 
or that of a strong paring chisel, is retained, but the blade is 
slightly inclined in its length as at.;, fig. 420, to avoid touching 
the surface to be wrought except with its cutting edge, and the 
length of the tool supplies a little elasticity to relieve the friction 
of the back stroke. 

Although all the various forms of hand-turning tools are more 
or less employed as fixed tools, still the greater part of the work 
is done with the point tool, (such as g, in the plan fig. 426,) the 
angle of which should be slightly rounded; but for working 
into an angle, the point of the tool is thrown off as at h, so that 
its shaft may avoid either side of the angle, and it is then called 
a side-tool. For internal works, and in small apertures espe- 
cially, the abrupt curvature requires particular attention to the 
central position of the tool i, and a frequent sacrifice of the 
most proper form of the chamfer or edge. I will now describe 
a few of the slide-rest tools in the previous order, namely, those 
for soft wood, for hard wood, for brass, and for iron. 

The fixed tools for soft loood require the same acute edges, and 

!y tangential positions, as those used by hand ; and if these 

it is quite immaterial whether the tool touch 



Pig* 427. 




the work above or below the . hut the central line, or //. 

liir. 1 : >, is the most usual. The soft -wood gouge, or hook-tool, is 

M M 



530 FIXED TOOLS FOR HARD WOOD AND IVORY. 

successfully imitated by making an oblique hole in the eud of a 
bar of steel, as seen in two views in fig. 427, but it is not very 
lasting ; or a bar of steel may be bent to the form of fig. 428, 
and sharpened internally, either rounded to serve as a gouge, 
or straight and inclined as a chisel, but neither of these tools 
admits in itself of adjustment for center. 

The difficulty of center is combated by the use of a tool 
exactly like a common gouge or chisel, but only an inch or two 
long, and with a cylindrical stem also an inch or two long, by which 
it may be retained at any height, in the end of abar of iron, having 
a nearly perpendicular hole and an appropriate side screw for 
fixing the tool; this construction is abundantly strong for wood. 

The fixed tools for hardwood and ivory, follow the several forms 
of the hand-tools, figs. 382 to 405, pp. 518-19, except in having 
parallel stems; they are always placed horizontally, and are 
treated in all respects just as before. Care should be taken, how- 
ever, that the end of the tool is its widest part ; in order that, if 
it be sent in below the surface of the work, as in cutting a 
groove, it may clear well, and not rub against the sides. 

In sharpening the tools intended for hard wood and ivory, 
the oil-stone should be applied principally at the end, or on the 
chamfer of the tool, as this will not reduce the height of center, 
which it is always important to retain. If, however, the tools 
should eventually become chamfered off, after the manner of 
fig. 406, p. 519, they may be annealed, and thrown up to place 
the chamfered part in the line of the general face ; they are then 
re-hardened, and ground up as at first. But as most of the 
slide-rests for wood-turning are fitted into pedestals by means 
of a cylindrical stem with a vertical screw adjustment, the tools 
may be at all times accurately centered when particular care is 
required ; and this provision is of still greater importance, with 
the several revolving cutters applied to the slide-rest, which will 
be hereafter adverted to. 

The Jixcd tools for brass and for iron, \\ hether used in the lathe 
or the planing machine, will be considered in one group, the 
principal difference is, that the tools for brass present an angle 
of nearly 90 degrees, the tools for iron an angle of 60, to the 
superficies to be wrought. Indeed the angles or edges of the 
cube, may be considered as the generic forms of the tools for 
brass, and the angles or edges of the tetrahedron, as the generic 






FIX | Kill II H ASS AM) IKO\. 

forms of the tools for iron ; (lint is, supposing the edges or 
plain's of these solids to be hud almost in contact with tin: line 
of motion or of the cut, in order that they may fulfil the constant 
conditions of the paiing tools, described at page 462, and again 

M'eil to ;it pages \r: to 174. 

The fixed tools for brass and similar alloys resemble, as in hand- 
turning, the more simple of the hardwood tools, except that they 
are sharpened a trifle thicker on the edge; they are, howc\ 
nearly rest tic ted to the point tool, the narrow round tool, and 
to the side tool, \\liieh is represented Atj, fig. 426. It is ground 
so that the two cutting edges meet at an angle not exceeding 
about 80 degrees, that in proceeding into rectangular corners 
it may clear each face by about five degrees, and it will then cut 
in either direction, so as to proceed into the angle upon the 
cylindrical line, and to leave it upon the plane surface, or it may 
be applied just in the reverse manner without intermission. 

\\hen the tool is used for rough work the corner is slightly 
rounded, hut in finishing it is usually quite sharp; and as it 
di tiers only some ten degrees from the solid angle of a cube, it 
is abundantly strong. If the tools acted upon a considerable 
extent or width of the brass, they would be liable to be set in 
vibration ; but as the paths of the cutters are determined by the 
guide principle employed, the point fulfils all that can be desired. 

The fixed tools for iron, present more difficulties than the 
generality of the foregoing kinds ; first, the edges of the tools are 
thinner, and more interfered with in the act of grinding, as the 
vertical height of the cutting edge is reduced when cither face 
of the >M _ r round ; and secondly, they are exposed to far 

more severe strains from the greater hardness of the material, 
and the less sparing manner in which it is reduced or wrought, 
owing to its smaller price and other circumstances; and there- 
fore, the most proper and economic forms of the tools for iron 
:ire highly deserving of attention. 

The fracture of n tool when it is overloaded, commonly points 
out the line of greatest resistance or strain. The tool fig. 429, 
on next page, although apparently keen, is very weak, and it is 
besides disp.ed to pursue the line at which its wedge-formed 
. mity meets the work, or to penetrate at an angle of some 
30 degrees (see | . Figure I .'.. would probably break 

through a line drawn nearly parallel with the face a b, of the 

M II 2 



532 

work under formation ; that portion should therefore be made 
very nearly parallel with a b, the line of resistance, in order 
to impart to the tool the strength of the entire section of the 
steel ; so that should it now break, it would have a much longer 
line of fracture. The tool thus altered is very proper for brass, 
an alloy upon which acute tools cannot be favourably employed. 

Figs. 429. 430. 431. 432. 433. 




But with the obtuse edge of fig. 430, other metals will be 
only removed with considerable labour, as it must be remembered 
the tool is a wedge, and must insinuate itself as such amongst 
the fibres of the material. To give the strengthened tool the 
proper degree of penetration, the upper face is next sloped as 
in 431, to that angle in which the minimum of friction and the 
maximum of durability of the edge most nearly meet; and 
which, for iron, is shown to be about 60 degrees, as in the trian- 
gular tool fig. 409. The three planes of pointed tools for iron, 
meeting at 60 degrees, constitute the angle of the tetrahedron, 
or the solid with four equilateral planes, like a triangular pyra- 
mid, the base and sides of which are exactly alike. 

But the form of 431 would be soon lost in the act of grinding ; 
therefore to conclude, the tool is made in the bent form of 
fig. 432, in which the angles of 431 are retained, and the tool 
may be many times ground without departing from its most 
proper form. This is in effect extending the angle of the tetra- 
hedron, into the triangular prism ground off obliquely, or rather, 
;IN seen in the front view fig. 433, into a prism of five sides, the 
front angle of which varies from 60 degrees to 120 degrees, and 
is slightly rounded, the latter being most suitable for rough 
work, sometimes the front of the prism is half-round, at other 
times quite flat, these forms are shown in fig. 439. 

The extremities of figs. 431 and 432, approach very closely to 
the form of the graver, used for engraving on steel and copper- 
plates, than which, no instrument works more perfectly. The 
slender graver, whether square or lozenge, is slightly bent, and 



n\i i IKON. 



has a flattened handle, M> that the riil^e behind the point may 
lie s,i nearly parallel with, and MI completely buried in, the line 
or groove under format ion, M to be prevented or checked, by 
the surface c rom digging into tin- work. Tin-, is another 

continuation of the tact, that the line of penetration is that of 
the lower face of the cutter or wedge, or that touching the work. 

In adopting the crank-formed tools 432, the principle must 
not be carried into excess, as it must be remembered, we can 
ne\er expunge r/tixlicity from our materials, whether viewed in 
relation to the machine, the tool, or the work. 

The tool .should be always grasped as near the end as prac- 
ticable, therefore the hook or crank should occupy but little 
length ; as the distance from the supposed line of the fixing 
screw c, to the edge of the tool, being doubled, the flexure of the 
instrument will be fourfold; when trebled, ninefold; in fact as 
the square. And also as the flexure may be supposed to occur 
from near the center of the bar, (that is neglecting the crook,) 
the point of the tool should not extend beyond the central line 
o; otherwise when the tool bends, its point would dig still 
deeper into the work from its rotation on the intersection of c 
and o; the point situated behind the central line would spring 
airiiy from, or nut of, instead of into the work. To extend the 
r of the cranked tools, they are commonly forged so that the 
point is nearly level with the upper surface of the shaft, as in 
ti-. I :J^ ; they then admit of being many times ground before 
they reach the central line, and they are ultimately ground, 
(always at the end of the prism and obliquely,) until the hook 

/ 434. 436. 



w 

^_ 


x 


& 1 


- 


\ 

\ 435. 


! 





437. 



ntirely lost. This avoids such frequent recurrence to the 

. but it is a departure from the right principle, to allow 

the point to extend beyond the center line 0. See Appendix, 

\ U, page 8 

\vorks of the lathe and planing-machiue frequently present 



534 



NASMYTH S TOOL GAGE. 




439. 



angles or rebates, chamfers, grooves, and under-cut lines, 
which require that the tool should be bent about in various 
ways, in order that their edges may retain as nearly as possible 
the same relations to all these surfaces, as the ordinary surfacing 
tools figs. 431 and 432 have to the plane a b. For instance, the 
shaft of the tool 431, when bent at about the angle of 45 degrees, 
becomes a side cutting and facing tool, as shoAvn in plan in fig. 
434, in elevation in 435, and in perspective in 436 ; and in like 
manner, the cranked tool 432, when also bent as in 434, becomes 
437, and is also adapted to working into angular corners upon 
either face. 

Mr. Nasmyth's tool gage, shown in elevation in 438, and in 
plan in 439, entirely removes the uncertainty of the angles given 
c to these irregular bent 

Fig?. 438. tools : for instance, when 

] a the shaft of the tool is 
laid upon the flat surface 
and applied to the iron 
cone c, whose side mea- 
sures about 3 with the 
perpendicular, it serves 
p with equal truth for s, the 
tool for surfaces ; p,f, the 
* side-cutting tools, used 
also for perpendicular 
f cuts and fillets ; and u 

for undercut works. 
In applying tools to lathe works of small diameters, it is 
necessary to be very exact, and not to place them above the 
center, or they immediately rub ; and as this soon occurs with 
tools having so small an angle, it appears desirable to make the 
cone gage for small lathe works of about twice the given angle, 
and to mark upon the cone, a circle exactly indicative of the 
height of center; the tool can be then packed up to the center 
line, with one or two slips of sheet iron, to be afterwards placed 
beneath the tool when it is fixed in the lathe rest. In small 
hollow works, the most lasting of the crank-formed tools, 
are entirely inapplicable, indeed so much attention is required 
to prevent the tool from rubbing against the interior sur- 
faces, that the ordinary angles cannot be employed, and the 




Ill; IR BAR. TRIANGULAR CUTTER BAR. 535 



'' fPS* ceases to be useful, hut in every other case it should 

uitly resorted to; tin- additional thickness a, is required 
to make it applicable to the crank-formed tools.* 

, represents n cutter introduced in the Block Ma- 
chinery at Portsmouth, to lessen the ditliculty of making and 
restoring the tools, for turning the wrought-iron pins for the 
sheaves; it c< a cylindrical wire \\hich, from being ground 

off obliquely, presents an elliptical edge; the tool is fixed in a 
stock of iron, terminating in an oblique hole, with a binding 
screw. The tool, when used for iron, in the "pin turning 
lathes," was made solid, when used for turning the surfaces of 
the wooden shells, in the "shaping engine/' it was pierced with 
a central hole ; the latter could only facilitate the process of 
sharpening, without altering the character of the edge, which 
continued under the same circumstances as when solid. 



Figs. 440. [ 441. 





443. 

442. 




About sixteen years back, the author made for his own use, a 
tool such as fig. 140, but found that with rough usage the cutter 
was shivered away, on account of its breadth, and he was soon 
led to substitute for the solid cylinder, a triangular cutter, the 
final edi;e of which was slightly rounded, and placed more nearly 
perpendicular, in a split socket with a side screw, as in fig. 441. 
The strength of the edge was greatly increased, and it became, 
in fact, nn exact copy of the most favourable kind of tool for 
the lathe, or pla-iing-machine, retaining the advantage that the 

The general similitude between some of the author's figures, 429 to 439, 
(engraved in Jan. 1840), and part of those in Mr. James Niwmyth's article on 
Tools, in Buchanan's Mill Work (published in Deo. 1841), is solely due to their 
being each indebted to the some individual (namely, to Mr. Joseph Clement), for 
the general theory advanced, and which associates the principles of machine took 
ftal that are of comparatively modern date, with those of cutting tools gene- 
rally, oven of the most primitive kinds. 



536 FINISHING OR SPRINGING TOOLS. 

original form could be always kept, with the smallest expendi- 
ture of time, and without continually re-forging the blade, to 
the manifest deterioration of the steel from passing so frequently 
through the fire ; it being only requisite to grind its extremity 
like a common graver, and to place it so much higher in the 
stock as to keep the edge at all times true to the center. 

A right and a left hand side tool for angles, the former seen 
in figs. 412 and 443, were also made; the blade and set screw 
were placed at about 45, and at a sufficient vertical angle, to 
clear both the inside of a cylinder of three inches diameter, and 
also to face the bottom or surface. These side tools answered 
very well for cast iron; but fig. 441, the ordinary surfacing tool, 
is excellent for all purposes, and has been employed in many 
extensive establishments.* 

In turning heavy works to their respective forms, a slow 
motion and strong pointed tools are employed; but in finishing 
these works with a quicker rate of motion, there is risk of putting 
the lathe in a slight tremor, more particularly from the small 
periodic shocks of the toothed wheels, which in light finishing 
cuts are no longer kept in close bearing as in stronger cuts. 

Under these circumstances, were the tools rigid and penetra- 
tive, each vibration would produce a line or scratch upon the 
surface, but the finishing or hanging tools, figs. 444 and 445, 
called also springing tools, which are made of various curves and 
degrees of strength, yield to these small accidental motions. 
The first resembles in its angles the rest of the tools used for 
brass, the second those for iron, their edges are rectilinear, and 

* The prismatic cutters admit of the usual variations of shape : sometimes two 
binding screws are used, and occasionally a tail screw, to receive the direct strain of 
the cut. When the blades are only used for cutting in the one direction, say from 
right to left, they may, with advantage, be ground with a double inclination ; for aa 
all these pointed tools work laterally, the true inclination of some 60 to the 
narrow facet or fillet operated upon, is then more strictly attained. 

Considerable economy results from this and several other applications, in which 
the cutter and ita shaft are two distinct parts. The small blades of steel admit of 
being formed with considerable ease and accuracy, and of being hardened in the 
most perfect manner. And when the cutters are fixed in strong bars or shafts of 
iron, they receive any required degree of strength, and the one shaft or carriage 
will serve for any successive number of blades. 

The blades are sometimes made flat, or convex in the front, and ground much 
thinner, to serve for soft wood ; the tools for hard wood and ivory, being more 
easily ground, do not call for this application of detached blades. 



I I si- n is.. I MILS. TOOLS FOR LEAD, TIN, ETC. 






sometimes nn inch \\idc. The width and elasticity of these 
finishing tools, pii-MMit tlicin acting otherwise than H.S serapers, 
fur n-iii<>\iii-_' tin- slight superficial roughnes-s, without det ract in- 
fnnu the accuracy of form prc\ ioiisly gi\cn. In a somewhat 
Minilar manner tlir broad hand flat tool, rendered elastic b;. 

lal .support, as in tig. 411), page 'fl\, is frequently used for 
smoothing brass works, und others turned with the slide rest. 



446. 



447. 



448. 







I'..-- ill 



445. 




*. 1 li' and 1 17 represent a very excellent finishing tool, 
introduced hy Mr. Clement, for planing cast and wrought iron, 
and steel; it resembles the cranked tools generally, but is 

!itcr, it is made smooth and Hat upon the extremity; or rather 
in a very minute degree rounded. This tool is sharpened 

:ily upon the oilstone, and is used for extremely thin cuts, 
generally one quarter of an inch wide, and when the corners just 
escape touching, the work is left beautifully smooth; the edge 
should on no account stand in advance of the centre line. But 
to avoid the chatters so liable to occur in brass works, Mr. Cle- 
ment prefers for that material the elastic planing tool, 
and -UD, its edge is situated considerably behind the- i\ uter. 
In corn-hiding the notice of the turning tools, it may be ueces- 
to add a few words on those used for lead, tin, zinc, copper, 
and their ordinary alloys. The softest of these metals, such as 
lead, tin, and soft pewter, may be turned with the ordinary 
tools for soft wood; but for the harder metals, such as zinc, and 
hard alloys containing much antimony, the tools resemble those 
u>ed for the hard woods, and they are mostly employed dry. 

Copper, whieh is much harder and tougher, is turned \u;h 
tools similar to those for wrought-iron, but in general they are 
sharpened a little more keenly, and water is allowed to drop 



538 TOOLS FOR COPPER; LUBRICATING FLUIDS, ETC. 

upon the work to lessen the risk of dragging or tearing up the 
face of the copper, a metal that neither admits of being turned 
or filed with the ordinary facility of most others. Silver and 
gold, having the tenacious character of copper, require similar 
turning tools, and they are generally lubricated with milk. 

In the above, and nearly all the metals except iron and those 
of equal or superior hardness, there seems a disposition to 
adhere, when by accident, the recently removed shaving gets 
forcibly pressed against a recently exposed surface, (the metals 
at the time being chemically clean, see page 432, Vol. I.,) this 
disposition to unite is nearly prevented when water or other 
fluid is used. 

Water is occasionally resorted to in turning wrought iron and 
steel ; this causes the work to be left somewhat smoother, but 
it is not generally used, except in heavy work, as it is apt to rust 
the machinery, oil fulfils the same end, but is too expensive for 
general purposes. See Appendix, Note AR., page 983. 

Cast iron having a crystalline structure, the shavings soon 
break, without causing so much friction as the hard ductile 
metals ; cast iron is therefore always worked dry, even when the 
acute edges of 60 degrees are thickened to those of 80 or 90, 
either from necessity, as in some of the small boring tools, or 
from choice on the score of durability, as in the largest boring 
tools and others. Brass and gun-metal are also worked dry, 
although the turning tools are nearly rectangular, as the copper 
becomes so far modified by the zinc or tin, that the alloys, 
although much less crystalline than cast iron, and less ductile than 
copper, yield to the turning tools very cleanly without water. 

But when tools with rectangular edges are used for wrought 
iron and steel, on account of the greater cohesion of these 
materials, they must be lubricated with oil, grease, soap and 
water, or other matter, to prevent the metals from being torn. 
And the screw cutting tools, many of which present much surface 
friction, and also rectangular or still more obtuse edges, almost 
invariably require oil or other unctuous fluids, for all the metals. 

It will be shown in the practice of metal turning, that the 
diamond point, figs. G4 and 65, page 178, Vol. I., is occasionally 
used in turning hardened steel and other substances; figs. 72 to 
74 are constantly used in engraving by machinery, and in gra- 
duating mathematical instruments. See Appendix, Notes AS. 
to AV. pages 983 to 1001. 



589 



( HAI'TKK \\\. 
BORING TOOLS. 



SECT. I. UoKINO BITS FOR WOOD. 

THK process of boring holes may be viewed as an inversion of 
that of turning; generally the work remains at rest, and the tool 
is revolved and advanced. Many of the boring and drilling tools 
have angular points, which serve alike for the removal of the 
material, and the guidance of the instrument ; others have blunt 
guides of various kinds for directing them, whilst the cutting 
is performed by the end of the tool. 

Commencing as usual with the tools for wood, the brad-awl 
fig. 450, may be noticed as the most simple of its kind ; it is a 
cylindrical wire with a chisel edge, which rather displaces than 
removes the material ; it is sometimes sharpened with three 
facets as a triangular prism. The awl, fig. 451, used by the 
\\ ire- workers, is less disposed to split the wood ; it is square and 
sharp on all four edges, and tapers off very gradually until near 
the point, where the sides meet rather more abruptly. 

The generality of the boring instruments used in carj 
are fluted, like reeds split in two parts, to give room for the 
shavings, and they are sharpened in various ways as shown by 
figures 152 to 456. Fig. I.V.! is known as the shell, and also as 
the gouge-bit, or quill-bit, it is sharpened at the end like a gouge, 
and when revolved it shears the fibres around the margin of the 
hole, and removes the wood almost as a solid core. The shell- 
hit < are in very general use, and when made very small, they 
are used for boring the holes in some brushes. 

1 .">:;, the xii'xin-lit, is generally bent up at the end to 
make a taper point, terminating on the diametrical line; it acts 
something after the manner of a common point drill, except 
that it possesses tin- keen edge suitable for wood. The spoon-bit 
union use, the coopers' dowel-bit, and the table-bit, 
for making the holes for the wooden joints of tables, are of this 



540 



REEDED OR FLUTED BITS FOR WOOD. 



kind; occasionally the end is bent in a semicircular form, 
such are called duck-nose-bits from the resemblance, and also 
brush-bits from their use ; the diameter of the hole continues 
undiniinished for a greater depth than with the pointed spoon-bit. 



Figa 450. 451. 452. 453. 454. 



455. 



456. 





The nose-bit, fig. 454, called also the slit-nose-bit, and auger-bit, 
is slit up a small distance near the center, and the larger piece 
of the end is then bent up nearly at right angles to the shaft, 
so as to act like a paring chisel ; and the corner of the reed, near 
the nose also cuts slightly. The form of the nose-bit, which is 
very nearly a diminutive of the shell-auger, fig. 455, is better 
seen in the latter instrument, in which the transverse cutter lies 
still more nearly at right angles, and is distinctly curved on the 
edge instead of radial. The augers are sometimes made three 

O " 

inches diameter, and upwards, and with long removable shanks, 
for the purpose of boring wooden pump-barrels, they ai;e then 
called pump-bits. 

There is some little uncertainty of the nose-bits entering 
exactly at any required spot, unless a small commencement is 
previously made with another instrument, as a spoon-bit, a gouge, 
a brad-awl, a center-punch or some other tool ; Avith augers 
a preparatory hole is invariably made, either Avith a gouge, 
or with a center-bit exactly of the size of the auger. When 
the nose-bits are used for making the holes in sash bars, for 
the wooden pins or doAvels, the bit is made exactly parallel, 
and it has a square brass socket which fits the bit ; so that the 
Avork and socket being fixed in their respective situations, the 
y Hide-principle is perfectly applied. A. "guide tube" built up 



CBNTBR-B1T8 FOR WOOD. 



as n tripod which the workman steadies with his foot, has ! 
recently applied ly Mr. Charles May, of Ipswich, for boring the 
i- h.-lcs in railway sleepers exactly perpendicular* 

The gimlet fig. l.")i; is also a tinted tool, but it terminates in a 
sharp worm or screw, beginning as a point and extending to the 
full diameter of the tool, which is drawn by the screw into tin- 
wood. The principal part of the cutting is done by the angular 
corner intermediate between the worm and shell, which acts 
much like the auger, the gimlet is worked until the shell is full 
of wood, when it is unwound and \\ithdrawn to empty it. 

The centcr-bit, tig. 4.">7, shown in three, views, is a very 
beautiful instrument, it consists of three parts, a center point or 
pin, filed triangularly, which serves as a guide for position ; a thin 
shearing point or iiickt-r, that cuts through the fibres like the 
point of a knife; and a broad chisel edge or cutter, placed 
obliquely to pare up the wood within the circle marked out by 
the point. The cutter should have both a little less radius and 
less length than the nicker, upon the keen edge of which last 
the correct action of the tool principally depends. 

Many \ariations are made from the ordinary center-bit, fig. 
l.'iT ; sometimes the center -point is enlarged into a stout cylin- 

1 plug, so that it may ex- Fig8 . 457 . 458 . 459 

aetly fill a hole previously made, 
and cut out a cylindrical coun- 
tersink around the same, as for 
the head of a screw bolt. This 
tool, known as the pluy Of 
bit, is much used in making 
frames and furniture, held toge- 
ther by screw-holts. Similar 
but with loose cutters 
inserted in a diametrical mor- 

in a stout shaft, are also used in ship-building for inhmng 
the heads of bolts and washers, in the timbers and planking. 

The nine-cooper's center-bit is very short, and is enlarged 

behind into a cone, so that immediately a full eask has been 

bored, the nme pings up the hole until the tap is inserted. The 

vr-l.it deprn or possessing only the pin 

.,.! Dicker, i railed a hntt>,n-tol, it is used for boring and 

See Minute* of Convention lust. Civil Engineer*. 1842, page 76. 





VARIOUS CENTER-BITS FOR WOOD. 

cutting out at one process, the little leather disks or buttons, 
which serve as nuts for the screwed wires in the mechanism 
connected with the keys of the organ and piano-forte. 

The expanding center-bit, shown on a much smaller scale in 
fig. 460, is a very useful instrument; it has a central stem with a 
conical point, and across the end of the stem is fitted a transverse 
bar, adjustable for radius. Where the latter carries only a lancet- 
shaped cutter it is used for making the margins of circular 
recesses, and also for cutting out disks of wood and thin materials 
generally ; when, as in Mr. James Stone's modification, the 
expanding center-bit has two shearing points or nickers, and one 

chisel-formed cutter, it serves for making 
Fig. 460. grooves for inlaying rings of metal or wood 

in cabinet-work, and other purposes.* See 

Appendix, note A W., p. 1001. 

The above tools being generally used for 

woods of the softer kinds, and the plankway 
of the grain, the shearing point and oblique chisel of the center- 
bit, fig. 457, are constantly retained, but the corresponding tools 
used for the hard woods assume the characters of the hard wood 
tools generally. For instance, a, fig. 458, has a square point, 
also two cutting edges, which are nearly diametrical, and 
sharpened with a single chamfer at about 60 degrees; this is the 
ordinary drill used for boring the finger-holes in flutes and 
clarionets, which are afterwards chamfered on the inner side 
with a stout knife, the edge of which measures about 50 
degrees. The key-holes, are first scored with the cup-key tool, b, 
and then drilled, the tools a, and b, being represented of corres- 
ponding sizes, and forming between them the annular ridge 
which indents the leather of the valve or key. 

\Vhen a, fig. 458, is made exactly parallel, and sharpened up 
the sides, it cuts hard mahogany very cleanly in all directions of 
the grain, and is used for drilling the various holes in the small 
machinery of piano-fortes ; this drill (and also the last two), is 
put in motion in the lathe ; and in fig, 459, the lathe-drill for 
hard woods, called by the French langue de carpe, the center- 
point and the two sides melt into an easy curve, which is 
sharpened all the way round, and a little beyond its largest part. 
Various tools for boring wood have been made with spiral 

* See Trans. Soc. of Arts, vol. xxxi. p. 250. 



TWISTED OR SriltM. HITS FOR WOOD. 






:.T t!i;it the -havings may be enabled to ascend the 

hollow worm, and thereby sa\ ihle of so frequently with- 

draw in:; the hit. implc, the shaft of fig. 461. the ringle- 

tbrged as a half- round bar, nearly as in the section 
above ; it is then coiled into an open spiral with the flat side 
\ard>, to constitute the cylindrical surface, and the end is 
foniu-d almost the same as that of the shell auge.r, fig. ! 
The tirixtrd-yimlrt, tiu'- l' ; ', is made with a conical shaft, around 
which is tiled a half-round groove, the one edge of which become- 
thereby sharpened, so as gradually to enlarge the hole after the 
first penetration of the worm, which, from being smaller than 
in the common gimlet, acts with less risk of splitting. 
Pigs. 461. 402. 403. 404. 465. 466. 467. 468. 




The ordinary screw auger, fig. 463, is forged as a parallel 
blade, of steel, (seen in the section, fig. 4(5 1-, which also refers 
to I'- and ttj.j,) it is twisted red-hot, the end terminates in 
a worm by which the anger is gradually drawn into the work, 
as in the u'imlet, and the two angles or lips are sharpened to cut 
at the extreme ends, and a little up the sides also. 

The same kind of shaft is sometimes made as in fig. 1 t'4, with 
a plain conical point, with two scoring cutters and two chisel 

.es, which their obliquity from the slope of the worm: 

it is as it were a double center-bit, or one with two lips grafted 
on a spiral .shaft. The same shaft has been also made, as in 
tiu'. I ''", ith a common drill point, and proposed for metal, 
but this se< cly called for; but it is in this form very 

ctl'iv'm- in Hunter's pat. -boring machine, intended for 

stones not harder than sandstones; the drill is worked by a 






544 TWISTED OR SPIRAL BITS FOR WOOD. 

cross, guided by a tube, and forced in by a screw cut upon the 
shaft carrying the drill ; so that the stone is not ground to 
powder, but cast off in flakes with very little injury to the drill. 

Another screw auger, which is perhaps the most general after 
the double-lipped screw auger, fig. 463, is known as the American 
screw auger, and is shown in fig. 466 ; this has a cylindrical 
shaft, around which is brazed a single fin or rib ; the eud is filed 
into a worm as usual, and immediately behind the worm a small 
diametrical mortise is formed for the reception of a detached 
cutter, which exactly resembles the nicking point and chisel 
edge of the center-bit ; it may be called a center-bit for deep 
holes. The parts are shown detached in fig. 467. The loose 
cutter is kept central by its square notch, embracing the central 
shaft of the auger : it is fixed by a wedge driven in behind, and 
the chisel edge rests against the spiral worm. Spare cutters are 
added in case of accident, and should the screw be broken off, 
a new screw and mortise may be made by depriving the instru- 
ment of so much of its length. The instrument will be found 
on trial extremely effective ; and on account of the great space 
allowed for the shavings, they are delivered perfectly, until the 
worm is buried a small distance beneath the surface of the hole. 

The Americans have also invented an auger, said to be 
thoroughly applicable to producing square holes, and those of 
other forms : the tool consists of a steel tube, of the width of 
the hole, the end of the tube is sharpened from within, with the 
corners in advance or with four hollowed edges. In the center 
of the square tube works a screw auger, the thread of which 
projects a little beyond the end of the tube, so as first to pene- 
trate the wood, and then to drag after it the sheath, and thus 
complete the hole at one process ; the removed shavings making 
their escape up the worm and through the tube. For boring 
long mortises, two or more square augers are to be placed side 
by side, but they must necessarily be worked one at a time.* 

Fig. 468, the last of this group of spiral drills, is used in 

This is described in Gill's Technical repository, vol. xL page 317. The author 
baa never seen one ; it seems far too complex an instrument for general purposes, 
and its success appears to be overrated. The tools, figs. 461 to 466, are also 
i'ed to America; whether truly or not it is impossible to say. Fig. 461 is in 
j .;irtial use. The twisted gimlet is a good tool, but as it is somewhat more expen- 
sive than the common kind, it is less used. These several instrumeuts are proba- 
bly derived from the common screw auger, fig. 463, which is, I believe, English. 



MODES Of ROTATIN'. It HILLS FOB WOOD. '> I ."> 

many, and two of the instruments were brought from that 
country and deposited in the Museum of the Society of Arts, by 
Mr. Bryan Donkin.* The tool acts as a hollow taper bit or 
rimer, and the M-IVU -form point and shaft, assist in drawing it 
into tlu> wood; but the instrument must pass entirely through 
for making cylindrical holes.f 

The most usual of the modes of giving motion to the various 
kinds of boring bits, is by the ordinary carpenter's brace with 
a crank-formed shaft. The instrument is made in wood or 
IIH tal, and at the one extremity has a metal socket, called the 
pad, with a taper square hole, and a spring-catch used for retain- 
ing the drills in the brace when they are withdrawn from the 
work, and at the other, it has a swivelled head or shield, which 
is pressed forward horizontally by the chest of the workman ; 
or when used vertically, by the left hand, which is then com- 
monly placed against the forehead.J 

The ordinary carpenter's brace is too familiarly known to 
require further description, but it sometimes happens, that in 

corners and other places there 

, . , Fig. 469. 

is not room to swing round the 

handle, the angle-brace, fig. 469, 
is then convenient. It is made 
entirely of metal, with a pair of 
l>e\il pinions, and a winch han- 
dle that is placed on the axis 
of one of these, at various distances from the center, according 
to the power or velocity required. Sometimes the bevil wheel 
attached to the winch handle, is three or four times the diameter 
of the pinion on the drill ; this gives greater speed but less 
power. 

The augers, which from their increased size require more 
power, are moved by transverse handles ; some augers are made 
with shanks, and are rivetted into the handles just like the 

See Tram., vol. xliv., p. 75. 

t The cooper's bit is sometimes made with a gimlet worm, a semi-conical shell, 
and a conical plug to stop the hole until the tap is inserted. 

J The carpenter's brace is sometimes fixed vertically, with the power of revolv- 
ing and of being depressed by a lever, in some reepects like the smith's press drill, 
fig. 494, page 558. See also Manuel du Tourneur, 1816, Plate IX., vol ii. 

Fig. 469 is reduced from Plate IX. of the Manuel du Tourneur. 

N N 




546 DRILLS FOR METAL. 

gimlet ; occasionally the handle has a socket or pad, for receiv- 
ing several augers, but the most common mode, is to form the 
end of the shaft into a ring or eye, through which the transverse 
handle is tightly driven. The brad-awls, and occasionally the 
other tools requiring but slight force, are fitted in straight 
handles ; many of the smaller tools are attached to the lathe 
mandrel by means of chucks, and the work is pressed against 
them, either by the hand, or by a screw, a slide, or other con- 
trivance ; figs. 458 and 459, are always thus applied. 

SECT. II. DRILLS FOR METAL, USED BY HAND. 

The frequent necessity in metal works, for the operation of 
drilling holes, which are required of all sizes and various degrees 
of accuracy, has led to so very great a variety of modes of per- 
forming the process, that it is difficult to arrange with much 
order the more important of these methods and apparatus. 

It is, however, intended to proceed from the small to the 
large examples: in the present section some of the general 
forms of the drills for metal will be first noticed ; in the next 
section will be traced the modes of applying hand power to 
drills, commencing with the delicate manipulation of the 
watchmaker, proceeding gradually to those requiring the different 
kinds of braces, and ending with the various apparatus for driv- 
ing large drills by hand-power. In the fourth section the 
machine processes will be adverted to, commencing with the 
ordinary lathe, and ending with the boring apparatus for the 
largest cylinders ; the concluding section of this chapter will be 
devoted to the various drills, cutters, and broaches required for 
making conical or taper holes. 

The ordinary piercing drills for metal do not present quite so 
much variety as the wood drills recently described, the drills 
for metal are mostly pointed, they consequently make conical 
holes, which cause the point of the drill to pursue the original 
line, and eventually to produce the cylindrical hole. The com- 
parative feebleness of the drill-bow, limits the size of the drills 
employed with it to about one-quarter of an inch in diameter ; 
but as some of the tools used with the bow, agree in kind with 
those of much larger dimensions, it will be convenient to con- 
sider as one group, the forms of the edges of those drills, which 
cut when moved in either direction. 






DOUBLE CUTTING DRILLS FOR METAL. 



549 



Figs. 470, 471, and 472, represent, of their largest sizes, the 
usual forms of drills proper for the reciprocating motion of the 
drill-bow, because their cutting edges being situated on the line 



Fig*. 470. 471. 472. 



478. 



474. 



475. 




of the axis, and chamfered on each side, they cut, or rather 
scrape, with equal facility in both directions of motion. 

Fig. 470 is the ordinary double-cutting drill, the two facets 
forming each edge meet at an angle of about 50 to 70 degrees, 
and the two edges forming the point, meet at about 80 to 100 ; 
but the watchmakers who constantly employ this kind of drill, 
sometimes make the end as obtuse as an angle of about 120 
degrees ; the point does not then protrude through their thin 
works, long before the completion of their work. Fig. 471, with 
two circular chamfers, bores cast-iron more rapidly than any other 
reciprocating drill, but it requires an entry to be first made with 
a pointed drill ; by some, this kind is also preferred for wrought 
iron and steel. The flat-ended drill, fig. 472, is used for flattening 
the bottoms of holes. Fig. 473 is a duplex expanding drill, 
used by the cutlers for inlaying the little escutcheons and plates 
of metal in knife handles; the ends are drawn full size, and the 
explanation will be found at page 135 of the first volume. 

I ? \- is also a double-cutting drill ; the cylindrical wire is 
tiled to the diametrical line, and the end is formed with two facets. 
This tool has the advantage of retaining the same diameter when 
it is sharpened ; it is sometimes called the Swiss drill, and was 
employed hy M. I,c Riviere, for making the numerous small 
holc>, in the delicate punching machinery for mamifaetni 
perforated sheets of metal and pasteboard ; these drills are Mime- 
timcs made either semicircular or flat at the extremity, and 
as they are commonly employed in the lathe, they will be 

N N 2 



548 



SINGLE CUTTING DRILLS FOR METAL. 



further noticed in the fourth section, under the title of half-round 
boring bits. 

The square countersink, fig. 475, is also used with the drill- 
bow ; it is made cylindrical, and pierced for the reception of a 
small central pin, after which, it is sharpened to a chisel edge, as 
shown. The countersink is in some measure a diminutive of the 
pin drills, fig. 482 to 485, page 550; and occasionally circular 
collars are fitted on the pin for its temporary enlargement, or 
around the larger part to serve as a stop, and limit the depth to 
which the countersink is allowed to penetrate, for inlaying the 
heads of screws. The pin is removed when the instrument is 
sharpened. 

By way of comparison with the double-cutting drills, the ordi- 
nary forms of those which only cut in one direction, are shown in 
figs. 476, 477, and 478. Fig. 476 is the common single-cutting 



478. 



479. 



480. 



481. 




drill, for the drill-bow, brace, and lathe ; the point, as usual, is 
nearly a rectangle, but is formed by only two facets, which 
meet the sides at about 80 to 85 ; and therefore lie very nearly 
in contact with the extremity of the hole operated upon, thus 
strictly agreeing with the form of the turning tools for brass. 
Fig. 477 is a similar drill, particularly suitable for horn, tortoise- 
shell, and substances liable to agglutinate and clog the drill ; the 
chamfers are rather more acute, and are continued around the 
edge behind its largest diameter, so that if needful, the drill 
may also cut its way out of the hole. 

Fig. 478, although never used with the drill-bow, nor of so 
small a size as in the wood-cut, is added to show how completely 
the drill proper for iron, follows the character of the turning 
tools for that metal ; the flute or hollow filed behind the edge, 



llTTINC DRILL* H)K MKTAL. .', I'.l 

gives the hook-formed acute edge required in this too], which is 
in other respecN like f'i. 17<s the form proper for the cutting 
edge is shown more distinctly in the diagram a, fig. 482. 

Care should always be taken to have ;i proportional degree of 

tii;th in the shafts of the drills, otherwise they tremble and 

chatter when at work, or they occasionally twist off in the 

x -, the point should he also ground exactly central, so that 

both edges may cut. As a guide for the proportional thickness 

of the point, it may measure at b, fig. 179, the base of the cone, 

about one-fifth the diameter of the hole, and at j>, the point, 

about one-eighth, for easier penetration : but the fluted drills are 

made nearly of the same thickness at the point and base. 

In all the drills previously described, except fig. 474, the size 
of the point is lessened each time of sharpening ; but to avoid 
this loss of size, a small part is often made parallel, as shown in 
liir- 17'.'. In fig. 4s(), this mode is extended by making the drill 
with a cylindrical lump, so as to fill the hole : this is called the 
re-centering drill. It is used for commencing a small hole in a 
flat-bottomed cylindrical cavity ; or else, in rotation with the 
common piercing drill, and the half-round bit, in drilling 
small and very deep holes in the lathe : see sect. iv. p. 567. 
Fig. 480 may be also considered to resemble the stop-drill, upon 
which a solid lump or shoulder is formed, or a collar is tempo- 
rarily attached by a side screw, for limiting the depth to which 
the tool can penetrate the work. 

Fig. 481, the cone countersink, may be viewed as a multiplica- 
tion of the common single-cutting drill. Sometimes, however, 
the tool is filed with four equi-distant radial furrows, directly 
upon the axis, and with several intermediate parallel furrows 
sweeping at an angle round the cone. This makes a more even 
distribution of the teeth, than when all are radial as in the figure, 
and it is always used in the spherical cutters, or countersinks, 
known as cherries, which are used in making bullet-moulds. 

On comparison, it may be said the single-chamfered drill, fig. 
476, cuts more quickly than the double-chamfered, fig. 470, but 
that the former is also more disposed of the two, to swerve or 
run from its intended position. In using the double-cutting drills, 
it is also necessary to drill the holes at once to their full sizes, as 
otherwise the thin edges of these tools stick abruptly into the 
metal, and arc liable to produce jagged or groovy surfaces, which 



550 



PIN DRILLS FOR METAL. 



destroy the circularity of the holes ; the necessity for drilling 
the entire hole at once, joined to the feebleness of the drill-bow, 
limits the size of these drills. 

In using the single chamfered drills, it is customary, and on 
several accounts desirable, to make large holes by a series of two 
or more drills ; first the run of the drill is in a measure propor- 
tioned to its diameter, therefore the small tool departs less from 
its intended path, and a central hole once obtained, it is followed 
with little after-risk by the single-cutting drill, which is less 
penetrative. This mode likewise throws out of action the less 
favourable part of the drill near the point, and which in large 
drills is necessarily thick and obtuse ; the subdivision of the 
work enables a comparatively small power to be used for drilling 
large holes, and also presents the choice of the velocity best 
suited to each progressive diameter operated upon. But where 
sufficient power can be obtained, it is generally more judicious 
to enlarge the holes previously made with the pointed drills, by 
some of the group of pin drills, figs 482 to 485, in which the 
guide principle is very perfectly employed : they present a close 
analogy to the plug center-bit, and the expanding center-bit, 
used in carpentry. 

The ordinary pin-drill, fig. 482, is employed for making coun- 
tersinks for the heads of screw-bolts inlaid flush with the surface, 
and also for enlarging holes commenced with pointed drills, by 



Figs. 482. 



483. 



484. 




a cut parallel with the surface ; the pin-drill is also particularly 
suited to thin materials, as the point of the ordinary drill would 
soon pierce through, and leave the guidance less certain. When 



ROBERTA'S FIN DRILL. 

tins tool is used for iron, it is fluted as usual, and a, represents 
the form of one edge separately. 

.483 is a pin-drill principally used for cutting out large 
holes in cast-iron and other plates. In this case the narrow 
1 er removes a ring of metal, which is of course a less laborious 
process than cutting the whole into shavings. When this drill 
is applied from both sides, it may be used for plates half an inch 
and upwards in thickness ; as should not the tool penetrate the 
whole of the way through, the piece may be broken out, and the 
rough edges cleaned with a file or a broach. 

Fig. 484 is a tool commonly used for drilling the tube-platei 
for receiving the tubes of locomotive boilers ; the material is 
about f inch thick, and the holes 1J diameter. The loose 
cutter a, is fitted in a transverse mortise, and secured by a 
wedge ; it admits of being several times ground, before the notch 
which guides the blade for centrality is obliterated. Fig. 485 is 
somewhat similar to the last two, but is principally intended for 
sinking grooves; and when the tool is figured as shown by the 
dotted line, it may be used for cutting bosses and mouldings on 
parts of work not otherwise accessible. 

Many ingenious contrivances have been made to ensure the 
dimensions and angles of tools being exactly retained. In this 
class may be placed Mr. Roberts's pin-drill, figs. 486 and 487 ; 
in action it resembles the fluted pin-drill, fig. 482, but the iron 



Fig*. 486. JL 487. 




stock is much heavier, and is attached to the drilling-machine by 
the square tang ; the stock has two grooves at an angle of about 
10 degrees with the axis, and rather deeper behind than in 
front. Two steel cutters, or nearly parallel blades represented 
black, are laid in the grooves ; they are fixed by the ring and 
two set screws, * *, and are advanced as they become worn 
away, by two adjusting screws, a a, (one only seen,) placed at the 
angle of 10 through the second ring ; which, for the convenience 



552 LUBRICATION. DRILLS FOR MINERAL SUBSTANCES. 

of construction is screwed up the drill-shaft just beyond the 
square tang whereby it is attached to the drilling-machine. 
The cutters are ground at the extreme ends, but they also 
require an occasional touch on the oilstone, to restore the keen- 
ness of the outer angles, which become somewhat rounded by the 
friction. The diminution from the trifling exterior sharpening, 
is allowed for by the slightly taper form of the blades. 

The process of drilling, generally gives rise to more friction 
than that of turning, and the same methods of lubrication are 
used, but rather more commonly and plentifully ; thus oil is used 
for the generality of metals, or from economy, soap and water ; 
milk is the most proper for copper, gold, and silver ; and cast 
iron and brass are usually drilled without lubrication, as described 
at page 538. For all the above-named metals, and for alloys of 
similar degrees of hardness, the common pointed steel drills are 
generally used ; but for lead and very soft alloys, the carpenters' 
spoon bits and nose bits are usually employed, with water. For 
hardened steel and hard crystalline substances, copper or soft 
iron drills, such as fig. 67 or 71, page 178, Vol. I., supplied with 
emery powder and oil are needed; or the diamond drill-points 
66, 68, and 70 are used for hardened steel, with oil alone.* 

Having considered the most general forms of the cutting parts 

* The boring tools used for the mineral substances, are partly adverted to in 
the ninth chapter of Vol. I ; beginning with the bits used for the softest materials, 
those for boring through earth, sand, and clay, in order to obtain water, are enlarged 
copies of the shell, nose, and spiral bits used hi carpentry, attached to long vertical 
rods which are screwed together like jointed gun rods, and are worked by a cross 
at the earth's surface. The rods are drawn up by a windlass, and joint after joint 
is unscrewed, until the bit, with its contained earth, is brought to the surface. 
Various attempts have been made to avoid the tedious necessity for raising the 
rods, by the employment of a hollow cylinder or magazine resting on the bit, to 
receive the borings, and to be drawn up occasionally to be emptied. 

In boring large holes the earth is generally excavated by the process of " miser- 
ing up." The rods terminate in the " miter," which is a cylindrical iron case 
sometimes two to three feet diameter, with a slightly conical bottom, in which 
there is a slit much like the mouth of a plane, and covered with a leather flap to 
prevent the escape of the earth that has been collected. 

In sinking the Artesian wells, lined with cast-iron tubes attached end to end 
by internal flanges or screws, a spring tool is used, which expands when it is 
tbruat beneath the lower end of the series of pipea See the account of sinking 
the Artesian well at Messrs. Truman, Hanbury, and Co.'s Brewery, Minutes of 
Conversation, Inst. of Civil Eng., 1842, p. 192. 

The common pointed drill, is used for mineral substances not exceeding in hardness 
those enumerated under the terms, 1, 2, 3, of the Table of hardness, p. 158, VoL I., 



Ml I 1101)8 OF WORKING DRILLS BY HAND POWER. 553 

of drills, we will proceed to explain thr. modes in which they are 
put in action by hand-power, bc^innin^ ith those for tin- 
smallest diameters, and proceeding gradually to the largest. 

SECT. III. METHODS OP WORK I M. DKILLS BY HAND POWER. 

The smallest holes are those required in watch-work, and tin- 
general form of the drill is shown on a large scale in fi;: 
is made of a piece of steel wire, which is tapered off at the one 
end, flattened with the hammer, and then filed up in the form 
shown at large in fig. 570, p. 547 ; lastly, it is hardened in the 
candle. The reverse end of the instrument is made into a conical 
point, and is also hardened ; near this end is attached a little 
brass sheave for the line of the drill-bow, which in watchmaking 
is sometimes a fine horse-hair, stretched by a piece of whalebone 
of about the size of a goose's quill stripped of its feather. 

Fig. 488. 



The watchmaker holds most of his works in the fingers, both 
for fear of crushing them with the table vice, and also that he 
may the more sensibly feel his operations ; drilling is likewise 
performed by him in the same manner. Having passed the 
bow-string around the pulley in a single loop (or with a round 
turn), the center of the drill is inserted in one of the small 
center holes in the sides of the table vice, the point of the drill 
is placed in the mark or cavity made in the work by the center 
punch; the object is then pressed forward with the right hand, 
whilst the bow is moved with the left ; the Swiss workmen apply 
the hands in the reverse order, as they do in using the turn-bench*. 

and which include some of the marbles. Glass may also be drilled with fig. 470, 

or 471, lubricated with turpentine. The sandstones are readily bored in Hunter's 

patent stone boring-machine (see p. 54$, also Conv. Civ. Eng. 1842, p. 146), and the 

granites are not bored, but crushed by the jumper, or chisel point, see p. 170, Vol. 1. 

: the compact mineral*, such as 4, 5, 6 of the table, the grinding tools may 

be used with sand, but emery is more effective ; this powder may be also employed 

for minerals not exceeding the hardness of 7 and 8 ; but emery being somewhat 

I hardness to the ruby, this gem and the diamond, marked 9 and 10 in 

the table, require either diamond dust, or splinters of the diamond, the ouUide 

skin and natural angles of which, are much harder than the inside substance. See 

the ninth chapter of VoL I. generally, especially pages 178 to 180. 

See Vol. IV., page 18. 



554 DRILL BOW AND BREAST-PLATE. 

Clockmakers, and artisans in works of similar scale, fix the 
object in the tail-vice, and use drills, such as fig. 488, but often 
larger and longer ; they are pressed forward by the chest which 
is defended from injury by the breast-plate, namely, a piece of 
wood or metal about the size of the hand, in the middle of which 
is a plate of steel, with center holes for the drill. The breast- 
plate is sometimes strapped round the waist, but is more usually 
supported with the left hand, the fingers of which are ready 
to catch the drill should it accidentally slip out of the center. 

As the drill gets larger, the bow is proportionably increased 
in stiffness, and eventually becomes the half of a solid cone, 
about 1 inch in diameter at the larger end, and 30 inches long; 
the catgut string is sometimes nearly an eighth of an inch in 
diameter, or is replaced by a leather thong. The string is 
attached to the smaller end of the bow by a loop and notch, 
much the same as in the archery bow, and is passed through a hole 
at the larger end, and made fast with a knot ; the surplus length 
is wound round the cane, and the cord finally passes through a 
notch at the end, which prevents it from uncoiling. 

Steel bows are also occasionally used ; these are made some- 
thing like a fencing foil, but with a hook at the end for the knot 
or loop of the cord, and with a ferrule or a ratchet, around which 
the spare cord is wound. Some variations also are made in the 
sheaves of the large drills ; sometimes they are cylindrical with 
a fillet at each end ; this is desirable, as the cord necessarily 
lies on the sheave at an angle, in fact in the path of a screw ; 
it pursues that path, and with the reciprocation of the drill bow, 
the cord traverses, or screws backwards and forwards upon the 
sheave, but is prevented from sliding off by the fillet. Occasionally 
indeed, the cylindrical sheave is cut with a screw coarse enough 
to receive the cord, which may then make three or four coils for 
increased purchase, and have its natural screw-like run without 
any fretting whatever ; but this is only desirable when the holes 
are large, and the drill is almost constantly used, as it is tedious 
to wind on the cord for each individual hole. The structure of 
the bows, breast-plates, and pulleys, although often varied, is 
sufficiently familiar to be understood without figures. See 
Appendix, Note AY, page 1002. 

When the shaft of the drill is moderately long, the workman 
can readily observe if the drill is square with the work as regards 



itKII.L STOCKS AND DRILLING LATIIKS. 



561 



the horizontal plane; and to remove the necessity for the obser- 
vation of an assistant as to the vertical plane, a trifling weight 
is sometimes suspended from the drill shaft by a metal ring or 
hook, the joggling motion shifts the weight to the lower extre- 
mity; t lie tool is only horizontal when the weight remains central*. 
I ii many cases, the necessity for repeating the shaft and pulley 
of the drill is avoided, by the employment of holders of various 
kinds, or drill-gtockf, which serve to carry any required number 
<>f drill-points. The most simple of the drill-stocks is shown 
iu fig. 489; it has the center and pulley of the ordinary drill, 
Figs. 489. 




but the opposite end is pierced with a nearly cylindrical hole, 
just at the inner extremity of which a diametrical notch is 
filed. The drill is shown separately at a ; its shank is made 
cylindrical, or exactly to fit the hole, and a short portion is 
nicked down also to the diametrical line, so as to slide into the 
gap in the drill-stock, by which the drill is prevented from 
revolving ; the end serves also as an abutment whereby it may be 
thrust out with a lever. Sometimes a diametrical transverse 
mortise, narrower than the hole, is made through the drill-stock, 
and the drill is nicked on both sides; and Mr. Gill proposes 
that the cylindrical hole of 489, should be continued to the 
bottom of the notch, that the end of the drill should be filed off 
obliquely, and that it should be prevented from rotating, by a pin 
inserted through the cylindrical hole parallel with the notch; the 
taper end of the drill would then wedge fast beneath the pin.f 

Drills are also frequently used in the drillinr/- lathe ; this is a 
miniature lathe-head, the frame of which is fixed in the table 
vice ; the mandrel is pierced for the drills, and has a pulley for 

This is Analogous to Use level of the Indian matom and carpenters ; they 
squeeze a few drop* of water on the upper surface of the straight edge, which in 
made exactly parallel, and the escape of the fluid from either end, denotes that to 
be the lower of the two. 

t See Technical Repos., 1822, voL il, p. 149; also Bees'! Cyclopedia. 



556 



ROBISON'S AND ALLEN'S DRILL STOCKS. 




the bow, therein resembling fig. 490, except that it is used as 
a fixture. 

The figure 490 just referred to, represents one variety of another 
common form of the drill-stock, in which, the revolving spindle is 
fitted in a handle, so that it may be held in any position, without 
the necessity for the breast-plate ; the handle is hollowed out to 
serve for containing the drills, and is fluted to assist the grasp. 

Fig. 491 represents the socket of an "universal drill-stock" 
invented by Sir John Robison ; it is pierced with a hole as large 



Figs. 491. 



492. 



493. 



as the largest of the wires of which the drills are formed, and 
the hole terminates in an acute hollow cone. The end of the 
drill-stock is tapped with two holes, placed on a diameter ; the 
one screw a, is of a very fine thread, and has at the eud two 
shallow diametrical notches ; the other b, is of a coarser thread 
and quite flat at the extremity. The wire-drill is placed against 
the bottom of the hole, and allowed to lean against the adjust- 
ing-screw a, and if the drill be not central, this screw is moved 
one or several quarter-turns, until it is adjusted for centrality ; 
after which the tool is strongly fixed by the plain set-screw b. 

Fig. 492 is a drill-stock, contrived by Mr. William Allen : it 
consists of a tube, the one end of which has a fixed center and 
pulley much the same as usual ; the opposite end of the tube has 
a piece of steel fixed into it, which is first drilled with a central 
hole, and then turned as a conical screw, to which is fitted a 
corresponding screw nut n ; the socket is then sawn down with 
two diametrical notches, to make four internal angles, and 
lastly, the socket is hardened. When the four sections are 
compressed by the nut, their edges stick into the drill and retain 
it fast, and provided the instrument is itself concentric, and the 
four parts are of equal strength, the centrality of the drill is 



PUMP DRILL. SMITH'S BRACE, FT 557 

ice ensured. The outside of the nut. :iml the square hole 
in the key k, arc enrh taper, for more ready application ; and 
the drills are of the most simple kind, namely, lengths of wire 
pointed at each end, as in fig. 4 ( .W.* 

The sketch, fig. 492, is also intended to explain another 
useful application of this drill-stock, as an upriyht or pump-drill, 
a tool little employed in this country (except in drilling the 
t holes for mending china and glass, with the diamond-drill, 
fig. 70, vol. I.,) but as well known among the oriental nations as 
the breast-drill. The pump-drill is figured and explained on 
page 3 of the fourth volume of this work, to which the reader 
is referred ; occasionally the pump-drill and the common drill- 
stock are mounted in frames, by which their paths are more 
exactly defined; but these contrivances are far from being 
generally required, and enough will be said in reference to the 
use of revolving braces, to lead to such applications, if considered 
requisite, for reciprocating drills. See Appendix, Notes A. Z. 
to B.B. page 1003. 

Holes that are too large to be drilled solely by the breast- 
drill and drill-bow, are frequently commenced with those useful 
instruments, and are then enlarged by means of the hand-brace, 
which is very similar to that used in carpentry, except that it is 
more commonly made of iron instead of wood, is somewhat 
larger, and is generally made without the spring-catch. 

Holes may be extended to about half an inch in diameter, with 
the hand-brace ; but it is much more expeditious to employ still 
larger and stronger braces, and to press them into the work in 
various ways by weights, levers, and screws, instead of by the 
muscular effort alone. 

Fi^. I'.U represents the old smith's press-drill, which although 
cumbrous, and much less used than formerly, is nevertheless 
simple and effective. It consists of two pairs of wooden standards, 
bet ween which works the beam a b, the pin near a is placed at any 
height, but the weight w is not usually changed, as the greater 
or less pressure for large and small drills, is obtained by placing 
the brace more or less near to the fulcrum a ; and this part of 
the beam is shod with an iron plate, full of small center holes 
: lie brace. The weight is raised by the second lever c d, the 

See Technical Repository, vol. il, 1822, p. 147. 



558 



OLD PHESS DRILL FRAMES. 



two being united by a chain, and a light chain or rope is also 
suspended from d, to be within reach of the one or two men 
engaged in moving the brace. It is necessary to relieve the 
weight when the drill is nearly through the hole, otherwise, it 
might suddenly break through, and the drill becoming fixed, 
might be twisted off in the neck. 



Fig-s. 494. 



495. 




The inconveniences in this machine are, that the upper point 
of the brace moves in an arc instead of a right line ; the limited 
path when strong pressures are used, which makes it necessary 
to shift the fulcrum a; and also the necessity for re-adjusting 
the work under the drill for each different hole, which in 
awkwardly shaped pieces is often troublesome. 

A portable contrivance of similar date, is an iron bow frame 
or clamp, shown in fig. 495 ; the pressure is applied by a screw, 
but in almost all cases, whilst the one individual drills the hole, 
the assistance of another is required to hold the frame ; 495 
only applies to comparatively thin parallel works, and does not 
present the necessary choice of position. Another tool of this 
kind, used for boring the side holes in cast-iron pipes for water 
and gas, is doubtless familiarly known ; the cramp or frame 
divides into two branches about two feet apart, and these ter- 
minate like hooks, which loosely embrace the pipe, so that the 
tool retains its position without constraint, and it may be used 
with great facility by one individual. 

Fig. 496 will serve to show the general character, of various 
constructions of more modern apparatus, to be used for supply- 
ing the pressure in drilling holes with hand braces. It consists 
of a cylindrical bar a, upon which the horizontal rectangular 
rod b, is fitted with a socket, so that it may be fixed at any height, 



MODERN FRES8 DRILL FRAMES. 



or in any angular jiitiun, ly the set-screw c. Upon b slides a 
sockt t, \\ Inch is fixed at all distances from a, by its set-screw d, 
and lastly, this socket has a long vertical screw e, by which the 
brace is thrust into the work. 

object to be drilled having been placed level, either 
upon the ground, on trestles, on the work bench, or in the \ 
according to circumstances, the 
screws, c and d are loosened, and 
the brace is put in position for 
work. The perpendicularity of 
the brace is then examined with 
a plumb-line, applied in two posi- 
tions, (the eye being first directed 
as it were along the north and 
south line, and then along the east 
and west,) after which the whole is 
made fast by the screws c and rf. 
The one hole having been drilled, 
the socket and screws present great 
facility in rc-adjusting the instru- 
ment for subsequent holes, without 
the necessity for shifting the work, 
which would generally be at tended 
with more trouble, than altering the drill-frame by its screws. 

Sometimes the rod a is rectangular, and extends from the 
floor to the ceiling ; it then traverses in fixed sockets, the lower 
of which has a set-screw for retaining any required position. In 
the tool represented, the rod a, terminates in a cast-iron base, 
by which it may be grasped in the tail-vice, or when required it 
may be fixed upon the bench; in this case the nut on a is 
unscrewed, the cast-iron plate, when reversed and placed on 
the bench, serves as a pedestal, the stem is passed through 
a hole in the bench, and the nut and washer when screwed on 
the stem beneath, secure all very strongly together. Even 
in est;ibli>hments where the most complete drilling-machines 
driven by power arc at hand, modifications of the press-drill 
are among the indispensable tools: many arc contrived with 
screws and clamps, by which they are attached directly to 
such works as are sufficiently large and massive to serve as a 
foundation^ 




560 



EXPANDING BRACES; LEVER DRILL. 



Various useful drilling tools for engineering works, are fitted 
with left-hand screws, the unwinding of which elongate the 
tools; so that for these instruments which supply their own 
pressure, it is only necessary to find a solid support for the 
center. They apply very readily in drilling holes within boxes 
and panels, and the abutment is often similarly provided by 
projecting parts of the castings ; or otherwise the fixed support 
is derived from the wall or ceiling, by aid of props arranged in 
the most convenient manner that presents itself. 

Fig. 497 is the common brace, which only differs from that in 
fig. 496 in the left-hand screw ; a right-hand screw would be 
unwound in the act of drilling a hole when the brace is moved 
round in the usual direction, which agrees with the path of a 
left-hand screw. The cutting motion produces no change in 
the length of the instrument, and the screw being held at rest 
for a moment during the revolution, sets in the cut ; but towards 
the last, the feed is discontinued, as the elasticity of the brace 
and work, suffice for the reduced pressure required when the 
drill is nearly through, and sometimes the screw is unwound 

still more to reduce it. 

500. 







49S. 



501. 



The lever-drill, fig. 498, differs from the latter figure in many 
respects, it is much stronger, and applicable to larger holes ; 
the drill socket is sufficiently long to be cut into the left-hand 
screw, and the piece serving as the screwed nut, is a loop ter- 
minating in the center point. The increased length of the lever 
gives much greater purchase than in the crank-formed brace, 
and in addition the lever-brace may be applied close against a 



RATCHET-DRILL, CORNER-DIM I. 

surface whnv tin; crauk-brace cannot !>< tunn-d round ; in this 
case tlu- lever is only moved a half circle at a time, and i- then 
slid through for a new purchase, or sometimes a spanner or 
wrench is applied duvet ly upon the square drill-sod. 

1 is more conveniently fulfilled by the ratchet- 
({rill, fig. 499, apparently derived from the last; it is made by 

nu r rate:. iu the drill-shaft, or putting on the ratchet 

as a separate piece, and fixing a pall or detent to the handle; 

. itter may then be moved backward to gather up the teeth, 
and forward to thrust round the tool, with less delay than the 
l<-\ t-r in fig. 498, and with the same power, the two being of equal 
length. This tool is also peculiarly applicable to reaching into 
angles and places in which neither the crank-form brace, nor the 
It \i r-drill will apply. Fig. 500, the ratchet-lever, in part resem- 
the ratchet-drill, but the pressure-screw of the latter instru- 
ment must be sought in some of the other contrivances referred 
to, as the ratchet-lever has simply a square aperture to fit on the 
tang of the drill d, which latter must be pressed forward by some 
independent means. 

Fig. 501, which is a simple but necessary addition to the 
braces and drill tools, is a socket having at the one end a 
square hole to receive the drills, and at the opposite, a square 

: to tit the brace; by this contrivance the length of the drill 
can be temporarily extended for reaching deeply-seated holes. 
The sockets are made of various lengths, and sometimes two or 
three are used together, to extend the length of the brace to suit 
the position of the prop ; but it must be remembered, that with 
the additional length the torsion becomes much increased, and 
the resistance to end-long pressure much diminished, therefore 
the sockets should have a bulk proportionate to their length. 

The French brace, fig. 469, page 545, is also constructed in 
iron, with a pair of equal bevil pinions, and a left-hand center 
screw like the tools, fig. 497, 498, and 499 : it is then called the 

H-r-drill. Sometimes also, as in the succeeding figures 502 

and 503, the bevil wheels are made with a hollow square or a\i . 

. -net-lever, fig. 500; the driver then hangs loosely on 

th Mjiiarc shank of the drill tool, or cutter bar, and when the 

pinion on the handle is only one-third or fourth of the size of 

the bevil wheel with the square hole, it is an effective driver for 

ns uses: the long tail or lever serves to prevent the rotation 

o o 



SHANK S DIFFERENTIAL SCRE\V-D1ULL. 

of the driver, by resting against some part of the work or of the 
work-bench. 

All the before-mentioned tools are commonly found in a 
variety of shapes in the hands of the engineer, but it will be 




observed they are all driven by hand-power, and are carried 
to the work. I shall conclude this section with the description 
of a more recent drill-tool of the same kind, invented by Mr. 
A. Shanks of Glasgow. 

This instrument is represented of one- eighth size, in the side 
view, fig. 504, in the front view, 505, and in the section 500 ; it 
Figs. 504. 505. 506. 




is about twice as powerful as fig. 503, and has the advantage of 
feeding the cut by a differential motion. The tangent screw 
moves at the same time the two worm wheels a and b ; * the 
former has 15 teeth, and serves to revolve the drill ; the latter 
has 16 teeth, and by the difference between the two, or the odd 

* A principle first introduced iu Dr. Wollaston's Trochiometer, for couutiug 
the turns of a carriage wheel. 



l.iui i. it')HlN<. MACHINES. 

i, advances the drill slowly and continually, which may be 
thus explained. 

The lower wheel a, of 15 teeth, is fixed on the drill-shaft, and 
this is tapped to mvivr the center-screw c, of four threads per 
inch. The upper wheel of 16 teeth is at the end of a socket d, 
(which is represented black in the section fig. 506), and ia con- 
nected with the center-screw c, by a collar and internal key, 
which last fits a longitudinal groove cut up the side of the 
screw c ; now therefore the internal and external screws travel 
constantly round, and nearly at the same rate, the difference of 
one tooth in the wheels serving continually and slowly to pro- 
ject the screw c, for feeding the cut. To shorten or lengthen 
the instrument rapidly, the side screw e is loosened ; this sets 
the collar and key, free from the 1C wheel, and the center-screw 
for the time be moved independently by a spanner. 

The differential screw-drill, having a double thread in the large 
worm, shown detached at /, requires 7$ turns of the handle to 
move the drill once round, and the feed is one Olth of an inch 
for each turn of the drill ; that being the sum of 16 by 4. See 
Appendix, Note B C, page 1004. 

SECT. IV. DRILLING AND BORING MACHINES. 

The motion of the lathe-mandrel is particularly proper for 
giving action to the various single-cutting drills referred to; 
they are then fixed in square or round hole drill-chucks which 
screw upon the lathe-mandrel. The motion of the lathe is more 
uniform than that of the hand-tools, and the popit-head, with 
its flat boring flange and pressure-screw, form a most convenient 
arrangement, as the works are then carried to the drill exactly 
at right angles to the face. But in drilling very small holes in 
t he lathe, there is some risk of unconsciously employing a greater 
pn-smire with the screw, than the slender drills will bear. Some- 
times the cylinder is pressed forward by a horizontal lever fixed 
on a fulcrum : at other times the cylinder is pressed forward 
by a spring, by a rack and pinion motion, or by a simple lev. r, 
uui ri arrangement of this latter kind is that next to be 

described. 

In the manufacture of harps there is a vast quantity of small 

drilling, and the pressure of the cylinder popit-head is given by 

ms of a long, straight, double-emit d lever, which moves 

o a 



564 HARP-MAKER'S DRILLING-MACHINE. 

horizontally, (at about one-third from the back extremity,) upon 
a fixed post or fulcrum erected upon the back-board of the lathe. 
The front of the lever is connected with the sliding cylinder by 
a link or connecting rod, and the back of the lever is pulled 
towards the right extremity of the lathe, by a cord which passes 
over a pulley at the edge of the back-board, and then supports 
a weight of about twenty pounds. 

Both the weight and the connecting rod, may be attached at 
various distances from the fixed fulcrum between them. When 
they are fixed at equal distances from the axis of the lever, the 
weight, if twenty pounds, presses forward the drill with twenty 
pounds, less a little friction ; if the weight be two inches from 
the fulcrum and the connecting rod eight inches, the effect of 
the weight is reduced to five pounds ; if, on the other hand, the 
weight be at eight and the connecting rod at two inches, the 
pressure is fourfold, or eighty pounds. 

The connecting rod is full of holes, so that the lever may be 
adjusted exactly to reach the body of the workman, who, standing 
with his face to the mandrel, moves the lever with his back, and 
has therefore both hands at liberty for managing the work. 
Sometimes a stop is fixed on the cylinder, for drilling holes to 
one fixed depth ; gages are attached to the flange, for drilling 
numbers of similar pieces at any fixed distance from the edge : 
in fact, this very useful apparatus admits of many little additions 
to facilitate the use of drills and revolving cutters. 

Great numbers of circular objects, such as wheels and pulleys, 
are chucked to revolve truly upon the lathe- mandrel, whilst a 
stationary drill is thrust forward against them, by which means 
the concentricity between the hole and the edge is ensured. 

The drills employed for boring works chucked on the lathe, 
have mostly long shafts, some parts of which are rectangular or 
parallel, so that they may be prevented from revolving by a 
hook wrench, (page 218, Vol. I.,) a spanner or a hand-vice, 
applied as a radius, or by other means. The ends of the drill 
shafts are pierced with small center holes, in order that they 
may be thrust forward by the screw of the popit-head, either by 
hand or by self-acting motion ; namely, a connection between 
either the mandrel or the prime mover of the lathe, and the 
screw of the popit-head, by cords and pulleys, by wheels and 
pinions, or other contrivances. 



BORING BITS tSED IN Till I \MIK. 

drills, figs. 476 and 478, p. 548, are used for boring 
ordinary holes ; but for t |iiiring greater accuracy, or a 

more U ' of the same diameter, the lathe-drills, figs. 

507 to 509, are commonly selected. Fig. 507, which is drawn in 
tlnv. \ u \vs and to the same scale as the former examples, is cat led 
the naif-round bit, or the cylinder Int. The extremity is ground a 
little inclined to the ri^ht an^'lc, both horizontally and vertically, 
to about the extent of three to five degrees. It is necessary to 
turn out a shallow recess exactly to the diameter of the end of 
the bit as a commencement; the circular part of the bit fills 
the hole, and is thereby retained central, whilst the left angle 
removes the -sh.i\ing. This tool should never be sharpened on 
its diametrical face, or it would soon cease to deserve its appel- 
lation of half-round bit : some indeed give it about one-thirtieth 
more of the circumference. It is generally made very slightly 
smaller behind, to lessen the friction*; and the angle, not in- 
tended to cut, is a little blunted half-way round the curve, that 
it may not scratch the hole from the pressure of the cutting 
edge. It is lubricated with oil for the metals generally, but is 
used dry for hard woods and ivory, and sometimes for brass. 



Fig. 507. 




The rose-bit, fig. 508, is also very much used for light finishing 
cuts, in brass, iron, and steel ; the extremity is cylindrical, or in 
the smallest degree less behind, and the end is cut into teeth 
like a countersink ; the rose-bit, when it has plenty of oil, and 
but very little to remove, will be found to act beautifully, but 
this tool is less fit for cast-iron than the bit next to be described. 
The rose-bit may be used without oil for the hard woods and 



566 BORING BITS USED IN THE LATHE. 

ivory, in which it makes a very clean hole ; but as the end of 
the tool is chamfered, it does not leave a flat-bottomed recess 
the same as the half-round bit, and is therefore only used for 
thoroughfare holes. 

The drill, fig. 509, is much employed, but especially for cast- 
iron work; the end of the blade is made very nearly parallel, 
the two front corners are ground slightly rounding, and are 
chamfered, the chamfer is continued at a reduced angle along 
the two sides, to the extent of about two diameters in length ; 
this portion is not strictly parallel, but is very slightly largest in 
the middle or barrel-shaped : this drill is used dry for cast-iron. 

Fig. 509, in common with all drills that cut on the side, may, 
by improper direction, cut sideways, making the hole above the 
intended diameter; but when the hole has been roughly bored 
with a common fluted drill, the end of the latter is used as a 
turning tool, to make aaccurate chamfer, the bit 509 is then 
placed through the stay as shown in fig. 510, and is lightly sup- 
ported between the chamfer upon the work and the center of 
the popit-head ; the moment any pressure comes on the drill, 
its opposite edges stick into the inner sides of the loop, (as more 
clearly explained in fig. 511,) which thus restrains its position; 
much the same as the point and edges of the turning tools for 
iron dig into the rest, and secure the position of those tools. 

It is requisite the drill and the loop should be exactly central, 
fig. 510 shows the common form of the stay when fitted to the 
lathe-rest, but it is sometimes made as a swing-gate, to turn 
aside, whilst the piece which has been drilled is removed, and 
the next piece to be operated upon is fixed in the lathe. Some- 
times also the drill 509, has blocks of hardwood attached above 
and below it, to complete the circle ; this is usual for wrought 
iron and steel, and oil is then employed. 

These three varieties are exclusively lathe-drills, and are 
intended for the exact repetition of a number of holes of the 
particular sizes of the bits, and which, on that account, should 
remove only a thin shaving to save the tools from wear. 

The cylinder bits, however, may be used for enlarging holes 
below half an inch, to the extent of about one-third their 
diameter at one cut ; and for holes from half an inch to one 
inch, about one fourth their diameter or less, and as the bits 
increase in size, the proportion of the cut to the diameter should 
decrease. 



IS USBD I MB. 

Tin- cylinder bit is not intended to be used for drilling 
in the solid material, :uul as tin- piercing drills nrc apt to s\\. 
in drilling small and very deep holes, the following rotation in 
the tools is sometimes resorted to. A drill, 1L-. I7i>, p. 
tlmv-s!\t. niths diameter, is first sent in to the depth of an inch 
or upwards, and the hole is enlarged by a cylinder hit of one 
quarter inch diameter. The center at the end of the ho! 
then restored to exact truth, hy fig. tSU a re-centeriug drill, the 
plug of which exactly fits the hole made by the cylinder bit ; 
the extremity of the re-centering drill then acts as a fixed turn- 
ing tool, and should the first drill have run out of its position, 
480 corrects the center at the end of the hole. Another short 
portion is then drilled with 17<>, enlarged with the half-round 
bit, and the conical extremity is again corrected with the re- 
centering drill; the three tools are thus used in rotation until 
the hole is completed, and which may lie then cleaned out with 
one continued cut, made with a half-round bit u little larger 
than that previously used. 

Some of the large half-round bits are so made, that the one 
stock will serve for several cutters of different diameters. In the 
bit used for boring out ordnance, the parallel shaft of the boring 
bar slides accurately in a groove, exactly parallel with the bore 
of the gun ; the cutting blade is a small piece of steel affixed to 
the end of the half-round block, which is either entirely of iron, 
or partly of wood ; and the cut is advanced by a rack and pinion 
movement, actuated either by the descent of a constant weight, 
or by a self-acting motion derived from the prime mover, i 
making the spherical, parabolical or other termination to the 
bore, cutters of corresponding forms are fixed to the bar.* See 
Appendix, Notes B D to B I, pages 1005 to 1010. 

There are very many works which from their weight or size, 
cannot be drilled, in the lathe in its ordinary position, as it 
is scarcely possible to support them steadily against the drill ; 
but these works are readily pierced in the drilling-machine, 
which may 1, \itli a vertical mandrel, and 

The outside of the gun is usually turned, whiUt the boring is going on, by the 
hand-tools, figs. 423 and 424, page 527. A plug of copper U screwed into the bran 
guns to be perforated fur tlio touch-hole, copper being less injured by repeated 
discharge*, than the alloy of 9 parts copper and 1 part tin, used fur the general 
subattiucd of the gun ; the curved bit smooths off tlio end of the plug. 



568 



VERTICAL DRILLING-MACHINES. 



with the flange of the popit-head, enlarged into a table for the 
Avork, which then lies in the horizontal position simply by gravity, 
or is occasionally fixed on the table by screws and clamps. The 
structure of these important machines admits of almost endless 
diversity, and in nearly every manufactory some peculiarity of 
construction may be observed.* 

Figs. 512 and 513 exhibit NasmytVs "Portable Hand-drill," 
which is introduced as a simple and efficient example, that may 



Figs. 



512. 




513. 




serve to convey the general characters of the drilling-machines. 
The spindle is driven by a pair of bevil pinions, the one is attached 
to the axis of the vertical fly-wheel, the other to the drill-shaft, 
which is depressed by a screw moved by a small hand-wheel. 

Sometimes, as in the lathe, the drilling spindle revolves with- 
out endlong motion, and the table is raised by a treadle or by a 
hand-lever; but more generally the drill-shaft is cylindrical and 
revolves in, and also slides through, fixed cylindrical bearings. 
The drill-spindle is then depressed in a variety of ways; sometimes 
by a simple lever, at other times, by a treadle which either lowers 
the shaft only one single sweep, or by a ratchet that brings 
it down by several small successive steps, through a greater 
distance; and mostly a counterpoise weight restores the parts to 
their first position when the hand or foot is removed. Friction- 
clutches, trains of differential wheels, and other modes, are also 
used in depressing the drill-spindle, or in elevating the table by 
self-acting motion. Frequently also the platform admits of an 

* Probably no individual has originated so many useful varieties of drilling- 
machines, fa Mr. Richard Roberts, of the firm of Sharp, Roberts, and Co., 
Manchester. 



Mill! Mi lioKlM, M MINNIE, < I TTER BARS, I 

adjustment independent of that of the spindle, for the sake of 
admitting larger pieces; the horizontal position of the platform 
i* then retained by a slide, to which a rack and pinion move- 
ment, or an elevating screw, is added.* 



Drilling-machines of these kinds are generally used with thp 
ordinary piercing-drills, and occasionally with pin-drills; the lat- 
ter instrument appears to be the type of another class of boring 
tools, namely, cutter-bars, which are used for works requiring 
holes of greater dimensions, or of superior accuracy, than can 
be attained by the ordinary pointed drills. 

The small application of this principle, or of cutter-bars, is 
shown on the same scale as the former drills, in fig. 514; the 
cutter c, is placed in a diametrical mortise in a cylindrical 
boring bar, and is fixed by a wedge; the cutter c extends 
equally on both sides, as the two projections or ears embrace the 
sides of the bar, which is slightly flattened near the mortises. 

Cutter-bars of the same kind, are occasionally employed with 
cutters of a variety of forms, for making grooves, recesses, 
mouldings, and even screws, upon parts of heavy works, and 
those which cannot be conveniently fixed in the ordinary lathe. 
Fig. 515 represents one of these, but its application to screws 
will be found in the chapter on the tools for screw-cutting. 
Figs. 514. I 

3-e 



-KSh 

TZP *=- 




The larger application of this principle is shown in fig. 516, in 
which a cast-iron cutter-block is keyed fast upon a cylindrical 
liar, the block has four, six, or more grooves in its periphery. 

The platform in a drilling-machine, at Messrs. Perm's, Greenwich, is placed 
between two aide frames, with fillets a few inches apart, so that it is supported at 
any height, like a single drawer in an empty tier. The traverse of the drill-abaft 
ia rather more than equal to the space between the fillets. 

Figures 512 and 513 are transcribed from plate 29 of" Buchanan's Mill Work." 
by Rennie, 1841 ; and plates 29 to 33 a, of that work, contain various other 
drilling-machines, similar to, and explanatory of, those in general use. 



570 BORING MACHINES FOR 

Sometimes, the work is done with only one cutter, and should the 
bar vibrate, the remainder of the grooves are filled with pieces 
of hard-wood, so as to complete the bearing at so many points of 
the circle ; occasionally cutters are placed in all the grooves, and 
carefully adjusted to act in succession, that is, the first stands a 
little nearer to the axis than the second, and so on throughout, 
in order that each may do its share of the work ; but the last 
of the series takes only a light finishing cut, that its keen edge 
may be the longer preserved. In all these cutters the one face 
is radial, the other differs only four or five degrees from the right 
angle, and the corners of the tools are slightly rounded. 

These cutter-bars, like the rest of the drilling and boring 
machinery, are employed in a great variety of ways, but which 
resolve themselves into three principal modes : 

First, the cutter-bar revolves without endlong motion, in fixed 
centers or bearings, in fact, as a spindle in the lathe; the work 
is traversed, or made to pass the revolving cutter in a right line, 
for which end the work is often fixed to a traversing slide-rest. 
This mode requires the bar to measure between the supports, 
twice the length of the work to be bored, and the cutter to be 
in the middle of the bar, it is therefore unfit for long objects. 

Secondly, the cutter-bar revolves, and also slides with endlong 
motion, the work being at rest ; the bearings of the bar are then 
frequently attached in some temporary manner to the work to 
be bored, and are often of wood.* 

In another common arrangement, the boring bar is mounted 
in headstocks, much the same as a traversing mandrel, the 
work is fixed to the bearers carrying the headstocks, and the 
cutter-bar is advanced by a screw. The screw is then moved 
either by the hand of the workman ; by a star- wheel, or a 
ratchet-wheel, one tooth only in each revolution ; or else by a 
system of differential wheels, in which the external screw has a 
wheel say of 50 teeth, the internal screw a wheel of 51 teeth, 
and a pair of equal wheels or pinions drives these two screws 
continually, so that the advance of the one-fiftieth of a turn 
of the screw, or their difference, is equally divided over each 

* Cylinders of forty inches diameter for steam engines, have been thus bored, 
by attaching a cast-iron cross to each end of the cylinder; the crosses are boro.l 
exactly to fit the boring bar, one of thorn carries the driving gear, and the bar is 
thrust endlong by means of a screw, moved by a ratchet- or star-wheel. 



I \K< 1 t \ 1 IM i;H8, ETC. 

f the euttcr-har, much the same ns in the dif- 
ntial inotiuii ot' the screw-drill, fig. ."."I, page 562. 

Tliis second method only requires the interval between the 

fixed hearings of the cutter-bar, to be as much longer than the 

M as the length of the cutter-block ; hut the bar it-. If must 

ha\e more than twice the length of the work, aud requires to 

slide through the supports. 

Cutter-bars of this kind are likewise used in the lathe; in 
the act of boring, the end of the bar then slides like a piston 
into the mandrel. Such bars are commonly applied to the 
teal boring-machines of the larger kinds, which are usually 
fitted with a differential apparatus, for determining the progress 
of the cut ; the bar then slides through a collar fixed in the bed 
of the machine. 

In some of the large boring-machines either one or two 
hori/ontal slides are added, and by their aid, series of holes may 
be bored in any required arrangement. For instance, the 
several holes in the beams, or side levers, and cranks of steam- 
engines, are bored exactly perpendicular, in a line, and at any 
precise distances, by shifting the work beneath the revolving 
spindle upon the guide or railway ; in pieces of other kinds, the 
work is moved laterally during the revolution of the cutters, 
for the formation of elongated countersinks and grooves. 

Thirdly. In the largest applications of this principle, the 
boring bar revolves upon fixed bearings without traversing; and 
it is only needful that the boring bar should exceed the length 
of the work, by the thickness of the cutter-block, of which it 
has commonly several of different 
diameters. The cutter-block, now 
sometimes ten feet diameter, tra- 
verses as a slide down a hup' 
boring bar, whose diameter is 
about thirty inches. There is a 
groove and key to couple them 
together, and the traverse of the 
cutter-block down the bar, i> 
caused by a side-screw, upon the 
end of u Inch is a large wheel, that engages in a small pinion, 
/ to the >tHtioii:i: Of p> ilr-tal of the machine. ^ ith 

;tion of the cutter-bar, the great wheel is carried 




BROACHES FOR WOOD. 

around the fixed pinion, and supposing these be as 10 to 1, the 
great wheel is moved one-tenth of a turn, and therefore moves 
the screw one-tenth of a turn also, and slowly traverses the 
cutter-block. 

The contrivance may be viewed as a huge, self-acting, and 
revolving sliding-rest, and the diagram 517 shows that the cutter- 
bars are equally applicable to portions of circles, such as the 
D valves of steam-engines, as well as to the enormous interior 
of the cylinder itself.* See Appendix, Note B J, page 1010. 

All the preceding boring tools cut almost exclusively upon the 
end alone. They are passed entirely through the objects, and 
leave each part of their own particular diameter, and therefore 
cylindrical; but I now proceed to describe other boring tools 
that cut only on their sides, go but partly through the work, and 
leave its section a counterpart of the instrument. These tools 
are generally conical, and serve for the enlargement of holes to 
sizes intermediate between the gradations of the drills, and also 
for the formation of conical holes, as for valves, stopcocks, and 
other works. The common pointed drill, or its multiplication 
in the rose countersink, is the type of the series; but in general 
the broaches have sides which are much more nearly parallel. 

SECT. V. BROACHES FOR MAKING TAPER HOLES. 

The tools for making taper holes are much less varied than 
the drills and boring tools for cylindrical holes. Thus the 
carpenter employs only the rimer, which is a fluted tool like the 
generality of his bits ; it is sharpened from within, as shown in 
fig. 518, so as to act like a paring tool. Flutes and clarionets 

Figs. 518. 620. 521. 522. 523. 524. 525. 626. 

A 




528. ~ 



are first perforated with the nose-bit, and then broached with 
taper holes, by means of tools of this kind, which are very 

There is generally a small intermediate wheel between the two represented ; 
many other details of the large boring machines will also be found in " Buchanan's 
Mill Work," as already noticed. 



lll(i)\i|||:s KH \VOOI AM) MKTM.. 573 

fully graduated a to their dimensions. Fig. 519 represent* 
mum rimer, used by wheelwright* for inlaying the boxes of 
axletrees ; the loose blade is separated from the shell of the 
mMrumcut, by introducing slips of leather or wood between the 
two; the detached cutter fits on a pin at the front, aud is fi 
t>y a ring or collar against the shaft. 

A curious rimer for the use of wine-coopers, was invent 
the late Mr. John Hilton, by which the holes were made more 
truly circular, and the shavings were prevented from dropping 
into the cask. The stock of the instrument consisted of a 
hollow brass cone, seen in section in fig. 520 ; down one side 
there was a slit for containing a narrow blade or cutter, fixed by 
three or four screws placed diametrically. The tube was thus 
converted into a conical plane; the shavings entered within the 
tube, and were removed by taking out a cork from the small 
end of the cone.* 



The broaches for metal are made solid, and of various 
sections; as half-round, like fig. 521, the edges are then rectan- 
gular, but more commonly the broaches are polygonal, as in 
fig. 522, except that they have 3, 4, 5, 6, and 8 sides, and their 
edges measure respectively 60, 90, 108, 120, and 135 degrees. 
The four, five, and six-sided broaches are the most general, and 
the watchmakers employ a round broach in which no angle 
exists, and the tool is therefore only a burnisher, which com- 
presses the metal and rounds the hole. 

Ordinary broaches are very acute, and fig. 528 may be con- 
sidered to represent the general angle at which their sides meet, 
namely, less than one or two degrees; the end is usually 
chamfered off with as many facets as there are sides, to make a 
penetrating point, and the opposite extremity ends in a square 
/'/////. or shank, by which the instrument is worked. 

Square broaches, after having been filed up, are sometimes 
twisted whilst red hot; fig. 527, shows one of these, the rectan- 
gular section is but little disturbed, although the faces become 
slightly concave. The advantage of the tool appears to exist 
in its screw form: when it is turned in the direction of the spiral, 
it cuts with avidity and requires but little pressure, as it is 

Soe Tnutt. Soc. of Arts. 1880, vol. xlriii. pagi 



574 PARALLEL BROACHES FOR METAL. 

almost disposed to dig too forcibly into the metal : when turned 
the reverse way, as in unscrewing, it requires as much or more 
pressure than similar broaches not twisted. This instrument, if 
bent in the direction of its length, either in the act of twisting 
or hardening, does not admit of correction by grinding, like 
those broaches having plane faces. It is not much used, and is 
almost restricted to wrought iron and steel. 



Large countersinks that do not terminate in a point, are 
sometimes made as solid cones ; a groove is then formed up one 
side, and deepest towards the base of the cone, for the insertion 
of a cutter, see fig. 523. As the blade is narrowed by sharpen- 
ing, it is set a little forward in the direction of its length, to 
cause its edge to continue slightly in advance of the general 
surface, like the iron of a plane for cutting metal. 

Fig. 529 represents Mr. Richard Roberts' broach, in which 
four detached blades are introduced, for the sake of retaining 

Fig. 529. 



===1 



the cone or angle of the broach with greater facility. The bar 
or stock has four shallow longitudinal grooves, which are nearly 
radial on the cutting face, and slightly undercut on the other. 
The grooves are also rather deeper behind, and the blades are 
a little wedge-form both in section and in length, to constitute 
the cone, and the cutting edges. In restoring the edges of the 
blades, they are removed from the stock, and their angles are 
then more easily tested : when replaced, they are set nearer to 
the point, to compensate for their loss of thickness. 



Broaches are also used for perfecting cylindrical holes, as well 
as for making those which are taper. The broaches are then 
made almost parallel, or a very little the highest in the middle; 
they are filed, with two or three planes at angles of 90 degrees, 
as in figs. 524 or 525. The circular part not being able to cut, 
serves as a more certain base or foundation, than when the tool 
is a complete polygon; and the stems are commonly made 



r \H\I.I.KI. Huouiir.s. I>KIM.> AND BROACHES COM PA it i i 

small eiion;h to pass entirely through t! which thru 

agree very exactly a- Such tools are then-tun- rather 

entitled to the name of finishing drills, than broaches. 

The size of the parallel broaches is often ^li^htly increased, 
by placing a piece or two of paper at the convex part; leather 
and thin metal are also used for the same purpose. Gun-barrels 
are broached uith square broaches, the cutting parts of which 
are about eijrht to ten inches long; they are packed on the four 
sides with slips or spills of wood, to complete the circle, as in 
fiu'. r>'2(), in which the tool is supposed to be at work. The size 
of the bit is progressively enlarged by introducing slips of thin 
paper, piece by piece between two of the spills of wood and the 
broach; the paper throws the one angle more towards the 
center of the hole, and causes a corresponding advance in the 
opposite or the cutting angle. Sometimes, however, only one 
spill of wood is employed. 

A broach used by the philosophical instrument makers in 
finishing the barrels of air pumps, consisted of a thin plate of 
steel inserted diametrically between two blocks of wood, the 
whole constituting a cylinder with a scraping edge slightly in 
advance of the wood ; slips of paper were also added. 

According to the size of the broaches, they are fixed in 
handles like brad-uwls they are used in the brace, or the tap 
wrench, namely, a double-ended lever with square central holes. 
Sometimes, also, broaches are used in the lathe just like drills, 
and for large works, broaching machines are employed ; these 
are little more than driving gear terminating iu a simple kind 
of universal joint, to lead the power of the steam-engine to the 
tool, which is generally left under the guidance of its own edges, 
according to the common principle of the instrument. 



In drills and broaches, the penetrating angles are commonly 
more obtuse than iu turning tools; thus in drills of limited 
dimensions, the hook-form of the turning tool for iron is inap- 
plicable, and in the larger examples, the permanence of the tool 
is of more consequence than the increased fiction. But on account 
of the additional friction excited by the nearly rectangular edged, 
it is commonly necessary to employ a smaller velocity in boring 
than in turning corresponding diameters, in order to avoid soft- 
ening the tool by the heat generated ; and in the ductile fibrous 






576 DRILLS AND BROACHES COMPARED. 

metals, as wrought iron, steel, copper and others, lubrication 
with oil, water, &c., becomes more necessary than in turning. 

The drills and broaches form together a complete series. 
First the cylinder bit, the pin-drills, and others with blunt sides, 
produce cylindrical holes by means of cutters at right angles to 
the axis ; then the cutter becomes inclined at about 45 degrees, 
as in the common piercing-drill and cone countersink ; the angle 
becomes much less in the common taper broaches ; and finally, 
disappears in the parallel broaches, by which we again produce 
the cylindrical hole, but with cutters parallel with the axis of 
the hole. 

Still considering the drills and broaches as one group, the 
drills have comparatively thin edges, always less than 90 degrees, 
yet they require to be urged forward by a screw or otherwise, 
the resistance being sustained in the line of their axes. The 
broaches have much more obtuse edges, never less than 90, and 
sometimes extending to 135 degrees ; and yet the greater force 
required to cause the penetration of their obtuse edges into the 
material, is supplied without any screw, because the pressure in 
all these varied tools is at right angles to the cutting edge. 

Thus, supposing the sides of the broach extended until they 
meet in a point, as in fig. 528, we shall find the length will very 
many times exceed the diameter, and by that number will the 
force employed to thrust forward the tool be multiplied, the 
same as in the wedge, whether employed in splitting timber or 
otherwise ; and the broach being confined in a hole, it cannot 
make its escape, but acts with great lateral pressure, directed 
radially from each cutting edge ; and the broach under proper 
management leaves the holes very smooth and of true figure. 






( IIAPTER XXVI. 
SCREW-CUTTINO TOOIA 



SECT. I. INTRODUCTORY REMARKS. 

AN elementary idea of the form of the screw, or helix, is ob- 
tained by considering it as a continuous circular wedge; and it 
is readily modelled by wrapping a wedge-formed piece of paper 
around a cylinder; the edge of the paper then represents the 
line of the screw, and which preserves one constant angle to 
the ;t.\is of the contained cylinder, namely, that of the wedge. 

The ordinary wedge, or the diagonal, may be produced by the 
composition of two uniform rectilinear motions, which, if equal, 
produce the angle of 45, or if unequal, various angles more or 
less acute; and in an analogous manner, the circular wedge or 
the screw, may be produced of every angle or coarseness, by the 
composition of an uniform circular motion, with an uniform 
rectilinear motion. And as either the rectilinear or the circular 
motion may be given to the work or to the tool indifferently, 
tin-re are four distinct modes of producing screws, and which 
arc all variously modified in practice. 

The screw admits of great diversity ; it may possess any dia- 
meter; it may al>o have any angle, that is, the interval between 
the threads may be either coarse or fine, according to the ai. 
of the wedge, or the ratio of the two motions ; and the wedge 
may be wound upon the cylinder to the right hand or to the 
left, so as to produce either right or left-hand screws. 

The idea of double, triple, or quadruple screws, will be con- 
veyed by considering two, three, or four black lines drawn on the 
un< Ige of the wedge-formed paper, or likewise by two, 

three, or foin - or wires placed in contact, and coiled as a 

flat band around the cylinder, the angle remains unaltered, it is 
only a multiplication of the furrows or threads; and lastly, the 
screw may have any section, that is, the section of the worm or 

p P 



578 INTRODUCTORY REMARKS. 

thread may be angular, square, round, or of any arbitrary form. 
Thus far as to the variety in screws. 

The importance of this mechanical element, the screw, in all 
works in the constructive arts, is almost immeasurable. For 
instance, great numbers of screws are employed merely for con- 
necting together the different parts of which various objects are 
composed, no other attachment is so compact, powerful, or 
generally available; these binding or attachment screws require, 
by comparison, the least degree of excellence. Other screws are 
used as regulating screws, for the guidance of the slides and the 
moving parts of machinery, for the screws of presses and the like ; 
these kinds should possess a much greater degree of excellence 
than the last. But the most exact screws that can be produced, 
are quite essential to the good performance of the engines 
employed in the "graduation of right lines and circles and of 
astronomical and mathematical instruments; in these delicate 
micrometrical screws, our wants ever appear to outstrip the 
most refined methods of execution. 

The attempt to collect and describe all the ingenious con- 
trivances which have been devised for the construction of screws, 
would be in itself a work of no ordinary labour or extent : I must, 
therefore, principally restrict myself to those varied processes 
now commonly used in the workshops, for producing with com- 
parative facility, screws abundantly exact for the great majority 
of purposes. It has been found rather difficult to arrange these 
extremely different processes in tolerable order, but that which 
seems to be the natural order has been adopted, thus : 

There appears to be no doubt, but that in the earliest production 
of the apparatus for cutting screws, the external screw was the 
first piece made ; this plain circular metal screw was serrated and 
thus converted into the tap, or cutting tool, by which internal 
screws of corresponding size and form were next produced ; and 
one of these hollow screws, or dies, became in its turn the means 
of regenerating, with increased truth and much greater facility, 
any number of copies of the original external screw. In these 
several stages there is a progressive advance towards perfection, 
as will be hereafter adverted to. 

These hand processes are mostly used for screws, which 
are at least as long, if not longer than their diameters. The 
rotatory and rectilinear guides, and the one or several series of 






l>l\l>l'.\ OK TUB SUIUK 579 

eutt in- ('"nits, are then usually combined within the tool. 
Thi fii->t -rroup \\ill be considered in three sections, namely: 
1 1. On originating screws. 

111. On cutting internal screws, with screw-taps. 

1\ . On (in tin- external screws, with screw-dies. 

Suhx ( |iu nt improvements have led to the employment of the 
lathe, in producing from the above, and in a variety of ways, still 
more accurate screws. These methods are sometimes used for 
screws which possess only a portion of a turn, at other times for 
screws twenty or thirty feet long and upwards. The rotatory 
guide is always given by the mandrel, the rectilinear guide is 
variously obtained, and the detached screw-tool or cutter, may 
ha\e one single point, or one series of points which touch the 
circle at only one place at a time. This second group will be 
also considered in three sections, namely : 

V. On cutting screws, in the common lathe by hand. 
\ I. On cutting screws, in lathes with traversing mandrels. 

VII. On cutting screws, in lathes with traversing tools. 

It may be further observed that the modes described in the 
six sections are in general applied to very different purposes, 
and are only to a limited extent capable of substitution one for 
the other; it is to be also remarked that it has been considered 
convenient, in a great measure to abandon, or rather to modify, 
the usual distinction between the tools respectively used for 
wood and for metal. The eighth and concluding section of this 
chapter describes some refinements in the production of screws 
which are not commonly practised, and it is in some measure a 
sequel to the second section. 

SECT. II. ON ORIGINATING SCREWS. 

It appears more than probable, that in the earliest attempts 
at making a screw, a sloping piece of paper was cemented around 
the iron cylinder ; this oblique line was cut through with a stout 
knife or thiu-edgcd file, and was then gradually enlarged by 
hand until it gave a rude form of screw. Doubtless, as soon as 
the application of the hit i ally known, the work was 

mounted bet uters, so that the process of filing up the 

groove could be more easily accomplished, or a pointed turning 
tool could be employed to assist. Such, in fact, is one of the 
modes recommended by Plnmier, tor cutting the screw upon a 



580 VARIOUS MODES FORMERLY 

lathe-mandrel for receiving the chucks, even ill preference to 
the use of the die-stocks, which he urged were liable to bend 
the mandrel in the act of cutting the screw.* 

Nearly similar modes have been repeatedly used for the pro- 
duction of original screws; one account differing in several 
respects from the above, is described as having been very suc- 
cessfully resorted to, above fifty years back, at the Soho works, 
Birmingham, by a workman of the name of Anthony Robinson, 
before the introduction of the screw-cutting lathe. 

The screw was seven feet long, six inches diameter, and of a 
square triple thread ; after the screw was accurately turned as a 
cylinder, the paper was cut parallel exactly to meet around the 
same, and was removed and marked in ink with parallel oblique 
lines, representing the margins of the threads; and having 
been replaced on the cylinder, the lines were pricked through 
with a center-punch. The paper was again removed, the dots 
were connected by fine lines cut in with a file, the spaces were 
then cut out with a chisel and hammer and smoothed with a 
file, to a sufficient extent to serve as a lead or guide. 

The partly-formed screw was next temporarily suspended in 
the center of a cast-iron tube or box strongly fixed against a 
horizontal beam, and melted lead mixed with tin was poured 
into the box to convert it into a guide nut ; it then only remained 
to complete the thread by means of cutters fixed against the 
box or nut, but with the power of adjustment, in fact in a kind 
of slide-rest, the screw being handed round by levers f- 

Another very simple way of originating screws, and which is 
sufficiently accurate for some purposes, is to coil a small wire, 
around a larger straight wire as a nucleus; this last is fre- 
quently the same wire, the one end of which is to be cut into the 
screw. The covering wire, whose diameter is equal to the space 
required between the threads of the screw, is wound on close 
and tight, and made fast at each end. The coiled screw, being 
enclosed between two pieces of hard wood, indents a hollow or 
counterpart thread, sufficient to guide the helical traverse, and 
a fixed cutter completes this simple apparatus. See Appendix, 
Note 15 K, page 1010. 

* L' Art du Tourneur, by Plumier, 1701, pages 15 19. 

+ This mode, which is described in Gill's Tech. Repos. vol. vi. p. 261, is said 
to have excited at the time great admiration from its success. It is probable a 
gun-metiil nut wat cast upon this screw for use, after the screw was finished. 



EMPLOYF.D FOB OBICJI SCREWS. 

MlM.-hold purp'.M--, bftYQ been 

made of tinned iron wire; two covering wires are rolled on 
together, the one being r< n a space such as the 

ordinary hollow of tin- thread, and when these screws are 
dipped in a little melted tin, the two wires become sold 
;icr. 

Other in de> have heen resorted to for making original s. 
by indenting a smooth cylinder, \\ith a sharp-ed^ed cutter placed 
across the same at the required angle ; and trusting to the sur- 
face or rolling contact, to produce the rotation and traverse of 
the cylinder, with the development of the screw. In the most 
simple application of this method, a deep groove is made along a 
piece of board, in which a straight wire is buried a little beneath 
the surface; a second groove is made, nearly at right angles 
across the first, exactly to fit the cutter, which is just like a 
table knife, and is placed at the angle required in the screw. 
The cutter when slid over the wire, indents it, carries it round, 
and traverses it endways in the path of a screw ; a helical 
Hue is thus obtained, which, by cautious management may be 
perfected into a screw sufficiently good for many purposes. 

The late Mr. Henry Maudslay employed a cutter upon cylin- 
ders of wood, tin, brass, iron, and other materials, mounted to 
revolve between centers in a triangular bar lathe; the knife \\;ts 
hollowed to fit the cylinder, and fixed at the required angle on 
a block adapted to slide upon the bar; the oblique incision 
carried the knife along the revolving cylinder. Some hundreds 
of screws were thus made, and their agreement with one another 
was in many instances quite remarkable ; on the whole he gave 
the preference to this mode of originating screws.* 

Mr. Allan's apparatus for originating screws for astronomical 
and other purposes is represented in plan in fig. 580, in side 
elevation in fi. Ji.'ll, and .VJ-.i is the front elevation of the cutter- 
frame alone. The piece intended for the screw, namely, a a fig. 
530, is turned cylindrical, and with two equal and cylindi 
necks; it is supported in a metal frame with two semi-circnlnr 

The reader is also referred to the Trans. Sue. of Arta, vol. xlii., page : 
the description of Mr. Walsh's method of making original screws by rolling con- 
tact, or with a abort screw mounted as a milling-tool, to act only by pressure, (see 
abx> figs. 637 and 588, page 604 of this volume,) the method appears, however, to 
be circuitous, difficult, and very questionable. The instrument, fig. 80, page 
vol. i.. for cutting snakes in horn, is virtually an originator of screws. 



5S2 



ALLAN'S APPARATUS. 



bearings, b b, which are fixed on a slide moved by an adjusting 
screw c ; speaking of the apparatus the inventor says : 

" The instrument generates original screws perfectly true, of 
any number of threads, and right or left handed. In this case, 
the stock and cutter are made as in figs. 530, 531, and 532 ; 
the back of the stock is made into the segment of a circle, s ; 
aud the top of the cutter is continued into an index, t. The 
cutter is a single thread^ and moves on its edge, v, as a center. 
This must fit true, and the stock fit close to the cutter, to keep 
it perfectly steady : u, u, two screws, to adjust and fasten the 
cutter to any required angle. The cutter should be rather 
elliptical, for it is best to fit well to the cylinder at the greatest 
angle it will be ever used. When one turn has been given to 




Figs. 533. 



634. 



535. 



636. 







the cylinder, fig. 530, a tooth, w, is put into the cut, and 
screwed fast; this tooth secures the lead, and causes every 
following thread to be a repetition of the first ; and, though it 
might do without, yet this is a satisfactory security/' * 

* See Trans. Soc. of Arts, 1816, vol. xxxiv., p. 206. The engravings are copied 
from figs. 6 to 12 of plate 23. An instrument based on the same general plan is 
described in the Mech. Mag., 1836, vol. xxv., p. 377 ; but it is greatly inferior to 
the above. 



In cutting ordinal \ screws, the dies, shown separately in figs. 
533 to 586, the consideration of which is for the present deferred, 
take the place of the oblique cutter in tin igures. 

The screw is also originated, In traversing the tool in a right 
line alongside a plain revolving cylinder. Sometimes the tool 
has many points, and is guided by the hand alone; at other 
times the tool has but one single point, and is guided mechani- 
cally so as to proceed, say one inch or one foot in a right line, 
whilst the cylinder makes a definite number of revolutions. The 
tool is then traversed either by a wedge placed transversely to 
the axis, by a chain or metallic band placed longitudinally, or by 
another screw, connected in various ways with the screw to be 
produced, by wheel-work and other contrivances. 

It would be injudicious to attempt at this place the explana- 
tion of these complex methods of originating screws ; some of 
them will, however, be introduced in the course of this chapter, 
whilst, for greater perspicuity, others will be deferred unto its 
latter pages. The next section will be now proceeded with, on 
the supposition that a screw of fair quality has been originated 
by some of the means referred to. 

SECT. III. ON CUTTING INTERNAL SCREWS, WITH SCREW-TAPS. 

The screw is converted into the tap, by the removal of parts 
of its circumference, in order to give to the exposed edges a 
cutting action; whilst the circular parts which remain, serve 
for the guidance of the instrument within the helical groove, or 
hollow thread, it is required to form. 

In the most simple and primitive method, four planes were 
filed upon the screw as in fig. 537, but this exposes very obtuse 
edges which can hardly be said to cut, as they form the thread 
partly by indenting, and partly by raising or burring up the 
metal ; and as such they scarcely produce any effect in cast iron 
or other crystalline materials. Conceiving, as in fig. 537, only 
a very small portion of the circle to remain, the working edges 
of squared taps, form angles of (90 -f 45 or) 135 degrees with 
the circumference, and the angle is the greater, the more of the 
circle that remains. It is better to file only three planes as in 
fig. 538, but the angle is then as great as 120 degrees c\cn 
under the most favourable circumstances. 



584 



COMPARISON OF THE 



In taps of the smallest size it is imperative to submit to these 
conditions, and to employ the above sections. Sometimes small 
intermediate facets or planes, are tipped off a little obliquely 
with the file, to relieve the surface friction ; this gives the instru- 
ment partly the character of a six or eight-sided broach, and 
improves the cutting action. 



Figs. 537. 538 



540. 



541. 



542 




There appears to be no doubt, but that for general purposes, 
the most favourable angle for the edges of screw taps and dies, 
is the radial line, or an angle of 90 degrees. This condition 
manifestly exists in the half-round tap fig. 539, which is advo- 
cated in the annexed quotation from Sir John Robison, who in 
speaking of the tap, says, " I propose that this should be made 
half-round, as it will be found that a tap formed in this way 
will cut a full clear thread (even if it may be of a sharp pitch), 
without making up any part of it by the burr, as is almost 
universally the case, when blunt-edged or grooved taps are 
used." 

" It has sometimes been objected to me by persons who had 
not seen half-round taps in use, that, from their containing 
less substance than the common forms do, they must be very 
liable to be broken by the strain required to turn them in the 
work. It is proved, however, by experience, that the strain in 
their case is so much smaller than usual, that there is even less 
chance of breaking them than the stouter ones. Workmen are 
aware that a half-round opening bit makes a better hole and 
cuts faster than a five-sided one, and yet that it requires less 
force to use it." * 

Fig. 540, in which two-thirds of the circle are allowed to remain, 
has been also employed for taps; this, although somewhat less 
penetrative than the last, is also less liable to displacement with 
the tap-wrench. It is much more usual to employ three radial 
cutting edges instead of one only ; and, as in the best forms of 

* Select Papers read before the Soc. of Arts for Scotland, vol. i., page 41. 



vNSVEIlSE SECTIONS OP TAP*. 

tin y an- only required to cut in the one direction, or when 
they :uv sere\\ed into the nut, the *>ther edges are then cham- 
1\ -red to make room for the shaving ; then -hy giving the tap a 
section somewhat like that of a ratchet-wheel, with either tli 
tour, or five teeth, aa in figs. 5H and f> 1'.). 

It is more common, however, either to file up the side of the 
tap, or to cut by machinery, three concave or elliptical flutes, as 
in ."H2; this form sufficiently approximates to the desideratum 
of the radial cutting edges, it allows plenty of room for the 
shavings, and is easily wiped out. What is of equal or greater 
importance, it presents a symmetrical figure, little liable to 
accident in the hardening, either of distortion from unequal 
section, as in figs. 539 and 510, or of cracking from internal 
angles, as in 540 and 5-41.* 

Still, considering alone the transverse section of the tap, it 
will be conceived that before any of the substance can be re- 
moved from the hole that is being tapped, the circular part of 
the instrument must become embedded into the metal a quantity 
equal to the thickness of the shaving; and in this respect figs. 
537 and 538, in which the circular parts are each only the tenth 
or twelfth of the circumference, appear to have the advantage 
over the modern taps 511 and 542, in which each arc is twice as 
long. Such, however, is not the case, as the first two act more 
in the manner of the broach, if we conceive that instrument to 
have serrated edges; but figs. 541 and 542 act nearly as turning- 
tools, as in general the outer or the circular surface is slightly 
relieved with a file, so as to leave the cutting edges a, somewhat 
in advance of the general periphery; which is equivalent to 
chamfering the lower plane of the turning tool some 3 degrees 
(see page 534), to produce that relief which has been appro- 
priately named the angle of separation. 

But in the tup fig. 543, patented by Mr. G. Bodmer of Man- 
ehe>h-r, this is still more effectually accomplished. The instru- 
ment, instead of being turned of the ordinary circular section 

* In fluting tap*, as in cutting the teeth of wheels, the tap or wheel is fre- 
quently chucked in the lathe, just aa in turning ; but the mandrel is held at ret 
by the dividing-plate, and the tool ia a cutter, revolving horizontally, and tra- 
versed through the groove by the slide-rest screw. The round flutes are made 
with cutters having semicircular edges and placed centrally ; the ratchet-form 
flutes are made with thick saws or square-edged cutters, the one edge of these is 
placed to intersect the center of the tap, and leave the radial edge. 



58t) COMPARISON OP THE TRANSVERSE SECTIONS OP TAPS. 

in the lathe (or as the outer dotted line), is turned with three 
slight undulations, by means of an alternating radial motion 
given to the tool. From this it results, that when the summits 
of these hills are converted into the cutting edges, that not only 
are the extreme edges or points of the teeth made prominent, 
but the entire serrated surface becomes inclined at about the 
three degrees to the external circle, or the line of work, so as 
exactly to assimilate to the turning tool ; and therefore there is 
little doubt but that, under equal circumstances, Mr. Bodmer's 
tap would work with less friction than any other. 




546. 



The principle of chamfering, or relieving the taps, must not 
however, be carried to excess, or it will lead to mischief; in ex- 
planation of which the diagrams 544, 545, and 546 may be con- 
sidered parallel with the forms 429, 430, and 431, of page 532. 
For example, the tap, if sloped behind the teeth as in 544, would 
be much exposed to fracture; and the instrument being entirely 
under its own guidance, the three series of keen points would 
be apt to stick irregularly into the metal, and would not produce 
the smooth, circular, or helical hole, obtained when the tool 545 
is used, which may be considered parallel with the turning tool 
fig. 430. The relief should be slight, and the surfaces of the 
teeth' then assimilate to the condition of the graver for copper- 
plates (see page 532), and thereby direct the tap in a very 
superior manner. 

The teeth sloped in front, as in figs. 546, would certainly cut 
more keenly than those of 545, but they would be much more 
exposed to accident, as the least backward motion or violence 
would be liable to snip off the keen points of the teeth ; and 



of THE i vL SECTIONS OF TAP*. 



therefore, on the score of general y and usefulness, the 

radial and slightly rdirvnl teeth of fig. 545, or rather of 
are proper for working tups. 

It appears further to be quite impolitic, entirely to expunge 
the surface-bearing, or squeeze, from the taps and dies, when 
these are applied to the ductile metals; as not only does it, 
when slight, greatly assist in the more perfect guidance of the 
instrument, but it also serves somewhat to condense or compress 
the metal.* 

The transverse sections hitherto referred to, are always used 
for those taps employed in screwing the inner surfaces of the 
nuts, and holes required in general mechanism. The longi- 
tudinal section of the working tap, is taper and somewhat like a 
broach, the one end being small enough in external diameter 
to enter the blank hole to be screwed, and the other end being 
as large as the screw for which the nut is intended. 



Fig. 547. 



c 6 



t d 



f 
648. 





























In many cases a series of two, three, or four taps must be used 
instead of only one single conical tap, and the modifications 
in their construction are explained by the above diagrams; 
namely, fig. 547, the tap formerly used for nuts and thorough- 
fare holes, and fig. 548 the modern tap for the same purposes ; 
the dotted lines in each represent the bottoms of the threads. 

M the taps cut very freely, it i* the general aim to avoid the necessity 
for tapping cast-iron, which is a granular and crystalline substance, apt to crumble 
away in the tapping, or in the after use. The general remedy is the employment 
of bolts and nuts made of wronght-iron, or fixing screwed wrought-irou pins in the 
work, by means of transverse keys and other contrivances, and sometimes by the 
insertion of plugs of gun-metal, to be afterwards tapped with the screw-threads. 
In general also, the mall screws for cast-iron, are coarse and shallow in the thread 
compared with those for wrought-iron, stoel, and brass. 



MODERN FORMS OF TAPS. 

In the former kind, the thread was frequently finished of a 
taper figure, with the screw tool in the lathe ; after which either 
the four or three plane surfaces were filed upon it, as shown by 
the section at s ; the neck from ftoff was as small as the bottom 
of the thread, and the tang from g to h was either square or 
rectangular for the tap-wrench. The tang, if square was also 
taper, the tap-wrench then wedged fast upon the tap ; the sides 
of the tang, if parallel, were rectangular, and measured as about 
one to two, and there were shoulders on two sides to sustain the 
wrench. 

In the modern thoroughfare taps for nuts, drawn to the 
same scale in fig. 54-8, the thread is left cylindrical, from the 
screw-tool or the dies : then from a to b, or about one diameter 
in length, is turned down cylindrical until the thread is nearly 
obliterated ; from d to /, also nearly one diameter in length 
at the other end, is left of the full size of the bolt, and the 
intermediate part, b to d equal to three or four diameters, is 
turned to a cone, after which the tap is fluted as seen at s. 
The neck fff, as before, is as small as the bottom of the thread, 
and the square g h, measures diagonally the same as the turned 
neck. 

In using the modern instrument fig. 548, the hole to be 
tapped is bored out exactly to fit the cylindrical plug a b, which 
therefore guides the tap very perfectly in the commencement ; 
the tool is simply passed once through the nut without any 
retrograde motion whatever, and the cylindrical part d f, takes 
up the guidance when the larger end of the cone enters the 
hole ; at the completion, the tap drops through, the head being 
smaller than the bottom of the thread. The old four square 
taps could not be thus used, for as they rather squeezed than 
cut, they had much more friction; it was necessary to move 
them backwards and forwards, and to make the square for the 
wrench larger, to avoid the risk of twisting off the head of the 
tap. In taps of modern construction of less than half an inch 
diameter, it is also needful to make the squares larger than the 
proportion employed in fig. 548. 

In tapping shallow holes, as only a small portion of the end 
of the tap can be used, the screwed part seldom exceeds two 
diameters in length, and as they will not take hold when made 
too conical, a succession of three or four taps is generally 



MODES OF WORKING OR 1 > PS. 589 

required. The M-iru. d part of the first may be considered to 

IK! from to A <>i , of the second, from c to d, of the 

thinl from e to /; so that the prior tap may, in each case, 

prepare for the reception of the following one. The taps are 

generally made in sets of three ; the first, which is also called the 

entering or taper tap, is in most cases regularly taper throughout 

length; the second, or the middle tap, is sometimes tap* r, 

hut more generally cylindrical, with just two or three threads at 

the end tapered off; the third tap, which is also called the />///// 

orjinix/iinf/ tap, is always cylindrical, except at the two or three 

: i reads, which are slightly reduced. 



Taps arc used in various ways according to the degree of 
strength required to move them. The smallest taps should 
have considerable length, and should be fixed exactly in the axis 
of straight handles ; the length serves as an index by which the 
true position of the instrument can be verified in the course of 
work ; with the same view as to observation, and as an expeditious 
mode, taps of a somewhat larger size are driven round by a 
hand brace, whilst the work is fixed in the vice. Still larger 
taps require tap wrenches, or levers with central holes to fit the 
square ends of the taps; for screw-taps from one to two inches 
diameter, the wrenches have assumed the lengths of from four 
to eight feet, although the recent improvements in the taps 
have reduced the lengths of the wrenches to one-half. 

Notwithstanding that the hole to be tapped may have been 
drilled straight, the tap may by improper direction proceed 
obliquely, the progress of the operation should be therefore 
watched; and unless the eye serve readily for detecting any 
falseness of position, a square should be laid upon the work, 
and its edge compared with the axis of the tap in two positions. 

In tapping deeply-seated holes, the taps are temporarily 

lengthened by sockets, frequently the same as those used in 

drilling, which are represented in fig. 501, page 560; the tap 

ich can then surmount those parts of the work which would 

otherwise prevent its application. 

SometiiiH s, for tapping two distant holes exactly in one line, 
the ordinary taper tap, fig. 548, is made with the small cylin- 
diical part a b exceedingly long, so as to reach from the one 



590 



JONES'S TAP WITH LOOSE CUTTERS. 



hole to the other and serve as a guide or director. This is only 
an extension of the short plug a b, fig. 548, which it is desirable 
to leave on most taps used for thoroughfare holes. 

Some works are tapped whilst they are chucked on the lathe 
mandrel ; in this case the shank of the tap, if in false position, 
will swing round in a circle whilst the mandrel revolves, instead 
of continuing quietly in the axis of the lathe. Sometimes the 
center point of the popit-head is placed in the center hole in the 
head of the tap ; in those which are fixed in handles it is better 
the handle of the tap should be drilled up to receive the cylinder 
of the popit-head, as in the lathe taps for making chucks ; this 
retains the guidance more easily. 



Taps of large size, as well as the generality of cutting instru- 
ments, have been constructed with detached cutters. For those 
exceeding about l\ i ncn diameter, Mr. Richard Jones recom- 
mends two steel plugs a a, to be inserted within taper holes in 
the body of the tap, as represented in fig. 519, and in the two 
sections b and c ; the whole is then screwed and hardened. 



Fig. 549. 




The advance of the cutters slightly beyond the general line 
of the thread, is caused by placing a piece of paper within the 
mortises a a, and to relieve the surface friction, each alternate 
tooth in the middle part of the length of the tap is filed away. 
Sometimes the cutters are parallel, and inserted only partway 
through, and are then projected by set-screws placed also on 
the diameter as in the section c* 

The cutter-bar, fig. 515, p. 569, may also be viewed as a tap 
with detached cutters. The cylindrical bar is supported in tem- 
porary fixed bearings, one of which embraces the thread (some- 
times by having melted lead poured around the same), the bar 
moves therefore in the path of a screw. In cutting the external 






* See Trans. Soc. of Arts, 1829, vol. xlvii., p. 135. 



MASTER TAPS; SClii < I TTERS. 



501 



tin-fail, tin- . 1 is shifted inwards with the pro- 

gress of the work; or a straight cutter shifted outwards, serves 
fr making an internal screw: pointed instead of serrated 
(utters may be also used, they are frequently adjusted by a set- 
screw instead of tlu> hammer, and are worked by a wrench. 

This screw-cutter bar, independently of its use for large 
awkward works, is also employed for cutting, in their respective 
situations, screws required to be exactly in a Hue with holes or 
ti\< tl bearings, as the nuts of slides, presses, and similar works. 



Some taps or cutters are made cylindrical, and are used for 
cutting narrow pieces and edges, such as screw-cutting dies, 
screw-tools, and worm-wheels ; therefore it is necessary to leave 
much more of the circle standing, and to make the notches 
narrower than the width of the smallest pieces to be cut. But 
the grooves should still possess radial sides, and when these are 
connected by a curved line, as in fig. 550, there is less risk of 
accident in the hardening. The number of the notches increases 
\\ith the diameter, but the annexed figure would be better pro- 
portioned if it had one or two less notches, as inadvertently the 
teeth have been drawn too weak. 



Fig* 550. 651. 



S ft ft ft ft ft ft ft ft ft ft ft ft 




When the tool, figs. 550 and 551, is used for cutting the dies of 
die-stocks it is called an original tap, of which further particulars 
will be given in the succeeding section ; the tool is then fixed in 
the vice, and the die-stock is handed round, as in cutting an 
ordinary screw. When 55 1 is used for cutting up screw-tools, 
or the chasing-tools for the use of the turning-lathe, (figs. 404 
and 405, page 519,) the cutter is then called a hob, or a screw- 
tool cutter, and its diameter is usually greater ; it is now mounted 
to revolve in the lathe, and the screw-tool to be cut, is laid on 
the rest as in the process of turning, and is pressed forcibly 



592 WORM-WHEEL CUTTERS; TAPS FOR WOOD. 

against the cutter.* Fig. 551 is also used as a worm-wheel 
cutter, that is, for cutting or for finishing the hollow screw-form 
teeth, of those wheels which are moved by a tangent screw ; as 
in the dividing-engine for circular lines, and many other cases in 
.ordinary mechanism. The worm-wheel cutter is frequently set to 
revolve in the lathe, and the wheel is mounted on a temporary 
axis so as to admit of its being carried round horizontally by the 
cutter ; sometimes the wheel and cutter are connected by gear.f 

Attention has been hitherto exclusively directed to the forms 
of the taps used for metal, but those for wood are very similar, 
the tap fig. 542, p. 584-, with three or four flutes, being the most 
common ; those of largest size are cast in iron, and require only 
a little filing up to sharpen the teeth. 

Different taps with loose teeth, have been adopted for wood- 
screws of moderately large size, say exceeding \\ or 2 inches 
diameter. In the one case, shown in fig. 552, an ordinary wood- 
screw t, is first made, and at the bottom of the angular thread, 
a narrow parallel groove is cut in the lathe with a parting-tool ; 
the screw is then turned down to the size of the hole to be 
tapped, leaving it as a plain cylinder with the square helical 
groove represented in the piece t. 

The next process is to insert a pointed cutter c, in a diame- 
trical mortise, and when the wooden tap is in use, it is guided 
by the block g, which is bored to fit, and has two iron plates 
p, which enter the groove. The guide g is fixed to the work w, 
which is to be tapped; the bar glides forward in virtue of 

* In cutting up the inside screw-tool, fig. 404, in which the slope and the curva- 
ture of the teeth should be reversed, an internal screw-cutter has been recom- 
mended ; it is made like a screwed nut, notched longitudinally on its inner surface. 

Another method is proposed ; the inside screw-tool is laid in a lateral groove in 
a cylindrical piece of iron, and the tool and cylinder are cut up with the die-stocks as 
a common screw ; by which mode the inside screw-tool obviously becomes the exact 
counterpart of the hollow thread of that particular diameter. See Technological 
Repository, 1821, vol. vi., p. 292. The right-hand inside screw-tool is sometimes 
cut over a tolid left-hand hob, which is a more simple way of reversing the angle. 

t The contact of the ordinary tangent screw with the worm-wheel, resembles 
that of the tangent to the circle, whence the name ; but Hindley, of York, made 
the screw of his dividing-engine to touch 15 threads of the wheel perfectly, by 
giving the screw a curved section derived from the edge of the wheel, and smallest 
in the middle. See Smeaton's Miscellaneous Papers, p. 183. Prof. Willis, in hig 
Elements of Mechanism, 1841, p. 1635, explains the mode of cutting such a 
tangent screw, but shows that ita advantages are more apparent than re.il. 



CM, -i WOOD. 



593 



tin* screu t!r each succeeding passage the cutter is 

advanced a small distance, until the work is tapped of the full 
diameter; the hollow space between the guide g, and the work 
w, allows the cutter to pass entirely through the latter, the 
space being wider than the cutter. 

Another structure is shown in the Mum/rl du Tournevr. A 
hollow iron screw is made like fig. 553, and a hole is drilled at 
tin- termination of the thread, the extreme end of which is cham- 
fered on the inner surface with a file, to make a keen angular 
edge of the shape of the thread ; in its action the tool therefore 
somewhat assimilates to the plane, and the shavings escape 
through the center of the tube. 




This appears to be much less serviceable than the contrivance 
fig. 552, in which the helical guidance is perfectly at the com- 
mencement, and continues so until the end, notwithstanding the 
gradual formation of the thread, which may be cut at several 
repetitions instead of in one single cut, or in two cuts when two 
teeth are on opposite sides of the tube, fig. 553. The arrange- 
ment of fig. 552 may be considered as quite analogous to t 
of the sc: T liar, (fig. 515, page 569,) whereas the hollow 

tap, fig. 55:i, is just the converse of the screw box described at 
the beginning of the following section. 

SECT. IV. ON i 1 tllS(. I \ I I K\AL8CREWS,WITII SCREW DIES, 1 

For the convenience of arrangement, this section will be com- 
menced \\ it li t he description of the instrument which is commonly 
employed lor makinir loni: screws in the softwoods, namely, the 
screw box, of which fig. 554 is the section, tL'. .',:>:> the plan of 
the principal piece through the line a, and fig. 556 the cutter, 
shown the full size for a two-inch sc: 

Q Q 



59 i 



SCREW BOX FOR WOOD SCREWS. 



The screw box consists of two pieces of wood, accurately 
attached by two steady pins and two screws, so as to admit of 
separation and exact replacement; the ends of the thicker 
piece are frequently formed into handles, by which the instru- 
ment is worked. A perforation is made through the two pieces 
of wood; the hole in, the thinner piece is cylindrical, and 
exactly agrees with the external diameter of the screw, or o^. 
the prepared cylinder; and the hole in the thicker piece is 
screwed with the same tap that is to be used for the internal 
screws or nuts, and which is shown in three views in fig. 557. 
The cutter or V, has a thin cutting edge sloped externally to 
the angle of the thread, usually about 60 degrees, and thinned 
internally by a notch made with a triangular file ; the cutter is 
inlaid in the thicker piece of wood, and fastened by a hook-form 
screw bolt and nut. 

In placing the cutter, four different conditions require strict 
attention. Its angular ridge should lie as a tangent to the inner 
circle ; its edge should be sharpened on the dotted line b, or at 
an angle of about 100 degrees with the back; its point should 
exactly intersect the ridge of the thread in the box ; and it 
should lie precisely at the rake or angle of the thread, for which 
purpose it is inlaid deeper at its blunt extremity. 



555. 




The piece of wood for the screw is turned cylindrical and a 
little pointed ; it is then twisted into the screw box, the cutter 
makes a notch, which catches upon the ridge of the wooden 
worm immediately behind the cutter, and this carries the work 
forward, exactly at the rate of the thread. The whole of the 



OBt.w r.i\ ; s, in \\ i-j. \ i | . 

material is n-uu. \.-.l the shavings make tin n 

escape at tin- aprrtmv or m.>u: 

lu cutting the smallest screws, with this well-contrived and 
efft-t , inn. lit. the screw box is held in tin* Kit hand, and 

tlio work is screwed in with the right ; or the box is applied 
whiUt the work remains upon the mandrel of the lathe. V* 

thread is required to be continued close up to a shoulder, 
tlu- screw is cut up as far as the entire in>trument \\ill allow: 
tin- screw box is then removed, in order that the loose piece 
may be taken off from it, after which the screw is completed 
without impedim, 

Screws of half an inch diameter and upwards, are generally 
fixed iu the vice, whilst the screw box is handed round just like 
the dit jstoek. Tor large screws exceeding two or three inches 
diameter, two of the V's or cutters are placed in the box, so as 
to divide the work ; thereby lessening the risk of breaking the 
delicate edge of the cutter, the exact position of which is a 
matter of great nicety. The screw-box has been occasionally 
used for wooden screws of 4, 6, and 8 inches diameter, and 
upwards, and such large screws have been also made by hand, 
with the saw, chisel, mallet, and ordinary tools; but these large 
screws are now almost entirely superseded by those of metal, 
which, for most purposes, are greatly superior in every point of 
view. 



In cutting the metal screw, or the bolt, the tools are required 
to be the converse of the tap, as they must have internal instead 
of external threads, but the radial notches are essential alike in 
each. For small works, the internal threads are made of fixed 
sizes and in thin plates of steel, such are called screw plates ; 
for larger works, the internal threads are cut upon the edges of 
t \N o or three detached pieces of steel, called dies, these are fitted 
into grooves within diestocks, and various other contrivances 
which admit of the approach of the screwed dies, so that they 
may be applied to the decreasing diameter of the screw, 
from its commencement to the completion. 

The thickness of the screw plate is in general from about 
t \\o-thirds to the full diameter of the screw, and mostly several 
holes are made in the same plate ; from two to six holes are 

Q ' 



596 



SCREW PLATE. 



intended for one thread, and are accordingly distinguished into 
separate groups by little marks, as in fig. 558. The serrating 
of the edges, is sometimes done by making two or three small 
holes and connecting them by the lateral cuts of a thin saw, as 
in fig. 559. The notches alone are sometimes made, and when 
the holes are arranged as in fig. 560, should the screw be broken 
short off by accident, it may be cut in two with a thin saw, and 
thus removed from the plate. 

In making small screws, the wire is fixed in the hand-vice, 
tapered off with a file, and generally filed to an obtuse point ; 
then, after being moistened with oil, it is screwed into the one 
or several holes in the screw plate, which is held in the left 
hand. At other times, the work fixed in the lathe is turned or 
filed into form, and the plate is held in the right hand ; but the 
force then applied is less easily appreciated. The harp-makers 
and some others, attach a screw plate with a single hole to the 
sliding cylinder of the popit-head. See page 564. 



559. 



560. 



Figs. 558. 




The screw plate is sometimes used for common screws as large 
as from half to three-quarters of an inch diameter; such screws 
are fixed in the tail vice, and the screw plate is made from about 
15 to 30 inches long, and with two handles ; the holes are 
then made of different diameters, by means of a taper tap, so 
as to form the thread by two, three, or more successive cuts, and 
the screw should be entered from the large side of the taper 
hole. It is, however, very advisable to use the diestocks, in 
preference to the screw plates, for all screws exceeding about 
one-sixteenth of an inch diameter, although the unvarying 
diameter of the screw plate has the advantage of regulating the 
equal size of a number of screws, and as such, is occasionally 
used to follow the diestocks, by way of a gage for size. 

The diestock, in common witli other general tools, has received 
a great many modifications thot it would be useless to trace in 



gri- 1, than M> far as respects the \arietics in common 

use, or those which introduce any peculiarity of action in the 
cutting edges. A notion of the early contrivances for cutting 
metal screws will he gathered from the figures 561 to 5(51, which 
are copied half-size from Leopold's Thcatrura Machinanun 
erale, 1724.* For instance, fi-. 561 is the screw plate 
divided in two, and jointed together like a common rule; the 
inner edges are cut with threads, the lar-cr of which is 
judiciously placed near the joint, that it may be more forcibly 
compressed : there is a guide, a, a, to prevent the lateral dis- 
placement of the edges, which Mould be fatal to the action. 
Similar instruments are still used, but more generally for screws 
made in the turning lathe. 



Figs. 561. 




In one of these tools, the frame or stock is made exactly like 
a pair of flat pliers, but with loose dies cut for cither one or two 
sizes of threads. Plier diestocks are also made in the form of 
common nut-crackers, or in fact, much like fig. 5C1, if we consider 
it to have handles proceeding from a a, to extend the tool to 
about two or three times its length ; the guide a a is retained, 
and removable dies are added, instead of the threads being cut 
in the sides of the instrument. Screwing tools arc also made 
of one piece of steel, and to spring open, something like fig. 131, 
page 232, Vol. I., but shorter and stronger : the threads are cut 
on the sides or ends of the bosses, which are flat externally, for 
the convenience of compression in the tail vice. 

In general, however, the two dies are closed together in a 
straight line, instead of the arc of a circle: one primitive 
method, fig. o*'- J-, extracted from the work referred to, has b< 
thus remodelled; the dies are inserted in rectangular taper 

Moxon, Plumier, and others, describe similar took, and alto the screw box. 



598 



MODERN FORMS OF DIESTOCKS. 



holes in the ends of two long levers, which latter are connected 
by two cylindrical pins, carefully fitted into holes made through 
the levers, and the ends of the pins are screwed and provided 
with nuts, which serve more effectually to compress the dies 
than the square rings represented in fig. 564. 

The diestock in its most general form has a central rectangular 
aperture, within which the dies are fitted, so as to admit of 
compression by one central screw ; the kinds most in use being 
distinguished as the double chamfered diestocks, figs. 565 and 566 ; 



Figs. 565, 



566. 



567. 




569. 



and the single chamfered diestock, figs. 568 and 569, the handles 
of which are partly shown by dotted lines. In the former, the 
aperture is about as long as three of the dies ; about one-third 
of the length of the chamfer is filed away at the one end, for the 
removal of the dies laterally, and one at a time. In the single 
chamfered diestock 569, which is preferable for large threads, 
the aperture but little exceeds the length of two dies, and these 
'are removed by first taking off the side plate b a, which is either 
attached by its chamfered edges as a slide, or else by four screws ; 
these, when loosened, allow the plate to be slid endways, and it 
will be then disengaged, as the screws will leave the grooves at a, 
and the screw heads will pass through the holes at b. 

Sometimes dies of the section of fig. 567 are applied after the 
manner of 566, and occasionally the rectangular aperture of 



INI DP CURVATURE IK DIBS. 5M 



fig. Jc parallel on its inner ed^e*, and without tin 

j>!:ite ba\ the dies arc tlu n d by steel plates either ri\ 

or screwed to the diestock, as represented in fig. 570, or else by 
two steel pins Imried half- \\ ay in the sides of the stock, and the 
remaining half in the die, as shown in fig. 571. These variations 
arc of little moment, as are also those concerning the general 
form of the stock ; for instance, whether or not the handles 
proceed in the directions shown (the one handle *, being occa- 
sionally a continuation of the pressure screw), or whether tin- 
handles are placed as in the dotted position /. In small die- 
stocks, a short stud or handle is occasionally attached at ri<:ht 
angles to the extremity, that the diestock may be moved like a 
winch handle : and sometimes graduations are made upon the 
pressure screw, to denote the extent to which the dies are closed. 
These and other differences are matters comparatively unimpor- 
tant, as the accurate fitting of the dies, and their exact forms, 
should receive the principal attention. 

In general only two dies are used, the inner surface of each 
of which includes from the third to nearly the half of a circle, 
and a notch is made at the central part of each die, so that the 
pair of dies present four arcs, and eight series of cutting points 
or edges : four of which operate when the dies are moved in the 
one direction, and the other four when the motion is reversed ; 
that is when the curves of the die and screw are alike. 

The formation of these parts has given rise to much investiga- 
tion and experiment, as the two principal points aimed at require 
directly opposite circumstances. For instance, the narrower the 
edges of the dies, or the less of the circle they contain, the more 
easily they penetrate, the more quickly they cut, and the less 
they enmpress the screw by surface friction or squeezing, whieh 
last tends to elongate the screw beyond its assigned length. But 
on the other hand, the broader the edges of the dies, or the more 
of the circle they contain, the more exactly do they retain the 
true helical form, and the general truth of the screw. 

The action of screw cutting dies is rendered still more diHicnlt, 
because in -reneral, one pair of dies, the curvatures and angles of 
whieh admit of no change, are employed in the production of a 
screw, the dimensions of which, during its gradual transit from 
the smooth cylinder to the finished screw, continually change, 

1 or instance, the thread of a screw necessarily possesses two 



600 



PROPORTIONS OF MASTER TAPS. 



magnitudes, namely, the top and bottom of the groove, and also 
two angles at these respective diameters, as represented by the 
dotted lines in the diagrams, figs. 572, 574, and 576, (which are 
drawn with straight instead of curved lines). The angles arenearly 
in the inverse proportion of the diameters ; or if the bottom were 
half the diameter of the top of the thread, the angle at the bottom 
would be nearly twice that at the top. (The mode of calculating 
the angles, is subjoined to figs. 614 618, page 657.) 

The figures show the original taps, master taps, or cutters, from 
which the dies, figs. 573, 575, and 577, are respectively made; 
and in each of the three diagrams, the dies a are supposed to be 
in the act of commencing, and the dies b in finishing, a screw of 
the same diameter throughout, as that in fig. 572. 



Figs. 572. 

SMALL MASTER TAP. 

Same diameter at Screw. 



674. 

MEDIUM MASTER TAP. 
One depth larger than Screw. 



576. 

LARGE MASTER TAP. 
Two depths larger than Screw. 




Of course the circumstances become the more perplexing the 
greater the depth of the thread, whereas in shallow threads the 
interference may be safely overlooked. As the dies cannot have 
both diameters of the screw, it becomes needful to adopt that 
curvature which is least open to objection. If, as in. fig. 573, the 
curved edges of the dies a and b have the same radii as the 
finished screw, in the commencement, or at a, the die will only 
touch at the corners, and the curved edges being almost or quite 
out of contact, there will be scarcely any guidance from which to 
get the lead, or first direction of the helix, and the dies will be 



IM i KI KRENCB or C' i: IN i>r . 601 

likely to cut false screws, or else parallel grooves or rings.* In 

iiiltlitic.ii to . (1 edges present, at the commencement, 

a greater angle than that proper for the top of the screw, but at 

completion of the screw, or at b, the die and screw will be 

t counterparts, and will be therefore perfectly suitable to 

If, as in fig. 577, the inner curvature of the dies a and /> bo 
the same as in the blank cylinder, a will exactly agree both in 
diameter and angle at the commencement of the screw, but at 
the conclusion, or as at b, each will be too great, and the die and 
screw will be far from counterparts, and therefore ill adapted to 
each other. 

The most proper way of solving the difficulty in dies made in 
two parts, is by having two pairs of dies, such as 577 and 
and which is occasionally done in very deep threads, a mode that 
was first published by Mr. Allan, see figs. 535 and 536, page 582. 
But it is more usual to pursue a medium course, and to make 
the original tap or cutter, fig. 574, used in cutting the dies, not 
of the same diameter as the bolt, as in figs. 572 and 573, not to 
exceed the diameter of the bolt by twice the depth of the thread, 
as in figs. 576 and 577, but with only one depth beyond the 
exact size, or half-way between the extremes, as in figs. 574 and 
575, in \\ liieh latter it is seen the contact, although not quite 
perfect either at a or b, is sufficiently near at each for general 
practice. 

The obvious effect of different diameters between the die and 
screw must be a falsity of contact between the surfaces and 
angles of the dies; thus, in 573, the whole of the cutting falls 
upon e, the external angles, until the completion of the screw in 
b, when the action is rather compressing than cutting. In fig. 
577, the first act is that of compressing, and all the work is soon 
thrown on , the internal angles of the die, which become 

* Sometimes tho dies cut a fine, single-thread screw, of one-half or one-third 
the coarseness of that of the dies ; at other times, a fine double or triple screw, 
of the same rake or Telocity as the dies ; and occasionally the dies cut concentric 
rings. These accidental results are mainly to be attributed to the dicstocks being 
closed upon the screw-bolt obliquely, instead of at right angles ; the edges of the 
dies do not then approach in the required relationship, and the two dies each cut 
a distinct thread, instead of one thread in common. In the act of placing the 
dies the stock should be slightly " wriggled," or mored vertically, to allow the 
die* to select their true position on the bolt to be cut. 



602 INTERFERENCE OF CURVATURE IN DIE*. 

gradually more penetrative, but eventually too much so, being 
in all respects the reverse of the former. In the medium and 
most common example, fig. 575, the cut falls at first upon the 
external angles e, it gradually dies away, and it is during the 
brief transition of the cut from the external to the internal angles 
/, that is, when the screw is exactly half formed, that the com- 
pression principally occurs. 

The compression or squeezing, is apt to enlarge the diameter 
of the screw, (literally by swaging up the metal,) and also to 
elongate it beyond its assigned length, and that unequally at 
different parts. Sometimes the compression of the dies, makes 
the screw so much coarser than its intended pitch, that the screw 
refuses to pass through a deep hole cut with the appropriate tap ; 
not only may the total increase in length be occasionally detected 
by a common rule, but the differences between twenty or 
thirty threads, measured at' various parts with fine pointed 
compasses, are often plainly visible. 

Other and vastly superior modes for the formation of long 
screws, or those requiring any very exact number of threads 
in each inch or foot of their length will be shortly explained. 
Yet notwithstanding the interferences which deprive the die- 
stocks of the refined perfection of these other methods, they are 
a most invaluable and proper instrument for their intended use ; 
and the disagreement of curvature and angle is more or less 
remedied in practice, by reducing the circular part of the dies 
in various ways; and also in some instances, by the partial sepa- 
ration of the guiding from the cutting action. 

The most usual form of dies is shown in fig. 578, but if every 
measure be taken at the mean, as in fig. 579, the tool possesses 
a fair, average, serviceable quality; that is, the dies should be 
cut over an original tap of medium dimensions, namely, one 
depth larger than the screw, such as fig. 574 ; the curved surface 
should be halved, making the spaces and curves as nearly equal 
as may be; and the edges should be radial. Fig. 580, nearly 
transcribed from Leupold's figure, 502, has been also used, but 
it appears as if too much of the curve were then removed. 

Sometimes the one die is only used for guiding, and the other 
only for cutting : thus a, fig. 581, is cut over two different 
diameters of master taps, which gives it an elliptical form. A 
large master tap, fig. 576, is first used for cutting the pair of 



: , i n.\ v i M..I.I i , l\ nil - 






dies, this leaves the large parts of the curve in a: the 
subsequently cut over a small manf 



Fig*. 578. 579. 



ISO, 







In beginning the screw, the die a, serves as a bed with guiding 
edges, these indent without cutting, and also agree at the tl 
start, with the full diameter of the bolt ; with the gradual reduc- 
tion of the bolt, it sinks down to the bottom of a, which con- 
tinually presents an angular ridge, nearly agreeing in diameter, 
and therefore in angle with the nascent screw. The inconveni- 
ences of the dies, fig. 581, are, that they require a large and a 
small master tap for the formation of every different sized pair of 
dies, and which latter are rather troublesome to repair. The dies 
also present more friction than most others, apparently from 
the screw becoming wedged within the angular sides of the die a. 

In fig. 582, a construction advocated by Sir John Robison, 
the dies are first cut over a small master tap, fig. 573, the thn 
are then partially filed or turned out of b, to fit the blank cylinder; 
which therefore rests at the commencement upon blunt triangu- 
lar, curved surfaces, instead of upon keen edges; and as the 
screw is cut up, its thread gradually descends into the portions 
of the thread in b, which are not obliterated. About one-third 
of the thread is turned out from each side of the cutting die a, 
leaving only two or three threads in the center, as shown in tin- 
last view ; and the surface of this die is left flat, that it may be 
ground up afresh when blunted, and which is also done with 
other dies having plane surfaces.* 

Mr. Peter Krirand .Mr. William Jones have each proposed 
to assist the action of dies for large screws, by means of cult 
tlu-ir plans will be sufficiently explained by the diagrams, figs. 
583 and .".M. Mr. Keir applied this mode to large screws of 
square threads for gun carriages ; the dies were cut very shallow, 



Select Papers of the Society of ArU for Scotland, vol. i., p. 41. 



DIES WITH LOOSE CUTTERS; LEFT HAND SCREWS. 



say one-third of the full depth, and they were serrated on their 
inner faces to act like saws or files. The dies were used to cut 
up the commencement of the thread, but when it filled the shal- 
low dies, their future office was not to cut, but only to guide the 
ascent and descent of the stocks, by the smooth surfaces of the 
dies rubbing upon the top of the square thread. The remaining 
portion of the screw was afterwards ploughed out by a cutter 
like a turning tool, the cutter being inserted in a hole in the one 
die, and advanced by a set screw, somewhat after the manner 
represented in the figures 583 and 584.* 

Mr. Jones employed a similar method for angular thread screws, 
and the cutter was placed within a small frame fixed to the one 
die. The screw bolt was commenced with the pair of dies which 
were closed by the set screw a, 583, the cutter being then out of 
action. When the cutter was set to work by its adjusting 
screw b, it was advanced a little beyond the face of the die, and 
not afterwards moved ; but the advance of a, closed the dies upon 
the decreasing diameter of the screw, the cutter always continu- 
ing prominent and doing the principal share of the work.f 



Figs. 583. 



585. 



587. 




584. 



586. 



588. 



Fig. 585 is the plan, and 586 the side elevation, of an old 
although imperfect expedient, for producing a left-handed screw 
from a right-handed tap. It will be remembered the right and 
left hand screws only differ in the direction of the angle, the 
thread of the one coils to the right, of the other to the left hand ; 
and on comparing a corresponding tap and die, the inclinations 
of the external curve of the one, and the internal curve of the 



* Technical Repos., vol. viiL, pages 182 and 193. 
t Trans. Soc. of Arts, 1829, vol. xlvii., p. 135. 



WlimVnUTIl's SCREW STOCKS. 

oth< Airily diller in like manner as to direction. The 

!o employnl therefore is to carry a ri^ht-hand tap ar<> 
tin- screw to be cut; the temporary screw-cutter possesses the 
same interval or thread as before, but the cutting angles of the 
havini: the reu-rse direction of those of the die, the screw 
becomes left-handed. 

The one die in 585 and 5S6 is merely a blank piece of brass 
or iron without any grooves, the other is a brass die in which 
the tap is fixed ; as may be expected, the thread produced is not 
very perfect, but iu the absence of better means, this mode is 
available as the germ for the production of a set of left-hand 
taps and dies. Fijjs. 587 and 588 represent a different mode of 
originating a left-handed screw, proposed by Mr. Walsh; tin- 
tool is to be a small piece of a right-handed screw, which is 
hardened and mounted in a frame like an ordinary millinff or 
HH /-liny tool, and intended to act by pressure alone ; the diameter 
of the tool and cylinder should be like.* 

The screw stock first patented by the Messrs. Whitworth of 
Manchester, is represented in fig. 589 : three narrow dies were 
fitted in three equidistant radial grooves in the stock, the ends 
of the dies came in contact with an exterior ring, having on its 
inner edge three spiral curves, (equivalent to three inclined 
planes,) and on its outer surface a scries of teeth into which 
worked a tangent screw, so that on turning the ring by the 
screw, the three dies were simultaneously and equally advanced 
towards the center. 

These screw stocks were found to cut very rapidly, as every 
circumstance was favourable to that action. For instance, on 
the principle of the triangular bearing, all the three dies were 
constantly at work ; the original tap being slightly taper, every 
thread in the length of the die was performing its part of the 
work, the same as in a taper tap every thread of which removes 
its shaving, or share of the material ; and the dies were narrow, 
with radial edges, which admitted of bein^ easily sharpened. 

Thisdiestock has been abandoned by the Messrs. Whitworth, 

Sea Trans. Soe. of Arts, voL xliii., p. 127 ; this scheme is referred to likewue 
in the foot-note on page 581 of this volume. 

Some methods of making the tame taps and dies, serve for cutting rithrr right 
or left-hand screws, will be found in Trans. Soe. of Arts, vol. xli., p. 115 ; Ma*<l 
rfu Tourntur, vol. i., plate 23; and Mechanic's Magazine, 1836, voL xxv., p. 370* 
These contrivances appear, however, to possess little or no value. 



606 



WHITWORTH'S AND BOOMER'S SCREW STOCKS. 



in favour of their screw stock subsequently patented, which is 
represented in fig. 590. The one die embraces about one-third 
of the circle, the two others much less; the latter are fitted into 
grooves which are not radial, but lead into a point situated near 
the circumference of the screw-bolt ; the edges of the dies are 
slightly hooked or ground respectively within the radius, and 
they are simultaneously advanced by the double wedge and nut: 
the dies are cut over a large original, such as fig. 576, that is, 
two depths larger than the screw. The large die serves to line 
out or commence the screw, and the two others act alternately; 
the one whilst the stock descends down the bolt, the other 
during its ascent. 



Figs. 589. 



590. 





The last screw stock that will be here noticed is Mr. G. Bod- 
mer's of Manchester, for which he also has obtained a patent. 
It is seen that the one die embraces about one-third the screw, 
the other is very narrow ; the peculiarity of this construction is 
that a circular recess is first turned out of the screw stock, and a 
parallel groove is made into the same, the one handle of the stock, 
(which is shaded,) nearly fills this recess, and receives the small 
die. If the handle fitted mathematically true, it is clear it 
would be immovable, but the straight part of the handle is nar- 
rower than the width of the groove ; when the stock is turned 
round, say in the direction from 2 to 1, the first process is to 
rotate the handle in the circle, and to bring it in hard contact 
with the side 1, this slightly rotates the die also, and the one 
corner becomes somewhat more prominent than the other. When 



MODES OF USING DIES; BOLT-SCREWING MM 

tin- motion of the stock is reversed, tin- handle leaves the side 
1, of the groove, and strikes against the other side 2, and then 
the opposite angle of the die becomes the more prominent ; and 
that without any thought or adjustment on thr part of the 
workman, as the play of the handle in the groove 1, 2, is exactly 
proportioned to cause the required angular change in the die. 

cutting edges of the die act exactly like turning tools, 
and therefore they may very safely be bevilled or hooked as 
such ; as when they are not cutting, they are removed a little 
way out of contact, and therefore out of danger of bein^ 
snipped oil', or of being blunted by hard friction. The opposite 
die affords during the time an ctiicicnt guidance for the screw, 
and the broad die is advanced in the usual manner, by the 
pressure screw made in continuation of the second handle of 
the diestock; the dies are kept m their places by a side pi 
which is fitted in a chamfered groove in the ordinary manner. 



There is less variety of method in cutting external screws with 
the diestocks, than internal screws with taps, but it is desirable, 
in both cases, to remove the rough surface the work acquires 
in the foundry or forge, in order to economise the tools; and 
the best works are either bored or turned cylindrically to the 
true diameters corresponding with the screwing tools. 

The bolt to be screwed is mostly fixed in the tail vice ver- 
tically, but sometimes horizontally, the dies are made to apply 
fairly, (see foot-note, page 601,) and a little oil is applied prior 
to starting. As a more expeditious method suitable to small 
screws, the work is caused to revolve in the lathe, whilst the 
die-stock is held in the hand ; and larger screws are sometimes 
marked or lined out whilst fixed in the vice, the principal part 
of the material is then removed with the chasing tool or hand- 
screw tool, fig. 405, p. 519, and the screw is concluded in the 
diestocks. In cutting up large screw bolts, two individuals are 
required to work the screw stocks, and they walk round the 
e or screwing clamp, which is fixed to a pedestal in 
the middle of the workshop. 

For screwing large numbers of bolts, the engineer employs 
the bolt-screwing machine, which is a combination of the ordinary 
taps and dies, with a mandrel, driven by steam power. In tin- 
machine invented by Mr. Fox, the mandrel revolves, traverses, 



608 ROBERTS'S SCREWING TABLE, ETC. 

and carries the bolt, whilst the dies are fixed opposite to the 
mandrel ; or else the mandrel carries the tap, and the nut to be 
screwed is grasped opposite to it. In the machine invented by 
Mr. Roberts, the mandrel does not traverse, it carries the bolt, 
and the dies are mounted on a slide ; or else the mandrel carries 
the nut, and the tap is fixed on the slide. The tap or die gives 
the traverse in every case, and the engine and strap supply the 
muscle; of course the means for changing the direction of 
motion and closing the dies, as in the hand process, are also 
essential.* 

Mr. Roberts' screwing table is a useful modification of the bolt 
machine, intended to be used for small bolts, and to be worked 
by hand. The mandrel is replaced by a long spindle running 
loosely in two bearings ; the one end of the spindle terminates 
in a small wheel with a winch-handle, the other in a pair of jaws 
closed by a screw, in other respects like fig. 85, p. 201, vol. I. 
The jaws embrace the head of the bolt, which is presented 
opposite to dies that are fixed in a vertical frame or stock, and 
closed by a loaded lever to one fixed distance. In tapping the 
nut, it is fixed in the place before occupied by the dies, and the 
spindle then used, is bored up to receive the shank of the tap, 
which is fixed by a side screw. This machine ensures the rect- 
angular position of the several parts, and the power is applied 
by the direct rotation of a hand wheel. 



It will be gathered from the foregoing remarks, that the die- 
stock is an instrument of most extensive use, and it would 
indeed almost appear as if every available construction had been 
tried, with a general tendency to foster the cutting, and to 
expunge the surface friction or rubbing action ; by the excess 
of which latter, the labour of work is greatly increased, and 
risk is incurred of stretching the thread. 

Sec Buchanan's Mill Work, by Rennie, 1841. Plates 38 to 88 c. 

In Wright's Patent Machine for making " wood screws" for joinery work, the 
traverse of the mandrel is assisted by a screw guiilo of the same degree of ci 
ness as the fixed dies, and the blanks are advanced to the latter through the hollow 
mandrel, at the end of which they are retained by nippers, until the machine has 
screwed the former, and nupplies a new blank. In a former machine the traversing 
mandrel and a fixed turning tool were used ; the thread is cut from base to point, 
whilst the screw is supported in a back stay. For other modifications, see 
Lardner's Cyclopedia, Manufactures in metal, vol. i., pp. 201 9. 



OEM It VI UEMAKK8 ON DIE8TOCK8. ''"'' 

In tin p.:, -it diestocks tin- cutting is so much facilitated, 
that th. .ineed perhaps to less than the half of 

that i. quired with the old-fashioncu irly semicircular dies, 

; hut when the guidance is too far sacrificed, the greedy 
action of the dies is a source of mischief. For instance, the in- 
strument, fig. 5SO, with three dies moving simultaneously, has 
ded hccause of its risk of cutting irregular or 
"drunken " screws : for if, from the dies being improperly placed, 
the thread does not exactly meet, or lead into itself in the first 
revolution of the dies, hut finds its way in with a break in the 
curve, this break continues unto the end ; as the three points of 
////, so to speak, bein^ narrow, they may pursue the irregular 
line, thus giving to the dicstock a rolling or "wabbling" motion, 
instead of a steady quiet descent. This fault is also liable to occur 
in every diestock, in which there is any risk of the blank cylinder 
not being placed truly axial, from the dies touching only by 
points or narrow edges, instead of against a fair proportion of 
the curve; but, when the dies are moderately broad, there is 
more chance of the defect being afterwards corrected. 

Subsequently to the introduction, by Messrs. Whitworth, of 
their screw-stock, shown in fig. 589, they invented a diestock 
with four dies, the one side of each of which was radial. The 
dies acted two at a time, just like turning tools, they were quite 
free from rubbing, and were simultaneously advanced by two 
wedges yoked together by a cross piece, and moved by one screw. 
This ingenious plan was not however regularly adopted, on 
account of the deficiency of the guiding power, as the screw was 
supported between four series of points ; but it gave rise to the 
mode explained in tig. 590, in which the broad guide is judi- 
ciously introduced. 

It is difficult, however, to decide fairly and impartially upon 
the respective merits of diestocks, many of which approach very 
nearly to one another ; as whether the facility of cutting, or the 
truth of the screw, or any other point be made the standard of 
iparison, it is a judgment which must necessarily be given 
rather by opinion than by measure ; and the conditions which arc 
aimed at in all screw-stocks, arc in strictness unattainable in any, 
owing to the varying dimensions of the object to be produced. 

From many reasons, it appears needless to strain the applica- 
tion of the diestock to the production of long screws, which 

K R 



610 GENERAL REMARKS ON DIESTOCKS. 

require either a very precise total length, or a very precise equa- 
lity in their several parts. The main inconvenience results from 
unavoidably mixing the guiding and cutting in the same part of 
the one instrument ; an instrument which acts by producing a 
series of copies of the few threads in the dies, and which copies 
become collectively the long screw. This mode of proceeding 
is equally as impolitic, as setting out a line of 50 or 100 inches 
long, with a little rule measuring only one or two inches. 

Neither can it be desirableto cut long,and consequently slender 
screws, by an instrument used as a double ended lever, in the 
application of which, the screw, supported generally at the one 
end in the vice, is very liable to be bent ; as any small disturbing 
force at the end of the stock, is multiplied in the same proportion 
as the difference between the radii of the work and instrument. 
The liability to bend the screw is reduced to the minimum, in 
Mr. Allan's simple apparatus, (p. 582,) for cutting the screws 
for dividing engines and other superior works, but which mode 
is not adapted to ordinary screws ; the machines for screwing 
bolts entail also little risk of bending the screw. 

On the whole it appears questionable whether for short screws, 
which are the legitimate works of the diestock, some of the 
better forms of the two part dies are not as good as any ; 
and on the other hand it appears quite certain that for those 
screws in which particular accuracy is of real importance, that 
the screw cutting engine or turning lathe is beyond comparison 
more proper. This valuable engine will be soon referred to, and 
in it the distinct processes of guiding and of cutting are com- 
pletely detached, and each may independently receive the most 
favourable conditions ; whereas in all the modifications of the 
screw-stock they are more or less intimately commingled, and 
are to a certain degree antagonists. 

The screw-cutting lathe has also the advantage that one good 
screw having been obtained as a guide, its relative degree of 
perfection is directly imparted to the work, and it may be em- 
ployed for cutting very coarse or very fine screws, or in fact any 
of the various kinds referred to in the preliminary description.* 

Some remarks will be offered in the laat section, on the proportions aud 
forms of screws of a variety of kinds. 



. i in: ' i \ in |, 1 1 I 

ECT. V. OX SCREWS CUT BY DAM* IN TUP. I.ATHF. 

Great numbers of screws nrc required in works of wood, ivory 
and metal, that cannot he cut u ith the tnps and dies, or the other 
apparatus hitherto considered. This arises from the nature 
of the materials, the weakness of the forms of the objects, and 
the accidental proportions of the screws, many of which are com- 
paratively of very large diameter and inconsiderable length. 
These and other circumstances, conspire to prevent the use of 
the diestocks for objects such as the screws of telescopes and 
other slender tubes, those on the edges of disks, rings, l>oxes, 
and very many similar works. 

Screws of this latter class are frequently cut in the lathe with 
the ordinary screw tool, and by dexterity of hand alone ; there' 
is little to be said in explanation of the apparatus and tools, 
which then consist solely of the lathe with an ordinary mandrel 
incapable of traversing endways, and the screw tools or the 
chasing tools figs. 404 and 405, page 519, with the addition of 
the arm rest ; the details of the manipulation will be found in 
the practical section. 

The screw tool held at rest would make a series of i 
because at the end of the first revolution of the object, the points 
A B C of the tool would fall exactly into the scratches ABC 
commenced respectively by them. But if in its first revolution, 
the tool is shifted exactly the space between two of its teeth, at 
the end of the revolution, the point B of the tool, drops into the 
groove made by the point A, and so with all the others, and a 
true screw is formed, or a continuous helical line, which appears 
in steady lateral motion during the revolution of the screw in 
the lathe. 

It is likely the tool will fail exactly to drop into the groove, 
but if the difference be inconsiderable, a tolerably good screw is 
rtheless formed; as the tool being moved forward as equally 
as the hand will allow, corrects most of the error. But if the 
dilYerence be great, the tool finds its way into the groove with 
an abrupt break in the curve ; and during the revolution of the 
screw, as it progresses it also appears to roll about sideways, 
in-tead of being quiescent, and is said by workmen to be 
" drunk," this error is frequently beyond correction. 

It sometimes happens that the tool is moved too rapidly, and 

R 1. 



612 ON CUTTING SCREWS BY HAND. 

that the point C drops into the groove commenced by A ; in this 
case the coarseness of the groove is the same as that of the tool, 
but the inclination is double that intended, and the screw has a 
double thread, or two distinct helices instead of one ; the tool 
may pass over three or four intervals and make a treble or 
quadruple thread, but these are the results of design and skill, 
rather than of accident. 

On the other hand, from being moved too slowly, the point B 
of the tool may fail to proceed so far as the groove made by A, 
but fall midway between A and B ; in this case the screw has 
half the rise or inclination intended, and the grooves are as fine 
again as the tool ; other accidental results may also occur which 
it is unnecessary to notice. 

The assemblage of points in the screw tools proper for the 
hard woods, ivory and metals, renders the striking of screws in 
these materials comparatively certain and excellent, that is as 
regards those individuals who devote sufficient pains to the acqui- 
sition of the manipulation; but the softwoods, require tools with 
very keen edges of 20 to 30 degrees, and for these materials the 
screw tool is made with only a single point, as represented in figs. 
377 and 378, page 516. With such a tool, no skill will suffice 
to cut a good useful screw by hand alone, as the guiding and 
correctional power of the many points no longer exists ; and in 
consequence those screws in soft wood which are cut in the lathe, 
require the guidance to be given mechanically in the manner 
explained in the following section.* 

SECT. VI. ON CUTTING SCREWS IN LATHES WITH TRAVERSING 

MANDRELS. 

One of the oldest, most simple, and general apparatus for 
cutting short screws in the lathe, by means of a mechanical 
guidance, is the screw-m&ndrel or traversing -mandrel, which 

* The twisted moulds for upholsterers' fringes, are frequently screwed by hand ; 
a thin gouge, or a carpenters' fluted bit of the width of the groove, is ground very 
obliquely from the lower side BO as to leave two long edges or fangs projecting, and 
the tool is sharpened from within. An oblique notch is made by hand at the end 
of the mould as a commencement, and the tool wedging into the groove is guided 
along the rest at the same angle as the notch, whilst the lathe revolves slowly, 
and completes the twist at one cut. To make the second groove parallel with 
the first the finger IB placed beside the gouge, and within the first twist ; and so 
on with the others. The process i very pleasing from its rapidity and simplicity, 
and 'w also sufficiently accurate for the end proposed. 



IK\\I:USI\(. OR SCUKW-M \NURELS. 






appears to have been known, almost as soon as the iron mandrel 

ilM-lf wa> intn.diu 

Fig. 502 is copied from an old French mandrel mounted in a 
wooden frame, and with tin collars cast in two parts; the upper 
halves of the collars are removed to show the cylindrical necks of 
the mandrel, upon the shaft of which are cut several short screws. 
In ordinary turning, the retaining key k, which is shown detac 
in the \ie\v k, prevents the mandrel from traversing, as its 
angular and circular ridge enters the groove in the mandrel; 
but although not represented, each thread on the mandrel is 



\-.-. MI 




mum 





provided with a similar key, except that their circular arcs are 
screw-form instead of angular. In screw cutting, k is depressed 
to leave the mandrel at liberty; the mandrel is advanced slightly 
forward, and one of the screw-keys is elevated by its wedge until 
it becomes engaged with its corresponding guide-screw, and now 
as the mandrel revolves, it also advances or retires in the exact 
path of the screw selected. 

The modern screw-mandrel lathe has a cast-iron frame, and 
hardened steel collars which are not divided ; the guide screws 
are fitted as rings to the extreme end of the hardened steel 
mandrel, and they work in a plate of brass, which has six scollops, 
or semicircular screws upon its ed^e. \Vlien this mandrel is 
used for plain turning, its traverse is prevented by a cap which 
extends over the portion of the mandrel protruding through the 
collars.* 



For further detail* of the construction of the old screw-mandrel lathes, the 
reader is referred to Mozon, Plumier, Lcupold, Ac. ; and to pages 30 to 42 of the 



G14 APPLICATION OF THE SCREW-MANDREL. 

In cutting screws with either the old or modern screw-man- 
drel, the work is chucked, and the tool is applied, exactly in the 
manner of turning a plain object; but the mandrel requires an 
alternating motion backwards and forwards, somewhat short of 
the length of the guide screw, this is effected by giving a 
swinging motion or partial revolution to the foot wheel. The 
tool should retain its place with great steadiness, and it is there- 
fore often fixed in the sliding rest, by which also it is then 
advanced to the axis of the work with the progress of the 
external screw, or by which it is also removed from the center 
in cutting an internal screw. 

To cut a screw exceeding the length of traverse of the mandrel, 
the screw tool is first applied at the end of the work, and when 
as much has been cut as the traverse will admit, the tool is shifted 
the space of a few threads to the left, and a further portion is 
cut ; and this change of the tool is repeated until the screw 
attains the full length required. "When the tool is applied by 
hand, it readily assumes its true position in the threads, when it 
is fixed in the slide rest its adjustment requires much care. 

In screwing an object which is too long to be attached to the 
mandrel by the chuck alone, its opposite extremity is sometimes 
supported by the front center or popit head ; but the center 
point must then be pressed up by a spring, that it may yield to 
the advance of the mandrel : this method will only serve for very 
slight works, as the pressure of the screw-tool is apt to thrust 
the work out of the center. It is a much stronger and more 
usual plan, to make the extremity or some more convenient 
part of the work cylindrical, and to support that part within a 
stationary cylindrical bearing, or collar plate, which retains the 
position of the work notwithstanding its helical motion, and 
supplies the needful resistance against the tool.* 

fourth volume. And also to pages 90 to 92 of the same, for the figures and 
explanation of tbo modern screw-mandrel lathe, with cylindrical collars of 
hardened steel ; the durability of which has been occasionally brought into ques- 
tion by those who, it must be presumed, have not personally tried them. See 
remarks, page 52, of Vol. IV. 

* In cutting the screws upon the ends of glass smelling-bottles, and similar 
works incapable of being cut with steel tools, the bottle is mounted on a traversing 
mandrel, which is moved slowly by hand, and the cutting tool is a metal disk 
revolving rapidly on fixed centers, and having an angular edge fed with emery 
and water; in BOIUO rare cases a diamond is used as the cutting tool. 



SCREW-LATHES WITH TRAVERSING ' ". 

The amateur wh - dillieulty in cutting screws 

flying, or with the common mandrel :ui<l hniul-tool unassistedly, 
will find the screw mandrel an apparatus by fnr the most generally 
convenient fur those works, in wood, ivory, and metal turning, to 
which the screw box, and the taps and dies are inapplicable. 

the screw-mandrel requires but a very small cli 
apparatus, and whatever may be the diameter of the woiv 
ensures perfect copies of the guide screws, the half dozen 
varieties of which, will be found to present abundant choice aa 
to coarseness, iu respect to the ordinary purposes of turning. 

SECT. VII. ON CUTTING SCREWS IN LATHES WITH TRAVERSING 

TOOLS. 

! cat number of the engines for cutting screws, and also of 
the other shaping and cutting engines now commonly used, are 
clearly to be traced to a remote date, so far as their principles 
are concerned. 

For instance, the germs of many of these cutting machines, 
in which the principles are well developed, will be found in the 
primitive rose engine machinery with coarse wooden frames, and 
arms, shaper plates, cords, pulleys, and weights, described in the 
earliest works on the lathe, and referred to in pages 4 to 8 of 
Vol. I. ; whilst many others are as distinctly but more carefully 
modelled in metal, in the tools used in clock and watchmaking, 
many of which have also been published. 

The principles of these machines being generally few and 
simple, admit of but little change ; but the structures, which are 
most diversified, nay *il most endless, have followed the degrees 
of excellence of the constructive arts at the periods at which 
they have been severally made, combined with the inventive 
talent of their projectors. 

In most of the screw-cutting machines a previously-formed 
screw is employed to give the traverse, such are copying machines, 
and will form the subject of the present section; and a few 
other engines serve to oriyintitc screws, by the direct employ- 
ment of an inclined plane, or the composition of a rectilinear 
and a circular motion ; the notice of this kind of screw machi- 
will be deferred until the next section. 

The earliest screw-lathe Kn\\n to the author, bears the date 
of 15G9, and this curious machine, which is represented in 



616 



BESSON'S SCREW-CUTTING LATHE. 



fig. 593, is thus described by its inventor Besson ; "Espies de 
Tour en nulle part encore veiie et qui riest sans subtilite, pour 
engraver petit a petit la Vis a lentour de toute Figure ronde et 
solide, voire mesmes ovale." * 




The tool is traversed alongside the work by means of a guide- 
screw, which is moved simultaneously with the work to be 
operated upon, by an arrangement of pulleys and cords too 
obvious to require explanation. It is however worthy of 
remark, that bad and imperfect as the constructive arrangement 
is, this early machine is capable of cutting screws of any pitch, 
by the use of pulleys of different diameters ; and right and left 
hand screws at pleasure, by crossing or uncrossing the cord ; 
and also that in this first machine the inventor was aware that 
a screw-cutting-lathe might be used upon elliptical, conical, and 
other solids. 

The next illustration, fig. 594, represents a machine described 
as " A Lathe in which without the common art all sorts of screws 
and other curved lines can be made ; " this was invented by 

* The figure is copied half size from plate 9 of the work entitled " Des Instru- 
mentt MatMmatiquts et Mtchaniques, <kc., Inventees par Jaques Sesson." Firat 
Latin and French Edit., fol. 1569. Second Edit., Lyons, 1578 ; also a Latin Edit., 
Lyons, 1582. The same copper plates are used throughout. 



ORANI' NO IMIII. 






M. (irnmlj.an prior to 1729.* The constructive details of tins 
machine, which are also sufficiently apparent, are iu some 
respects superior to those in Hcsson's; but the two are alik- 
open to tin- iniprrlVrtioii due to the transmissions of motion by 
cords; and (nandjran's is additionally imperfect as the scheme 
represented, will fail to produce an equable traverse of the 




mandrel compared with its revolution, owing to the continual 
change in the angular relations between the arms of the bent 
lever, and the mandrel and cord respectively. Sometimes the 
spiral board or templet *, is attached to the bent lever, to 
act upon the end of the mandrel ; this also is insufficient to 
produce a true screw in the manner proposed. 

Several of the engines for cutting screws, appear to be derived 
from those used for cutting fusees, or the short screws of hyper- 
bolical section, upon which the chains of clocks and watches are 
wound, in order to counteract the unequal strength of the 
different coils of the spiral springs. The fusee engines, which 
are very numerous, have in general a guide-screw from which 
the traverse of the tool is derived, and the illustration fig. " 
selected from an old work published in 17 U, is not only one of 
the earliest, but also of the most exact of this kind; and it 
exhibits like-wise the primitive application of change wheels, for 
producing screws of varied coarseness from one original. 

Communicated to the " AcadSmic Koyale," in 17-'.', and printed in tho 
u Machiutt ttppnmritt," tome v. 1735. As a matter of arrangement, tbu figure 
belong* to Sect. VI., but as * specimen of early mechauum, ito preteut place 
eui more appropriate. 



618 



OLD FUSEE ENGINE WITH CHANGE WHEELS. 



This instrument is nearly thus described by Thiout. "A lathe 
which carries at its extremity two toothed wheels ; the upper is 
attached to the arbor, the clamp at the end of which holds the 
axis of the fusee to be cut, the opposite extremity is retained 
by the center ; the fusee and arbor constitute one piece, and are 
turned by the winch handle. The lower wheel is put in movement 
by the upper, and turns the screw which is fixed in its center : 
the nut can traverse the entire length of the screw, and to the 
nut is strongly hinged the lever that holds the graver or cutter, 
and which is pressed up by the hand of the workman. Several 
pairs of wheels are required, and the smaller the size of that 
upon the mandrel, the less is the interval between the threads 
of the fusee " *. 



Fig. 595. 




In the general construction of the fusee engine, the guide- 
screw and the fusee are connected together on one axis, and are 
moved by the same winch handle : the degree of fineness of the 
thread on the fusee is then determined by the intervention of a 
lever generally of the first order j a great variety of construc- 
tions have been made on this principlef, the mode of action will 
be more clearly seen in the next figure, wherein precisely the 
same movements are applied to the lathe for the purpose of 
cutting ordinary screws. 

The apparatus now referred to is that invented by Mr. Ilealey 

* Tkioufi Traiti d'Horloyerie, Mechanique ct Pratique, &c., 4to, Paris, 1741, 
vol. L, page 69, plate 27. The uamo of the iuventor is not given. 

f Three are described in Thiout's Treatise : namely, in plates 25, 26, and 27, 
the first by Regnaud de Chaalon. Other examples will be found in Heed's Cyclo- 
pedia, Article Fusee, Plates Horology, 36 and 37. 






. A I' I'll: 



619 



9o o o| * 



of Dublin, an amateur;* it is universal, or capable within 

iiu limits of cutting all kinds of screws, either right or left 

handed, and i in plan in tig. 590, in which C is the 

chuck which carries the work to be screwed, and / is the tool 

which lies upon r r the lathe-rest, that is placed at right angles 

lie bearer, and is always free to move in its socket *, as on a 

center because the binding screw is either loosened or rcm<>\< .1. 

On the outside of the chuck C is cut a < .ide screw, 

which we will suppose to be right-handed. The nut n n, which 
fits the screw of the chuck, is extended into a long arm, ami 
the latter communicates with the lathe-rest by the connecting 
rod c c. As the lathe revolves backwards and forwards the 
arm n (which is retained horizontally by a guide pin g), 
traverses to and fro as regards 
the chuck and work, and cai 
the lathe-rest r r, to oscillate in 
its socket *. The distance s t 
being half s r', a right hand screw 
of half the coarseness of the guide 
will be cut; or the tool being 
nearer to, and on the other side 
of, the center 8, as in the dotted 
position /', a finer and left haud 
screw will be cut. 

The rod c c may be attached in- 
differently to any part of n n y but 
the smallest change of the re- 
lation of * / to * r, would mar 
the correspondence of screws cut at different periods, and there- 
fore t and r should be united by a swivel joint capable of being 
fixed at any part of the lathe r. -t / /', which is omitted in Mr. 
llealcy's perspective drawing of the apparatus. 

:ie of the least perfect of the modes of originating 
screws, it should therefore be only applied to such as are 
short; as owing to the variation in the angular relation of the 
parts, tin motion given to the tool is not strictly constant or 
equable; when in the midway position, the several parts should 
lie - tt right angles to each other, in order, as far as 

possible, to :i\oid the error. The inequality of the screw is 

:ot described iu Tilloch's Philosophical Hag. for 1804, Vol. zu . \-\ 




620 



VARLEY'S SCKEW-CUTTIXG LATHE. 



imperceptible in the short fusee, and it would be there harmless 
even if more considerable ; but a perfect equality of coarseness 
or of angle, is imperative in longer screws, and those to be fitted 
one to the other, a condition uncalled for in the fusee, which 
has only to carry a chain. 

The apparatus invented by the late Mr. S. Varley, and repre- 
sented in plan in figs. 597 and 598, although it does not present 
the universality of the last, is quite correct in its action and far 
more available ; it is evidently a combination of the fixed man- 
drel, and the old screw-mandrel, fig. 592, p. 613. Four different 
threads are cut on the tube which surrounds the mandrel, and 
the connection between the guide screw and the work, is by 
the long bar b b, which carries at the one end a piece g filed 
to correspond with the thread, and at the other, a socket in 
which is fixed a screw tool /, corresponding with the guide at 
the time employed. 

598. 




' r 


* r 

| OO 




::V 

r r 




The lathe revolves with continuous motion; and the long bar 
or rod being held by the two hands in the position shown, the 
guide g, and the tool /, are traversed simultaneously to the left 
by the screw guide ; and when the tool meets the shoulder of 
the work, both hands are suddenly withdrawn, and the bar is 
shifted to the right for a repetition of the cut, and so on until 
the completion of the screw. The guide g, is supported upon 
the horizontal plate p, which is parallel with the mandrel, and 
the tool /, lies upon the lathe rest r. 

Beneath the tool is a screw which rubs against the lathe rest r, 
and serves as a stop, this makes the screw cylindrical or conical, 
according as the rest is placed parallel or oblique. For the 
internal screw, the tool is placed parallel with the bar, as in 
fig. 598 ; and the check screw is applied on the side towards the 
center, against a short bar, parallel with the axis of the lathe. 



LATHES WITH GUIDE-SCREWS \ M> Mi\\..K WHEELS. ' 

As in the .srrew-inamlrel lathes, the screws heroine exact 
eoptcs of the screw-guides, and to a , -lianism 

fulfils the ofliee of the slide-rest; but at the same time, more 
trouble is required for the adjustment of the apparatus. In 
general the guide-rod must be supposed to act somewhat as an 
inrumhrniice to the free use of the tool, which is applied in a 
less favourable manner, when the screw is small compared with 
the exterior diameter of the work, as it must then project con- 
siderably from the bar: so that on the whole the traversing 
mandrel is a far more available and convenient arrangement.* 

None of the machines which have been hitherto described, are 
proper for cutting the accurate screws, of considerable length or 
of great diameter, required in the ordinary works of the en- 
gineer; but these are admirably produced by the screw-cutting 
lathes, in whieh the traverse of the tool is effected by a long 
piide-screw, connected with the mandrel that carries the work, 
by a system of change wheels, after the manner employed a 
century back, as in fig. 595. The accuracy of the result now 
depends almost entirely upon the perfection of the guide-screw, 
and which we w ill suppose to possess very exactly 2, 4, 5, 6, or 
some whole number of threads in every inch, although we shall 
for the present pass by the methods employed in producing the 
original guide screw, which thus serves for the reproduction of 
those made through its agency. 

The smaller and most simple application of the system of 
change wheels for producing screws, is shown in fig. 599. The 
work is attached to the mandrel of the lathe by means of a 
chuck to which is also affixed a toothed wheel marked M. 
therefore the mandrel, the wheel, and the work partake of one 
motion iu common: the tool is carried by the slide-rest, the 
principal slide of which is placed parallel with the axis of the 
lathe as in turning a cylinder, and upon the end of the screw 
near the mandrel, is attached a tooth wheel S, which is made 
to engage in M, the wheel carried by the mandrel. 

As the win els are supposed to contain the same number of 
teeth, they will revolve in equal times, or make continually turn 
for turn ; and therefore in each revolution of the mandrel and 

The details of this apparatus will b found in the description of the same 
by Mr. Cornelius Varley, the nephew of the inventor, in the Trans. Soo. of Art*, 
TO!, zliii., p. 90, 1825. 



622 FIXED SLIDE-REST AND CHANGE WHEELS. 

work, the tool will be shifted in a right line, a quantity equal to 
one thread of the guide-screw, and so with every coil throughout 
its extent of motion. Consequently, the motion of the two axes 
being always equal and continuous, the screw upon the work 
will become an exact copy of the guide-screw contained in the 
slide-rest, that is, as regards the interval between its several 
threads, its total length, and its general perfection. 




But the arrows in M and S, denote that adjoining wheels 
always travel in opposite directions; when therefore the mandrel 
and slide-rest are connected by only one pair of wheels, as in 
fig. 599, the direction of the copy screw is the reverse of that of 
the guide. The right-hand screw being far more generally 
required in mechanism, when the combination is limited to its 
most simple form, of two wheels only, it is requisite to make 
the slide-rest screw left-handed, in order that the one pair of 
wheels may produce right-hand threads. 

But a right-hand slide-rest screw may be employed to produce 
at pleasure both right and left hand copies, by the introduction 
of either one or two wheels, between the exterior wheels M 
and S, fig. 559. Thus, one intermediate axis, to be called I, 
would produce a right-hand thread : two intermediate axes, I I, 
would produce a left-hand thread, and so on alternately; and 
this mode, in addition, allows the wheels M and S to be placed 
at any distance asunder that circumstances may require. 

In making double thread screws the one thread is first cut, 
the wheels are then removed out of contact, and the mandrel 
is moved exactly half a turn before their replacement, the second 
thread is then made. In treble threads the mandrel is twice 
disengaged, and moved one-third of a turn each time, and so on. 



FIXED SLIDE-REST AND tll.vNGE WHEELS. 



When i nt ( rmediate wheels are employed, it becomes necessary 
to build up from the bearers some descript ion of pedestal, or from 
tin- lathe-head some kind of bracket, which may serve to carry 
the axes or sockets upon which the interim mate wheels rev<> 
These parts hare received a great variety of modifications, three 
of which are introduced in the diagrams 600 to 602 ; the wheels 
supposed to be upon the mandrel, are situated on the dot 
line M M, and those upon the slide-rest on the line S S. 



i'..--. M . 



601. 



602. 



I t 




The rectangular bracket in fig. 600, has two straight mortises ; 
by the one it is bolted to the bearers of the lathe, and by the 
other it carries a pair of wheels, whose pivots are in a short 
piece, which may be fixed at any height or angle in the morr 
so that one or both wheels, I I, may be used according to cir- 
cumstances. In fig. 601, the intermediate wheel, or wheels, are 
carried by a radial arm, which circulates around the mandrel, 
and is fixed to the lathe head by a bolt passed through the 
circular mortise. In fig. 601, a similar radial arm is adjustable 
around the axis of the slide-rest screw, in the fixed bracket. 

Sometimes the wheel supposed to be attached to the slide- 
rest, is carried by the pedestal or arm, fixed to the bed or 
headstock of the lathe; in order that a shaft or spindle may 
proceed from the wheel S, and be coupled to the end of the 
slide-rest screw, by a hollow square or other form of socket, so 
as to enable the rest to be placed at any part of the length of 
the bearer, and permit a screw to be cut upon the end of a 
long rod.* 

The abaft sometime* terminates at each end In universal joints, in order to 
accommodate any trifling want of parallelism in the parts, if however the shaft 
be placed only a few degree* oblique, the motion transmitted ceases to be uniform, 
or it is accelerated and retarded in every revolution, which is fatal in screw cutting. 



TRAVERSING SLIDE-REST AND CHANGE WHEELS. 

This change in the position of the slide-rest, is also needful in 
cutting a screw, which exceeds the length the rest can traverse, 
as such long screws may then be made at two or more distinct ope- 
rations; before commencing the second trip the tool is adjusted 
to drop very accurately into the termination of that portion of 
the screw cut in the first trip, which requires very great care, in 
order that no falsity of measurement may be discernible at the 
parts where the separate courses of the tool have met. This 
method of proceeding, has however from necessity, been followed 
in producing some of the earliest of the long regulating screws, 
which have served for the production of others by a method 
much less liable to accident, namely, when the cut is made 
uninterruptedly throughout the extent of the work. 



In the larger application of the system of change wheels, the 
entire bed of the lathe is converted into a long slide -rest, the 
tool carriage with its subsidiary slides for adjusting the position 
of the tool, then traverses directly upon the bed ; this mode has 
given rise to the name " traversing or slide-lathe," a machine 
which has received, and continues to receive, a variety of forms 
in the hands of different engineers. It would be tedious and 
unnecessary to attempt the notice of their different construc- 
tions, which necessarily much resemble each other; more 
especially as the principles and motives, which induce the 
several constructions and practices, rather than the precise 
details of apparatus, are here under consideration. 

The arrangement for the change wheels of a screw-cutting 
lathe given in fig. 603, resembles the mode frequently adopted. 
The guide-screw extends through the 
middle of the bed, and projects at the 
end ; there is a clasp nut, so that when 
required, the slide-rest may be detached 
from the screw and moved independently 
of the same. The train of wheels is placed 
at the left extremity of the lathe ; there 
is a radial arm which circulates around the 
end of the main screw, the arm has one 
or two straight mortises, in which are 
fixed the axes of the intermediate wheels, 
and there are two circular mortises, by 




I SLIDE REST \M> IL1M LATHB. 

whirh the arm may la- secured to the lathe bed, in any required 
position, by its two binding screws. 

On comparing the relative facilities for cutting screws, either 
with the slide-n^t furnished with a train of wheels, or with the 
tra\ersing or screw-cutting lathe, the advantage will be found 
greatly in favour of the latter ; for instance : 

With the slide-rest arrangement, fig. 599, the work must be 
always fixed in a chuck to which the first of the change wheels 
can be also attached ; the wheels frequently prevent the most 
favourable position of the slides from being adopted; and in 
cutting hollow screws the change wheels entirely prevent the 
tool carriage of the slide-rest from being placed opposite to the 
center, and therefore awkward tools, bent to the rectangular 
form, must be then used. The slide-rest also requires frequent 
attention to its parallelism with the axis of the lathe, or the 
screws cut will be conical instead of cylindrical. 

With the traversing lathe, from the wheels being at the back 
of the mandrel, no interference can possibly arise from them, 
and consequently the work may be chucked indiscriminately on 
any of the chucks of the lathe ; every position may be given to 
the slide carrying the tool, and therefore the most favourable, 
or that nearest to the work, may be always selected, and the 
tools need not be crooked. As the tool carriage traverses at 
once on the bearers of the lathe, the adjustment for parallelism 
is always true, and the length of traverse is greatly extended. 



The system of screw-cutting just explained is very general 
and practical : for instance, one long and perfect guide-screw 
(which we will call the guide), containing 2, 4, 6, 8, 10, or any 
precise number of threads per inch having been obtained, it 
becomes very easy to make from it subsequent screws (or copies], 
which shall be respectively coarser and finer in any determined 
degree. The principal is, that whilst the copy makes one revo- 
lution, the guide must make so much of one revolution, or so 
many, as shall traverse the tool the space required between each 
thread of the copy ; and this is accomplished by selecting change 
wheels in the proportions of these quantities of motion, or, iu 
other words, in the proportion required to exist between the 
:uide-cre\v and the copy. 

In explanation, we will suppose the guide to have 6 threads 

8 8 



626 MODES OF COMPUTING THE TRAINS OF WHEELS 

per inch, and that copies of 18, 14, 12, 8, 3, 2, 1, threads per 
inch, are required : the two wheels must be respectively in the 
proportions of the fractions -^, T 6 T , T%J> > 1> 4> T> tne guide 
beiiig constantly the numerator. The numerator also represents 
the wheel on the mandrel, and the denominator that on the 
guide screw ; any multiples of these fractions may be selected 
for the change wheels to be employed. 

For example, any multiples of -^, as , -ff, -f , &c., will 
produce a screw of 18 threads per inch, the first and finest of 
the group ; and any multiples of 4, as -f-, '-^0, &c., will produce 
a screw of 1 thread per inch, which is the last and coarsest of 
those given. 

Screws 2, 4, or 6 times as fine, will result from interposing a 
second pair of wheels, respectively multiples of -^, 4> &> an d 
placed upon one axis. 

For instance, the pair of wheels -f-f-, used for producing a 
screw of 18 threads per inch, would, by the combination A, 
produce a copy three times as fine, or a screw of 54 threads per 
inch.* 

Combination A. Combination B. Combination C. 

M Interm. S M Interm. S M Interm. S 

24 60 120 24 27 53 

20 72 72 20 39 107 

And the wheels ^ used for the screw of one thread per 
inch, would, by the combination B, produce a copy three times 
as coarse, or of three inches rise. Whatsoever the value of the 
intermediate wheels, whether multiples of -|, , , &c., they 
produce screws, respectively of -|-, %, -f-, the pitches of those 
screws, which would be otherwise obtained by the two exterior 
wheels alone ; and in this manner a great variety of screws, 
extending over a wide range of pitch, may be obtained from a 
limited number of wheels. 

For instance, the apparatus Holtzapffel & Co. have recently 
added to the slide rest, after the manner of figs. 599 and 601, has 
a series of about fifteen wheels, of from 15 to 144 teeth, employed 
with a screw of 10 threads per inch; several hundred varieties 
of screws may be produced by this apparatus, the finest of which 
has 320 threads per inch, the coarsest measures 7-f inches in 

Fig. 601, represents the wheels referred to in combination A, and fig. 602, 
those in combination B. 



UBD IN SCREW CUTTIN'.. 627 

h coil or rise; and the screws may be made right or left 
handed, double, triple, quadruple, or of any number of threads. 
The tim-t combinations are only useful for self-acting turning, 
those of medium coarseness serve for nil the ordinary purposes 
of screws; whilst the very coarse pitches are much employed in 
ornamental works of the character of the Elizabethan twist: 
and iu cutting these coarse screws, the motion is given to the 
slide-rest screw, and by it communicated to the mandrel. 

The value of any combination of wheels may be calculated as 
vulgar fractions, by multiplying together all the driving wheels 
as numerators, and all the driven wheels as denominators, 
adding also the fractional value, or pitch, of the guide-screw ; 
thus iu the first example A : 

24 x 20 x 1 = 480 1 

or reduced to its lowest terms . 

60 x 72 x 6 = 25920 54 

The fraction denotes that -jV of an inch is the pitch of the 
crew, or the interval from thread to thread ; also that it has 54 
threads in each inch, and which is called the rate of the screw. 

And in C, the numbers in which example were selected at 
random, the screw would be found to possess rather more than 
35 threads per inch.* 

27 x 39 x 1 1114 1 

or reduced to ita lowest terms . 

53 x 107 x 6 89026 35,H, 

In imitation of the method of change-wheels, the slide-rest 
screw is sometimes moved by an arrangement of catgut bands, 
resembling that represented in Bessou's screw lathe, page 616. 

One band proceeds from the pulley on the mandrel to a spindle 
overhead having two pulleys, and a second cord descends from 
this spindle to a pulley on the sb'de-rest.f The method offers 

The fractions should be reduced to their lowest terms before calculation, to 
avoid the necessity for multiplying such high numbers. Thus the first example 
would become reduced to 4 x J x J = 4 > 4 , and would be multiplied by inspection 
aloue, as the numerators and denominators may be taken crossways if more con- 
renient ; thus J J is equal to \, and is also equal to J, fractions which are smaller 
than | and &, the lowest terms respectively of }* and fg; the second case could not 
be thus treated, and the whole numbers must there be multiplied, as they will not 
admit of reduction. Other details will be advanced, and tables of the combination* 
of the change-wheels will be also given, in treating of the practice of cutting screws. 

f This apparatus has been applied to cutting the expanding horn snakes. See 
Mantel du To*nu*r, first edit, 1796, vol. iL, plate 21 ; and second edit., 1816, 
voL iL, plate 16 ; see also page 124-5 of the fint volume of this work. 

8 S 2 



628 FIXED SCREW TOOLS FOR ANGULAR THREADS. 

facility in cutting screws of various pitches, by changing the 
puDeys, and also either right or left hand screws, by crossing or 
uncrossing one of the bands. 

The plan is unexceptionable, when applied for traversing the 
tool slowly for the purpose of turning smooth cylinders, or sur- 
faces (which is virtually cutting a screw or spiral of about 100 
coils in the inch) ; and in the absence of better means, pulleys 
and bands are sometimes used in matching screws of unknown 
or irregular pitches, by the tedious method of repeated trials ; 
as on slightly reducing, with the turning tool, the diameter of 
either of the driving pulleys, the screw or the work becomes 
gradually finer ; and reducing either of the driven pulleys makes 
it coarser ; but the mode is scarcely trustworthy, and is decidedly 
far inferior to its descendant, or the method of change wheels. 



The screw tools, or chasing tools, employed in the traversing 
lathes for cutting external and internal screws, resemble the 
fixed tools generally, except as regards their cutting edges ; the 
following figures 604 to 606 refer to angular threads, and 607 
and 608 to square threads. 

Angular screws are sometimes cut with the single point, fig. 
604, a form which is easily and correctly made; the general 
angle of the point is about 55 to 60, and when it is only 
allowed to cut on one of its sides or bevels, it may be used fear- 
lessly, as the shavings easily curl out of the way and escape. 
But when both sides of the single point tool are allowed to cut, 
it requires very much more cautious management ; as in the 
latter case, the duplex shavings being disposed to curl over 
opposite ways, they pucker up as an angular film, and in fine 
threads they are liable to break the point of the tool, or to cause 
it to dig into, and tear, the work. Sometimes, also, a fragment 
of the shaving is wedged so forcibly into the screw by the end 
of the tool, that it can only be extricated by a sharp chisel and 
hammer. 

In cutting angular screws, it is very much more usual and 
expeditious to employ screw tools with many points, which are 
made in the lathe by means of a revolving cutter or hob, figs. 
550 and 551, page 591. Screw tools with many points, are 
always required for those angular threads which are rounded 



CLEMENT'S AND BOOMER'S CHASING TOOLS. -'.:.!J 

at the top and bottom, and which arc theucc called rounded or 
round threads. 41 

Mr. Clement gives to the screw tool for rounded threads the 
profile of tig. 605, which construction allows the tool to be 
inverted, so that the edges may be alternately used for the pur- 
pose of equalizing the section of the thread. In making the tool 
605, the hob (which is dot led), is put between centers in the 
traversing lathe, and those wheels are applied which would serve 
to cut a screw of the same pitch as the hob ; the bar of steel is 
thru fixed in the slide rest, so that the dotted line or the axis of 
the tool intersects the center of the hob. The tool is afterwards 
hollowed on both sides with the file, to facilitate the sharpening, 
and it is then hardened. In using the tool, it is depressed 
until either edge comes down to the radius, proceeding from 
the (black) circle, which is supposed to represent the screw to 
be cut ; the depression gives the required penetration to the 
upper angle, and removes the lower out of contact.f 

Mr. Bodmer's patent chasing tool is represented in fig. 606 ; 
the cutter, c, is made as a ring of steel which is screwed internally 
to the diameter of the bolt, and turned externally with an 
undercut groove, for the small screw and nut by which it is held 
in an iron stock, *, formed of a corresponding sweep ; for dis- 
tinctness the cutter and screw are also shown detached. The 
center of curvature of the tool is placed a little below the center 
of the lathe, to give the angle of separation or penetration ; 
and after the tool has been ground away in the act of being 
sharpened, it is raised up, until its points touch a straight edge 
applied on the line a a of the stock ; this denotes the proper 
height of center, and also the angle to which the tool is 
intended to be hooked, namely 10 degrees: each ring makes 

Mr. Clement considers the many points to act with less risk than the single 
point, because in the processes of hardening, first the hob and then the tcrtic tool, 
they both become slightly enlarged, or a little coarser than the pitch of the 
screw; consequently port of the teeth cut on one side, and part on the other, 
but none of them on both sides of the points ; which latter action gives rise to 
confusion by interrupting the free escape of the shavings. 

t In making a hob with rounded threads, it is usual to prove whether the top 
and bottom of the thread are equally rounded, by driving two different pieces 
of lead into the hob with a hammer ; the two impressions will only fit together 
so as to exclude the light, when the departure from the simple angle is alike 
at the top and bottom of the hob, and that the thread is perpendicular or doe* 
not lean. Master taps are similarly proved. 



G30 



SCREW TOOLS FOR SQUARE THREADS. 



four or five cutters, and one stock may be used for several 
diameters of threads. 

Angular thread screws are fitted to their corresponding nuts 
simply by reduction in diameter; but square thread screws 
require attention both as to diameter and width of groove, and 
are consequently more troublesome. Square thread screws are, 
in general, of twice the pitch, or double the obliquity, of angular 
screws of the same diameters ; and, consequently, the inter- 
ference of angle before explained as concerning the diestocks, 
refers with a twofold effect to square threads, which are in all 
respects much better produced in the screw-cutting lathe. 

The ordinary tool for square thread screws is represented 
in three views in fig. 607 : the shaft is shouldered down so as to 
terminate in a rectangular part which is exactly equal to the 
width of the groove ; in general the end alone of the tool is 



Screw Tools for Angular Threads. 
Figs. 604. 



Screw Tools for Square Threads. 
Figs. 607. 



608. 




required to cut, and the sides are bevilled according to the 
angle of the screw, to avoid rubbing against the sides of the 
thread. Tools which cut upon the side alone, are also occa- 
sionally used for adjusting the width of the groove. In either 
case it requires considerable care to maintain the exact width 
and height of the tool ; the inclination of which should also 
differ for every change of diameter. 



i UK AUTHOR'S CUTTER-BAR FOR SQUARK THREADS. 631 

To obviate these severe] incom< ni. nces, the author several 
years back contrived a tool-holder, fig. 608, for carrying small 
blades made exactly rectangular. In height, as at h t the blades are 
alike, in width, u; they are exactly half the pitch of the threads, 
and they are ground upon the ends alone. The parallel blades 
are clamped in the rectangular aperture of the tool socket by the 
four screws c c ; and when the screws * *, which pass through 
the circular mortises in the sockets, are loosened, the swivel joint 
and graduations allow the blades to be placed at the particular - 
angle of the thread, which is readily obtained by calculation, 
and is estimated for the medium depth of the thread, or midway 
between the extreme angles at the top and bottom.* 

One blade, therefore, serves perfectly for all screws of the 
same pitch, both right and leffc-handed, and of all diameters ; as 
the tool exactly fills the groove, it works steadily, and the width 
of the groove and the height of center of the tool, are also 
strictly maintained with the least possible trouble. The depth 
of the groove, which is generally one sixth more than its width, 
is read off with great facility by means of the adjusting screw of 
the slide-rest ; especially if, as usual, the screw and its micrometer 
agree with the decimal division of the inch. 

The holder, fig. 60S, has been much and satisfactorily used for 
screws from about 20 to 2 threads per inch; but when the screw 
is coarse and oblique, compared with its diameter, the blade is 
ground away to the dotted line in /*, and is sometimes bevilled 
on the sides almost to the upper edge, to suit the obliquity of 
the thread, but without altering the extreme width of the tool. 

The tools for external screws of very coarse pitch, are neces- 
sarily formed in the lathe by aid of the corresponding wheels, 
and a revolving cutter bar resembling fig. 515, p. 569. The soft 
tool is fixed in the slide-rest, and is thereby carried against the 
revolving cutter bar, 515, which has a straight tool, either pointed 
or square as the case may be. The end of the screw-tool is thus 
shaped as part of an internal screw, the counterpart of that to 
be cut ; the face of the screw tool is filed at right angles to the 
obliquity of the thread, and the end and sides are slightly bevilled 
for penetration, previously to its being hardened. 

Internal square threads of small size, are usually cut with 

For the mode of calculating the angle* of screws, MO foot-note, p. 657. 



632 VARIOUS SCREW TOOLS OR CUTTERS. 

taps which resemble fig. 548, p. 587, except in the form of the 
teeth. When internal square threads are cut in the lathe, the 
tool assumes the ordinary form, of a straight bar of steel with a 
rectangular point standing off at right angles, in most respects 
like the common pointed tool for inside work. 

For very deep holes, and for threads of very considerable 
obliquity, cutter bars, such as fig. 515, p. 569, are used. The 
work and the temporary bearings of the bar, are all immoveably 
fixed for the time, and the bar advances through the bearings 
in virtue of its screw thread ; or otherwise a plain bar, having a 
cutter only, and not being screwed, may be mounted between 
centers in the screw lathe, and the work, fixed to the slide-rest, 
may traverse parallel with the bar by aid of the change wheels. 
The cutter bar in some cases requires a ring to fill out the space 
between itself and the hole, to prevent vibration, and it is neces- 
sary to increase the radial distance of the cutter between each 
trip, by a set screw, or by slight blows of a hammer. 

Very oblique inside cutters are turned to their respective 
forms with a fixed tool, in a manner the converse of that 
explained above ; and some peculiarities of management are 
required in using them, in order to obtain the under-cut form 
of the internal thread, but the consideration of which does not 
belong to this place. 



In cutting screws in the turning lathe the tool only cuts 
as it traverses in the one direction ; therefore whilst the cutter 
is moved backwards, or in the reverse direction, for the suc- 
ceeding cut, it must be withdrawn from the work. Sometimes 
the tool is traversed backwards by reversing the motion of the 
lathe; and in lathes driven by power, the back motionis frequently 
more rapid than the cutting motion, to expedite the process : at 
other times the lathe is brought to rest, the nut is opened as a 
hinge, so as to become disengaged from the screw, and the 
slide-rest is traversed backwards by hand, or by a pinion move- 
ment, and the nut is again closed on the screw, prior to the 
succeeding cut. This mode answers perfectly for screws of the 
same thread as the guide, and for those of 2, 4, 6, 8 times as 
coarse or as fine ; but for those of 2|-, 4, or any fractional times 
the value of the guide screw, the clasp nut cannot in general 
be employed advantageously. 



Ml. limns OF ADJUSTIV. Illi: I PIOM l -' KIW TOOLS. 633 



The progressive advance of the tool between each cut, is com- 
monly regulated by a circle of divisions or a micrometer on the 
slide-rest screw, which should always correspond with the decimal 
division of tin ini-li. The substance of the shaving may be pretty 
considerable after the lir>t entry is made, but it should dw indie 
away to a very small quantity, towards the conclusion of the 
screw. To avoid the necessity for taxing the memory with the 
graduation at \\hieh the tool stood when it was withdrawn for 
the back stroke, the author has been in the habit of employing 
a micrometer exactly like that on the screw, which is set to tin- 
same graduation, and serves as a remembrancer ; another method 
i^ to employ an arm or stop, which fits on the axis of the screw 
or handle with stiff friction, but nevertheless allows the tool to 
be shifted the two or three divisions required for each cut. 

In Mr. Roberta's screw lathe, the nut of the slide screw, 
instead of being a fixture, is made with two tails as a fork, which 
embraces an eccentric spindle ; by the half rotation of which 
spindle, the nut, together with the adjusting screw, the slide, 
and the tool, are shifted, as one mass, a fixed distance to and 
from the center, between each cut ; so as first to withdraw 
and then to replace the tool. Whilst the tool is running back, 
the screw is moved by its adjusting screw and divisions, the 
minute quantity to set in the tool for the succeeding cut, and the 
continual wear upon the adjusting screw, as well as the uncer- 
tainty of its being correctly 
moved to and fro by the indi- 6 
vidual, are each avoided. 

Sometimes, with the view 
of saving the time lost in 
running back, two tools are 
used, so that the one may 
cut as the tool slide traverses 
towards the mandrel, the 
other in the contrary direc- 
Mr. Shanks' arrange- 
ment for this purpose, as ap- 
to the screwing of bolts 
in the Inthe, is shown in 
fig. 609 ; / represents the 
front, and b the back tool, which are mounted on the one slide **, 




634 LONG SLENDER SCREWS, BACKSTAY, ETC. 

and all three are moved as one piece by the handle h, which 
does not require any micrometer. 

In the first adjustment, the wedge w, is thrust to the bottom 
of the corresponding angular notch in the slide s, and the two 
tools are placed in contact with the cylinder to be screwed. For 
the first cut, the wedge is slightly withdrawn to allow the tool/, 
to be advanced towards the work ; and for the return stroke, the 
wedge is again shifted under the observation of its divisions, 
and the slide s s, is brought forwards, towards the workman, up 
to the wedge; this relieves the tool/ and projects b, which is 
then in adjustment for the second cut ; and so on alternately. 
The command of the two tools is accurately given by the 
wedge, which is moved a small quantity by its screw and micro- 
meter, between every alternation of the pair of tools, by the 
screw h. 



In cutting very long screws, the same as in turning long 
cylindrical shafts, the object becomes so slender, that the con- 
trivance called a backstay, is always required for supporting the 
work in the immediate neighbourhood of the tool. The back- 
stay is fixed to the slide plate, or the saddle of the lathe which 
carries the tool, and is brought as near to the tool as possible ; 
sometimes the dies or bearings are circular, and fit around the 
screw; at other times they touch the same at two, three, or 
four parts of the circle only. Some of the numerous forms of 
this indispensable guide or backstay, will be hereafter shown. 

In using the screw-lathe with a backstay for long screws, it is 
a valuable and important method, just at the conclusion, to 
employ a pair of dies in the place usually occupied by the tool ; 
as they are a satisfactory test for exact diameter, and they 
remove trifling errors attributable to veins and irregularities of 
the material, which the fixed tool sometimes fails entirely to 
reduce to the general surface. The tool and backstay may be 
each considered to be built on the tops of pedestals more or less 
lofty, and therefore, more susceptible of separation by elasticity, 
than the pair of dies fixed in a small square frame. Sir John 
Robison has judiciously proposed, in effect, to link the backstay 
and turning tool together, by the employment of a small frame 
carrying a semicircular die of lignum-vitae, and a fixed turning 



MOPES 07 ORIGINATING AND IMPROVING SCREWS. 635 

tool, adjusted by a pressure screw; the frame to be applied cither 
in the liiiiul alone or in the slide rest, and to be inverted, so that 
the shavings may fall away without clogging the cutter. 

SECT. VIII. VARIOUS MODES OP ORIGINATING AND IMPROVIM. 
SCi: I< DING THOSE OF RAMSDEN, MAUU8LAY, BARTON, 

ALLAN, CL1 ND OTHERS. 

The improvement of the screw has given rise to many valuable 
schemes and modes of practice, which have not been noticed in 
the foregoing sections, notwithstanding their collective length. 
These practices, indeed, could not consistently have been placed 
in the former pages of this chapter, because some of them must 
be viewed as refinements upon the general methods, the earlier 
notice of which would have been premature; and others 
exhibit various combinations of methods pursued by different 
eminent individuals with one common object, and are therefore 
too important to be passed in silence, notwithstanding their 
miscellaneous nature. 

To render this section sufficiently complete, it appears needful 
to take a slight retrospective glance of the early and the modern 
modes of originating screws and screw apparatus ; some account 
of the former may be found in the writings of Pappus, who lived 
in the fourth century.* 

The progressive stages which may be supposed to have been 
formerly in pretty general use for originating screws, may be 
thus enumerated : 

1. The first screw-tap may be supposed to have been made by 
the inclined templet, the file, and screw-tool ; it was imperfect in 
all respects, and not truly helical, but full of small irregularities. 

2. The dies formed by the above were considerably nearer to 
perfection, as the multitude of pointed edges of 1, being passed 

The author haa been told by a classical friend, that in the works of Pappus 
Alexandrinus, a Greek mathematician of the fourth century, are to be found 
practical directions for making screws. 

The process is simply to make a templet of thin brass of the form of a right- 
angled triangle, the angles of which are made in accordance with the inclination 
uf the proposed screw. ThU triangle is then to bo wrapped round tho cyliu.l. r 
which is to be the desired screw, and a spiral line traced along its edge. The 
screw is subsequently to be excavated along this line. Minute practical direc- 
tions are given not only for every step of this process, but also for the division, 
setting out, and shaping the teeth of a worm-wheel of any required number of 
teeth to suit the screw. (Vide Pftppi Math. Col. lib. viii.. prob. zviiL) 



636 EARLY METHODS OF ORIGINATING SCREWS. 

through every groove of the die, the threads of the latter 
became more nearly equal iu their rake or angle, and also iu 
their distances and form. 

3. The screw cut with such dies would much more resemble 
a true helix than 1 ; but from the irregularities in the first tap, 
the grooves in the die 2 would necessarily be wide, and their 
sides, instead of meeting as a simple angle, would be more or less 
filled with ridges, and 3 would become the exact counterpart of 2. 

4. A pointed tool applied in the lathe, would correct the form 
of the thread or groove in 3, without detracting from its im- 
proved cylindrical and helical character; especially if the turning 
tool were gradually altered, from the slightly rounded to the 
acute form, in accordance with the progressive change of the 
screw. The latter is occasionally changed end for end, either 
in the die-stocks or in the lathe, to reverse the direction in 
which the tools meet the work, and which reversal tends to 
equalise the general form of the thread. 

5. The corrected screw 4, when converted into a master-tap, 
would make dies greatly superior to 2 ; it would also serve for 
cutting up screw tools ; and lastly, 

6. The dies 5 would be employed for making the ordinary 
screws and working taps ; and this completes the one series of 
screwing apparatus. 

One original tap having been obtained, it is often made 
subservient to the production of others ; for example, a screw 
tool, with several points cut over the corrected original 4, would 
serve for striking, in the lathe, other master-taps of the same 
thread but different diameters. The process is so much faci- 
litated by the perfection of the screw-tool, that a clever workman 
would thus, without additional correction, strike master-taps 
sufficiently accurate for cutting up other dies larger or smaller 
than 4. Sometimes also the dies 5 are used for marking out 
original taps a little larger or smaller than 4. 

As a temporary expedient, the screw tool may be somewhat 
spread at the forge fire to make a tool a little coarser, or it 
may be upset for one a little finer, and afterwards corrected 
with a file ; or screw tools may be made entirely with the file, 
and then employed for producing, in the lathe, master-taps of 
corresponding degrees of coarseness and of all diameters. 

These are in truth some of the progressive modes by which 



n SI:K KM. INK \\irn I\<I.INM> M.\\K. 



687 



under MTV careful management, great numbers of good useful 
screwing apparatus have been produced, and which answer per- 
!y well for all the ordinary requirements of " binding " or 
" attachment" screws ; or as the cement by which the parts of 
mechanism, and structures generally, arc firmly united together, 
hut \\nli the power of separation and reunion at pleasure. 

In this comparatively inferior class of screws, considerable 
latitude of proportion may be allowed, and whether or not their 
pitches or rates have any exact relationship to the inch, is a 
matter of indifference as regards their individual usefulness; but 
in superior screws, or those which may be denominated " regu- 
lating" and " micrometrical" screws, is does not alone suffice 
that the screw shall be good in general character, and as nearly 
as possible a true helix ; but it must also bear some defined pro- 
portion to the standard foot or inch, or other measure. The at- 
tainment of this condition has been attempted in various ways, 
to some of which a brief allusion was made in the second sec- 
tion, and a few descriptive particulars will now be offered. 



Fig. 610. 




The apparatus for cutting original screws by means of a wedge 
or inclined plane, appears to be derived from the old fusee engine, 
a drawing of which is given in fig. 610; in principle it is perfect, 



638 FUSEE ENGINE WITH INCLINED PLANE. 

and it is also universal within the narrow limitation of its 
structure *. 

The handle h, gives rotation to the work ; and at the same 
time, by means of the rack r r, and the pinion fixed on its axis, 
the handle traverses a slide which carries on its upper surface a 
bar i; the latter moves on a center, and may be set at any incli- 
nation by the adjusting screw and divisions; it is then fixed by 
its clamping screws. The slide s, carries the tool, and the end 
of this slide rests against the inclined plane z, through the inter- 
vention of a saddle or swing piece ; the slide and tool are drawn 
to the left hand by the chain which is coiled round the barrel b, 
by means of a spiral spring contained within it. 

Supposing the bar i i, to stand square or at zero, no motion 
would be impressed on the tool during its traverse, which we will 
suppose to require 10 revolutions of the pinion. But if the bar 
were inclined to its utmost extent, so that we may suppose the 
one end to project exactly one inch beyond the other, in reference 
to the zero line or the path of the slide, then during the 10 re- 
volutions of the screw, the tool would traverse one inch, or the 
difference between the ends of the inclined bar i ; and it would 
thereby cut a screw of the length of one inch, or the total incli- 
nation of the bar, and containing ten coils or threads. 

But the inclination of the bar is arbitrary, and may be any 
quantity less than one inch, and it may lean either to the right 
or left ; consequently the instrument may be employed in cutting 
all right or left hand screws, not exceeding 10 turns in length, 
nor measuring in their total extent above one inch, or the maxi- 
mum inclination of the bar. 

The principle of this machine may be considered faultless ; but 
in action it will depend upon several niceties of construction, 
particularly the straightness of the slide and inclined bar, 
the equality of the rack and pinion, and the exact contact 
between the tool slide and the inclined plane. These difficulties 
augment very rapidly with the increase of dimensions; and 

* The drawing is the half size of fig. 1, plate xvii. of Ferdinand Berthoud's 
Eaai tur L' Horlogeric, Paris, 1763. M. Berthoud says, " The instrument is the 
most perfect with which I am acquainted; it is the invention of M. le Lievre, 
and it has been reconstructed and improved by M. Gideon Duval." The templet 
or shaper plate determines the hyperbolical section of the fusee. Plate 37 of 
Rees's Cyclopedia contains an engraving of a different modification of the fuseo 
engine, also with an inclined plane, which is ascribed to Hiudley of York. 



REID'S SCREW ENGINE. RAMSDEN'S DIVIDING ENGINE. 639 

probably the inachiue made by Mr. Adam Reid exclusively for 
cutting screws, is aa large as can be safely adopted ; the inclined 
plane is 44 inches long, but the work cannot exceed ly/j inch 
ilium., 24 inch long, or ten threads in total length. The ap- 
plication of the iiulimil plane to cutting screws is therefore 
too contracted for the ordinary wants of the engineer, which 
are now admirably supplied by the screw-cutting lathes with 
guide screws and change wheels. 

The accuracy of screws has always been closely associated 
with the successful performance of engines for graduating circles 
and right lines, and the next examples will be extracted from 
the published accounts of the dividing engines made by Mr. 
Ramsden.* 

* Thia eminent individual received a reward from the Board of Longitude, upon 
the condition that he would furnish, for the benefit of the public, a full account of 
the methods of constructing and using his dividing machines, and which duly 
appeared in the following tracts : " Description of an Engine for dividing Mathe- 
matical Instruments, by Ramsden, 4 to, 1777." Also, "Description of an Engine 
for Dividing Straight Lines, by Ramsden, 4to, 1779," from which the following 
particulars are extracted : 

The circular dividing engine consisted of a large wheel moved by a tangent 
screw ; the wheel was 45 inches diameter, and had 2160 teeth, so that six turns 
of the tangent screw moved the circle one degree ; the screw had a micrometer, 
and also a ratchet wheel of 60 teeth, therefore one tooth equalled one-tenth of 
a minute of a degree. The screw could be moved a quantity equal to one single 
tooth, or several turns and parts, by means of a cord and treadle, so that the 
circular works attached to the dividing wheel could be readily graduated into the 
required numbers, by setting the tangent screw to move the appropriate 
quantities ; the dividing knife or diamond point always moved on one fixed 
radial line, by means of a swing frame. 

In ratching or cutting the wheel, says Mr. Ramsden, " the circle was divided 
with the greatest exactness I was capable of, first into 5 parts, and each of these 
into 3 ; these parts were then bisected 4 times ; " this divided the wheel into 240 
divisions, each intended to contain 9 teeth. The ratching was commenced at 
each of the 240 divisions, by setting the screw each time to zero by its micro- 
meter, and the cutter frame to one of the great divisions by the index ; the 
cutter was then pressed into the wheel by a screw, and the cutting process 
was interrupted at the ninth revolution of the screw. It was resumed at the 
next 240th division (or nine degrees off), as at first, and so on. 

This process was repeated three times round the circle, after which the ratching 
was continued uninterruptedly around the wheel about 300 times ; this completed 
the teeth with satisfactory accuracy. The tangent screw was subsequently made, 
as explained in the text 

Thejfrrf application of the tangent screw and ratchet to the purposes of gradu- 
ation, appears to have been in the machine for cutting clock and watch wheels, by 
Pierre Fardoil ; see plat* 23 of Thiout's Trait c 1/orlvgerit, 4c. Paris, 1741. At 
page 55 is given a table of ratchets aud settings for wheels from 102 to 800 Ueth. 



640 



RAMSDEN'S SCREW-CUTTING ENGINES. 



In Mr. Ramsden's description of his dividing engine for 
circles, he says : " Having measured the circumference of the 
dividing wheel, I found it would require a screw about one 
thread in a hundred coarser than the guide screw." He goes on 
to explain that the guide-screw moved a tool fixed in a slide 
carefully fitted on a triangular bar, an arrangement equivalent 
to a slide-rest and fixed tool ; the screw to be cut was placed 
parallel with the slide and the guide-screw and copy were con- 
iiected by two change wheels of 198 and 200 teeth (numbers in 
the proportion required between the guide and copy), with an 
intermediate wheel to make the threads on the two screws in 
the same direction. As no account is given of the mode in 
which the guide-screw was itself formed, it is to be presumed 
it was the most correct screw that could be obtained, and was 
produced by some of the means described in the beginning of 
the present section. 

Mr. Ramsden employed a more complex apparatus in origi- 
nating the screw of his dividing engine for straight lines, which 
it was essential should contain exactly 20 threads in the inch; 
a condition uncalled for in the circular engine, in which the 
equality of the teeth of the wheel required the principal degree 
of attention. This second screw-cutting apparatus, which may 
be viewed as an offspring of the circular dividing engine, is 
represented in plan, in fig. 611, and may be thus briefly ex- 
plained. 



Fig. 611. 




The guide-screw G is turned round by the winch, and in each 
revolution moves the larger tangent wheel one tooth; the 



KAMSDEN'S SCREW-CUTTINO ENGINES, ETC. ''<ll 

tangent wheel has a small central boss or pulley/;, to which is 
attached tin- one end of an elastic slip of steel, like a watch- 
spring; tin- other end of the slip is connected with the slide*, 
that carries the tool /, in a right line beside the screw C, which 
hitter is the piece to he cut ; and (', is connected with the gu; 
A G, by a bcvil pinion and wheel, g and c, as 1 to 6. 

To proportion the traverse of the tool to the interval or pitch 
of the seieu, two dots were made on the slide *, exactly five 
inches asunder; and in that space the screw should contain I'll) 
coils, to be brought about by GOO turns of the handle. The 
irnidc-screw was moved that number of revolutions, and the 
diameter of p, was reduced by trial, until the COO turns traversed 
the slide exactly from dot to dot ; these points were observed 
at the time through a lens placed in a fixed tube, and having 
a fine silver wire stretched diametrically across the same as an 
index.* 

The late Mr. Henry Maudslay, devoted an almost incredible 
amount of labour and expense, to the amelioration of screws and 
screwing apparatus; which, as regarded the works of the mill- 
wright and engineer, were up to that time in a very imperfect 
state. With the view of producing screws of exact values, he 
employed numerous modifications of the chain or band of steel, 
the inclined knife, the inclined plane, and indeed each of the 
known methods, which however he remodelled as additions to the 

See " Description of an Engine for Dividing Straight Lines," pages 13 to 16. 

In the construction of his dividing engine for straight lines, Ramsden very closely 
followed his prior machine for circular lines, if we conceive the wheel spread out as 
a rectilinear slide. On the one edge of the main slide which carried the work, was 
cut a screw-form rack, with twenty teeth per inch, which was moved by a short 6xcd 
crew of the same pitch, by mean* of ratchets of 50, 48, or 32 teeth respectively; the 
crew could be moved a quantity equal to one single tooth, or to several turns and 
parts, by means of a treadle. To obtain divisions which were incompatible with 
the subdivision of the inch into 1000, 960 or 640 parts, the respective values of one 
tooth, the scale was laid on the slide at an angle to the direction of motion ; when 
the swing frame was placed to traverse the Icnife at right angles to the path of the 
slide, the graduations were lengthened ; when the knife was traversed at right 
angle* to the Mique position of the scale being divided, they were shortened. This 
was to a small degree equivalent to having a screw of variable length. In cutting 
the screw-form teeth of the rectilinear dividing engine, the entire length, namely, 
25-6 inches, was first divided very carefully by continual bisection into spaces of 
eight-tenths of an inch, by hand as usual, and the screw-cutter was placed at zero 
at each of these divisions, pressed into the edge of the slide, and revolved 
sixteen times ; after three repetitions at each of the principal spaces, the entire 
length was niched continuously until the teeth were completed. 

T T 



G42 MAUDSLAY'S METHODS OF ORIGINATING SCREWS. 

ordinary turning-lathe with a triangular bar; a natural result, 
as he was then in the frequent habit of constructing that 
machine, and which received great improvement at his hands. 

It was noticed at page 581, that of all the methods he gave 
the preference to the inclined knife, applied against a cylinder 
revolving in the lathe, by means of a slide running upon the bar 
of the lathe; which besides being very rapid, reduced the 
mechanism to its utmost simplicity. This made the process to 
depend almost alone on the homogeneity of the materials, and 
on the relation between the diameter of the cylinder and the 
inclination of the knife ; whereas in a complex machine, every 
part concerned in the transmission of motion, such as each axis, 
wheel and slide, entails its risk of individual error, and may 
depreciate the accuracy of the result ; and to these sources of 
disturbance, must be added those due to change of temperature, 
whether arising from the atmosphere or from friction, especially 
when different metals are concerned. 

A rod of wood, generally of alder and about two feet long, was 
put between the centers, and reduced to a cylinder by a rounder 
or witchet (fig. 343, p. 487), attached to a slide running on the 
bar ; the slide with the inclined knife was then applied, and the 
angle of the knife was gradually varied by adjusting screws, until 
several screws made in succession, were found to agree with 
some fixed measure. The experiment was then repeated with 
the same angle, upon cylinders of the same diameter, of tin, 
brass, and other comparatively soft metals, and hundreds, or 
it might almost be said, thousands of screws were thus made. 

From amongst these screws were selected those which, on 
trial in the lathe, were found to be most nearly true in their 
angle, or to have a quiescent gliding motion ; and which would 
also best endure a strict examination as to their pitch or inter- 
vals, both with the rule and compasses, and also when two were 
placed side by side, and their respective threads were compared, 
as the divisions on two equal scales. 

The most favourable screw having been selected, it was em- 
ployed as a guide-screw, in a simple apparatus which consisted 
of two triangular bars fixed level, parallel, and about one foot 
asunder, in appropriate standards with two apertures ; the one 
bar carried the mandrel and popit heads as in the ordinary bar 
lathe. The slide rest embraced both bars, and was traversed 






Ml : riMM.s 01 <; SCREWS. 



thcrriipou by the k'liide-Ncrew placed about midway between the 
bars ; the guide-screw and mandrel wcrt generally connected by 
three wheels, or rKe by two or four, when the guide and copy 
were required to have the reverse direction. The mandrel was 
not usually driven by a pulley and cord; but on the extremity 
of the mandrel was fixed a light wheel, with one arm serving as 
a winch handle for rapid motion in running back ; and six or 
cij;ht radial anus, (after the manner of the steering wheels of 
lar^e vessels,) by which the mandrel and the screw were slowly 
handed round during the cut. 

In a subsequent and stronger machine, the bar carrying the 
mandrel stood lower than the other, to admit of larger change 
wheels upon it, and the same driving gear was retained. And 
in another structure of the screw-cutting lathe, Mr. Maud>lay 
placed the triangular bar for the lathe heads in the center, 
whilst a large and wide slide-plate, moving between chamfer 
bars attached to the framing, carried the sliding rest for the 
tool : in this last machine, the mandrel was driven by steam 
power, and the retrograde motion had about double the velocity 
of that used in cutting the screw. Indeed these machines may 
be fairly considered to be the precursors of the present screw 
cutting lathes, in which the detached triangular bars or slides 
have been exchanged for one strong bearer with two ridges or 
fillets, upon which the slide plate moves for guiding the trav> 
of the tool. 

The relations between the guide-screw and the copy were 
varied in all possible ways : the guide was changed end for end, 
or different parts of it were successively used ; sometimes aUo 
t\u> guide-town were yoked together with three equal wheels, 
their nuts being connected by a bar jointed to each, and the 
center of this link, (whose motion thus became the mean of that 
of the guides,) was made to traverse the tool. Steel screws \\ 
also cut and converted into original taps, from which dies were 
made, to be themselves used in correcting the minor errors, and 
render the screws in all respects as equable as possible. In fact, 
licme that he could devise, which appeared likely to benefit 
the result, was carefully tried, in order to perfect to the utmost, 
tlu helical character and equality of subdivision of the screw. 

Mr. Maudslay succeeded by these means, after great perse- 
;mce, in making a very excellent brass screw about s>>. 

T T 2 



644 MAUDSLAY'S ADJUSTMENT FOR TOTAL LENGTH. 

feet long, and which, compared with standard measure, was 
less than one sixteenth of an inch false of its nominal length. 
Taking the error as the one-thousandth part of the total length 
of the screw, which was beyond its real quantity, to make from 
it a corrected screw by the system of change wheels, would 
have required one wheel of 1000 teeth, and another of one tooth 
less, or 999 ; but in reality the error was much less, and perhaps 
nearer the two-thousandth of an inch; then the wheels of 2000 
and 1999 teeth would have been required; consequently the 
system of change wheels is scarcely applicable to the correction 
of very minute errors of length. 

The change of the thousandth part of the total length, was 
therefore given to the tool as a supplementary motion, which 
might be added to, or subtracted from the total traverse of the 
tool, in the mode explained by the diagram, fig. 612, in which 
all details of construction are purposely omitted. The copy C, 
and the guide-screw G, are supposed to be connected by equal 
wheels in the usual manner; the guide-screw carries the axis of 
the bent lever, whose arms are as 10 to 1, and which moves in a 
horizontal plane ; the short arm carries the tool, the long arm is 
jointed to a saddle which slides upon a triangular bar i i. 



Fig. 612. 




In point of fact, the tool was mounted upon the upper of two 
longitudinal and parallel slides, which were collectively traversed 
by the guide-screw G. In the lower slide was fixed the axis or 
fulcrum of the bent lever, the short arm of which was connected 
by a link with the upper slide, so that the compensating motion 
was given to the upper slide relatively to the lower. 

The triangular bar i i, when placed exactly parallel with the 
path of the tool would produce no movement on the same, and 
C, and G, would be exactly alike ; but if i i, were placed out of 
parallelism one inch in the whole length, the tool, during its 
traverse to the left by the guide-screw G, would be moved to 
the right by the shifting of the bent lever one-tenth of the 
displacement of the bar, or one-tenth of an inch. 



MAUDSLAY, BARTON, TROi 

B whiNt tin- ^'nide-screw O, from being coarser than 
required, nioud the principal slid .'--thousandth part of 

the total length in excess; the bent lc\er and inclined xtrftif/ht 
bar i t, pulled back the upper or compensating slide, the 
thousnndth part, or the quantity in excess; making the absolute 
ir.se uf t : \actly seven feet, or the length reqnin-d for 

the- new screw C, instead of seven feet and one-sixteenth of an 
inch the length of O. To have lengthened the traverse of the 
tool, the bar i , must have been inclined the reverse way ; in other 
words, the path of the tool is in the diagram the difference of the 
two motions; in the reverse inclination, its path would bethe*M// 
of the two motions, and t i being a straight line, the correction 
would be evenly distributed at every part of the length.* 

Whilst Mr. Maudslay's experiments in perfecting the screw 
were being carried on, his friend Mr. Barton,f paid frequent 
manufactory, and also pursued a similar course. 
M r. Barton preferred, however, the method of the chain or flexible 
band, for traversing the tool the exact quantity ; because the 
reduction of the diameter of the pulley or drum, afforded a very 
ready means of adjustment for total length ; and all the wheels 
of the mechanism being individually as perfect as they could 
be made, a near approach to general perfection was naturally 
anticipated on the first trial. This mode, however, is subject to 
the error introduced by the elasticity or elongation of the chain or 
band, and which is at the maximum when the greatest length of 
chain is uncoiled from the barrel. 

These two individuals having therefore arrived, by different 
methods, as near to perfection as they were then resj 
capable of; each made a screw of the same pitch, and 
inches long, and the two when placed side by side were found 
exactly to agree throughout their length, and were considered 

vet. The two screws were submitted in 1810 to the 
scrutiny of that celebrated mathematical instrument maker, the 
Mr. Kdw. Troughton, F.R.S., &c., who examined them by 
means of two powerful microscopes with cross wires, such as are 
used for reading off the graduations of astronomical instruments; 
applied like a pair of the most refined compasses, to measure the 

The apparatus was fitted to the aeoond crow-lathe of those described, and 
the inclined bar wan placed on temporary wooden standards. 
f Subsequently Sir J. Barton, Comptroller of the Mint, Ac. 



016 BARTON'S APPLICATION OF TWO PAIRS OF DIES. 

equality of some 20, 50, or 100 threads, taken indiscriminately 
at different parts of the length of the screws.* From this 
severe trial it resulted, that these screws, which to the unassisted 
sight, and for almost every purpose of mechanism, were unexcep- 
tionable, were found to be full of all kinds of errors, being 
unequally coarse at different parts, and even irregular in their 
angles, or "drunk." This rigid scrutiny led both parties to fresh 
and ultimately successful efforts, but of these our limits will only 
allow us to notice one, apparently derived from the use of the 
two microscopes. 

Mr. Barton employed two pairs of dies upon the one screw ; 
the dies were fixed at various distances asunder upon one frame 
or bar, and the screw was passed through them. This was found 
to distribute the minute errors so completely, that little re- 
mained to be desired ; as it is obvious that at those parts where 
the screw was too coarse, the outer sides of the threads were 
cut, and which tended to shorten the screw ; and where it was 
too short, the inner sides were cut, which tended to lengthen the 
screw ; in fact the two parts temporarily situated within the dies, 
were continually endeavouring to approximate themselves to the 
fixed unvarying distance, at which the dies were for the time 
placed.f 

Mr. Maudslay did not restrict his attention to the correction 
of the screw for the purposes of science, J but he also effected a 
great many improvements in the system of taps and dies, by 
which they were made to cut instead of squeeze : as to him are 
due the introduction of the three cutting edges, and the division 
of the taps into the series of three, namely, the entering or 
taper tap, the middle, and the plug tap, by which shallow holes 

* The microscope had been long used in the process of graduating instruments, 
but this invaluable mode of employing two microscopes in combination, was first 
successfully practised by Mr. Trough ton. 

+ Mr. Barton informed the author that he employed the screw corrected in the 
above manner, in his engraving machine employed for cutting with the diamond, 
the lines as fine as 2000 in the inch, on the steel dies referred to in the note on page 
42, vol. i. ; and he said " that such was the accuracy of the mechanism, that if a line 
were missed, the machine could be set back for its insertion without any difference 
being perceptible." The author unintentionally ascribed the first application of 
the diamond to turning steel, to Sir John Barton (see note, page 179, vol. i.), 
whereas it had been used long before by Ramsden in cutting the hardened- 
steel screw for his rectilinear dividing engine. See his tract, pages 14, 15. 

The accuracy of a screw cut by Mr. Maudslay, and employed in Mr. Donkin's 
rectilinear dividing engine, ia indisputably shown at page 654 of this volume. 



MAUDSLAY'S IMPROVEMENT IN SCREWING TOOLS, i 

or dead holes, in cast iron, can be safrly i ; j<cd with full 
threads, a rant re impossible. 

This engineer also made a scries of taps, from six i: 
diameter, for attaching the pistons of steam-engines to t! 
piston rods, to the smallest used in scres\ -plates for watch work. 
The diameters of these taps were derived from the ordinary 
subdivision of the inch into eighths and sixteenths; and their 
threads were jointly dctcnninrtl by the respective strength of 
each screw, and the choice of defined rates, such as -\, '> \, I, 1 1, 
6, 8, &c., threads per inch. To have employed one constant 
le or proportion between the diameter and pitch, would have 
introduced many fractions into the rates of pitch, and an irre- 
gularity of strength in the screws themselves. The formation of 
these taps was rendered comparatively easy, after he had intro- 
duced the true original screw and the system of change wheels, 
as a common practical apparatus ; many copies of these screw 
threads have found their way to other workshops, and have 
ed to influence the construction of similar tools of various 
proportions. 

Indeed, I believe it may be fairly advanced, that during the 
period from 1800 to 1810, Mr. Maudslay effected nearly the 
entire change from the old, imperfect, and accidental practice of 
screw-making, referred to at page 635, to the modern, exact 
and systematic mode now generally followed by engineers ; and 
he pursued the subject of the screw with more or less ardour, and 
at an enormous expense, until his death in 1835. The results 
have been so important, and are so well appreciated amongst 
mechanical men generally, that they may be considered fully 
to deserve the short digression to which they have led. 

In IMtl, Mr. Allan was rewarded by the Society of Arts for 
his method of cutting micrometer screws with dies : the repre- 
sentation and description of the instrument will be found at page 
re it is shown in the act of cutting an original screw with 
an inclined knitX Micrometer screws are cut in this apparatus 
much in the same manner, except that about one-third of the 
thread is cut with the large die, fig. 535, the inner curvature 
of which agrees with the curvature of the blank cylinder, and 
the screw is finished with the smaller die, 5:5(5, cut by an original 
of the same diameter as the finished screw. The piece pre- 
pared for the screw must always have two cylindrical ends to 



CiS CLEMENT'S MODE OF ORIGINATING SCREWS. 

fit the semicircular bearings b b ; this arrangement prevents the 
screw from being bent in the process of cutting, but which 
latter operation is accomplished entirely with the dies.* 

About the year 1820, Mr. Clement devised and put in practice 
a peculiar mode for originating the guide-screw of his screw-lathe, 
the steps of which plan will be now described. 

1. He procured from Scotland some hand-screw tools cut 
over a hob with concentric grooves ; and to prevent the ridges 
or points of the screw tools, from being cut square across the 
end, the rest was inclined to compensate for the want of angle 
in the hob or cutter. 

2. A brass screw was struck by hand, or chased with the tool 1. 

3. The screw 2, was fixed at the back of a traversing mandrel, 
and clipped between two pieces of wood or dies to serve as a 
guide, whilst 

4. A more perfect guide-screw was cut with a fixed tool, and 
substituted on the mandrel for 3 : as Mr. Clement considered 
the movement derived from the opposite sides of the one screw, 
became the mean of the two sides, and corrected any irregu- 
larities of angle, or of drunkenness. 

5. A large and a small master-tap m, fig. 613, were cut on the 
traversing mandrel with a fixed tool, the threads were about an 
inch long, and situated in the middle of a shaft eight or ten 
inches long ; the small master-tap was of the same diameter as 
the finished screw, the large master-tap measured at the bottom 
of the thread the same as the blank cylinder to be screwed, as 
in figs. 572 and 576, page 600. The master-taps m, were used 
in cutting up the rectangular dies required in the apparatus 
shown in fig. 613, and now to be described. 

6. On the parallel bed of a lathe, were fitted two standards or 
collar-heads h h f , intended to receive the pivots of the screw to 
be cut, on the extremity of which was placed a winch handle, or 
sometimes an intermediate socket was interposed between the 

* Mr. A. Ross considers that the friction of Mr. Allan's apparatus is apt to retard 
the traverse of the screw, and therefore to cut the bottom of the thread too wide or 
rounding. In his practice he uses the large and small dies for a short period at the 
commencement and conclusion of the process, but he cuts out the principal bulk of 
the material, by a fixed tool inserted within a radial mortise in a semicircular 
copper die ; the copper is indented more and more with tho progress of the work, 
and serves as an efficient guiilo, whilst thecuttiug in accomplished with considerably 
leas friction, and in a superior manner, by the cutter or turning-tool. 



\C, 8CBBW8. 

crew and tin- winch, to carry tin end of the bed. 

; ti-d had also an accurate slide plate x .', running freely upon 

'lie slide-plate had two tails which passed l>e>ide tin- head //, 

and at the other end, a projection through which was made a 

transverse rectangular mortise for the dies, the one end of the 




mortise is shown by the removal of the front die d, and the back 
die d' is seen in its proper situation ; one extremity of each die 
was cut from the large master tap TO, and the other from the 
small. The clamp or shackle c c, was used to close the two dies 
upon the screw simultaneously ; it is shown out of its true posi- 
tion in order that the dies and mortise may be seen, but when in 
u>e the shackle would be shifted to the right, so as to embrace 
the diew/'A. The plain extremity c' rested against the back die, 
whilst the screw c bore against the front die, through the inter- 
vention of the washer loosely attached to the clamp to save 
the teeth from injury; the pressure screw c had a graduated 
head and an index, to denote how much the dies were closed. 

7. A cylinder about two feet long, prepared for the screw, 
was placed between the heads h /*', and the large dies, whose inner 
edges were of the same diameter as the cylinder, were closed 
upon it moderately tight, and the screw was turned round with 
the winch, to trace a thread from end to end ; this was repeated 
a few times, the dies being slightly closed between each trip. 

8. A screw-tool was next fixed on the slide * *', in a chamfer 
slide / /' with appropriate adjusting screws, so as to follow the 

ami remove a shaving, much the same as in turning; the 
dies having arrived at one end of the screw, the same s< 
tool, or a second tool, was placed on the opposite side of the 
slide-plate, so as to cut dm > turn movement. With 

the progress of the screw, the screw-tool was applied at a 



650 CLEMENT'S MODE OF ORIGINATING SCREWS. 

variety of distances from the pair of dies, as well as on opposite 
sides of tlie screw, so that the metal was cut out by the tool, and 
the dies were used almost alone to guide the traverse. Of course 
the dies were closed between each trip, and when the screw was 
about half cut up, the small dies were substituted for the large 
ones used at the commencement of the process. 

9. The screw thus made, which was intended for a slide-rest, 
was found to be very uniform in its thread, and it was used 
for some time for the ordinary purposes of turning. When how- 
ever it was required to be used for cutting other screws, it was 
found objectionable that its rate was nearly nine, whereas it 
was required to have eight threads per inch ; it was then used 
in cutting a new guide-screw by means of a pair of change 
wheels of 50 and 56 teeth, which upon calculation were found 
to effect the conversion with sufficient precision. 

10. From 9, the screw of 24> inches in length, one of 8 feet 
in length was obtained; the thread was cut one-third its 
depth, with the wheels, successive portions being operated upon, 
and the tool being carefully adjusted to the termination of the 
part previously cut. The general truth of the entire length was 
given by a repetition of the tedious mode of correction repre- 
sented in the figure, with the dies and tool applied upon a bearer 
rather exceeding the full length of the screw.* 

Although the processes 7 and 8 will produce a most uniform 
screw, Mr. Clement attaches little importance to the use of the 
dies and guide-frame alone, when several screws are wanted 
strictly of the same length. Of some few thus made, as nearly as 
possible under equal circumstances, two screws were found very 
nearly to agree, and a third was above a tenth of an inch longer 
in ten inches. This difference he thinks to have arisen in mark- 
ing out the threads, from a little variation in the friction of the 
slide, or a difference in the first penetration of the dies. 

The friction of the slide, when sufficient to cause any retard- 

* Mr. Clement also made a very superior steel screw of about five feet in length 
and three inches diameter, precisely by the method 10, before he had completed tho 
screw lathe he now commonly uses : and Mr. Whitworth followed precisely the 
same method in obtaining his standard screw, of about the length of 24 feet and 
half-inch pitch ; except that a claap nut was used instead of the dies. It was 
produced from a short screw cut by Mr. Clements; the correctional process 
occupied two months, and was carried with a most strict regard to avoid the 
unequal expansion of the screw and apparatus employed upon it 



:.l\'s UK I I II I M Ml |.|\ I!)IN(, |;\. 

ation, he considers to produce a constant and accumulative 
cltect ; first as it were, mine-in;,' the, screw of 15 threads JHT 
inch, say to tin- fineness of !."} ; thru acting upon that of 15$- 
n-.inrinu' it to 15 J, and so on; and that to such an extent, as 
occasionally to place tin; screw entirely beyond the correctional 
process. This cannot be the case when the thread is i 
marked out with the change wheels, instead of the diea. 



One very important application of the screw, is to the gradua- 
tion of mathematical scales, the screw is then employed to move 
a platform, which slides very freely, and carries the scale to be 
graduated; and the swing frame for the knife or diamond point 
is attached to some fixed part of the framing of the machine. 
Supposing the screw to be absolutely perfect, and to have fifty 
threads per inch, successive movements of fifty revolutions, would 
move the platform and graduate the scale exactly into true 
inches; but on close examination, some of the graduations will 
be found to exceed, and others to fall short of the true inch. 

The scales assume, of course, the relative degree of accuracy 
of the screw employed. No test is more severe ; and when these 
scales are examined by means of two microscopes under a mag- 
nifying power of ten or twenty times, the most minute errors 
become abundantly obvious, from the divisions of the scales, fail- 
to intersect the cross wires of the instrument; the result 
clearly indicates, corresponding irregularities in the coarseness of 
the screw at the respective parts of its length. An accustomed 
eye can thus detect, with the microscope, differences not exc> 
in'4 the one thirty-thousandth part of an inch, the twenty-: 
thousandth part being comparatively of easy observation. 

From Mr. Donkin's investigation of the subject, he was led to 
conclude that it is quite impossible to produce a screw which 
shall be absolutely free from error, when micrometrically pro\ 
and in 1 S23, he was in consequence led to consider that as Mr. 
.dslay's method of the bent lever and inclined straiyht bar, 
would compensate the error of total length in a nearly per 
screw, a similar mode might he applied to all the intermediate 
errors, by the employment of :i \perimentally obtained by 

ethod of continual bisection employed in hand dividing. 

It having been explained i nee to the diagram on page 

' I I, that the inclination given to the bar i i, would mince the 
effective length of a screw, and the reverse inclination would 



DONKI.V'S RECTILINEAR DIVIDING ENGINE. 

increase it, Mr. Donkin considered that from the observed fact 
of one half of the screw, (as estimated by counting the number 
of threads,) being generally too coarse, and the other half too 
fine, the compensation would require the one half of the bar i i, 
to be inclined to the right as in the diagram, and the other half 
to the left, in fact thus bending the right line into an obtuse angle. 

Extending this mode, upon the presumption that the quarters, 
eighths, or sixteenths, of the screw were also dissimilar, the 
bar would require many flexures instead of the one only, giving 
to it a more or less zig-zag character, or rather that of a gently 
undulating line. The undulations being proportioned experi- 
mentally, to effect such compensations, as should add to the 
movement of the upper platform or supplementary table, where 
the screw was too fine, and subtract from its motion, where the 
screw was too coarse ; so as, from a screw known to be slightly 
irregular, to produce the divisions of a scale, or the thread of 
another screw, considerably nearer to equality. 

He carried out this project in 1826, and he has satisfactorily 
proved the existence of a correctional method, which is within 
reach of any clever workman who will devote sufficient patience 
to the adjustment of the engine, and which latter will be now 
briefly explained. 

Mr. Donkin's dividing machine consists first of a table or 
platform moving on a railway, the platform being supported by 
four or any greater number of wheels, that may be required 
for preventing flexure and for diminishing friction. The upper 
edges of the two rails on which the wheels turn, are made as 
perfectly straight as possible, the rails lie in the same horizontal 
plane; and they are placed at 'any convenient distance from 
each other. The table or platform is guided laterally in its 
course upon the rails, by four wheels, of which two are placed 
on each side of one of the rails ; two wheels turn on fixed axles 
on one side of the rail, whilst the two on the other side are 
held tight to the rail by means of springs, thus preventing any 
deviation from the rectilinear course in which the platform 
ought to travel. To the under side of the platform is attached 
a clasp-nut, the two parts of which are so constructed, as to be 
applied to, or separated from the main screw, which lies below 
the platform, and is exactly parallel with the rails, or with the 
line in which the platform is made to move. 

To effect the compensation, the platform or table consists 



I.ONKIV'S RECTILINEAR IMVliUM. i:\..: f,.Y; 

of nn upper and lower plate, which arc of a small inde- 

pendent motion. The low IT plate carries the fulcrum of the 
ben: .MS,, amis arc at right angles and as fifty to one, 

r moves in the vertical plane, so that its longer arm lies by 
gravity alone on the cunili near edge of the compensation bar; the 
upper platform is pressed endlong against the shorter arm of 
bent lever, by a spring which always keeps them in close contact. 

The attachment of the two platforms is peculiar; the upper, 
rides upon four rollers or rather sectors, and the two plates are 
connected by two slight rods placed transversely between tl 
the ends of the rods are fixed over the one rail to the lower, and 
over the other rail to the upper platform; the bars consequently 
fulfil the oilicc of the radius bars of a parallel rule, and suffice 
by their flexure alone, for the very limited and exact motion 
required in the upper table. 

The compensating bar which is of the length of the screw, or 
2 I inches, has 48 narrow slips of metal placed like the keys of 
a piano-forte, each having an appropriate adjusting and fixing 
screw, by which the ends of the pieces may be placed in a con- 
tinuous line, or any of them may be placed above or below the 
line as required in the following mode of compensation. For 
change of total length and adjustment for temperature, the curved 
bar is more or less inclined, as in the former example, except 
that it is placed edgeways or vertically ; it is attached to the out- 
side of one of the rails, by a pivot which intersects the one end 
of its curvilinear edge, and the other end is raised or depressed 
by a screw, which effects the adjustment for temperature. 

Conceiving the length of the guide-screw divided into 48 
equal parN, denoted by the figures to 48, it would be first 
ascertained by two fixed microscopes, if the halves of the srr 
measured from to 24, and from 24 to 48, were absolutely 
equal quantities; if not, the central slip or finger would be 
cd or lowered until on repeated trials the due correctional 
movement was applied to the table. The two halves would be 
similarly bisected and corrected in the points 12 and 36, and 
the quarters atrain bisected in 6, 18, 80, and 42; and the 
eighths when also bisected, would extend the examination to 
the points 0, 3, 6, 9, &c., to 48. The easiest method is to com- 
pare the path of the slide, with the divisions of a superior scale, 
fixed upon the slide or platform of the machine. 

It would now be needful to divide the whole into three ; 



<>.') l DONKIN'S RECTILINEAR DIVIDING ENGINE. 

by the comparison of the spaces from to 16, from 16 to 32, 
and from 32 to 48, the points 16 and 32, being adjusted until 
exactly equal, which is the most difficult part of the work ; and 
then these three distances being bisected four times, every 
point of the 48 would have been examined, and some of them 
twice over. These adjustments having been repeatedly verified, 
during which a very frequent recurrence to the total length is 
imperative ; the concluding step is to file off the corners of the 
48 slips very carefully, so as to convert them into a line with 
undulations, slight it is true, but which represent fifty-fold the 
actual errors in the guide-screw ; and therefore shift the table 
simultaneously with its general traverse, so as to apply the 
exact corrections for inequality, at every point examined and 
found to be in error. 

But the term error must be received in a very restricted sense, 
as it deserves to be noticed, that Mr. Donkin first used a screw 
made by Mr. Maudslay, and the maximum deflection of the 
curved edge of the compensation bar from a straight line, was 
very nearly the eighth of an inch, indicating the maximum error 
of the screw to have been about the 400th part of an inch ; and 
as the curve was nearly limited to a single undulation, or a hill 
at one end, it may be presumed this minute error was in part 
attributable to a difference in the material, a source of perplexity 
from which no care is a sufficient protection. The dividing engine 
was employed as a traversing lathe in cutting a new screw, and 
which, although it had the advantage of the compensation, only 
reduced the error of the new screw to about one-third the 
quantity of that of the first; as shown by the new curve assumed 
by the compensation bar, its deflection being -^ of an inch, when 
re-adjusted in the tedious and anxious method described.* 

Having at length concluded the remarks on some of the most 



* In the paat year, 1842, Mr. Donkin has made a similar but enlarged dividing 
engine. The length of traverse of the new machine is 42 inches, the screw has 40 
threads in the inch, the compensation bar is as 60 to 1, and the value of one single 
tooth in the counting wheel is equivalent to the 60,000th part of an inch ; that of 
the first machine having been the 30,000th part. 

It is to be hoped that Mr. Donkin will complete his labours, by publishing a 
detailed account of these machines, the latter of which, in particular, exhibits 
throughout its structure a most refined contrivance and execution, of which no 
adequate idea can possibly be conveyed within the limits of this slender notice, 
nor without exact drawings of the details, to the arrangement of which great 
attention has been bestowed. 



OKNERAL CHARACTERS OF SCREW THREAD*. C55 

i od and scientific efforts that have been employed in pro- 
ducing and i .MI;,' the screw, I shall in the next and con- 
section of this already extensive chapter, proceed to the 
of a variety of important considerations and con- 
ditions, which practically influence the proportions, forms, and 
general character of screws, to adapt them to multifarious pur- 
poses in the mechanical and constructive arts. 



SECT. IX. SCREW THREADS CONSIDERED IN RESPECT TO THEIR 
PROPORTIONS, FORMS, AND GENERAL CHARACTERS. 

The proportions given to screws employed for attaching 
together the different parts of work, are in nearly every case 
arbitrary, or in other words, they are determined almost by 
experience alone rnther than by rule, and with little or no aid 
from calculation, as will be shown. 

In addition to the ordinary binding screws, which although 
arbitrary, assume proportions not far distant from a general 
average, many screws, either much coarser or finer than usual, 
are continually required for specific purposes ; as are likewise 
other screws of some definite numbers of turns per inch, as 2, 
10, 12, 20, &c., in order to effect some adjustment or movement 
having an immediate reference to ordinary lineal measure. 
But all these must be considered as still more distant, than 
common binding screws, from any fixed proportions, and not to 
be amenable to any rules beyond those of general expediency. 

Neither the pitch, diameter, nor depth of thread, can he- 
adopted as the basis from which to calculate the two othci 
measures, on account of the different modes in which the three 
influence the effectiveness of the screw ; nor can the proportions 
suitable to the ordinary f inch binding screw, be doubled for the 
1 inch screw, or halved for that of $ inch ; as every diameter 
requires its individual scale to be determined in great measure 
by experiment, in order to produce something like a mean 
proportion between the dissimilar conditions, which will be 
separately explained in various points of view. 

The reasons for the uncertainty of measure in the various 
fixing screws required in the const native arts, arc sufficiently 
manifest ; as first, the force or strain to which a screw is exposed, 
either in the act of fixing, or in the office it has afterwards to 



G56 RELATIVE STRENGTHS OF SCREWS. 

perform, can rarely be told by calculation ; and secondly, a 
knowledge of the strain the screw itself will safely endure with- 
out breaking in two, or without drawing out of the nut, is 
equally difficult of attainment ; nor thirdly, can the deduction 
for friction be truly made from that force the screw should other- 
wise possess, from its angle or pitch, when viewed as a mecha- 
nical power, or as a continuous circular wedge. 

The force required in the fixing of screws takes a very wide 
range, and is faintly indicative of the strain exerted on each. 
The watchmaker, in fixing his binding screws, employs with great 
delicacy a screw-driver, the handle of which is smaller than an 
ordinary drawing pencil : while for screws, say of five inches 
diameter, a lever of six or seven feet long must be employed by 
the engineer, with the united exertions of as many men. But 
in neither case do we arrive at any available conclusion, as to 
the precise force exerted upon, or by each screw; nor of the 
greatest strain that each will safely endure. 

The absolute measures of the strength of any individual screw 
being therefore nearly or quite unattainable, all that can be done 
to assist the judgment, is to explain the relative or comparative 
measures of strength in different screws, as Betermined by the 
three conditions which occur in every screw; whether it be right 
or left handed, of single or of multiplex thread, or of any section 
whatever; and which three conditions follow different laws, and 
conjointly, yet oppositely, determine the fitness of the screw for 
its particular purpose, and therefore tend to perplex the choice. 

The three relative or comparative measures of strength in dif- 
ferent screws are : first, the mechanical power of the thread, which 
is derived from its pitch ; secondly, the cohesive strength of the 
bolt, which is derived from its transverse section ; and thirdly, 
tfie cohesive strength of the hold, which is derived from the inter- 
placement of the threads of the screw and nut. 

These conditions will be first considered, principally as regards 
ordinary binding screws, and screw bolts and nuts, of angular 
threads, and which indeed constitute by far the largest number 
of all the screws employed ; screws of angular and square threads 
will be then compared. 

The comparative sections, figs. 614 to 617, represent screws of 
the same diameters, and in all of which the depth of the thread 
is equal to the width of the groove; figs. 615 and 617 show the 



RELATIVE Si OH SCREWS. 



57 



nary proportions of } inch angular and squarr thrr-adscrcws ; 
' 1 I and G16 are respectively as fine and as coarse again as 615. 



Fig* 014. 

fv.\\\\\\\v 






615. 




514 



617. 

r r.Ln_a-Q, 



\ , I V 

m 

A . * \ \ ' I 



Various measures of the screws which require little further 
explanation are subjoined in a tabular form ; and the relative 
degrees of strength possessed by each screw under three different 
points of view, are added. 



IIKASU RES AND RELATIVE STRENGTHS OF THE SCREWS. 


Fig. 
614 


Fig. 
615 


Fig. 
616 


Fig. 
617 


External diameters in hundredtha of an inch 


75 


75 


75 


75 


;ial diameters in hundredths of an inch . . 


65 


55 


35 


55 


N umber of threads per inch, or rota of the screws 


20- 


10- 


5- 


5- 


ha and widths of the threads in hundredth)* 


05 


Id 


20 


10 


A nglea of the threads on the external diameters* 


1 16' 


2 33' 


5 6' 


6 5* 


Angles of the threads on the internal diameters* 


1 28' 


3 28' 


10" 47' 


.; ;.:. 


Relative mechanical powers of the threads . . 


20 


10 


5 


5 


Relative cohesive strengths of the bolts . . . 


4 


3 


1 


3 


Relative cohesive strengths of hold of the screws 


65 


55 


35 


274 


Relative cohesive strengths of hold of the nuts . 


75 


75 


70 





* The angles "of tho threads of screws are calculated trigonomotrically, the 
circumference of the bolt being considered as the base of a right-angled triangle, 
snd the pitch as the height of tho same. 

The author has adopted the following mode, which will be found to require the 
fewest figures ; namely, to divide the pitch by the circumference, and to seek the 
product in tho table of tangents; decimal numbers are to be used, and it is 
sufficiently near to consider the circumference as exactly three times the 

F<>r the external angle of fig. 616 say 20 -f- 2-25 = -OSS3, and this quotient by 
Hutt. m's Tables gives 5 deg. 5 min. 

Fur the internal angle of fig. 614 say -05 -j- 1-95=0-2564, and by Hutton's Tables, 
1 dcg. 28 min. 

In this method the pitch is considered a* the tangent to the angle, and the division 
s the change of the two sides of the given right-angled triangle, for two others, 
the larger of which is 1 or unity, for the convenience of using the tables. 

U U 



C58 HELATIVE STRENGTHS OF SCREWS. 

Square thread screws, have about twice the pitch of angular 
threads of similar diameters, and 617 estimated in the same 
manner as the angular, will stand by comparison as follows. The 
square thread, 617, will be found to be equal in power to 616, the 
pitch being alike in each. In strength of bolt to be equal to 615, 
their transverse areas being alike. And in strength of hold, to 
possess the half of that of 615, because the square thread will 
from necessity break through the bottom of the threads, or an 
interrupted line exactly like the dotted line in 616, that denotes 
just half the area or extent of base, of the thread of 615 ; which 
latter covers the entire surface of the contained cylinder, and 
not the half only. 

The mechanical power of the thread, is derived from its pitch. 
The power, or the force of compression, is directly as the number 
of threads per inch, or as the rate; so that neglecting the friction 
in both cases, fig. 614 grasps with four times the power of 616, 
because its wedge or angle is four times as acute. 

When however the angle is very great, as in the screws of 
fly-presses which sometimes exceed the obliquity of 45 degrees, 
the screw will not retain its grasp at all j neither will a wedge of 
45 degrees stick fast in a cleft. Such coarse screws act by 
impact ; they give a violent blow on the die from the momentum 
of the fly, (namely, the loaded lever, or the wheel fixed on the 
press-screw,) being suddenly arrested ; they do not wedge fast, 
but on the contrary, the reaction upwards, unwinds and raises 
the screw for the succeeding stroke of the fly-press. 

Binding screws which are disproportionately coarse, from 
leaning towards this condition, and also from presenting less 
surface-friction, are liable to become loosened if exposed to a 
jarring action. But when, on the contrary, the pitch is very 
fine, or the wedge is very acute, the surface friction against the 
thread of the screw is such, as occasionally to prevent their 
separation when the screw-bolt has remained long in the hole 
or nut, from the adhesion caused by the thickening of the oil, 
or by a slight formation of rust. 

The cohesive strength of the bolt, is derived from its transverse 
section. The screw may be thus compared with a cylindrical rod 
of the same diameter as the bottom of the thread, and employed 
in sustaining a load; that is, neglecting torsion, which if in 
excess may twist the screw in two. The relative strengths are 



IMI.'iu \\( K OF AQREEM PIKH. ;.V.| 

-. i,t,,i ',;. the squares of the smaller diameters: in the 
screws of 20, 1", and ."> angular threads, the smaller diameters 
are 65, r> ; the squares of these numbers are 4225, 8" 

and 1225, which may be expressed in round numbers as 4, 8, 1 ; 
and therefore, the coarsest screw C 1C, has transversely only one- 
fourth the area, and consequently one-fourth the strength of the 
;ire-entL-d in the three diagrams. 

The cohesive strength of the hold, is derived from the helical ridge 
of the external screw, being situated within the helical groove of 
tin- internal screw. The two helices become locked together with 
a degree of firmness, approaching to that by means of which t In- 
different particles of solid bodies are united into a mass ; as one 
or both of the ridges must be in a great measure torn off in the 
removal of the screw, unless it be unwound or twisted out. 

A slight difference in the diameter or the section of a screw 
and nut, is less objectionable than any variation in the coarse- 
ness or pitch ; as the latter difference, even when very minute, 
will prevent the screw from entering the hole, unless the screw 
is made considerably smaller than it ought to be, and even then it 
will bear very imperfectly, or only on a few places of the nut. 

To attempt to alter a screwed hole by the use of a tap of a 
different pitch, is equally fatal, as will be seen by the annexed 
diagram fig. G18. For instance, the upper line a, contains exactly 
! threads per inch, and the middle line or b, has 4J threads ; they 
only agree at distant intervals. The lowest line c, shows that 
which would result from forcing a tap of 1 threads such as a, 
into a hole which had been previously tapped with the 4 thread 
screw b, the threads would be said to cross, and would nearly 

Fig. 618. 

/vwvvy- 




d< >;i i\ caeh other; the same result would of course occur from 
employing 4 or 5 thread dies on a screw of 4^ threads per inch. 
<-f<>re. unless the screw tackle exactly agree in pitch with 
u u 2 



6GO RELATIVE STRENGTHS OF SCREWS AND NUTS. 

the previous thread, it is needful to remove every vestige of the 
former thread from the screw or hole ; otherwise the result drawn 
at c, must ensue in a degree proportionate to the difference of 
the threads, and a large portion of the bearing surface, and con- 
sequently, of the strength and the durability of the contact, would 
each be lost. Some idea may thence be formed of the real and 
irremediable drawback frequently experienced from the dis- 
similarity of screwing apparatus ; nearly to agree will not suffice, 
as the pitch should be identical. 

The nut of a f -inch screw bolt is usually f inch thick, as it 
is considered that when the threads are in good contact, and 
collectively equal to the diameter of the bolt, that the mutual hold 
of the threads exceeds the strength either of the bolt or nut ; 
and therefore that the bolt is more likely to break in two, or the 
nut to burst open, rather than allow the bolt to draw out of the 
hole, from the thread stripping off. 

"\Vhen screws fit into holes tapped directly into the casting's or 
other parts of mechanism, it is usual to allow still more threads 
to be in contact, even to the extent of two or more times the 
diameter of the screw, so as to leave the preponderance of 
strength greatly in favour of the hold ; that the screw, which 
is the part more easily renewed, may be nearly certain to break 
in two, rather than damage the casting by tearing out the thread 
from the tapped hole. 

Should the internal and external screws be made in the 
same material, that is both of wood, brass or iron, the nut or 
internal screw is somewhat the stronger of the two. For example, 
in the screw fig. 615, the base of the thread is a continuous 
angular ridge, which occupies the whole of the cylindrical surface 
represented by the dotted line. Therefore the force required 
to strip off the thread from the bolt, is nearly that required to 
punch a cylindrical hole of the same diameter and length as the 
bottom of the thread ; for in either case the whole of the cylin- 
drical surface has to be stripped or thrust off laterally, in a 
manner resembling the slow quiet action of the punching or 
shearing engine. 

But the base of the thread in the nut, is equal to the cylindrical 
surface measured at the top of the bolt, and consequently, the 
materials being the same, and the length the same, considering 
the strength of the nut for 615 to be 75, the strength of the bolt 



KM \ I I \M> NtTS. '''! 

would l> ', or tin v \vould he respeet ively as the diameters 

of the tup and bottom of the thread; although when the holt 
ru.lr> through the nut, the thread of the holt derives a slight 
additional strength, from the threads situated beyond the nut, 
and which ser\e as an almtnient. 

It is however probable that the angular thread will not strip 
off at the base of the threads, cither in the screw or nut, but w ill 
break through a line somewhere between the top and bottom : 
but these results will occur alike in all, and will not therefore 
materially alter the relation of strength above assumed. 

Comparing 01 4, 015, and 010, upon the supposition that the 
bolts and nuts exactly fit or correspond, the strengths of the three 
nuts arc alike, or as 75, and those of the bolts are as 05, .').",, and 
.nid therefore the advantage of hold lies with the bolt of finest 
thread ; as the finer the thread, the more nearly do the bolt and 
nut approach to equality of diameter and strength. 

Supposing however for the purpose of explanation, that 
instead of the screws and nuts being carefully fitted, the screws 
are each one-tenth of an inch smaller than the diameters of the 
respective taps employed in cutting the three nuts ; Oil would 
draw entirely out without holding at all; the penetration and 
hold of (515 would be reduced to half its proper quantity ; and 
that of i'.16 to three-fourths ; and the last two screws would strip 
at a line more or less elevated above the base of the thread ; and 
therefore the more easily than if the diameters exactly agreed. 

The supposed error, although monstrous and excessive, shows 
that the finer the thread, the greater also should be the accuracy 
of contact of such screws; and it also shows the impolicy of 
employing fine threads in those situations where they will be 
subjected to frequent screwing and unscrewing, and also to much 
strain. As although when they fit equally well, fine threads are 
somewhat more powerful than coarse, in hold as well as in 
mechanical power; the fine are also more subject to wear, and they 
from such wear, a greater and more rapid depreciation of 
strength, than threads of the ordinary degrees of coarseness. 

lu a screw of the same diameter and pitch, the ultimate 

ngth is diminished in a twofold manner by the increase of 

tin- tlfjith of the thread ; first it diminishes the transverse area of 

the bolt, whieh i> therefore more disposed to break ill two; and 

udly, it diminishes the individual strength of each thread, 



: COMPARISON OF SQUARE AND ANGULAR THREADS. 

which becomes a more lofty triangle erected on the same base, 
and is therefore more exposed to fracture or to be stripped off. 

But the durability of machinery is in nearly every case increased 
by the enlargement of the bearing surfaces, and therefore as the 
thread of increased depth presents more surface -bearing, the deep 
screw has consequently greater durability against the friction or 
wear, arising from the act of screwing and unscrewing. The 
durability of the screw becomes, in truth a fourth condition, to 
be borne in mind collectively with those before-named. 

It frequently happens that the diameters of screwed works are 
so considerable, that they can neither break nor burst after the 
manner of bolts and nuts ; and if such large works yield to the 
pressures applied, the threads must be the part sacrificed. If the 
materials are crystalline, the thread crumbles away, but in those 
which are malleable and ductile, the thread, instead of stripping 
off as a wire, sometimes bends until the resisting side presents a 
perpendicular face, then overhangs, and ultimately curls over : 
this disposition is also shown in the abrasive wear of the screw 
before it yields. 

Comparing the square with the angular thread in regard to 
friction, the square has less friction, because the angular edges 
of the screw and nut, mutually thrust themselves into the 
opposed angular grooves in the manner of the wedge. The 
square thread has also the advantage of presenting a more direct 
thrust than the angular, because in each case the resistance is 
at right angles to the side of the thread, and therefore in the 
square thread the resistance is very nearly in the line of its axis, 
whereas in the angular it is much more oblique. 

From these reasons, the square thread is commonly selected 
for presses, and for regulating screws, especially those in which 
rapidity of pitch, combined with strength, is essential ; but as 
regards the ordinary attachments in machinery, the grasp of the 
angular thread is more powerful, from its pitch being general I v 
about as fine again, and as before explained, angular screws and 
nuts are somewhat more easily fitted together. 

The force exerted in bursting open a nut, depends on the 
angle formed by the sides of the thread, when the latter is con- 
sidered as part of a cone, or as a wedge employed in splitting 
timber. For instance, in the square thread screw, the tlm ;ul 
forms a line at right angles to the axis, and which is dotted in 



M HI:\V NUTC, ""I n> AM> !H\ IDI:I). 



868 



figure 610; it is not therefore a cone, but simply compresses 
the nut, or attempts to force the metal before it. In tin- deep 
thread tig. <>20, the wedge is obtuse, and exerts much less 




bursting effort than the acute cone represented iu the shallow 
thread screw fig. <'>21 ; therefore the shallower the angular 
thread, the more acute the cone, and the greater the strain it 
throws upon the nut. The transverse measure of nuts, whether 
they are square or hexagonal, is usually about twice the diameter 
of the bolt, as represented in the figures, and this in general 
suffices to withstand the bursting effort of the bolt.* 

Those nuts, however, which are not used for grasping, but 
for the regulating screws of slides and general machinery, are 
made much thicker, so as to occupy as ranch of the length of 
the screw as two, three, or more times its diameter ; this greatly 
increases their surface- contact, and durability. 

Should it be required to be able to compensate the nut, or to 
re-adapt it to the lessened size of the screw when both have 
been worn, the nut is made in two parts and compressed by 
screws, or it is made clastic, so as to press upon the screw. The 
nuts for angular threads are divided diametrically, and re-united 
by two or more screws, as in fig. G22, in fact, like the semi- 
circular bearings of ordinary shafts ; as then by filing a little of 
the metal away from between the two halves of the nut, they 
may be closed upon the angular ridges of the thread. 

The nuts of square threads, by a similar treatment, would on 

being closed, fit accurately upon the outer or cylindrical surface 

of the square thread screw, but the lateral contact would not be 

red ; these nuts are therefore, divided transversely, as shown 



* In the table of the dimensions of nuts, in Temploton'a Engineer's Pocket 
Companion, the transforms measures decrease in the larger nuts ; the breadth of 
the nut for a 4 inch bolt is stated as 1 inch, that for a 2| iuch bolt as 4 inches. 



G64 



NUTS CAPABLE OF BEING ADJUSTED. 



in fig. 623, or they are made as two detached nuts placed in 
contact. When therefore a small quantity is removed from 
between them with the file, or that they are separated by one or 
more thicknesses of paper, the one half of the nut bears on the 
right hand side of the square worm, the other on the left. 

Either of these methods removes the " end play," or the " loss 
of lime," by which expression is meant that partial revolution, 
to and fro, which may be given to a worn screw without pro- 
ducing any movement or traverse in the slide upon which the 
screw acts. It is usual, before cutting the nuts in the lathe or 
with screw taps, to divide the nuts, and to re-unite them with 
soft solder, or it is better to hold them together with the perma- 
nent screws whilst cutting the thread. 

But the screws of slides are very apt to become most worn in 
the middle of their length, or at the one end, leaving the other 
parts nearly of their original size : it is then best to replace 



Figs. 622. 



623. 



624. 



625. 




them by new screws, as the former method of adjusting the 
nuts cannot be used; although recourse may occasionally be 
had to some of the various methods of springing, or the elastic 
contrivances commonly employed in delicate mathematical and 
astronomical instruments. Although these should be perfectly 
free from shake or uncertainty of motion, they do not in general 
require the firm, massive, unyielding structure of engineering 
works and machinery. 

Two kinds of the elastic nuts alone are shown; in fig. C>~2 1 the 
saw-cut extends throughout the length of the nut, but sometimes 
a portion in the middle is left uncut ; the nut is usually a little 
set-in, or bent inwards with the hammer, so as to press upon the 
screw. In fig. C25, the two pieces a and b, bear against opposite 



DIFFERENT .SECTIONS OF SCREW Til Hi: \ Ms. 

side* of tin- tin-cat!, :m<l /> only is li\. .1 t,, tin- slide, as in fig. 623; 
tin- corn now accomplished hy interposing loosely around 

tin- screw, and between tlie halves of the nut, n spiral spring 
MiHieiently >; ome the friction of the slide upon the 

fittings; the same contrivance is variously modified, sometimes 
two or four spiral springs are placed in cavities parallel with the 
screw. 

The slide resists firmly any pressure from a to b, as the fixed 
half of the nut lies firmly against the side of the thread presented 
in that direction, but the pressure from b to a is sustained alone 
by the spiral spring ; when therefore the pressure exceeds the 
strength of the spring, the slide nevertheless moves endways to 
tin- extent of the misfit in the piece A, and which, but for the 
spring, would allow the slide to shake endways. In absolute 
cflect the contrivance is equivalent to a single nut such as b 
alone, which although possessing end play, if pulled towards b 
by a string and weight, would always keep in contact with the 
one side of the worm, unless the resistance were sufficient to 
raise the weight. The method is therefore only suited to works 
requiring delicacy rather than strength, and the spring, if 
excessively strong, would constantly wear the two halves of the 
nut \\ith injudicious friction and haste. 



The several threads represented in figs. 620 to 638, may be 
considered to be departures from the angular thread fig. 626, and 
the square thread fig. 635, which are by far the most common. 

The choice of section is collectively governed : First, by the 
facility of construction, in which the plain angular thread excels. 
Secondly, by the best resistance to strain, which is obtained in 
the square thread. Thirdly, by the near equality of strength in 
the internal and external screw. For similar materials the space 
and thread should be symmetrical, as in the square thread, and 
in fiL's. r^r, to ;:JO, which screws are proper for metal works 
generally; whereas in dissimilar materials, the harder of the t\\o 
h<.nld have the slighter thread, as in the iron screws figs. 
to (>:U, intended to he screwed into wood ; the substance of the 
screw is supposed to lie below the line, and the head to the rijrht 
hand. Fourthly, by the resistance to accidental \iolence, either 
to the screws, or to the screwing tools, which is best obtained hy 
the > angles or edges, as in the several rounded 



666 DIFFERENT SECTIONS OF SCREW THREADS. 

threads. This fourfold choice of section, like every other feature 
of the screw, is also mainly determined by experience alone. 

Fig. 626, in which the angle is about 60 degrees, is used for 
most of the screws made in wood, whether in the screw-box or 

the turning lathe ; and also 
Sections derived from the for a very large proportion 

,-,. ANGULAR THREAD. ' r i 

of the screw bolts of ordinary 

626 v/VVVVVVVVVV mechanism. Sometimes the 

points of the screw tool mea- 
sure nearly 90 degrees, as in 
.... the shallow thread, fig. 627, 
628 /VVVVVVVV VV used for the thin tubes of 

telescopes ; or at other times 
J A/WWVWW they only measure 45 de- 

eso AAAAAAAAAA/ grees as in the very deep 

VVVVVVVVV threap, 628, used for some 

031 JUU\J\JU\JU\J\_Aj mathem f ic J and other in- 

struments; the angles repre- 

632 AAAAAAAAAA7 sented mav be considered as 

nearly the extremes. 

633 x lx'lxl/lXlXl/lXlx'lXl/1 I n originating accurate 

screws, the angular thread is 

634 \J\_J\_A_J\_A_J\_J\_J\_J\A always selected, because the 

figure of the thread is still 
maintained, whether the tool 

Sections derived from the > .-, j 

BQDABK THREAD. cut on one or on both sides 

of the thread, in the course 

635 I I I _| LJ I L I of the correctional process. 

Fig. 629 is the angular 

636 ^| O O ("S (~*} r~^ thread in which the ridges 

LJ LJ LJ LJ LJ are more or less truncated, 

to increase the strength of 

\ f^i i i f i 1^1 ri 4~lif hr^lf* if" mnv np viPWPfl 

637 \J \J \J LJ LJ I 

as a compound of the square 

638 _^ / u ^ ^ and angular thread. 

Fig. 630 is the angular 

thread in which the tops and bottoms are rounded; it is much used 
in engineering works, and is frequently called a round thread.* 

* See foot-note on p. 670. 



DIFFERENT SECTIONS OF SCREW THREADS. 

I tin- thread is more acute, and truncated only at the 
Ix.ttnm of the screw, this is used for j >rk, and greatly 

increases the hold upon t lie wood; 632 is obviously derived from 
631, and is used for the same purpose. 

In 633, which is also a screw for wood, the face that sustains 
the hold is rectangular, as in the square thread, the other is 
'.led. l-'i^. 03 1 is the form of the patent wood screw, some- 
times called the (ieriuan screw; it is hollowed to throw the 
advantage of bulk, in favour of the softer material, or the wood, 
the head of which is supposed to be on the right hand. In the 
last four figures, the substance of the screw is imagined to be 
situated below the line, and that of the wood above. 

The screws which are inserted into wood are generally made 
taper, and not cylindrical, in order that they may cut their own 
nut or internal thread ; some of them are pointed, so as to pene- 
trate without any previous hole being made : they merely thrust 
the fibres of wood on one side. Screws hold the most strongly in 
wood, when inserted horizontally as compared with the position 
in which the tree grew, and least strongly in the vertical position. 

Fig. 635 represents the ordinary square thread screw; the 
space and thread are mostly of equal width, and the depth is 
either equal to the width, or a trifle more, say one sixth. 

is a departure from 635, and has been made for 
-scs : and 637 has obviously grown out of the last from the 
obliteration of the angles; various proportions intermediate 
between 637 and 630 are used for round threads. 

In some cases where the screw is required to be rapid, one 
single shallow groove is made of angular, square, or circular sec- 
tion, leaving much of the original cylinder standing, as in fig. ' 

very slight purposes, a pin only is fitted to the groove, to 
serve as the nut ; should the resistance be greater, many pins, or 
a comb may be employed, and this was the earliest form of nut; 
otherwise a screwed nut may be used with a single thread. But 
when the greatest resistance is required, the surface bearing of 
the nut is extended, by making the thread, double, triple, &c. by 
rnttiui: one or more intermediate grooves and a counterpart nut. 

The nuts or boxes of very coarse screws for presses are now 
mostly cut in the lathe, although, when the screwing i 
were less perfectly understood, the nuts were frequently . 
Sometimes lead, or alloys of similar fusibility, were poured iu 



C68 TANGENT SCREWS, PIEDMONT SCREW WHEELS. 

betwixt the screw and the framework of the machinery (see 
note, p. 293, also 322-3, vol. 1) ; but for nuts of brass and gun- 
metal, sand moulds were formed. The screw was always 
warmed, to avoid chilling the metal ; and for brass, it was some- 
times heated to redness and allowed to cool, so as slightly to 
oxidize the surface, and lessen the disposition to a union or 
natural soldering of the screw and nut. It was commonly 
necessary to stretch the brass by an external hammering, to 
counteract the shrinkage of the metal in the act of cooling, and 
to assist in releasing from the screw, the nut cast upon it in 
this manner. The mode is by no means desirable, as the screw 
is exposed to being bent from the rough treatment, and to being 
ground by particles of sand adhering to the brass. 

The tangent screws used for screw wheels, have mostly angular 
or truncated angular threads, fig. 629, as screws absolutely square 
cannot be fitted with good contact and freedom from shake 
between the thread and teeth ; and probably the same rules by 
which the teeth of ordinary wheels and racks are reciprocally 
set out, should be also applied to the delineation of the teeth of 
worm-wheels, and the threads or teeth of their appropriate screws. 

Tangent screws are occasionally double, triple, or quadruple, 
in order that 2, 3, or 4 teeth of the wheel may be moved during 
each revolution of the screw. In the Piedmont silk-mills, this 
principle is carried to the extreme, as the screw and wheel become 
alike, and revolve turn for turn ; the teeth supposing them to be 
20, are then identical with those of a 20 thread screw, the angular 
coils of which cross the axis at the angle of 45, that is when 
the shafts lie at right angles to each other ; other proportions 
and angles may be adopted. In reality they fulfil the office of 
bevel wheels, or rather of skew-bevel wheels, in which latter also 
the axes, from being in different planes, may cross each other 
so that the skew-bevel wheels may be in the center of long 
shafts, but which cannot be the case in ordinary bevel wheels, 
the teeth of which lie in the same plane as the axis of the wheel. 
The Piedmont wheels act with a very reduced extent of bearing 
or contact surface, and a considerable amount of the sliding 
action of screws, which is disadvantageous in the teeth of wheels, 
although inseparable from all those with inclined teeth, and which 
are indeed more or less distant modifications of the screw.* 

* Wheii the obliquity of tlio tectU of worm-wheels is small, it gives a very 



IN. \-CB8 PROM THE DISSIMILARITY OP SCREWS. 669 

somewhat in detail the dillVrcnt forms of 
screws, and the circumstances which adapt thorn to their several 
purposes, I have now to consider some of the inconveniences 
which ha\e unavoidably arisen from the indefinite choice of 
proportions in ordinary screws, and also some of the means that 
have heen proposed for tin ir correction. The slight discussion 
of the more important of these topics will permit the introduc- 
tion of various additional points of information on this almost 
inexhaustible subject, the screw. 

No inconvenience is felt from the dissimilarities of screws, so 
l<>ii as the same screwing tools are always employed in effecting 
repairs in, or additions to, the same works. But when it is 
considered, how small a difference in either of the measi 
will mar the correspondence of the screw and nut ; and further 
the very arbitrary and accidental manner, in which the propor- 
tions of screwing apparatus have been determined by a variety 
of individuals, to suit their particular wants, and without any 
attempt at uniformity of practice (sometimes on the contrary, 
with an express desire to be peculiar), it is perhaps some matter 
of surprise when the screws made in different establishments 
properly agree. Indeed their agreement can be hardly expected, 
unless they are derived from the same source, and that some 
considerable pains are taken not to depart from the respective 
proportions first adopted. 

In a few isolated cases this inconvenience has been partially 
remedied by common consent and adoption, as in the so-called 
(iir-pmnp thread, which is pretty generally used by the mak 
of pneumatic apparatus ; and to a certain degree also in some 
of the screws used in gas-fittings and in gun-work. But the 
non-existence of any common standard or scale, enhances both 
the delay and expense of repairs in general mechanism, and leads 
to the occasional necessity for making additional sizes of tools to 
match particular work>, however extensive the supply of screw 
apparatus. 

Tliis perplexity is felt in a degree especially severe and costly, 
as regards marine and locomotive engines, which from necessity, 
have to he repaired in localities far distant from those in which 
they were made; and therefore require that the packet station, 

smooth action, bat at the expense of friction; but in ordinary toothed wheels, the 
teeth are exactly square aerow or in the plane of the axis, and the aim is to employ 
rolling contact, w i th the greatest possible exclusion of sliding, from amongst the tooth. 



670 



TABLES WHICH HAVE BEEN SELECTED 



or railway depot, should contain sets of screwing tackle, corres- 
ponding with those used by every different manufacturer whose 
works have to be dealt with: otherwise, both the delay and 
expense are from necessity aggravated. 

Mr. Whitworth has suggested that for steam machinery and 
for the purposes of engineering in general, " an uniform system 
of screw threads" should be adopted, and after having used 
some prior scales, he has proposed the following table, which 
may be justly considered as a mean between the different kinds 
of threads used by the leading engineers. 

Mr. Whitworth' s Table for Angular TJiread Screws.* 



Diameters in inches . . . 


i 


ft 


3 


& 


1 


1 


I 


i 


1" 


i| 


il 


ii 


H 




i| 


1: 


2" 


Nos. of threads to the inch 


2(i 


IS 


1C 


14 


1-2 


11 


lo 


9 


S 


7 


7 


6 





5 


5 


4!- 


4* 


Diameters in inches . . . 


2! 


-'i 


2| 


3" 


3] 


31 


^ 


4" 


M 


U 


4 


5" 


>l 


54 


H 


V 




Nos. of threads to the inch 


4 


4 


Si 


34 


N 


3-1 


3 


3 




3j 


21 




N 


2i 







As regards the smaller mechanism, made principally in brass 
and steel, such as mathematical instruments and many others, 

* In selecting this scale, the following judicious course was adopted : An 
extensive collection was made of screw-bolts from the principal workshops 
throughout England, and the average thread was carefully observed for dif- 
ferent diameters. The J inch, inch, 1 and 1 inch, were particularly selected, 
and taken as the fixed points of a scale by which the intermediate sizes were 
regulated, avoiding small fractional parts in the number of threads to the inch. 
The scale was afterwards extended to 6 inches. The pitches thus obtained for 
angular threads were as above : 

" Above the diameter of 1 inch the same pitch is used for two sizes, to avoid 
small fractional parts. The proportion between the pitch and the diameter varies 
throughout the entire scale. 

" Thus the pitch of the 1 inch screw is |th of the diameter ; that of the inch 
ith, of the 1 inch Jth, of the 4 inches ^th, and of the 6 inches ^th. 

" The depth of the thread in the various specimens is then alluded to. In this 
respect the variation was greater than in the pitch. The angle made by the sides 
of the thread being taken as an expression for the depth, the mean of the angle in 
1 inch screws was found to be about 55, which was also nearly the mean in screws 
of different diameters. Hence it was adopted throughout the scale, and a constant 
proportion was thus established between the depth and the pitch of the thread. I n 
calculating the former, a deduction must bo made for the quantity rounded off, 
amounting to Jrd of the whole depth, t. e., Jth from the top, "and Jth from the 
bottom of the thread. Making this deduction, the angle of 55 gives for the actual 
depth rather more than gths, and less than |rds of the pitch." Quoted from the 
Abstract of Mr. Whilworth't Paper, given in the Proceedings of the Institution of 
cert, 1841, p. 157-160. The entire paper is oho printed separately. 



M HI.U 1 IIKIIAI)-. 






tin- screws in the above scale below half au inch diameter are 
admit t < il to be too coarse; and the acute angular threads which 
are not rounded, are decidedly to be preferred from their greater 
ilt licacy and durability, that is when their strengths are propor- 
tioned to the resistance to which they arc exposed. In these 
respects the following table may be considered preferable. 

Table for Small Screwt of Fine Anyular ThrtadtS 



Diameters in vulgar fractions of the inch 


\ 


H 


; 


: 


1 


11 


1 


1 


: 








Diameter* in hundths.of the inch nearly 


:, 


17 


44 


11 


:;: 


31 


51 





>:, 





20 


Number of threads to tho inch . . . 


11 


1." 


U 


m 


m 


24 


u 


H 





m 


M 


Diameters in hundredth* of the inch . 


1> 


11 


14 


u 


Ifl 


,,;, 


PI 


"7 


u,} 


i 


04 


Number of thread* to the inch . . . 


:;.; 


u 


u 


u 


t-- 


:,.; 


;,; 






H 


100 



* This table was arranged by Mr. Chidson, of Liverpool, who made, first, a set 
of coarse angular thread tape from J to 1 inch, agreeably to the terms of Mr. 
\\ hitworth's table, giving to the screw tool the angle of 55 degrees, and also a 
set of square thread taps, of tho some diameters, and, as usual, of twice the pitch. 
This led Mr. Chidson to set out and construct a series of finer and deeper threads, 
from 4 inch to 14 hundred ths diameter, agreeably to the arrangement in the 
second table, and with screw tools of the angle of 45 degrees. 

I have great pleasure in stating my individual opinion of the suitability of the 
table to its intended purpose, and on comparing tho screws with those of similar 
diameters used by Holtzapffel and Co., I found about one third to be nearly 
identical in pitch, one third to be slightly coarser, and the others slightly finer. 
As regards the workmanship of these tape, made by Mr. Chidson fur his own use, 
and principally with his own hands, by means of the change wheels and single 
point tools, it gives me great pleasure to report most favourably. 

The tables above given, and which have been teUcUd and not calculated, will 
serve to explain the inapplicability of the mode of calculation proposed in various 
popular works ; namely, for angular thread screws, to divide the diameter by 8 
f>r tho pitch, when, it is said, such screws will all possess the angle of 34 degree* 
nearly ; and for square threads to divide by 4, thus giving an angle of 7 degree* 
nearly ; therefore 

Angular thread screws of 86421 4 J inches diameter. 

would have pitches of 1 I 4 i i & & inches rise. 

or rates of 1 1 J 2 4 8 16 32 threads per inch. 

which differ greatly from 2434(8 12 20 Whitworth's observational numbers. 

By the use of the constant divisor 8, the one-inch screw agrees with Whit worth's 
table, the extremes are respectively too coarse and too fine ; as instead of 8 being 
employed, the actual divisors vary from about 5 to 16, and therefore a theoretical 
mode would probably require a logarithmic schema Bat were this followed out 
with care, tho adjustment of the fractional threads so obtained, for those of whole 
numbers, would completely invalidate the precision of the rule; and the result 
would not bo in any respect better than when adjusted experimentally, as at present. 



G72 AGREEMENT OP SCREWS WITH STANDARD MEASURES, 

There is little doubt that if we could entirely recommence the 
labours of the mechanist, or if we could sweep away all the screw- 
ing tools now in use, and also all the existing engines, machines, 
tools, instruments, and other works, which have been in part made 
through their agency, these proposed scales, or others not greatly 
differing from them (as the choice is in great measure arbitrary), 
would be found of great general advantage ; the former for the 
larger, the latter for the smaller works. But until all these myriads 
of objects are laid on one side, or that repairs are no longer wanted 
in them, the old tools must from absolute necessity be retained, 
in addition to those proposed in these or any other schemes. It 
would be of course highly judicious in new manufacturing esta- 
blishments to adopt such conventional scales, as they would, to 
that extent, promote this desirable but almost impracticable end, 
namely, that of unity of system ; but which, although highly 
fascinating and apparently tenable, is surrounded by so many 
interferences, that it may perhaps be considered both as needless 
and hopeless to attempt to carry it out to the full, or to make 
the system absolutely universal : and some of the circumstances 
which affect the proposition will be now briefly given. 



First, agreement with STANDARD MEASURE, although convenient, 
is not indispensable. It may be truly observed, that as regards 
the general usefulness of a screw such as 615, which was sup- 
posed to measure f inch diameter, and to have 10 threads per 
inch, it is nearly immaterial whether the diameter be three or 
four hundredths of an inch larger or smaller than f of an inch ; 
or whether it have 9, 9 T V, 9|, 10, or 11, threads per inch, or 
any fractional number between these; or whether the thread 
be a trifle more or less acute, or that it be slightly truncated or 
rounded ; so long as the threads in the screw and nut are but 
truly helical and alike, in order that the threads mutually bear 
upon each other at every part ; that is, as regards the simple 
purpose of the binding screw or bolt, namely, the holding of 
separate parts in firm contact. And as the same may be said 
of every screw, namely, that a small variation in diameter or 
pitch is commonly immaterial, it follows, that the good office of 
a screw docs not depend on its having any assigned relation to 
the standard measure of this or any other country. 

Secondly, The change of system would cause an inconvenient 



SURROUNDED BY VARIOUS DIFFICULTIES. T.i 

increase in the number of icrewing tool* wed. Great numbers 

of :md useful screws, of accidental measures, have 1- 

made by various mechanieians; and the author hopes to be 
excused for citing the example with which he is most familiar. 

Between the years 17911800, the author's father m.\ 
few \arii ties of taps, dies, hobs, and screw tools, after the modes 
explained at pages 635 and G36 ; these varieties of pitch were 
ultimately extended to t\u l\e kinds, of each of which was for i 
a deep and shallow hob, or screw tool-cutter. These, when 
measured many years afterwards, were found nearly to possess 
in each inch of their length, the threads and decimal parts that 
are expressed in the following table. 

Approximate Valuti of I. I. IldtzapfftPi Original Screw Thrtndt. 



Number . . . 
Threads in 1 inch 


1 

6-58 


2 


3 


4 

13-00 


6 


6 

19-89 


7 
22-12 


8 
2571 


9 1 10 
23-88 36-10 


11 
39-83 


12 



Tkt aitffU <(f On dtp thrtatU u about 50 dtgrttt ; o/UttihaUoif 00 dtgrta. 

This irregularity of pitch would not have occurred had the 
screw-lathe with change-wheels been then in use ; but such was 
not the case. For a long series of years I. I. Iloltzapftel, (in 
conjunction with his partner, I. G. Deycrlein, from 1804 to 
1827,) made, as occasion required, a large or a small screw, a 
coarse or fine, a shallow or deep thread, and so forth. By 
which accumulative mode, their series of working taps ami die*, 
together with screw tools, gages, chucks, carriers, and a variety 
of subordinate apparatus, became extended to not less than one 
hundred varieties of all kinds. 

About one-third of these sizes have been constantly used, up 

to the present time, both by II. & Co., and by other persons to 

whom copies of these screw tackles have been supplied, and 

consequently many thousands of screws of these kinds have 

ii made : this implies the continual necessity for repairs and 

alterations in old works, which can only be accomplished by 

;nir the original sizes. 

Since the period at which II. & Co. made their screw lathe, 
they have employed the aliquot threads for all screws above half 
an inch; indeed, most of the^c have also been cut in the st : 
lathe. To have introduced the same method in the small bind- 
ing screws which are not made in the screw lathe, but with the 
-locks and chasing tools, would have doubled the number of 

x x 



G7i AGREEMENT OF SCREWS WITH STANDARD MEASURES, 

their working-screw tackle, and the attendant apparatus ; with 
the risk of confusion from the increased number, but without 
commensurate advantage as regards the purposes to which they 
are applied. 

Doubtless the same reasons have operated in numerous other 
factories, as the long existence of good useful tools has often 
lessened, if not annulled, the advantage to be derived from a 
change which refers more immediately to engineering works ; 
and in which a partial remedy is supplied, as steam-engines, &c. 
are frequently accompanied with spare bolts and nuts, and also 
with corresponding screw apparatus, to be employed in repairs ; 
the additional cost of such parts being insignificant, compared 
with the value of the machinery itself. 

Thirdly : Unless the standard sizes of screws become inconve- 
niently numerous, many useful kinds must be omitted, or treated 
as exceptions. For instance, in ordinary binding screws, more 
particularly in the smaller sizes, two if not three degrees of 
coarseness should exist for every diameter, and which might be 
denominated the coarse, medium, and fine series; and again, 
particular circumstances require that threads should be of 
shallow or of deep angular sections, or that the threads should 
be rounded, square, or of some other kinds ; in this way alone, 
a fitness for all conditions would inconveniently augment the 
number of the standards. 

In many cases besides, screws of several diameters are made 
of the one pitch. In order, for example, that the hole when 
worn may be tapped afresh, and fitted with screws of the same 
pitch or thread, but a trifle larger ; * or that a partially worn 
screw may be corrected with the dies or in the lathe, and fitted 
with a smaller nut of the same pitch. A succession of taps of 
the same pitch also readily permits a larger screw to be employed, 
when that of smaller diameter has been found to break, either 
from an error of judgment in the first construction of the 
machine, or from its being accidentally submitted to a strain 
greater than it was intended ever to bear.f 

* This is dono in some of the patent screws for joinery work, so that when 
the thread in the wood is deteriorated from the frequent removal of the screw, 
another of the same pitch, but larger diameter, may be substituted. 

t Mr. Clement has screw taps of }, J, 1, 1J, 1J, If, 1J, &c., inch diameter, and 
all of seven threads per inch. Holtzapfiel and Co. have taps, &c., for screws of ten 
threads per inch of fifteen different kinds, which are used for slides and adjust- 
mente, besides less extensive repetitions of other threads. 



SURROUNDED BY VARIOUS DIFFICULTIES. < ''< " 

It is also in some cases requisite to li:i. and left hand 

screws of the same pitch, that, amongst other purposes, they 
may effect simultaneous yet opposite adjustments in machin 
as in some universal chucks: and also some few screws, the 
threads of which are double, triple, quadruple, and so forth, for 
ng to screws of small diameters considerable rapidity of pitch 
or traverse, or a fixed ratio to other screws associated with them, 
in the same piece of mechanism. 

I'oiirthly : Friction prevents the strict maintenance of standard 
gaffes for screws. The universality of system, to be perfect, should 
admit that a bolt made tl. in London, should agree with 

a nut made ten or fifty years hence in Manchester, which is not 
called for, nor perhaps possible, if an absolute fit be required : 
in reference to this we must commence by a small digression. 

In comparing the Exchequer Standard Yard Measure \\ith 
the copies made from it, friction in no way interferes, as the two 
measures are successively observed through two fixed micro- 
scopes, as before adverted to. But we cannot thus measure a 
cylinder, as either callipers, or a counterpart cylinder placed in 
contact, must be employed as the test; aud each time of trial 
the cylinder is absolutely, although very slightly worn, by the 
traverse of the surfaces against each other; the form of the 
cylindrical gage being simple, to increase its durability, it is 
worked to the figure after having been hardened. 

In nicaMiring a screw, the callipers are insufficient, and the 
one screw must be screwed into the other: from this trial much 
more motion, friction, aud abrasion arise. Further, the se. 
gage cannot, from its complex form, be readily figured after 
material has been hardened; and if hardened subsequently to 
the helical form having been given, the measure become, m 
some degree, altered, from the action of the fire and water, 
ii is a fatal objection. 

I'mlcr ordinary and proper management, the production of a 
number of similar pieces may be obtained with sufficient exacti- 
tiu! ng to the tool some constant condition. For example, 

a hundred nuts tapped with the same tap, will be very nearly 
alike in their thread ; and a hundred screws passed through tin- 
hole of a screw-plate, \\ ill similarly agree in size, because of the 
ant dimensions of the tools, for a moderate period. 

In practice, the same relative constancy is given to the dies 

x x 2 



G7G AGREEMENT OF SCREWS WITH STANDARD MEASURES, 

of die-stocks and bolt-screwing engines, and partly so to the 
tools of the screw-cutting lathe. Sometimes the pressure or 
adjusting screw has graduations or a micrometer ; and numerous 
contrivances of eccentrics, cams, and stops, are employed to 
effect the purpose of bringing the die or turning-tool to one 
constant position, for each succeeding screw ; these matters are 
too varied and general to require more minute notice. Part of 
such modes may serve sufficiently well for ten, or a hundred 
screws, provided that no accident occur to the tool ; but if it 
were attempted to extend this mode to a thousand, or a hundred 
thousand pieces, the same tool could not, even without accident, 
endure the trial: it would have become not only unfit for 
cutting, but also so far worn away as to leave the last of the 
works materially larger than the first. 

In respect to screws, the instrument, the size of which claims 
the most importance, is perhaps the plug-tap, or that which 
removes the last portion of the material, and therefore deter- 
mines the diameter of the internal thread ; but as the tap is 
continually, although slowly, wearing smaller, the first and last 
nut made with it unavoidably differ a little in size. It is on 
account of the wearing of the tap, amongst other circumstances, 
that when screws and nuts are made in large numbers, and are 
required to be capable of being interchanged, it becomes needful 
to make a small allowance for error, or to make the screws a 
trifle smaller than the nuts. 

In order to retain the sizes of the taps used by Holtzapffel&Co. 
Fig. 639. they some years ago made a set of original taps 
exactly of the size of the proposed screws, and to 
be called A ; these, when two or three times 
used, to rub off the burrs, were employed for 
cutting regulating dies B, of the form of fig. G39, 
with two shoulders, so that the dies could be 
absolutely closed, and yet leave a space for the 
shavings or cuttings. In making all their plug- 
taps, they are first prepared with the ordinan r 
shop tools, until the taps are so nearly com- 
pleted, that, grasped between the regulating dies B, the latter 
close within the fortieth or fiftieth of an inch, therefore leaving 
the dies B next to nothing to perform in the way of cutting, 
but only the office of regulating the diameter of the working 




SURROUNDED in \ VICIOUS DIFFICULTIES. 

.--taps. Should the dies H moot with any accident, tlio taps 
A, which have to this stage been only used for one pair of 
regulating dies, exist for making repetitions of B. This method 
has been loimd to fulfil its intruded purpose very ellVetually for 
several years, but at the same time it is not proposed to apply 
this or any other system universally. 

In conclusion, it may be said that by far the most important 
argument in favour of the adoption of screws of aliquot pitches 
applies to steam machinery and similar large works, and that, 
principally, because it brings all such screws within the province 
of the screw-lathe with change-wheels, which has become, in 
ueerin^' establishments and some others, a very general tool. 
This valuable tool alone, renders each engineer in a great measure 
independent of his neighbour, as screws of 2, 2J, 2$, 3, 10, or 
20 threads in the inch, are readily measured with the common 
rule, and copied with the screw-wheels, and a single- pointed tool, 
or an ordinary comb or chasing tool with many points. 

And therefore, with the modern facility of work, were engineers 
severally to make their screw tackle from only the written mea- 
sures of any conventional table, they would be at once abundantly 
within reach of the adjustment of the tools, and that without any 
standard gages; the strict introduction of which would almost 
demand that all the tools made in uniformity with them should 
emanate from one center, or be submitted to some office for 
inspection and sanction, and this would be indeed to buy the 
occasiunul advantage at too dear a rate. 

It must, however, be unhesitatingly granted, that the argu- 
ment applies but little, if at all, to a variety of screws which from 
their smaller size are not made in the screw-lathe, but with die- 
stocks and the hand-chasing tools only ; and which arc employ d 
in branches of art that may be considered as almost isolated 
i one another, and therefore not to require uniformity. 

For instance, the makers of astronomical, mathematical, and 
philosophical instruments, of clocks and watches, of guns, of locks 
and ironmongery, of lamps, and gas apparatus, and a multitude 
of other work*, possess, in each case an amount of skill which 
appl; tically to these several occupations; so that iinle^ 

the works made by each are returned to the absolute makers for 
repaiaiion. tiny an- at any rate.M nt to an indiv idual engaged in 
the same line of business. 



678 PECULIAR MODES OF MAKING SCREWS. 

Under these circumstances, it is obvious that the gunmakers, 
watchmakers, and others would derive little or no advantage from 
one system of threads prevailing throughout all their trades ; 
in many of which, as before noticed, partial systems respec- 
tively adapted to them already exist. The means employed 
by the generality of artizans^in matching strange threads, are, in 
addition, entirely independent of the screw lathe, and apply 
equally well to all threads, whether of aliquot measures or not ; 
as it is usual to convert one of the given screws, if it be of steel, 
into a tap, or otherwise to file a screw tool to the same pitch by 
hand, wherewith to strike the thread of the screw or tap ; and 
when several screws are wanted, a pair of dies is expressly made. 

But at the same time that, from these manifold considerations, 
it appears to be quite unnecessary to interfere with so many 
existing arrangements and interests, it must be freely admitted 
that advantage would ultimately accrue from making all new 
screws of aliquot measures ; and which, by gradually superseding 
the old irregular threads, would tend eventually, although slowly, 
to introduce a more defined and systematic arrangement in 
screw tackle, and also to improve their general character. 



The author has now concluded the various remarks he pro- 
poses to offer on the formation of the screw for the general 
purposes of mechanism; on the modes pursued by various 
celebrated mechanicians for its improvement ; and on various 
practical considerations which influence the choice of screws : 
but he is desirous briefly to advert to some few peculiar, inter- 
esting and practical methods of producing this important 
element of construction. 

The threads of wrought-iron screws have been forged whilst 
red hot, between top and bottom swage tools, having helical 
surfaces like those of screw dies ; screws have been twisted 
whilst red hot, out of rectangular bars, by means of the tail vice 
and hook wrench; as in making screw augers. Screws intended 
for ordinary vices, have been compressed whilst cold, somewhat 
as with die-stocks ; the lever is in this case very long, and the die 
is a square block of hardened steel, with an internal square 
thread screw, left smooth or without notches. The thread is 
partly indented and partly squeezed up, the diameter of the 



AND WARREN'S CAST-IRON SCREWS. ;.' 

iron cylinder being less than that of the finished screw: this 
action severely teats the iron.* 

A patent was taken out in 1S30 by Mr. Wilks, for making 
both the boxes and screws of tail vices and presses in malleable 
cast-iron. The peculiarities in the moulding processes are that 
tin- core for the hollow worm, or box, is made in a brass core box, 
divided longitudinally into three parts, which arc filled separately, 
and closed together with a stick of wood in the center, to stiffen 
the core and serve for the core print. The core box is then con- 
nected by rings, like the hoops of a cask : this completes the core, 
which is removed, dried, and inserted in a mould made from a 
model of the exterior of the box, constructed as usual. 

In moulding the solid screw, the moulding-flask is a tube with 
a cap having an internal thread, exactly like that of the screw ; 
the tube is filled with sand, and a plain wooden rod, nearly equal 
in diameter to the axis of the screw, is thrust in the sand, to 
form a cavity. The screwed tap is then attached to the flask, 
and a brass screw, exactly like that to be cast, is guided into the 
sand by means of the screw-cap, and taps a thread in the sand 
mould very accurately. The screw-cap is then removed, and the 
second part of the flask, in which the head of the vice-screw has 
been moulded, is fitted on, and the screw is poured. 

After having been cast, the screws and boxes arc rendered 
malleable in the usual way, except that they are placed vertically ; 
in general the box is slightly corrected with a screw-tap. 

Large quantities of screws have been produced by .M r. Warren's 
pat (lit process for manufacturing screws of malleable cast-iron 
for joinery work : a most ingenious plan is employed therein for 
\\ hiding the models into and out of the solid sand-mould, which 
is thereby made beautifully smooth and accurate. After the last 
description the general method will be readily understood, it' it 
he considered that the first side of an ordinary flask is rammed 
full of sand on an iron plate having conical projections like the 
Is of screws, in regular lines half an inch asunder, and ribs to 
form the channels by \\hich the metal is to be admitted. The 
when tilled is placed in a machine, beneath a plate of metal 



Applied by the Wright*' Vice makers of Birmingham. 8e Technological 

itory, vol. vi., p. 289. For the mode of soldering the thread in the box or the 

hollow screw of the rioe, M* the MUM paper, and also ToL I, p. 443, of this work. 



680 PERKINS'S AND SCOTT'S SCREWS FOR CAST-IRON PIPES. 

with screwed holes, also half an inch asunder, and each fitted 
with a pattern screw, terminating above in a crank like a winch 
handle, say of inch radius. 

Any of these screws on being turned by its crank with the 
fingers, would pierce the sand as in Wilks's process ; but by em- 
ploying a crank-plate pierced with a like number of holes, to 
receive the pins of all the cranks, the whole of the screw models 
are twisted in at once, and removed with the same facility. 

The notches of the screws are cut by a circular saw ; if large 
they may be moulded. The cast-iron screws are subsequently 
rendered malleable, by the decarbonizing process described in 
the former volume, pages 259-260.* 

Mr. Perkins's patent cast-iron water-pipes, with screw joints, 
may be considered as another example. The patent pipes are 
connected with right and left hand screws and loose sockets, 
which draw the ends of the pipes into contact, or rather against 
a thick greased pasteboard washer interposed between them. 
The pipes are made entirely by foundry- work, and from patterns 
and : core-boxes divided in halves, in the ordinary manner. 
Mr. Perkins says that although the patent pipes possess several 
advantages over ordinary cast-iron pipes with the spigot and 
faucet joint, they are produced at the same price, and save much 
ultimate expense in fixing.f 

In Mr. Scott's subsequent patent for joining cast-iron and 
other pipes for various fluids, the method commonly known as 
the "union-joint" is employed, and which offers additional 
facility in the removal of one pipe from the midst of a series. 
Each pipe has at one end a projecting external screw, and at 
the other a projecting fillet or flange ; the socket is cast loosely 
around the pipe, but is prevented from being removed or lost by 
the projections at each end of the same. The inside screw of the 
socket cast upon the first pipe , screws upon the external screw 
of the next pipe b, until the socket comes in contact with the fillet 
on a, and thus draws a and b into close contact with the washer 
that is placed between them. One cast-iron pipe and its appro- 

* Date of Mr. Warren's patent for an improved machine for making screws, 4th 
August, 1841 ; described in Rep. of Patent Inv. for March 1843, also in the Glasgow 
Mechanics' and Engineers' Mag., same date. The machine was constructed by 
Mr. Ingram of Birmingham, and is successfully worked by him. 

t Date of patent, 21st Sept. 1841, described in Rep. of Patent Inv. Oct. 1841. 



Il\\l)'- (nMt'RESSED SCREWS, ETC. 

print i socket a iv moulded at one operation, which is curiously 
accomplished by the use of two sand cores, the inner of which 
is of the length of the pipe, and solid as usual; the outer core 
uide aa a loose ring around th.- mm T. The union-joint is 
differently produced by Mr. Scott in wrought-iron and soft 
metal pipes.* 

A peculiar method of making screw joints is employed in 
Mr. Hand's patent collapsible tubes for preserving paints, |>n, vi- 
sions, &c. The tin, whilst at the ordinary atmospheric tempe- 
rature, is forced, almost as a cement, into the screwed recesses of 
brass or iron moulds; and the threads arc thus made to assume 
the helical form, with great rapidity, uniformity, and perfection. f 

Indeed it is diflicult, nay impossible, to find the limit of the 
methods employed in producing, or those of subsequently em- 
ploying this interesting object, the screw; which not only enters 
in endless variety into appliances and structures in metal, wood, 
and other materials, but is likewise rendered available in most 
different yet important modes, as in the screw-piles for sandy 
foundations, screws for raising water, for blowing furnaces, 
ventilating apartments, and propelling ships. 

Should it appear that the formation of the screw has been 
treated in greater detail than the other subjects with which 
it is associated, either as regards the modes of proceeding or 
the mechanism employed; the author would observe that it 
appeared to him that by this mode alone he could introduce, in 
something like order, a variety of interesting particulars, which 
although they have occupied very many pages, are but as a 
fragment of what might be said on a subject which has engrossed 
so much attention. 

Date of patent, 6th July, 1842. See Mechanics' Magazine, 1843, page 104. 

t Rand's second patent for making collapsible vessels, 29th Sept 1842. U in lor 
the first patent the tin was drawn into tube, (sec vol. L, p. 431,) and the convex and 
screwed ends were cast and soldered in ; by the improved method the entire vessel 
is made from a small thick perforated disk of tin by one blow of a fly-press. The 
lower part of the mould has a shallow cylindrical cup, concave and tapped at the 
bane ; the upper part of the mould is a cylinder as much smaller than the cup as 
the intended thickness of the metal, which, on the blow being given is compressed 
into the screw, and ascends four or five inches up the cylinder or ruin. For large 
IMS a hydrostatic press is employed. 



682 



CHAPTER XXVII. 

SAWS. 
SECTION I. DIVISION OF THE SUBJECT FORMS OF SAW TEETH. 

THE saw is the instrument which is almost exclusively em- 
ployed for converting wood, ivory, and various other substances, 
from their original forms to those shapes required in the arts ; 
and in general, the thin serrated blade proceeds along the super- 
ficies of the required object, whether they be plane, circular, 
or irregular, and effects its office with considerable speed and 
accuracy, and comparatively insignificant waste. Unless a tree 
is felled with the axe, the saw is employed, first, in the forest in 
separating the tree from its roots, and cutting it into lengths 
convenient for transport ; the saw is next used at the saw -pit in 
converting the timber into plank and scantling of various dimen- 
sions ; and the saw is subsequently employed in the workshop, 
by the joiner, cabinet-maker, and numerous other artisans, in 
reducing the plank or board into smaller pieces, ready for the 
application of the plane, the file, and other finishing tools. In 
some elaborate and highly ornamental arts, the saw as will be 
shown is nearly the only instrument used. 

Many of the machines now employed in sawing are, as it will 
be seen, derived from similar processes before executed, and in 
many cases less perfectly so, by hand labour. The saw is but 
little used for similar preparatory works in metal, the figuration 
of which is for the most part, accomplished by the furnace, 
the hammer, or rollers; matters that have been described in 
the first volume. 

It is proposed to consider saws in two groups, namely, recti- 
linear saws, and circular saws : the precedence will be given to 
the more simple kinds, or those rectilinear saws used by hand, 
and generally without additional mechanism; conditions which 
do not apply to the circular saw, which is always combined vitli 
some portion of machinery. And for the perspicuity of the whole 
subject, it has been thought best to place the general remarks 
on the forms of teeth of saws, at the beginning of the chapter; 



GENERAL REMARKS ON SAW!. '-"> 

from which arrangement many advantages appear to arise, 
notwithstanding that it implies the necessity for adverting to 
various saws, before their specific or particular descriptions have 
:> given, and which objection will be in part removed by the 
pivxious inspcetion of the table on page G99. 

The blade of the rectilinear saw is usually a thin plnte of 
sheet steel, whieh in the first instance is rolled of equal thick- 
ness throughout : the teeth arc then punched along its edge, 
previously to the blade being hardened and tempered, after 
which it is smithed or hammered, so as to make the saw quite 
flat. The blade is then ground upon a grindstone of consider- 
able diameter, and principally crossways, so as to reduce the 
thickness of the metal from the teeth towards the back. When, 
by means of the hammer, the blade has been rendered of 
uniform tension or elasticity, the teeth are sharpened with a 
file, and slightly bent, to the right and left alternately, in order 
that they may cut a groove so much wider than the general 
thickness, as to allow the blade to pass freely through the 
groove made by itself. The bending, or lateral dispersion of 
the teeth, is called the set of the saw.* 

The circular saw follows the same conditions as the recti- 
linear saw, if we conceive the right line to be exchanged for the 
circle ; with the exception that the blade is, for the most part, 
of uniform thickness throughout, unless, as in the circular veneer 
saws, it is thinned away on the edge, as will be explained. 

It is to be observed that the word pitch, when employed by 
the saw-maker, almost always designates the inclination of the 
face of the tooth, up which the shaving ascends ; and not the 
intrnal from tooth to tooth, as in wheels and screws. 

In the following diagrams of teeth, which, for comparison, are 
drawn of equal coarseness or size, some kinds are usually small, 
and seldom so distant as $ an inch asunder: these are described 
as having 2, 3, 4, 5, to 20 points to the inch,- and such of the 
other teeth represented as are used by hand, are commonly 
from about ^ to 1J inch asunder, and arc said to be of or 1^ 
inch space, although some of the circular saws are as coarse as 
2 to 3 inches and upwards from tooth to tooth. 

For the mode of hardening and tempering saw*, the reader ia referred to vol. i., 
pp. 249250, of this work : and for the principled upon which they are flattened 
and rendered of uniform elasticity, to the Mine Tolume, pp. 414 422. 



684 



FORMS OF SAW TEETH. 



The usual range of size or space for each kind of tooth, is 
accordingly expressed beside the diagrams; as are also the angles 
of the faces, and of the tops of the teeth, measured from the line 
running through the point of the teeth, or the edge of the saw. 



Figs. 
640 



644 



653 




ANGLES. ORDINARY 
Face & Back. SPACE. 
deg. deg. 

110 & 70 1 to H 



641 4JVLJVUVLMJVl_M 90 & 60 

643 A/vWW 12 & 60 



1 to 




105 & 45 

90 & 30 
75 & 15 



1 to 1J 
I to 1J 

| to 1 

I to 1 

MO 24 



Also from 3 
to 60 points 
iu each inch. 



90 & 
60 & 


50 
15 


1 to 4 

1 to 2 




90 & 


30 


to 34 


Sometimes 








each alter- 








nate tooth is 








cut out, and 


75 & 


20 


| to 34 


then called 

ski/i-tooth. 


60 & 


10 


g to 34 




45 & 


5 


I to 34 





The angle of the point itself will be found by subtracting the 
angle of the back from that of the face of the tooth, or the less 
from the greater of the first two numbers. 



FORMS OF SAW TEETH. 

The four varieties of teeth at the commencement of the an- 
nexed group, from presenting the same angK -s in cither direction 
also cut in both din -ti.ns; in fact, the face and back may !> 
considered to change places in each alu -nuite cut. These tenth 
are u>cd t'r such cross-cutting saws as have a handle at each 
end, and are worked by two or more men; aa in cutting down 
S and dividing them win -n they have been felled; and similar 
saws are used for the soft building stones when they arc first 
raised from the quarry. Fig. 640 is called the peg-tooth, or 
Jlmm-tooth, and is much used in North America and elsewhere ; 
ti.u r . 'ill, the M-tooth, which is so named from its resemblance to 
the letter, is now but very rarely employed; fig. 61:2, the half- 
moon-tooth, is used in South America for cross-cutting; and 
fig. 043 is that commonly described as the cross-cutting-tooth, 
although in England the peg-tooth or 040, the hand-saw-tooth 
or 645, and the gullet-tooth 050, are also used for cross-cutting 
timber, more especially the last form when sharpened more 
acutely than usual, and used to cut in one direction only. 

Referring to the preliminary remarks on cutting tools, pages 
457 to 468 of the present volume, it will be seen that saws were 
considered to belong to the group of scraping tools, and that < 
and/, fig. 816, were viewed as the generic forms of the teeth, the 
le of which is commonly 60 degrees, from the circumstance 
of the simple angular teeth being mostly produced by angular 
notches, filed with two of the sides of an equilateral triangular 
file; and therefore the points assume the same angle as the 
spaces, or 60 degrees. 

But the angle of 60 degrees is variously placed; for instance, 
the teeth in fig. 043 are said to be upright, or to have no pitch ; 
and the teeth in fig. 646 to be flat, or to have considerable 
pitch : these may be considered as the extremes of this kind of 
tooth, between which every inclination or pitch is more or less 
used ; but, for the sake of definition, four varieties have been 
assumed, the- straight lines of which are 15 degrees asunder. 

Fig. 643, as already explained, is the ordinary tooth for cross- 
cutting, and which, from presenting equal angles on each side, 
is said to be of upright pitch. The tooth that is, however, more 
t-rally used for small cross-cutting saws is fig. 644, which 
i> im-limd ah. nit 15 degrees from the last. This form of 
tooth, called slight pitch, is used for the cross-cutting saws for 



686 FORMS OF SAW TEETH. 

firewood ; those for joiners' use ; and also for those employed 
in cutting up ivory ; in which latter case the blade is stretched 
in an iron frame. 

Fig. 645 is the tooth in most general use : it is known as 
ordinary pitch or the hand-saw-tooth. The face is perpendicular, 
and the back inclines at an angle of 30 from the edge of the 
saw, or the line of work. Most of the saws used by cabinet- 
makers and joiners are thus toothed, or rather at an inclination 
intermediate between figs. 644 and 645. 

The tooth, fig. 645, is likewise generally employed for saws 
used for metal; for circular saws used for fine work, including 
veneer-saws, and for many of the circular saws for cross-cutting. 

In fig. 646 the face of the tooth is " set forward" or stretches 
beyond the perpendicular, at an inclination of 15 degrees : this 
kind is employed in mill-saws used abroad for soft woods, and 
they are the most inclined of those teeth formed by the two 
faces of the triangular file at the one process. 

Nearly the same tooth as fig. 646 is also used for circular saws 
and cutters for metal. The object is then to assimilate the points 
to those suitable to tools for turning the metals ; therefore, the 
angle of separation betwixt the end of the tooth and the plane 
to be wrought, is made small. The hook form of the point is 
incidental to the employment of the triangular file, and is also 
proper for the material to be cut. 

Fig. 647 is a form of tooth that is set forward like 646, but 
the point is more acute than the last five, or it is about 45 
degrees instead of 60. It is used for some circular saws, 
and occasionally also for pit saws and cross-cut saws; and is 
frequently employed for cutting soft Bath stone. 

Sometimes the acute angular notch is not continued to an 
internal angle ; a method adopted in some mill saws, both those 
of ordinary or perpendicular pitch, fig. 648, and those of greater 
pitch or inclination, fig. 649 ; the former being more common 
for rectilinear, the latter for circular saws. Various intermediate 
forms are met with. 

The three kinds of teeth, figs. 647, 648, and 649, from being 
more acute than 60 degrees, cannot be sharpened with the 
ordinary three-square or equilateral file, as it will not reach to 
the bottoms of the teeth. The mill-saw file is then used, namely, 
a thin flat file with square or round edges, as the definition 



FORMS OP SAW TEETH. 

of the internal an^le is not needful; althougb given by the punch 
in the forma 1 !ic tooth. The angular mill-saw teeth arc 

employed, partly because tbcy are more easily sharpened than 
the gullet teeth, which conclude the series of diagrams. 

The teeth, figs. 650 to fig. 653, are called yullt-t teeth, on 
account of the large hollow or gullet that is cut away in front of 
each tooth, in continuation of the face; and they are also known 
as briar teeth. The tooth is in general cut by one punch filling 
the entire space ; but two punches, an angular and a gullet 
punch have been occasionally used. 

The gullet is adopted to allow the tooth to be sharpened with 
a round or half-round tile, by which the face of the tooth becomes 
concave when viewed edgeways, and acquires a thin and nearly 
knife-like edge, as will be explained. The increased curvilinear 
space allows more room for the sawdust, and is less disposed to 
retain it than the angular notch. 

For the facility of explanation, the faces of the teeth differ 
fifteen degrees in pitch, and the tops of the tooth are variously 
inclined to the edge of the saw, as tabulated. The medium 
kinds, figs. 651 and 652, are perhaps more common, although the 
saw-maker forms the teeth originally more acute, for the facility 
of first sharpening; and the sawyer sometimes neglects to 
file the gullets in the same proportion as the tops, by which the 
advantage attending the gullets is in a measure lost. Each 
alternate tooth appears to be deeper than the others ; but this 
only arises from the peculiar mode of sharpening the gullet with 
a round or half-round file, which makes a broad chamfer, the 
of which is elliptical. 

For the general purposes of pit saws, and also for straight and 
circular mill-saws, the medium teeth, 651 and 652, are suitable; 
hut for hard woods, as mahogany, rosewood, and others, and also 
for cross-cutting, the form should lean towards fig. 650; and 
for soft woods and ripping with the grain, towards the more 
inclined tooth, iig. 653. The whole of the forms of teeth may 
materially diverted from those originally given by the saw- 
make r, in the important process of sharpening, and which will 
In- now described, as the most proper way of concluding the 
remarks respecting the angles or bevils given to the edges of the 
teeth, independently of their simple profiles. 



CSS SHARPENING AND SETTING SAWS. 

SECT. II. SHARPENING AND SETTING SAWS. 

The processes denominated sharpening and setting a saw, con- 
sist, as the names imply, of two distinct operations : the first 
being that of filing the teeth until their extremities are sharp ; 
the second, that of bending the teeth in an equal manner, and 
alternately to the right and left, so that Avhen the eye is directed 
along the edge, the teeth of rectilinear saws may appear exactly 
in two lines, forming collectively an edge somewhat exceeding 
the thickness of the blade itself. 

Circular saws require exactly similar treatment, if we con- 
sider the tangent of the circle to be substituted for the right 
line ; and therefore the sharpening of straight saws will be first 
described, and those peculiarities alone which attach to the 
sharpening of circular saws will be then separately noticed. 

Setting the teeth, which in practice is always subsequent to 
the sharpening, will also be placed subsequently in the section ; 
the commencement of which will be devoted to the modes of 
holding the saw in the operation of sharpening, and the descrip- 
tion of the files used. 

In sharpening the saw it is mostly fixed perpendicularly, and 
with its teeth upwards, various modes being adopted according 
to circumstances. The tail-vice used by the saw-maker in 
sharpening the saw, measures from nine to twelve inches wide 
in the chops, and also nine to twelve inches high, or above the 
screw ; proportions exceeding those of tail-vices used by mecha- 
nicians generally. Slips of wood, or clamps of sheet lead bent 
to the figure of the jaws of the vice, are interposed between the 
saw and the vice, so that the elasticity of the wood, or the 
inelasticity of the lead may give a firm hold, and prevent the 
disagreeable screeching noise that accompanies the action of 
the file when the saw is insecurely held ; and the greater the 
noise the less the amount of work that is done. 

The joiner employs a wooden vice resembling that of the saw- 
maker as to proportions, but it is fixed in the screw-chops of his 
work-bench. 

In sharpening pit-saws, the sawyer seldom finds it necessary 
to remove the handles or frames. The long or whip-saw, and 
others not having frames, are supported in the sawing-horse, a 
trestle about five feet long and two feet high, with four or five 



II \M> FILES USED IN MIMUT.MVO SAWS. 

uprights or wooden pegs, sawn half-way through to receive tin: 
X edge of the blade; tin- horse HUM -> the edge of the saw 
about three feet from the ground. 

A more convenient mode is to have ;\juin(i'ii-/iore t fig. 654, the. 
two halves of which open somewhat like the jaws of a pair of 
pliers ; \vhen the saw has been inserted, the legs of the horse are 
ided by the stretchers at the ends, and fix the blade. 




The tiles used in sharpening saws are triangular, round, hnlf- 
round, and mill saw-files. The equilateral triangular files, com- 
monly designated as three-square files, vary from about three to 
nine inches long; for small saws they are generally taper; for 
large, sometimes nearly parallel, when they arc called blunts, a 
term applied to other nearly parallel files. The triangular file 
i> lAclusively used for the teeth of fiir*. t! [:'> to '. ('>, and more or 
less for all the rectilinear teeth. For small teeth, the double- 
cut Lancashire files are the most used, on account of the kcen- 
of their edtres and the common size is 4$ inches long. The 
generality of other saw-files are single or float-cut, that kind of 
file tooth being considered to 'cut sweeter,' and do more work. 

Konnd files from 5 to 8 inches long, arc used in saw-mills for 
the ;;nllets of the teeth, figs. 650 to <>.">:*, and flat files for the 
tops; but the pit-sawyer and some others always employ half- 
round files, as the one instrument may be then applied to 
both pur hesc files arc always blunt or parallel. 

Mill saw- tiles are in general thin, flat and parallel, from 6 to 
1 1 inches long, float-cut on the sides, and with smooth, square 

\ ^ 



690 GENERAL REMARKS ON SHARPENING SAWS. 

edges. Sometimes, however, they have round and cutting edges, 
and are of taper figure. 



The five ordinary modes of sharpening saws will be explained 
and illustrated by enlarged diagrams in three views, which denote 
the ways in which the teeth are bevelled and set ; but a few 
general observations that apply to each mode will be first given. 

In general, the angles of the points of the saw-teeth are more 
acute, the softer the material to be sawn, agreeably to common 
usage in cutting tools ; and the angles of the points, and those 
at which the files are applied, are necessarily the same. Thus 
in sharpening saws for metal, the file is generally held at 90 
degrees, both in the horizontal and vertical angle, as will be 
shown ; for very hard woods at from 90 to 80 degrees, and for 
very soft woods at from 70 to 60 degrees, or even more acutely. 
The vertical angle is about half the horizontal. 

In general the horizontal angle of the file is alone important, 
(that is, considering the saw-blade vertical and with the teeth 
upward,) although to assist the action of the file it is customary 
to depress the handle a little below the point of the file, and 
only to file on those teeth which are bent from the operator. 
When the tooth that is bent towards the individual is filed, it 
vibrates with much noise, and is disposed to strip off the teeth 
from the file, instead of being itself reduced. 

To insure the action of each tooth, the edge of the saw should 
he quite straight ; it is therefore occasionally topped, by laying 
the file divested of its handle, lengthways upon the teeth, 
and passing it along once or twice, to reduce these few points 
which may be above the general level. The file is pressed hard 
at the two ends of the saw, where the blade is less worn, and is 
applied lightly in passing the middle ; the file should be held 
perfectly square, to reduce the edges alike. The new point of 
each tooth is then made to fall as nearly as possible upon the 
center of the little facet, thus exposed by the process of topping 
or ranging the teeth ; and the faces or fronts of the teeth are 
always filed before the tops of the same. 

When the file is perfectly square to the saw-plate, every tooth 
is sharpened exactly alike, and in direct succession, that is, in the 
order 1, 2, 3, 4. Whenever the file is inclined, the teeth 1, 3 



UPRNINO SMITIl's-SAW Mini. 



7. 9, are to tin- ri;,'ht, and the teeth :', I, 

6,8, t > the lilt, after \\liich they are set in the same order; 
80 as collectively to form a double line of points, somcuhat 

mbling the tail of a bird, when the section is coarsely mag- 
nified and exaggerated as in the several diagrams to be given. 
The teeth are the more set, the softer or the uettcr the w 

first (/idt/ruiti on sharpening saws, fig. i'>.~>.~>, represents in 
plan and two elevations the saw-teeth that are the most easily 
shai -pencil, namely. tlue of the frame-saw for metal, commonly 

: by the smith ; the teeth of this saw are not set or bent 
in the ordinary manner, owing to the thickness and hardness of 
the blade, and the small size of the teeth. 

Fig. 655. 




The smith's >aw blade, when dull, is placed edgeways upon the 
jaws of the vice, and the teeth, which are placed upwards, are 
slightly hammered ; this upsets or thickens them in a minute 
degree, and the hammer face reduces to a general level those 
teeth which stand highest. They are then filed with a triangular 
file laid perfectly square, or at ninety degrees to the blade, both 
in the hori/.ontal direction h, and the vertical v, until each little 
facet just disappears so as to leave the teeth as nearly as possible 
in a line, that each may fulfil its share of the work. 

The most minute kind of saws, those which are made of broken 
watch-springs, have teeth that are also sharpened nearly as in 
the diagram, fig. C55, but without the teeth being either upset 
or bent; as in very small saws the trifling burr, or rough win- 
edge thrown up by the file, is a sufficient addition to the thick- 
ness of the blade, and is the only set they receive. 

Three modes of spacing out the teeth of fine saws will be 
now described, and which modes, although not employed by the 
saw-maker, may assist the amateur who is less accustomed to 
the use of the file. 

^ I 



692 



MAKING AND SHARPENING FINE SAW TEET1I. 



Fine saw teetb are sometimes indented with a double chisel, 
fig. 656, the one edge of which is inserted each time in the 
notch previously made, and the other edge makes the following 
indentations the intervals thus become exactly alike, and the 
teeth are completed with the file. For still more delicate saws 
recourse may be had to a little bit of steel bent at the end as 
a minute rectangular hook, which is magnified in fig. 657 ; the 
hook or filing guide, being inserted into each tooth as it is suc- 
cessively formed, regulates the distance of the file for the next 
tooth, as the file is allowed to bear slightly against the blunt 
and hardened end of the hook. 



Figs. 6. 



657. 




658. 



The third mode is used for piercing and inlaying saws, these 
measure about one one-thirtieth of an inch wide, one one-hun- 
dredth thick, and have about twenty points to the inch for wood, 
thirty for ivory, forty for ebony and pearl, and sixty for metals. 
They are made from pieces of watch-spring, which are straight- 
ened by rubbing them the reverse way of their curvature through 
a greasy rag, after which they are cut into strips with shears. 
When the saw is either being made, or sharpened, it is kept 
distended in its frame, and is laid in a shallow groove or kerf 
in a plate of brass embedded in the wood block, fig. 658, which 
is clamped to the table. First, the back of the blade is filed 
smooth and round ; the edge is then smoothed ; after which the 
teeth are set out, beginning near the handle of the frame. 

The spaces between the teeth are determined, in this case, by 
the facility with which the hand appreciates any angular position 
to which it is accustomed. Thus in the act of filing the teeth, 
the file is always used, say at an horizontal angle of twenty 
degrees with the blade the file is sent once through the first 
tooth, and allowed to rest for an instant without being drawn 
backwards ; the file still resting in the first notch of the blade 1 , 
as shown in elevation, is then placed two to five degrees nearer 
square in the horizontal angle, or at fifteen degrees with the 



SHARPENING FECj-TKETII AND MILL-RAW TBRTII. 098 

blade, inMcail of for :in instant on 

the edge of the wood block, and raised out of the notch ; the 
i on the block, as in the dotted line, is 
:\ccd on the saw at twenty degrees, its first position. 1'y 
the two l:it -nil movements it is shifted a trifle to the right, and 
a second notch is made at the spot thus determined. The 
routine is continued, and after each traverse of the file the 
stepping process is repeated, during which the file rests alter- 
nately on the saw blade, and on the edge of the block, by which 
curious yet simple mode the spaces of the teeth are given with 
great rapidity and exactness. 

In this first range each notch has only received one stroke of 
the file; but three or four ranges, commenced from the oth. r 
end of the blade, are required to bring the teeth up sharp. 

The second diagram, fig. 659, illustrates the peg-tooth; but it 
may also be considered to apply to 641, the M-tooth, and, in part, 
to the mill-saw-tooth, 648. The points of the cross-cutting 
saws for soft woods are required to be acute or keen, that they 
may act as knives in dividing the fibres transversely. 

Fig. 659. 




^ides 1, 5, 9, that is, the left of each alternate tooth, are 
tiled with the horizontal angle denoted by h, and then the 
opjx s of the same teeth, or 2, 6, 10, with the reverse 

inclination, or h' . The other teeth arc then treated just in tin- 
same manner, from the other side of the blade; that K first the 
l . and then 11,7, 3, are successively filed, the work 
being thus completed in four ranges. The first and second 
ranges are accomplished, a few inches at a time, throughout the 
re length of the saw ; after which the third and fourth are 
plcted in the same interrupted order. 



694 



SHARPENING HAND-SAW TEETH. 



The third diagram, fig. 660, may be considered to refer gene- 
rally to all teeth the angles of which are 60 degrees, (or the 
same as that of the triangular file,) and that are used for wood. 
The most common example is the ordinary hand-saw tooth; but 
teeth of upright pitch, such as the cross-cut saw, fig. 643, or of 
considerable pitch, as in 646, are treated much in the same 
mcinner. 

Fig. 660. 




The teeth having been topped, the faces 1, 5, 9, are first filed 
back, until they respectively agree with a dotted line a, sup- 
posed to be drawn through the center of each little facet 
produced in the topping; the file is then made to take the 
sides 2 and 3 of the nook until the second half of the facet is 
reduced, and the point of the tooth falls as nearly as may be on 
the dotted line a. The two sides 6 and 7, those 10 and 11, and 
all the others, are similarly filed in pairs. The latter process 
reduces the second series of faces 3, 7, 11, to their proper 
positions, and therefore when the saw is changed end for end, it 
only remains to file the tops or sloping lines 4, 8, 12. 

The first course takes the face only of each alternate tooth ; 
the second course the back of the former and face of the next 
tooth at one process; and the third course takes the top 
only of the second series, and completes the work. This order 
of proceeding is employed, that the faces of the teeth may be in 
each case completed before the tops or backs. 

The fourth diagram, fig. 661, which follows next in order, 
exhibits also in three elevations a somewhat peculiar form of 
tooth, namely, that of the pruuing-saw for green wood. The 
blade is much thicker on the edge than the back, so that the 
teeth are not set at all. The teeth are made with a triangular 
file, applied very obliquely as to horizontal angle, as at h, 
sometimes exceeding 45 degrees, but without vertical inclination 



SHARPENING PRUNING AND GULL!: KKTII. 



as at r; and the facet of the teeth are nearly upright, as in the 
hand -saw. 

fig. Ml. 

^<y ^<y "v/ ^/ ^j < 

tvx"~ // \\ // KS: 



Looking at the priming-saw in profile, it appears to have large 
and small teeth alternately; this only arises from the excessive 
be\il employed; the large sides of the teeth are very keen, and 
each vertical edge is acute like a knife, and sharply pointed ; 
in consequence of which it cuts the living wood with a much 
;u-r surface, and less injury to the plant, than the common 
hand-saw tooth. 

The fifth diagram, fig. 662, explains the method employed in 
sharpening gullet or briar-teeth ; in these, as before explained, 
there are large curvilinear hollows, in the formation of which 
the faces of the teeth also become hollowed so as to make the 
projecting angles acute. 




The jru 1 lets, 3, 7, 11, are first filed, and from the file crossing 
the tooth very obliquely, as at v v in the section, the point of the 
tooth i \t. mis around the file, and gives the curvature represented 
in the plan. The file should not be so large as the gullet; 
it is therefore requisite that the file be applied in two posi- 
tions, lir>t upon the face of the one tooth, and then on the 
hack of the preceding tooth. The tops of the teeth, 4, 8, 1 -2, 



C96 



Ml TING SAWS, AND THE REQUISITE TOOLS. 



are next sharpened with the flat side of the file, the position 
of which is of course determined by the angles c and d ; the 
former varies with the material from about 5 to 40 degrees with 
the edge, and the latter from 80 to 60 degrees with the side of 
the blade ; the first angles in each case being suitable for the 
hardest, and the last for the softest woods. The alternate teeth 
having been sharpened, the remainder are completed from the 
other side of the blade, requiring in all four ranges. 

The gullet-tooth accomplishes, in a different manner, and 
in one possessing some peculiar advantages, that which occurs 
from the horizontal inclination of the file in most other cases ; 
and although the position may seem difficult, it will be found 
very manageable, as the hollow forms a convenient bed for the 
file. See Appendix, Note B L, page 1011. 

The saw having been sharpened, it is afterwards set, or, as 
before explained, the teeth are bent. The best mode is that 
which is almost always adopted by the saw-maker, who fixe:- iu 
the tail-vice a small anvil or stake with a rounded edge, such as 
fig. 663. The saw is held with its teeth along the center of the 
ridge, and the teeth are bent upon, or rather around the curve of 
the stake, with two or three light blows of a small hammer also 
shown, the face of which is at right angles to the handle, and 
narrow enough to strike one tooth only. 




The set, or lateral curve, given to each alternate tooth, is in 
measure determined by the curve of the stake, the edge of 
which, for fine saws, has a ridge like a pointed gothic window. 
Half the teeth having been bent, the saw is changed end for 
end, and the intermediate teeth are similarly treated. 



gAW-si I Pi ii Us. < ir.i i I.AB 8AWB. 






Those uho HI of the saw, employ 

tlu- saw-tet for bending the teeth : it consists of a narrow blade 
of steel, \\itl >us width* tor dill'i rent saws; fig. 

is tor larire, and fig. 665 for small saws. In u-m- the 
saw-.sc't, tht: sau : i to remain in the clamp* after ha. 

been tiled, and the alternate teeth are inserted a little \\;< 
that notch whieh tits the blade the most exactly; and they are 
bent over by applying a small force to the handle, whieh is either 
d up or depressed equally for each tooth. 

In some few cases saw-set pliers, fig. G6G, are used. Two 
adjustments are required, respectively to determine the quantity 
of the tooth which shall be bent, and the angle that shall be ^ 
to it. The quantity is adjusted by shifting the stop It, which 
i> held by the thumb-screw c, that passes through a mortise in b; 
the angle of the part bent is adjusted by the screw d. The tooth 
is first giasped between the jaws of the pliers, which are then 
rotated until the screw d touches the blade. 



Fig. 666. 




In which way soever the saw is set, it requires to be accom- 
plished with great uniformity, so that the two series of points 
may form two exact lines. It is proper to change ends with 
the blade in order that each side may have, as nearly as possible, 
the same treatment ; as unless the two sides of the saw are very 
nearly in the same condition, or set alike, the saw is apt to run, 
or cut a crooked instead of a straight path ; it cuts most rapidly 
on the side that is most set, and consequently glances off in a 
- too rapid encroachment. 



The only changes in ;he circular saw, arise from the 

ditlereuee between the riirht line ami the curve; that is. the files 
are applied in the same relation to the tangent of the circle, that 



698 



SHARPENING AND SETTING CIRCULAR SAWS. 



they are to the rectilinear edge of the straight saw. When 
the teeth of circular saws are topped, a small lump of grindstone 
is held upon the saw-bench and against the revolving saw, and 
moved continually sideways ; the highest teeth are soon rubbed 
down, indeed almost in a moment, as only a very small quantity 
is thus removed from them ; sometimes a file is used instead of 
the stone. 

In sharpening circular saws with angular teeth, and the tops 
of gullet-teeth, they are clamped between two upright boards, 
connected by a screw passing through the center of the saw. 
For saws of small diameter the three are nipped in the vice ; 
but for large saws, the boards are shaped like the letter T, and 
are screwed against an upright post or the side of the bench, by 
a screw bolt and nut. 

In gulleting circular saws, the two boards grasping the saw 
are often fixed at an angle of about 30 degrees, by which the 
file is brought to the horizontal position, and the saw is turned 
over when the gullets on one side have been finished. 



Fig. 667. 



In setting the teeth of the circular saw, all the former modes 
may be employed ; and also one other little instrument which 
is represented in fig. 667. It consists of a bed or anvil of steel, 
which is held in the vice at a; it has an axis c, placed at such a 
distance from the sloping plane on a, as suits the radius of the 
saw; and the end b of the upper piece, which is somewhat elastic, 
is filed to a corresponding angle, and is besides pointed so that 
the blow of the hammer may only bend or set one tooth at a 
time, as shown by the dotted lines in the inverted plan b'. The 
axis, shown detached and in the other view at c', is a turned 
block of brass having a shoulder to fit the hole in the saw, two 
diametrical mortises for the pieces of steel a and b, and also five 
binding screws to retain the several parts in position. 

SECT. III. RECTILINEAR SAWS USED BY HAND. 

Rectilinear saws used by hand, are divisible into three groups, 
as arranged and tabulated on the next page. 




899 



TABLB OP TUB DIMENSIONS OP RKCTIUNRAR SAWS. 

Thefrst column rtfrrt to (he payee *h" the MMM and their utet an dtitribed. 
Tl<e latt column refen to At Birmingham iron wire and ikttt mm gage : the comparison of 
dinary linear meemtre it ffiren in At table an page 1013 of the Appendix. 



' 


TAFKR SAWS, MOSTLY WITHOUT PKAMES. 


m**>~<~*-*. 


I :: 
1 . 


Width at 




Wi.lth t 

. .: : . , .. : 


1 : 

i H 


: 

Tooth. 


'. 

M | .. 


: - 

roi 

:<. 
:-: 

70S 

711 
712 

713 

725 

72fi 

728 


Cross-cut saw .... 
; it, IT whip law . 


4 to 10 ft. 
J. 8 - 
4 6 - 


6 to 12in. 
9-12- 
7 - 11 


3 to 7 in. 
34-5 - 
3 - 41 - 


. 
160 *6 


} to 1 in. 
i - 1 - 
I.I. 


I'J - 10 

15 - If- 
ia - 15 

'.. : 
M 

18 to 19 
18 - 19 
18 - lil 
19 - 
19 - 20 
18 - 21 
10 - 1'j 
IS - 19 
19 - 20 
13 - If 


Felloe, or pit turnicg saw 
WM a ka*tl< at out t*J. 


4. . 

: . : 

] . . 


3- 4- 

Widthat 

: 


a -s - 

Width at 
narrow end 


i . 
; . 


! S 

!' ' 




2Sto30in. 
20 - 28 - 

1-2 - -j-; . 
: .14. 
20 - 24 - 
10 - 20 . 
18 - 26 - 
8-18. 
6-12 - 
10 - 24 - 


7 to 9 in. 
6 -8 - 
5-74- 
5-74- 
44 - 74 - 
4 -6 - 
24 - 34 - 
lj - 2. - 
1 1 - 

g - :; - 


3 to 1 in. 
3-84- 
24.3 - 
24-3 - 
2 - 24 - 
2 - 24 

l':! 4 : 
|: : 

i-l*- 


644&645 
644 661 


34 

5 
6 
7 
8 
6 to 8 
7 - 8 
8 - 9 
9 - 10 
4 - 7 


Hiklf rip uw. . 
Hand saw 
Broken space or fine hand 
Panel saw 
Fine panel saw .... 
Chert saw, (for tool chests) 
Tal.K- saw 
Compass, or lock saw . . 
* K yh'.le or fret saw . . 
Pruning saw .... 


(2). PARALLEL SAWS WITH BACKS. 


With a kanJlt atonttnJ. 


i 

!.. . 


Width of 

i: 




1 : . : 

Tooth. 


I'oinU per 
inch. 


'. . : 

vi. .:. 




16to20in. 
14-18- 
lo - 14 - 
6 - 10 - 
8 - 8 - 


31 10 4in. 

?:8: 

14-2- 


644&645 


10 
11 
12 


21 
22 
23 

15 to 22 






Doretail 




(\mili rutttr'w saw . . . 


5-8- 


14-24. 


(3). PARALLEL SAWS USED IN FRAMES. 


Gtntelktd Unfflkiray. 


i, -: : 

i. . .. 


.. 
I. . . 




Form of 

! ' . 


: ; 
inch. 


.... f 

M ' .. 


Mill saw . . 


4 to 8 ft 
4 - 6 - 
4- 5- 

24 - 86 - 

-22- 

15 - 30 - 

3 - 5 - 
3- 5. 


4 to 5 in. 
3 -4 - 

4 -r, . 

2"-S4- 
1 -3 - 

A- 1- 

14-8 . 

M: 

A- A- 


648&651 
645 

644 
645 

644 

;: 

645 




{to lin. 
,:i: 

3-4- 
3- 4- 

4 - !_>. 
10 - 20 - 
4-6- 
10-14- 
40 - 60 - 
15 - 40 - 


10 to 14 


Mill saw webb .... 


r. - -Ji 

19 . 23 

19 - -J2 
19 - -J4 
l:i - -'4 
22 - 24 
20 - 26 

A to ,J, 


Chair- maker's H.I 
Wood-cotter's wv, 
Continental frame saw . . 
'Turning, or sweep saw . 
Ivory saw 
s frame saw . . 
I'i'-P-iiu- - iw ... 
Inlaying or bohl saw . . 



Tkote Satct marted vi*A an Atteritk are uttd for Circular and Curvilinear Work*. 



700 GENERAL REMARKS ON SAWS. FELLING-SAWS. 

The first kind of saw is usually taper ; and if long, it has a 
handle at each end as in the pit-saw ; but if short, or not 
exceeding about thirty inches in length, it has only a handle at 
the wide end, as in the common hand-saw. 

The second kind of saw is stiffened by a rib placed on the 
back of the saw, and parallel with the teeth ; the rib or back is 
generally a cleft bar of iron or brass ; as in the tenon-saw, dove- 
tail-saw, and others. 

The third kind of saw is provided with an external skeleton, 
by which the saw-blade is strained in the direction of its length, 
like the string of a bow; as in the turning or sweep-saw for wood, 
and the bow-saw or frame-saw for ivory. 

These three classes of saws differ much in proportions and 
details, as will be seen by the inspection of the foregoing table, 
and the subsequent remarks. The longest saws are placed at 
the beginning of each group, and the names mostly denote tho 
ordinary purposes of the respective instruments. 

Immediately subsequent to the description of the several 
saws, some account will be given of the general purposes of each 
instrument, and of its manipulation. The numbers prefixed to 
the table, refer to these respective remarks, which are expressed 
somewhat in detail, owing to the importance of the instruments 
themselves, and the circumstance that many of the topics will 
not be resumed. Whereas the turning, boring, and screw-cutting 
tools, the subject matters of the previous chapters, will be more 
or less returned to, in speaking of the practice of turning. 



The saw which claims priority of notice, is that used in felling 
timber, when the axe is not employed for the purpose. 

The felling-saw mostly used of late years in this country, is 
a taper blade about five feet long, with ordinary gullet teeth, 
closely resembling the common pit-saw, except that the teeth 
are sharpened more acutely. 

The handle of the wide end, fig. 668, is fixed by an iron bolt 
and wedge; that at the narrow end, fig. 669, is calculated for 
two men, and is made of wood, except a plate of iron at the 
bottom attached by rivets or screws to the wood, so as to make 
a crevice for the saw, which is fixed therein by a wooden wedge 
on the upper surface of the blade. 

AVheu the saw has entered a moderate distance, wedges are 



PELLIN'i \M> CROSS- (' 






driven in to present the weight of the tree from closing the saw- 
kerf and fix i lade; and it is needful the handles should 
be removeable, that one or other may lie taken off, to allow 
aw to be withdrawn lengthways, which could not be done, were 
the handl I on. 




In cross-cutting saws, the straight handles are sometimes 
attached as in fig. 670, by a piece of sheet-iron serving as a 
ferrule, and extending in two flaps which embrace the saw, and 
are riveted to it. 

I. 671 and 672 represent two other kinds: the former is 
attached by a bolt and key, and the spike is riveted through the 
wooden handle. la the latter the handle is perforated for 
the reception of a slender rod of iron, slit open as a loop to 
receive the saw-blade, and which is drawn tight by means of the 
nut and washer above the handle. 



Fig*. 670 




Some of the cross-cutting saws used in the colonies for 

large logs, arc made as long as twelve, fourteen, and sixteen 

. nine to eleven inches v.ide in the center, and six or seven 

inches at the ends. The peg-tooth is commonly used for them. 

The lomj saw, fiit saw, or whip saw, which follows in the table, 



702 



LONG, WHIP, OR PIT SAW. 



is also the next saw that is commonly applied to the piece of 
timber, which is then placed over the saw-pit, iu order that 
the saw may be used in the vertical position by two men, called 
respectively the top-man and the pit-man, the former of whom 
stands upon the piece of timber about to be sawn. The positions 
of the men are highly favourable, as they can give the saw a 
nearly perpendicular traverse of three or four feet ; and in the 
up or return stroke, the saw is removed a few inches from the 
end of the saw cut, to avoid blunting the teeth, and to allow 
the sawdust free escape. 

The long saw varies from about six to eight feet in length, 
according to the size of the timber. To adapt it to the 
hands of the sawyers, it has at the upper part a transverse 
handle or tiller, fig. 673, and at the lower a box, fig. 674. The 

tiller consists of a bar of iron, 
divided at the lower part to 
receive the blade, to which it 
is fixed by a square bolt pass- 
ing through the two, and 
fastened by a wedge ; and at 
the upper end, the tiller is 
sometimes formed as an eye 
for a wooden stick, or else it 
is made as a fork, and the 



Figs. 673. 674. 




handle is riveted on. 

The handle at the lower 
part, fig. 674, is simply a 
piece of wood four or five 
inches diameter, and twelve 
to sixteen long, turned as a 
handle at each end ; a dia- 
metrical notch is made half 
way through the center to 

admit the saw blade, which is fixed by a wooden wedge. Some- 
times the bottom handle of the long saw is a flat iron loop, 
as in fig. 675, with a space for the fixing wedge, and an eye 
for the wooden handle. Occasionally a screw box is used, or 
one like fig. 674, but with the one handle screwed in, so that 
its point may bear upon the saw, in place of the wedge. In 
all cases it is desirable the lower handle should be capable of 
being easily removed. 



PIT FRAME-SAW. SAWPIT. 



708 



Tin /jit framc-iaw, fig. 076, is commonly used for deals, and 
for such pieces of the foreign hard woods as are small enough 

.H frame, which is about two feet wide, 
frame-saw blade has two holes above or at the wider end, 
one below, and is 

the wooden 

frame by two iron buckles 
or loops, which are split 
about half way round. 
The upper buckle fits 
squarely and firmly to 
the top head, and re- 
ceives, above its lower 
side, two pins passing 
through the holes in the 
saw. The lower buckle 
is similarly cleft, and re- 
ceives one pin only ; this 
buckle is drawn tight by 
a pair of equal or fold- 
ing wedges, beneath the 
bottom transverse piece. 
The blade is usually 
five or six feet long, and 
thinner than that of the 
whip saw, which latter 

although it may be used for the widest timbers, is more wasteful. 
Insome few cases, where the double frame, fig. 676, is inapplicable, 
as in removing a plank from outside a very large log, the single 
frame, 677, is used ; but this latter is generally narrow, and 
employed alone for small curvilinear works. 




It is now proposed to give some few particulars of the sawpit, 
and the modes employed by the sawyers in marking out the 
timber preparatory to sawing. 

-awpit varies from about twenty to fifty feet in length, 
four to six feet in width, and five to six feet in depth ; it has two 
stout timbers rnnnini: the whole length, called ride strokes, and 
transverse, pieces at each end, called head (tills, upon which the 
one end of the timber rests, whilst the other end is supported 



704- MARKING OUT ROUND TIMBER. 

on a transome, or a joist lying transversely upon the strakes : 
a second transome, is used in case of the first breaking ; this is 
called a trap transome. 

Sometimes holdfasts, or L-formed iron brackets, are added to 
the head-sills, by which thick pieces of plank are fixed horizon- 
tally; screw chops are also used for fixing short pieces of hard- 
M r ood vertically or edgeways, for slitting them. 

In cutting deals into thin boards, three deals, which from 
being as many as the frame of the saw will include, are called a 
pit-full, are placed vertically against the stake, and are securely 
attached to it by a rope passed once round the deals and the 
lower end of the stake, and strained by a binding-stick. 

Foreign timbers and hard woods are mostly squared with the 
axe or adze, for the convenience of transport and close stowage on 
shipboard, and such square pieces are readily marked out with 
the chalk line into the scantling, or the planks and boards 
required. More skill is called for in setting out the lines upon 
our native timbers, which are mostly converted into plank, or 
the various pieces, without being previously chopped square. 

The converter determines in which direction the tree can be 
cut most profitably into plank, and the section chosen is usually 
that, which when opened, shows the greatest curvature or irre- 
gularity ; this section is supposed to be shown longitudinally by 
a, b, c, d, fig. 678, and, on a larger scale and transversely, by 
e' e, fig. 679 ; the central points a and b, and the line b c, being 
given by the converter, who also gives instructions as to the 
thicknesses desiredin the planks. The sawyer's firstobject is accu- 
rately to mark the margins of the irregular central plane, abed, 
so truly, that when the lines are followed with the saw, the sur- 
face shall be true and thoroughly out of winding or twist. 

The sawyer gets the timber on the sawpit, with the hollow 
side upwards : that being always first marked : it is plumbed 
upright, or, so that the plumb-line, suspended by the hand at z, 
exactly intersects the line b c, which has been marked on the 
end. The butt is then secured from rotating, by dogs or staples, 
s s, fig. 679, driven both into the end of the timber and into the 
vertical face of the head-sill; for which purpose the two ends of 
the dogs are bent at right angles, both to each other and to thr 
intermediate part of the dog, the extremities of which are pointed 
with steel, made chisel-form, and hardened. 



i-ii i i- \K \ n>nv 



s \\\ : s... 



A chalk-line is now stretched in the dotted line from a to b t 
r.nd pul illy upwards, exactly in the plane in which it 

is desired to act . ng is then let go, as in discharging an 

arrow, and striking the timher. it leaves thereupon a portion of 
the white or black chalk with which the line was rubbed. 




Should the curvature of the timber be such that, as in the 
mple, the chalk-line would scarcely reach the hollow, it is 
strained on the dotted line a, b, and left there ; the plumb-line is 
held in the hand at z, and an assistant holds a piece of chalk on 
the top of the timber at the point e. The principal then observes, 
in the same glance, that the plumb-line z, intersects the string 
a b, the line b c, and also the point of the chalk, showing them 
all to be in the plane of vision ; a mark is then made at e. Marks 
are similarly made at/ and g, or as many places as may be re- 
quired ; and, lastly, the points a ff,fff,fe, and e b, are connected 
by short lines struck with the chalk-line around the curve. 

The required thickness of the planks is then taken in the 
compasses, with a little excess for the waste of the saw, and two, 
three or more planks are pricked off on each side the center 
e' e t fig. 679 ; until, from the circular section of the timber, its 
surface becomes so inclined, that the compasses would measure 
a slanting instead of a horizontal distance, and w Inch would 
diminish the thickness assigned to the boards. 

The sawyer then holds the compasses as at y, and fixing his eye 
on the part of the wood perpendicularly beneath the off leg of 






706 MARKING OUT ROUND TIMBER. 

the compasses, he removes the instrument and pricks a mark 
therewith ; after which the compasses are replaced as at y, to see 
that the mark is correct. This is repeated at different points in 
the length, and the chalk-line is stretched from point to point 
thus set out with the compasses, and marks the edges of the 
intended saw cuts with sufficient certainty. 

The timber is now turned over, or with cto d, fig. 678, upper- 
most and the end line exactly perpendicular as before. Should 
the piece be very crooked or high-backed, the sawyer may be 
unable to see over it, and observe the central marks at the ends 
of the timber ; such being the case, the points e,f, g, are trans- 
ferred to e',f, g', on the top of the timber, by the mode ex- 
plained by the figure 679, supposed to be a section through the 
plane e e'. A dog is driven into the timber near e', and from the 
dog a plumb-line, x' x, is suspended ; the distance e x, is then 
measured with a common rule, and measured backwards from 
x' to e ' , by which process e' becomes exactly perpendicular to e ; 
the points / and g are similarly treated to obtain the points/'^' ; 
after which the central line is made at four operations, through 
c, e',f,g', d', the plank lines are set out with the compasses as 
before explained. 

Large timber is usually cut into plank as in fig. 679 ; the 
planks are sometimes flatted or their irregular edges are sawn 
off and for the most part wasted ; but this is not generally done 
until the wood is seasoned and brought into use. 

When many planks are wanted of the same width, it is 
a more economical mode, first to leave a central parallel balk, 
as in fig. 680, by removing one or two boards from each 
side, and then to flat the balk, or reduce it into planks. The 
central line is in this case transferred from the lower to the 
upper side, by aid of the square and rule, instead of by the 
plumb-line. 

According to Hassenfratz, the setting out shown in fig. 681 is 
employed in large wainscot oak, in order to obtain the greatest 
display of the medullary rays which constitute the principal 
figure in this wood; and the same author strongly advocates 
the method proposed by Moreau, and represented in fig. 682, 
in which he says one-sixth more timber is obtained than by any 
other mode, and also that the pieces are less liable to split and 
warj) ; but on examination there does not appear to be any 



SAWING STRAIGHT, AND CURVILINEAR WORKS. 707 



to incur tho increased trouble in marking and 
sawing the timber on this method.* 



the timber has been properly marked out, the sa\ 
take their r places, upon the timber and in the pit: 

tin- saw is sloped :i little from the perpendicular ; that is, sup- 
posing tlic piece about eighteen inches through or deep, the saw 
when it touches the top angle, is held off about two inches from 
the bottom. A few short trip> arc then very carefully made, as 
much depends on the saw entering well; and should it fail to 
hit the line, the blade is sloped to the right or left at about the 
angle of 15 degrees, to run the cut sideways and correct the 
inei.Mon in its earliest stage. It is usual to take all the cuts as 
in figs. 679 and GSO, to the depth of three or four feet, and then 
the whole of them a further distance, and so on. 

\Vhrn the saw has penetrated three or four feet, a wooden 
heading wedge is driven iuto the cut, to separate the timber, for 
the relief of the saw ; and when, from the length of the cut, the 
timber is sufficiently yielding, the hanging wedge is used, which 
is a stick of timber about twelve to twenty inches long and an 
inch Mpiarc, with a projection to prevent the wedge from falling 
through. The wedges lessen the friction upon the saw ; but if 
too greedily applied they split the wood, and tear up the loose 
parts sometimes observed in planks. 

In sawing straight boards, it is advantageous that the saw 
should be moderately wide, as it the better serves to direct the 
ilincar path of the instrument; but for curvilinear works, as 
tin- felloes of carriage wheels, the sawyer employs a much 
narrower saw, to enable him to follow the curve. The blade of 
one kind of felloe-saw is about five feet long, and it tapers from 
nearly four inches at the wide, to two inches at the narrow end; 
it is used with a tiller and box, exactly the same as the ordinary 
long saw, and also without a frame. 

The more general felloe-saw, or pit-turning gaw, has a blade 

about li inch wide, and is stretched in a frame exactly like those 

reprcM-ntcd in tigs. 676 and 677. The turning-saw with two 

he best where it can be applied ; sometimes the 

Traits de PArt d* Ckarptntier, par J. H. Hauenfratz. 4 to. Para, 1804. 
PUtelS. 

2 



708 nir, HAND, PANEL 

frame is obliged to be made single, and with a wire and screw 
nuts, by which the saw is strained as in fig. 677, page 703. 

In cutting-out very small sweeps, as in the small wheels or 
trucks for wooden gun-carriages, no frame whatever can be used, 
and slender blades about five or six feet long, five-eighths of an 
inch wide, with a handle at each end, were employed for this 
purpose during the late war. In using the various pit-turning 
saws, the thick plank having been sawn out in the ordinary 
manner, the work is marked off on one side from a pattern or 
templet, and then held down, upon the head-sill of the saw-pit 
and one transom, by means of the holdfast before noticed. 



The rip-saw, half-rip, hand-saw, broken space, panel-saw, and 
fine-panel, which, in respect to appearance, are almost alike, may 
be considered to be represented by fig. 683 ; their differences of 
size will be gathered from the dimensions in the table ; the 
chest-saws are merely diminutives of the above, and such as are 
used for small chests of tools, whence their name. 



Fig. 683 




This kind of saw is made taper, in order that the blade may 
possess a nearly equal degree of stiffness throughout, notwith- 
standing that it is held at the one end, and receives at that end, 
as a thrust, the whole of the power applied to the instrument ; 
the greater width also facilitates the attachment of the handle. 
AVcre the blade as wide at the point, as at the handle or heel, 
it would add useless weight, and instead of being a source of 
strength, it would in reality enfeeble the saw, which from the 
increased weight at the far end, would be more flexible near the 
handle than at the point. 

It will be seen that the saws in this group are progressively 
smaller and finer. The rip-saw has the coarsest teeth, and 
which are of slight pitch, or mid-way between the upright or 
cross-cutting teeth, fig. 643, und those of ordinary pitch, fig. 645 ; 
the half-rip is similar, but a little finer ; these two are used in 
carpentry for ripping or cutting fir-timber rapidly with the grain. 



\\D INS rut | 01 i MI:IR USE. 

The hand nml fine-hand saws arc somewhat liner in tin- teeth, 
which are of ordinary pitch, or the lace of the tooth i> perpen- 
dicular; the hand-saws are much used hy the joiner for ordinary 
purposes, ami also hy the eahinet maker, for cutting iniiho- 
and other hardwoods with the grain. 

panel and line-panel arc still finer saws of the same kind, 
which probably derived their name from ha\inu' been made for 
cutting out panels, \\hen ouk and other wainscottiug were more 
common in our bouses than plastered \\alls ; and they ma; 
considered as intermediate between the handsaw, by which 
most of the work is done, and the tenon or back-saw hereafter 
to be described. 

The same workman does not require cacb of the six saws, but 
commonly selects the two or three most suited to his particular 
class of work; they are principally used for still further preparing 
the woods to their several purposes, after they have been cut at 
the sawpit into planks and boards. The outlines of the works are 
marked out upon the surface of the plank by aid of the rule, 
compasses and chalk line, or the straight edge and square, with 
much greater facility than setting out the round timber into 
planks, which has been already explained. The board having 
been marked, is rested upon a sawing stool or trestle, the height 
of which is about 20 inches; if the work be long two stools an 
employed. The workman commonly places his right knee upon 
the board to fix it, and applies the saw on the portion that o 
hangs the end of the stool. 

The saw is grasped in the right hand, and the left is applied 
to the board, in order that the end of the thumb may be pl;i< 
just above the teeth and against the smooth blade of the saw, to 
ie it to the line; the saw is then drawn backwards a few 
inches, with light pressure, to make a slight notch, a short gentle 
down-stroke is then made almost without pressure. In the lir>t 
the length and vigour of the stroke of the saw are 
gradually increased, until the blade has made a cut of two to 
tour inches in depth ; after which the entire force of the ridit 
arm is employed, the saw is used from point to heel, and in 
extreme cases, the whole force of both arms is used to urge the 
saw forward. The blade is occasionally -it .,- d to lessen the 
friction, the end of a tallow candle bein- mostly used, or < 
- lard smeared on leather. 



710 INSTRUCTIONS FOR USING THE 

In most instances little or no pressure is directed edgeways, 
or on the teeth ; and when the effort thus applied is excessive, 
the saw sticks so forcibly in the wood, that it refuses to yield to 
the thrust otherwise than by assuming a bow or curved form, 
which is apt permanently to distort the saw from the right line. 
The fingers should never be allowed to extend beyond the handle, 
or they may be pinched between it and the work. 

In order to acquire the habit of sawing well, or in fact, of 
performing well most mechanical operations, it is desirable to 
become habituated to certain defined positions. Thus in sawing, 
it is better the work should, as often as practicable, be placed 
either exactly horizontal or vertical ; the positions of the tools 
and the movements of the person will also be then constantly 
either horizontal or vertical, instead of arbitrary and inclined. 

In sawing, the top of the sawing stool should be horizontal, 
the edge of the saw should be exactly perpendicular, when seen 
edgeways, and nearly so when seen sideways ; the eye must 
watch narrowly the path of the saw, to check its first disposition 
to depart from the line set out for it. If however, the eye be 
directed either so far from the right or left side of the blade as 
to form a material angle with the line of the cut, the hand is 
liable almost uuconsciously to lean from the eye, and thence to 
incline the saw sideways. It is therefore best to look so far 
only on the right and left of the blade alternately, as to be just 
able to see the line, and thence to detect the smallest deviation 
of the instrument at the very commencement of its departure. 
And then, by twisting the blade as far as the saw-kerf will allow, 
the back being somewhat thinner than the edge, the true line 
may be again returned to ; indeed, by want of caution, the saw 
may be made to cross the line and err in the opposite direction. 
It is however, best to make it a habit to watch the blade so 
closely as scarcely to require any application of the correctional 
or steering process at all. The saw, if most set on the left side, 
or having teeth standing higher on the left side, cuts more 
freely on that side, and has a tendency to run or arcuate to- 
wards the left ; and under the reverse circumstances the saw is 
disposed to run to the right. 

Thick works are almost always marked on both sides the 
plank, and the piece is turned over at short intervals, so that a 
portion of the work is performed from each side ; the saw-cut 



IIV.ND SAW. TABLE AND COMPASS SAW. 711 

trill then ns.siiinc a aeries of slight ;< the ri.u'ht and left 

altci :,iul will depart less from tin- true line, than if these 

irbanees had c fleet from the one side only, and thus pro- 
duced an accumulating error, or a line swerving in one d: 
tion :d Mm . or as a sweep of a large circle. The practice of 
changing sides with the work will, under most circumstances, 
be found to lessen the errors incidental to the process, and the 
practice is therefore especially desirable for beginners. 

The work is not always placed on the sawing-stool, as in some 
cases it is laid on the bench, and fastened down upon the same 
with the holdfast or hand screws, and with the intended cut 
situated beyond the edge of the bench ; the workman then 
stands erect, and uses the saw with both hands, placing the back 
of the saw towards his person, and sawing from it; this with 
many is a favourite position. In some cases, especially in MI, all 
and thick works, the wood is fixed perpendicularly in the screw- 
chops of the bench, and the saw is applied horizontally. These 
modes are both good, inasmuch as they relieve the individual 
from the necessity for holding the work with the knee, and he 
is less restrained in the action of the limbs. 

In using the hand-saw for preparing hardwood for turning, the 
log is either laid on the common X-form sawing horse or else it 
is fixed in the jaws of the tail- vice, which latter mode is gene- 
rally more convenient. In speaking of sharpening the saw, it 
was shown that the points of saw-teeth, proper for hardwoods, 
are somewhat less acute than those for deal and ordinary timber. 

The remarks on the hand-saws hare been given in greater 
detail than those which follow, because it is considered these 
instructions will assist in the manipulation of all the other saws 
used by hand. 

Ki-rs. r,M ;in ,l r,v~> represent the narrow tujvr UMTS n-rd fur 
cutting curves and sweeps, especially those required in wide- 
ids. Compared with the generality of saws, these are made 
thicker on the edge, and are ground thinner on the back, to 
allow them more freedom in twisting round curves, the smallest 
of which require the narrowest Ida* 

The table-saw, and the compass or lock-saw, fig. 684, which only 
differ in *i/e, resemble the hand-saws in their general structure 
and in the forms of their teeth, except that the blades are smaller 
and nan dow them to lie as a tangent to the curve. 



712 



KEY-HOLE AND PRUNING SAWS. 



The key -hole or fret saw-blade, 685, which is drawn to the 
same scale as the last, is held in a saw-pad, or a handle having 
a stout ferrule with a mortise and screws, so that the blade may 
be strongly grasped; and as the handle is perforated throughout 
its length, either the whole or part only of the blade may be 
allowed to project. The key-hole saws are sometimes fixed in 
a handle like that for a file, which is less proper. 



Figs. 684 




The table, compass, and key-hole saws, all require care in 
their use, for if much pressure is thrown on the teeth, they 
stick fast in the material, and a violent thrust is liable to bend 
and permanently injure, or indeed, to break the saws; and be- 
sides, their paths are the less easily guided, the more vigorously 
they are used. It would be desirable, if in the narrow taper 
saws with only one handle, we more frequently copied the 
Indian, who prefers to reverse the position of the teeth so that 
the blade may cut when pulled towards him, instead of in the 
thrust; this employs the instrument in its strongest instead 
of its weakest direction, and avoids the chance of injury. The 
inversion of the teeth, which in India is almost universal, 
is with us, nearly limited to some few of the key-hole and 
pruning saws. 

Pruning-saws are often made exactly like the table and com- 
pass-saws, fig. 684, recently described, but with teeth which are 
coarser, thicker, and keener than those for dry wood. The forms 
of teeth figs. 644, and 645, namely the hand-saw tooth, and slight 
pitch, are used, and also the double teeth, fig. 661, which are 
rarely employed but for living timber. An excellent modifica- 
tion of the pruning-saw is to mount the blade at the end of a 
light pole 4 to 6 feet long, so that the edge of the blade may 
form an an^le of about 150 degrees with the handle. This saw 
may be applied to branches eight or ten feet from the ground ; 
the inclination of the blade just suffices for the onward pressure, 



TENON, SASH, CARCASE, AND DOVETAIL SAWS. 7)3 

and the saw cuts in the pull instead 

of in the thrust, which is both more commodious to the indi- 
vidual, and free from the risk of accident to the blade. 

FSg. 666. 



Many pruning-saws are made with blades nearly parallel in 
width, but as thick again on the edge as on the back, and with 
double teeth, fig. 661. The larger pruning-saws of this kind, 
fig. 686, are mounted as carving-knives, or with straight h.-mdlcs 
of buck-horn; such blades measure from 8 to 10 inches long, 
and i to 5 inch wide; the smaller kind are made as clasp or 
pocket-knives, and are of about half the dimensions given. 



The next group of saws enumerated in the table, are Parallel 
Saws with Backs; those most commonly known are in some 
measure particularised by their names, as tenon-saws, sash-saws, 
carcase-saws, and dovetail saws; they only difler in size, as 
already shown, and they are represented by fig. 687. 



Fig. 687. 




The blades of the back-saws are thin, and require to be very 
carefully hammered; the handle of the saw is affixed to the 
blade itself by the screws. The back is either a piece of stout 
sheet-iron or brass folded together, first as an angle between 
tup and bottom tools, and then closed with the hammer upon a 
parallel plate thicker than the saw. When the inside of the 
groove has been tiled to remove the irregularities, the two edges of 
the back are grasped in the tail vice, and the ridge is hammered 
to make the edges spring together almost as a pair of forceps, 
back is held upon the blade by this elasticity or grasp alone, 
and the blade only penetrates about half-way down the groove. 

The general condition of the blade depends in <;reat measure 
upon that of the back, which should not be exposed to ronjrh 



714 BACK SAWS. SAWING BLOCKS. 

usage ; as a blow on the middle of the back tends to throw the 
blade more in that part, and make it crooked on the edge, a 
fault that may be in general corrected by tapping slightly upon 
the back near the ends, in order to drive the blade as much 
inwards at those parts as in the center, and balance the first 
error. When the blade itself is buckled, which is less liable to 
occur than with hand-saws, from the more careful manner in 
which the back saws are used, the saw must be taken to pieces 
and the blade corrected on the anvil as in other cases. 

The back-saws, which are much employed for accurate works, 
are often assisted or guided by sawing -blocks, in which one or 
more saw-kerfs, that have been very carefully made, serve to 
guide the blades ; consequently this method saves a part of 
the trouble in marking out the lines to be cut, and also of the 
risk of making incorrect incisions. The sawing block, fig. 688, 

which is of the ordinary form, is 

F- cog 

a trough made parallel both inside 
and out, and having three saw-kerfs, 
which are all exactly vertical. The 
one kerf is at right angles to the side 
of the block, and serves for cutting 
off pieces, the ends of which are required to be perfectly square ; 
the two other saw-kerfs are at angles of 45, and slope opposite 
ways : these serve for cutting mitres, or the bevilled joints always 
employed for uniting mouldings at right angles to each other, 
as in picture frames and panels. The work is simply held close 
to the further side of the box, and with the line of division 
opposite the saw-kerf, the saw is then allowed to pursue the 
direction given by the saw-kerf; and when many pieces of 
similar length are wanted, stops are added to the block. The 
joiner frequently uses the shooting boards represented on page 
502, for sawing as well as planing, especially when the work is 
to be planed immediately after on the same shooting board ; the 
saw is then applied parallel with, but slightly in advance of, the 
face against which the sole of the plane rubs. 

Before concluding the remarks on saws with backs, fig. 687, 
it appears desirable to offer some particulars on the modes of 
constructing tenons and dovetails, from which most useful and 
general modes of uniting materials, two of these saws have 
derived their names. 




TENONS AND MORTISES. 



718 



In a rectangular frame, represented partly finished in fig. 689, 
tin . .us are commonly made on the shorter pieces, called the 
rails, and the mortises on the longer or the styles, which arc 
always left somewhat longer than ultimately requm !, t<> 
them frin breaking out, either in making the mortises or in 
wedging up the frame. In carpentry, the panel is fitted in a 
groove, as at a, and is inserted or planted before the frame is 
glued up ; but in cabinet-work the panel is fitted in a rebate, as 
at b, and is fixed by slips of wood after the frame is finished. 



Aft; 689. 







When the styles and rails have been planed up to their 
widths and thicknesses, (see pp. 498 to 503), the internal length 
of the frame is marked on the styles at / /, and the width on 1 1 < 
rails at w w \ these lines are scribed on the four sides of each 
piece, with the square and scriber. The additional lines ft 
indicating the ultimate length of the style, are also mark 

The width of the enlarged tenon t t', is from one-half to two- 
thirds that of the entire rail; the inner haunch t, is required 
to be lower than the groove or rebate, and the outer haunch /', 
is generally about three times as wide as the inner, to leave 
room for the wedges, and the end wood of the style exterior to 
them. The thickness of the tenon is commonly about one-third 
that of the style, but from the mode of work, its actual thiek- 
ness, if not exceeding about J-inch, becomes exactly the same 
as the \\idth of the mortise-chisel eniph 

The appropriate ehi> ! having been selected, the 



716 TENONS AND MORTISES. 

g g, corresponding with its width, are gaged on each edge of the 
styles and rails. Frequently the mortise-chisel is slightly stuck 
into the work to imprint its own width, by which to adjust the 
gages ; and every piece is gaged from the face side, so that when 
the whole are put together they may be flush with one another. 

The several styles to be mortised, if small, as in cabinet work, 
are placed side by side with their inner edges upwards, and are 
fixed upon the bench with the holdfast ; the mortises are then 
commenced near the outer end, m ', 690. The styles, if large 
as in carpentry, are placed upon the stout mortising stool ; the 
workman sits upon them, and begins near the inner end m. 

The mortises are made half-way through from the inner side 
of the rails, and are completed from the outer ; and the opera- 
tion is by no means difficult, provided the mortise-chisel, which 
although narrow is very thick and strong, is kept exactly per- 
pendicular to the side of the wood, and truly to the gage-lines. 
The chisel is mostly held with its face towards the operator, and 
the first cut is perpendicular and about one-sixth from the end 
of the mortise, as at a, fig. 690 ; the chisel is driven with two 
or three blows of a mallet of proportionate size ; the second cut 
is inclined, as at b, and between each of the inclined blows, the 
chisel is moved to loosen the chips. By the two cuts a trian- 
gular portion of wood or a core is loosened, and which is prized 
up by thrusting the chisel backwards through the dotted arc, 
the bevil or bulge of the chisel then resting upon the angle of 
the wood as a fulcrum. 

The neighbouring lines in fig. 690 show the successive cuts 
employed in making the mortise ; some workmen prefer taking 
the cuts a and b alternately, always prizing up the chips by 
thrusting the chisel from them, after each cut b ; others prefer 
taking most of the cut a, at an earlier stage of the work. When 
the triangular incision reaches half way through the wood, it is 
extended in length cither by sloping cuts with the chisel, as at b, 
or Mith perpendicular cuts, as at c. 

At the completion of the inner half of the mortise, the face 
of the chisel must be applied exactly perpendicular at each end, 
as a and c, and in releasing the shavings, the handle is moved 
towards the center of the mortise, using the cutting edge as the 
fulcrum, and not the angle of the wood, which would be thereby 
bruised. The style is now turned over, and the remaining half 



CUTTING TENONS. l>o\ r.T \ II.1. 717 

of the mortise is eomph trd ; hut i cuds :u 1 for 

tin- reception of the wedges, as marked in the diagram. The 
moi : ostly left from the n ii-( 1, although when 

the two incisions do not exactly meet, it is needful to purr dun 
the inequalities with an ordinary chisel. 

-utting of the tenon is less difficult of explanation than 
the mortise. The shoulders, or tin MOM, 

are generally made with the dovetail or carcase-saw, whilst the 
rail lies on the bench against the sawing-stop, or a peg near 
the corner of the bench; the rail maybe held with the holdfast 
if preferred. The side or longitudinal cuts are usually made 
with the tenon or sash-saw, the rail being then fixed perpen- 
dicularly in the bench-screws. 

These cuts, which remove two thin rectangular pieces called 
cheeks, should be made with great accuracy, and so as just to 
avoid encroaching on the gage lines ; as the tenon is left from 
the saw, or at most the angle is cleared out with the corner of a 
chisel applied almost as a knife. 

The haunches are marked by laying the end of the rail in 
contact with the gage lines on the inner side of the style, and 
marking the tenon from its corresponding mortise. 

Tenons and mortises do not in all cases extend through the 
wood, and as they cannot be then wedged up, they have to 
depend exclusively on good fitting or surface contact, and the 
glue ; in many cases also, screw-bolts, straps, and wooden pins 
are used to draw the tenon into the mortise in various w 
subjects that are too varied to be here particularized. 

In mortises that are wider or deeper than usual, it is a com- 
mon practice to remove a portion of the wood with center-bits, 
or nose-bits, and to complete the mortises with firmer chisels. 



Dovetailed joints are employed for uniting the ends of boards 
at right angles to each other, as in boxes, drawers, and nume- 
rous other works. The dovetails are made of several forms ; 
thus, fig. 691 is a kind of factitious dovetail, in which the boards 
are first mitred, or their edges are planed at the angle of 
45 degrees, and slightly attached by glue or otherwise ; a few 
cuts leaning alternately a few degrees upwards and downwards 
are then made with a back-saw upon the angles, pieces of 
veneer are afterwards glued and drawn into the notches. This 



718 



SETTING OUT DOVETAILS. 



method is principally employed in toys and very common works, 
which are then said to be mitred and keyed ; the hold is much 
stronger than might be expected. 



Fig. 691. 



692. 



693. 




Fig. 692 represents the ordinary dovetail joint ; p, fig. 693, the 
pins, and d, fig. 693, the dovetails of which the same is com- 
posed. In some cases the pins and dovetails are nearly alike in 
size, and this makes the strongest attachment ; but in joinery 
and cabinet work, the dovetails are made on the front or more 
exposed part of the work, and the pins are cut of only one- 
fourth or less the size of the dovetails, in order that but little 
of the end wood may be seen. Usually the pins are the first 
made; as in making ordinary dovetails as well as tenons, 
the surfaces are left from the saw, this instrument must be well 
applied to produce the close joints met with in works of the best 
quality. 

In setting out dovetailed works, the sides and ends of the 
box are first marked across on both sides with the gage or 
square at g g, which lines indicate both the inside measures of 
the box and the bottoms of the pins and dovetails ; the portions 
beyond the lines are left a trifle longer than ultimately required. 
Very little care is taken in setting out the pins ; indeed, their 
distances are usually marked with a pencil, without the rule or 
compasses, and the two external pins are always left nearly as 
strong again as the others. 

One of the fronts, fig. 694, is fixed upright in the bench- 
screws, and the pins are sawn as shown at a a. These saw cuts 
are made exactly perpendicular, and terminate upon the gage 
lines ; but horizontally they are sloped opposite ways, so that 



v \\\ IN.. \M ( I I MM. IH.N l.r.MI S. 






;. pili in about as wide again on tin- inner as on the on 
side of t of tin- l)ox. Tin- wood between the dovetail 

pins is generally cut out with the bow or turning saw, leaving the 
space as at b, fig. 694; and the spaces are then pared out with 
tin tinner chisel from opposite sides, as at c, i 1 being 

placed exactly on the gage lines, but slightly overhanging, so 
that the insides are cut hollow rather than square, to insure the 
exact contact at the inner and outer edges of the dovetails. 

When the wood between the pins is removed entirely with 
the chisel, this instrument is driven with the mallet perpendicu- 
larly into the wood just in advance of the gage-line, and sloping 
cuts are then made to form a notch half-way through the wood 
as at/; and when the space has been thus cleared, a more careful 
vertical cut is made exactly upon the gage-line itself, as in the 
former case. 




The dovetails are next marked from the pins, and thus become 
their exact counterparts. In marking the dovetails, the end piece 
d, fig. 695, is laid upon the bench, and the pins in p are placed 
exactly vertical, and in their intended positions ; and lastly, the 
scriber is passed along the two sloping sides of every pin. The 
gage lines are followed with the dovetail saw, the waste of the 
tool being taken from the hollows, so as to leave the gage lines 
almost standing: the hollows between the dovetails are now 
removed with the chisel unless the work is very large, when, as 
in cutting away the wood between the dovetails, the frame saw 
may be previously employed. 

As the gage lines are almost left in sight, the pins and dove- 
tails are mutually a trifle too large, so that in driving them 
together, they somewhat compress each other, and produce that 
close accurate contact to be observed in good works ; and which 



720 



VARIOUS KINDS OF DOVETAILED JOINTS. 



gives rise to so much surface-friction, that the glue might in 
some cases be nearly dispensed with between the joint ; but if 
the pins are left too large, they split the wood. 

Whilst the chisel is being employed in dovetailing, it is usual 
to lay the several pieces of wood upon the bench, with their ends 
slightly extending beyond each other, like a flight of steps, an 
arrangement that admits of every edge being readily seen and 
operated upon ; the pieces are fixed in this position by the hold- 
fast, and when they have been cut half-way through, they are 
turned over, and finished from the other side. 

Figs. 696 to 701 represent in plan, and in one group, the 
several ways of dovetailing the edges of boxes and similar works: 
fig. 696 is the mitre and key joint, and fig. 697 the common 
dovetail joint already spoken of, in which the pins and dovetails 
are both seen from the outside of the box. In the four other 
kinds the parts are more or less concealed, and they may be con- 
sidered to increase in the difficulty of construction, in the order 
in which they are represented. It is supposed that the pins 
which are on the upper pieces marked p, are made before the 
dovetails on the pieces d, and before scribing which latter from 
the pins, chalk is rubbed on mahogany and other dark woods, 
to make the lines more conspicuous. 



Figs. 696. 697. 



698. 



699. 



700. 



701. 




Fig. 698 is the half-lap dovetail, which is much used for the 
front of drawers. The pins in p, or the front of the drawer, are 
first marked, and the wood is also gaged at the end to denote 
how far the pins shall extend inwards : the saw can only be used 
obliquely, as shown by the dotted line, and the pins are finished 
with the chisel applied on the lines a and d. When, however, 
the drawer front is to be veneered, the pins are often sawn quite 
through on the line d, as the pins may be thus more easily cut, 
and the veneer conceals the saw-kerfs in the drawer front. The 
dovetails on the sides of the drawer, or d, are afterwards marked 






VARIOUS KINDS OF DOVETAILED JOINTS. 721 

and cut as in the first example, fig. 697, but of their exact 

In fig. 699, sometimes called i\\o tecret dovetail, the pins and 
dovetails are both concealed, as neither of them extend through 
tin- work ; the saw can be only used at the angle of 45 degrees, 
either for the pins or dovetails, and most of the work is done 
with the chisel. The angle is filled in with a corner line. 

The lap dovetail, fig. 700, is often used for writing-desks, and 
similar works with rounded edges, and not having corner lines: 
the front of tin- dt>k, or p, is first rebated out to leave the lap, 
the pins are then made in this piece, and the dovetails are after- 
wards scribed on d, and made as in the last case ; only a small 
portion of the end wood is then seen at the ends of the desk, 
and this is in great measure removed from observation when the 
angle is rounded. 

The mitre dovetail, fig. 701, requires each piece to be rebated 
out square, as in p, fig. 700; and after the pins and dovetails 
have been respectively made, the square rebates are converted 
into a mitre joint with a rebate plane. When finished, neither 
the pins, nor the modes of their concealment, are distinguishable 
and the work appears to have a plain mitre joint. 

\Vlirn the lid of a box has a dovetailed rim, or that the box 
and lid only differ in respect to depth, the box is technically 
said to have a tea-chest top, and four pieces of wood, sufficiently 
deep to make both the box and its cover, are then dovetailed 
together in either of the ways before mentioned. When the top 
and bottom of the box are also added, the six pieces present the 
appearance of a rectangular block, and which is known as 
a carcase, a term also applied to other entire framings. The 
saw used in cutting open the carcase, or in separating the top of 
the box from the bottom, is thence called a carcase saw. 

This mode of work, besides saving much of the labour of 
dovetailing, ensures the exact agreement in size, and the general 
. rspondence of the two parts; which it would be more diffi- 
cult to obtain if they were separately made, especially in sloping 
works, such as portable writing-desks and others of similar 
character. 

In every case where the box and the lid are made together, 
the line of dr. .Mn is gaged on the four sides exteriorly, and 
one of the dovetail pins is placed upon that line ; but it is made 

3 A 



722 DOVETAILED WORKS. SMITHES SCREW-HEAD SAWS. 

fully as wide again as the others, to admit of division, and ye 
be of the ordinary size. If the joint-pin were made as usual, or 
left square, the carcase, on being cut open, would exhibit the 
rectangular lines of the pin and dovetail; to avoid which the 
joint-pin and dovetail should be pared away to the mitre, and 
then the cover and the box will also exhibit a mitre joint. 

The top and bottom are fitted in various ways : sometimes 
they are glued on the square edges of the sides, but generally 
the sides and the top are both rebated, just as represented in 
fig. 700, on the supposition that p is the top, and d the side of 
the box ; or they are rebated and mitred as in fig. 701. 

A box made as above described, with mitred dovetails, with 
mitred joint-pins, and with the top and bottom rebated and 
mitred, would not show any joint, either within or without the 
box, except those constituting the margins of the twelve super- 
ficies of the work : in fact the joints would alone occur at the 
several angles, and escape observation, as will be apparent from 
the inspection of figure 701. 

Such a box if neatly made, would be a finished specimen of 
work, but so much care is seldom taken, and it is more usual to 
employ corner lines and lippings to conceal the joints, or else to 
cover the box with veneers, and all of which are sometimes 
mitred. In these cases the interior frame or the carcase of the 
box is of common mahogany, and dovetailed in the manner of 
fig. 697 ; or in very inferior works, the fabric is of deal attached 
by glue and brads, the principal reliance being then placed on 
the veneer for uniting the parts and concealing the defects. 

Having concluded this long but important digression, respect- 
ing the formation of tenons and dovetails, the consideration will 
be now resumed of the saws enumerated in the table on page 699. 



The smith's screw head-saw, fig. 702, which, in the table, 
follows the back saws last noticed, differs from them in propor- 
tions, and also in the handle, which resembles that of a file ; the 
blade is generally also thicker and harder, to accommodate it to 
its work. Some of the screw head-saws are made considerably 
smaller than those noticed in the table, the blade being a piece 
of watch-spring fixed in a brass back ; but these little tools are 
generally made by the watch-maker, or other artizan requiring 
them. 



COMB-CUTTER'S DOUBLE SAW. 



723 



In all screws that are made in the turning lathe, it is 

desirable, in separating them from the neighbouring metal, to 

the- turning tool, and to nick them in rather small behind 

the head. The little neck that i left, is broken through, just 



Fig. 702. 



flattened with a file, and then slightly notched with a triangular 
file, as an entry for the screw-head saw; by these means the 
risk of notching the head otherwise than truly diametrical is 
avoided. 

The comb-cutter's double saw shown in profile in fig. 704 
and in section on a larger scale in fig. 703, is called a " stadda" 
and has two blades so contrived as to give, with great facility 
and exactness, the intervals between the teeth of combs, from 
the coarsest, to those having from 40 to 45 teeth in the inch. 

The blades of the saw, or its plates, are made of thick steel, 
and are ground away on the edge as thin as the notches in the 
comb, either in the manner of a or b, and they have about 10 
to 20 points in the inch, of slight pitch, fig. 644. The plates are 
fixed in the two grooves in the wooden handle or stock, by 
means of the stuffing, either two long wooden wedges, or folds 
of brown paper ; the plates would rest in contact but for the 
introduction of the thin slip or tongue of metal /, called a 
languid, which is of the thickness of the teeth required in the 
comb, the one blade is in advance of the other from -rrth to 



Fig*. 70S. 




of an inch. At the first process a notch nearly of the full 
depth is made in the comb c, and a second notch is commenced ; 

3 A 2 



JM GAGE-SAW, HACK-SAW, FRAME-SAWS. 

at the next process the notch in advance is deepened, and a 
third commenced, and so on consecutively. 

The gage-saw, or gage-vid, is used to make the teeth square 
and of one depth. The saw is frequently made with a loose 
back, like that of ordinary back-saws, but much wider, so that 
for teeth |- f f inch long, it may shield all the blade except 
f inch of its width respectively, and the saw is applied 
until the back prevents its further progress. Sometimes the 
blade has teeth on both edges, and is fixed between two parallel 
slips of steel connected beyond the ends of the saw blade by two 
small thumb-screws, as in fig. 705; the less common instru- 
ment is represented, because it is useful for other purposes. 

Double saws, fig. 706, analogous to those of the comb-maker, 
have been also frequently applied to cutting metal racks, similar 
to those used in air-pumps. The blades, which in 706 are 
shaded, are as thick as the widths of the spaces, and are sepa- 
rated by a parallel slip of metal, represented white, exactly 
equal to the thickness of the teeth; the separating slip also 
serves as the stop to make the teeth of one depth from the 
surface ; the three parts are strongly united by two or more 
screws, or bolts and nuts. The rack-saw if carefully made 
fulfils its work with considerable accuracy ; the dotted lines at a, 
denote the succeeding step, those at b, the square notches when 
completed, and c, the teeth when rounded, which is done after- 
wards with a file. In modern practice, however, the teeth of 
wheels and racks are usually cut and rounded at the one process, 
which is performed in appropriate machines. 



The third division of the table on page 699, refers to parallel 
saws used in frames, of which the measures are tabulated. 

The saw-frames of these and other kinds, keep the blades 
straight, give them tension and enable the force to be applied 
virtually as in the Indian saws, or by pulling the blades, thereby 
avoiding the risk of buckling them. From these several reasons 
the blades of frame-saws may be made very thin, consequently 
they act with less labour and waste, and may in general be used 
more vigorously than those saws having only a thrusting handle 
at the one end. The blades are sometimes left a trifle thicker 
where the pins are to be inserted, and these parts are softened 
by being pinched between red-hot tongs, prior to drilling the 
pin-holes by which they are attached to their frames. 



MILL-SAWS, PIT VKN'XCR SAW. ' II H Il-MAKER's SAW. 725 

The mill-taw, and mill-taw web, at the beginning of this group, 
are used in vertical saw machines, which will be described in 
the fourth section of this chapter. It will suffice here to observe, 
that the first, or mill-saws, which are the larger and stouter, 
are employed for sawing round timber into thick planks; and 
tin- null -saw webs, for cutting deals into thin boards. 

The veneer taw formerly in use at the snw-pit was, except- 
ing the blade, a copy of the pit-frame saw, fig. 676, p. 708, and 
skilful sawyers would therewith cut about six veneers from the 
solid inch of wood. Snialli r veneer saws more nearly resembling 
that shown in fig. 708 were also used by cabinet-makers, who 
would cut seven or eight veneers in each inch from smaller 
pieces of wood, fixed upright in the chops of the bench, two 
individuals being mostly required. The hand veneer saws, are 
now scarcely used in England. 

The chairmaker's saw is in general a diminutive of the ordinary 
pit saw, and has a central blade strained by buckles and wedges. 
The work is fixed horizontally upon the bench by the hold-fast, 
the saw is grasped by the side rails with both hands, and 
with the teeth from the operator, who stands in the erect 
posture. He can thus saw with great rapidity and accuracy all 
straight and slightly curved pieces, not exceeding in width half 
the span of the frame, which is sometimes nearly as wide as the 
length of the blade. The wheelwright employs precisely the 
same saw for cutting the felloes of wheels; the timber, wide 
enough for two felloes, is then fixed in the ordinary tail-vice. 

The three following figures represent different kinds of frame 
saws, in which the blades are neither strained by buckles and 
wedges, nor placed centrally, as in those hitherto considered. 

There is a central rod or stretcher, to which are mortised two 
end pieces that have a slight power of rotation on the stretcher; 
the end pieces are at the one extremity variously adapted to 
receive the saw, and at the other they have two hollows for a 
coil of string, in the midst of which is inserted a short lever. 
On turning round this lever the coil of string becomes twisted 
and shortcut 1 1 . it therefore draws together those ends of the 
cross pieces to which it is attached, whilst the opposite ends 
from separating, strain the sa\\ in a manner the most simple, 
Tin- tension of the blade is retained by allowing 
the lever to rest in contact with the stretcher, as represented, 



76 WOOD-CUTTER'S SAW, CONTINENTAL FRAME SAW. 

but wheii the saw is not in use, the string is uncoiled one turn 
to relieve the tension of the blade and frame, one or other of 
which may be broken by an excessive twist of the string. 

In the wood-cutter s saw, fig. 707, the end pieces are much 
curved, and one of them extends beyond the blade, which is 




embedded in two saw-kerfs, and held by a wire at each end ; 
the blade is therefore always parallel with the frame of the saw, 
which is mostly used vertically. The end piece alone is grasped 
at r and I, by the right and left hands respectively ; the wood is 
laid in an X form sawing-horse, and is sometimes held by a 
chain and lever, or less frequently in a strong pair of screw-chops. 




The Continental frame-saw used abroad for the general pur- 
poses of carpentry and cabinet-making, is shown in fig. 708; 
in the largest of these the blades are about three feet long, one 



I. SAWING HORSE. 



727 



and a half to three inches wide, and very thin; and others as 
small as half those sites are also used. The wooden handles, 
/* ft, shown also detached and of twice the size at A', have cylin- 
drical stems, \\lnrh i>i through the end pieces; they are cut 
through longitudinally for admitting the sheet iron T form 
clamps, \\ln .;'li In-Ill by a rivet passing through the 

handle outside the frame; the blade is fastened between each 
pair of clamps by a pin or screw. 

The handles being cylindrical, the saw can be placed at all 
angles with regard to the frame, and may therefore be employed 
for cutting off pieces of indefinite length, provided they do not 
exceed the width from the blade to the stretcher, which latter is 
forked at the extremities to embrace the cross pieces, and this 
allows it to be shifted nearer to the string when required for 
wide pieces. Before using the saw it should be observed to 
place the blade exactly in a plane, or out of winding. 

Most of the works performed in England with the hand-saw, 
the tenon, dovetail, and similar saws, are abroad accomplished 
with frame-saws of various sizes ; the pieces are mostly fixed, 
either to or upon the bench, and the contrivance for holding long 
works, shown in fig. 709, is also general on the Continent. 



Fig. 709. 




rt 




^ 


] Rg. 710. 




, J \ 


O 







The work to be sawn is passed through the triangular opening 
in a wooden frame, nearly in the form of the letter A ; when the 
frame and work lie at an obtuse angle, they constitute a three- 
legged stool. The upper edges of the board become wedged 
fast in the angular sides of the triangle, and the lower side of 
the board rests on the cross piece of the supposed letter, which 
may be placed at various heights, according to the size of the 
work, as it rests on two moveable pegs. In sawing small works, 
the man rests his knee on the work near the top of the frame, 
and the board is changed end for end when sawn through half 
its length. Triangular frames, with various modifications, are 



728 TURNING OR SWEEP SAW, IVORY SAW. 

also commonly used abroad instead of the saw-pit ; but our own 
occasional method, namely, a pair of trestles about six feet 
high, is much better, as each of the sawyers is then far more 
favourably situated than when the timber is placed aslant.* 

The turning -saw, or sweep-saw, fig. 710, which is also called the 
frame-saw, or bow-saw, resembles fig. 708, except in its smaller 
size and greater proportionate width of frame j this will be 
apparent, as the figures are drawn to the same scale. 

Its handles have always cylindrical wires that pass through 
the end rails; the wires are sawn diametrically to admit the 
saw blade, and are drilled transversely for the pins ; frequently 
the one handle has an undercut notch, as represented on a 
larger scale, so that the saw may be removed sideways from 
the one handle, and allowed to move as on a joint upon the 
other, a provision that is often turned to a useful account. 

In using the bow-saw the work is mostly fixed vertically, and 
therefore the blade is used horizontally ; but the frame is placed 
at all angles, to avoid the margin of the work, and it is fre- 
quently necessary to twist the handles or pins during the cut, 
to modify the position of the frame. It often happens that the 
cut has to be commenced from a hole or aperture, in which case 
the tension of the blade is relieved by a turn of the stretcher, 
and the saw is disconnected at one end for its introduction. The 
disunion of the blade is also convenient for withdrawing it side- 
ways, without the tedious necessity for retracing the tortuous 
course by which it may have entered the work. 



It still remains to notice those saws, the frames of which 
may be considered to be slightly flexible, and to form the three 
sides of a rectangle. The ivory-saw, which has been already 
figured and described at pages 146 and 147 of the first volume, 
is the largest of this kind, and the full particulars have been 
there given, of its use in the preparation of ivory. Sometimes 
the frames of saws for ivory are made of iron, and without the 
adjusting screw clamp ; the frame is then sprung inwards by 
means of a long hook whilst the saw is inserted. 



* These nnd relative matters are fully described and figured by A. R. Emy, in 
hia Traiti ckl' Art de la Charpcnterie. Paris, 1837. Plates 2 to 11. 



SMITH'S FRAME SAWS, JOINT SAW. 

The smith's frame-taw, fijr. 7 1 1 , i*. m-:irly a copy of the saw 
last referred to, and it almost always possesses a screw and nut 
for stretching the blade. 

The mode of using the saws, for metal, is tin- reverse of that 
in saws for wood ; as for metal, the motion should be slow, and 
pressure somewhat considerable, and the necessity for each 
of these conditions increases with the hardness of the material. 
The saw is almost invariably moistened with oil or tallow-grease, 
and in the back strokes the pressure on the blade is discon- 
tinued, but the saw is not raised from the bottom of the notch ; 
in this respect the action resembles that of the file. 

The smith's frame-saw is the common instrument used in 
metal works for the removal of pieces that are in excess, and in 
many cases instead of the whole substance being cut through, a 
notch is made on two sides of the work, and the center part is 
broken. This saw is also used for making notches and grooves, 
much the same as in cabinet-work ; but except in small works, 
preference is given to the figuration of materials by casting, 
forging, and other modes already described. 



1 




713. 




712. 



The side frame-saw, fig. 712, although far less common, is 
greatly preferred by some workmen; thus, in making the joints 
of drawing instruments, much depends on the correct use of the 
frame-saw, by which the notches are made for the reception of 
the steel plates used in the joints, and fig. 712, in which the 
blade is more immediately under observation, is preferred to 
fig. 711. For routing out the concave part, a saw like fur. 713 
is used, niid iiiM-rted a little way into the joint, until the holes 
in the joint and tool are sufficiently opposite to admit the end of 
a taper pin ; the joint -saw or router is then moved to and fro, 
and as the concavity is cut auay. the pin is set forward until its 
cylindrical part causes the two holes to be exactly opposite, and 
then the work is completed. 



730 PIERCING SAW AND PIERCED WORKS. 

Piercing-saw blades commonly measure from 3 to 5 inches 
long, and they are fixed in very light frames, such as fig. 714, 
which are from about 2 to 4 inches deep from the saw to the 
back ; in some instances piercing-saws exceed the depth of 
8 inches, as in m, fig. 716. The blades are fixed between small 
screw clamps, the inner sides of which are mostly cut like files. 
Sometimes, as in fig. 715, the clamp near the handle is extended 
as a wire through the handle, and is tightened by a nut at the 
extremity, somewhat as in a violin-bow ; but in general the slide 
is considered sufficient and preferable, as when it is loosened 
the tension of the saw can be appreciated with the fingers, and 
retained with the thumb-screw. 



Fig. 714. r> 715. 




Some kinds of silversmith's works are pierced with this instru- 
ment, and embellished with the graver. When the design is 
original, the engraving is usually first done, and the interstices 
are cut out with the saw. But for the convenience of repetition, 
recourse is had to brass pattern plates, pierced and engraved 
like the finished work ; the brass pattern is laid on the work, 
and all its interstices are marked through with a fine scriber. 
In copying designs from any article of silver, the new piece is 
laid upon the original, the interstices of which are smoked 
through with a lamp : and in curvilinear works that cannot be 
pierced while straight, the pattern is dabbed with printing-ink, 
a paper is laid thereon, and rubbed on its upper surface with a 
burnisher; the paper thus printed is then pasted upon the 
object to be pierced. The under side of the original is printed 
from, to make the copy direct and not reversed. 

The outline having been obtained by one of the above modes, 
a hole is made with the breast-drill in every piercing, and where 
practicable, the holes form the circular terminations of the 
apertures. The several curves are then followed with the saw, 
which is used vertically, and with the handle downwards, whilst 
the plate is held horizontally upon the pin of the jeweller's 



PIERCED WORKS. SILVERSMITH'S AND JEWELLER'S BENCH. 731 

bench with the fingers, in order that both the work and the saw 
may be freely twisted about in sawing out the several parts. 

The silver-piercer sits at the silversmith's and jeweller's ordi- 
nary work-bench, formed like a round table, with four or six 
semicircular scollops, about IS inches diameter around it ; the 
pins, or omall filing boards, are about 3 inches square, and pro- 
ject inwards into the bottoms of the hays or scollops, each of 
which has a skin or a leather bag nailed around its edge, that 
serves to collect the filings removed from the work. 

This form of work-table is adopted, in order that a central 
lamp may serve for the four or six workmen, each of whom has 
a glass globe 6 to 8 inches diameter, filled with water, to act as 
a condensing lens, and direct a strong light to the spot occupied 
by his work. Spirits of wine are added to the water, to prevent 
it from freezing and bursting the globe. The benches are fre- 
quently made semicircular, and placed against a window, as the 
circular bench requires a sky-light. 

The amateur can employ in piercing, a small square filing- 
board with a fillet beneath, by which it is fixed horizontally 
in the ordinary vice. Should he prefer fixing the work, it may 
be still held horizontally, provided he employs a hand-vice, and 
pinches it by the half of its joint in the tail-vice, so as to place its 
jaws horizontally. In passing round the small curves, the strokes 
of the saw must be short, quick, and feeble; in the larger curves 
the full length of the blade may be more vigorously used. 

Some of the very minute pierced works are drilled and then 
finished with small files, as in the plates formerly used for 
covering the balances of watches, but in general the file is not 
used. The piercing saw is also employed for cutting out small 
escutcheons and other pieces for inlaying. 

From the pierced works, appear to have been derived those 
inlaid works, consisting of curved and flowing Hues, which are 
produced by a method that may be called counterpart -saw inr/, 
and in which two plates of differently coloured materials, whether 
wood, metal, ivory, tortoise, or pearl shell, are temporarily fixed 
together, and then cut through at the same time with a fine 
hair-like saw. By this process the removed pieces so exactly 
correspond in form with the respective perforations, that when 
the two colours are separated and interchanged, the one ma- 
terial forms the ground, the other the inlay or pattern, and 



732 INLAYING, OR BUHL-SAW. 

vice versd : and the pieces fit so nearly together, that the route 
of the saw is only visible as a fine line on close inspection. 

These works receive the general name of inlaid or marquetry 
works; and also the specific names of buhl-works and reisner- 
works, from their respective inventors.* 

The saws used in piercing and inlaying scarcely differ but in 
size: thus, the black line m, in fig. 716, is drawn from a large 
piercing saw of metal, and the dotted line w, from an ordinary 
buhl-saw of wood : the former measures eight inches from the 
blade to the frame, the latter twelve or sometimes twenty inches, 
to avoid the angles of large works. The wooden frames are 
made of three pieces of wood, halved and glued together to con- 
stitute the three sides of a rectangle, after which two pieces are 
glued upon each side, each at the angle of 45 degrees across the 
corners : the whole, when thoroughly dry, is cut round to the 
form represented. The screws for giving tension to the blade, 
although commonly added, are seldom used, as the frame is only 
sprung together at the moment of fixing the saw, and by its 
reaction stiffens the blade. 

The buhl-cutter sits astride a horse, or a long narrow stool, 
fig. 717, having near the one extremity two vertical jaws lined 
with brass at the top ; the one jaw is fixed, the other is notched 

* The term marquetry seems to be employed to designate all kinds of inlaid 
work, known in France as marqueterie en bois, and marqueterie en mital. It 
includes not only the works of counterpart sawing, in which flowers, animals, 
landscapes, and other objects are represented in their proper tints, by inlaying 
and without the aid of the artist's pencil ; but it also includes those geometrical 
patterns composed of angular pieces, laid down in succession more after the manner 
of ordinary veneering : and amongst which, the specimens of parquetage, or inlaid 
floors, appear to claim a place. 

Boule work, and reisner work, are considered by the virtuosi to apply exclu- 
sively to the works of two celebrated fbeniates of those names, both settled in 
France ; the former, an Italian, in the reign of Louis XIV., the latter, a German, 
in the time of Louis XIV. to XV. Their cabinet works were as much celebrated 
for their graceful forms or outlines, as for their embellishment with inlaying. 

Boule, mostly employed dark-coloured tortoise-shell inlaid with brass, in flowing 
patterns, occasionally ornamented with the graver. Reisner, used principally as 
the ground tulip-wood (called in France bois de rose,) inlaid with flowers in dark 
woods, grouped in a much less crowded manner than in ordinary marquetry. 
Keisuer occasionally combined therewith bands and margins, in which the woods 
were contrasted as to the direction of the grain, as well as colour. 

The terms buJil or lool work appear to be corrupted from boule, and now refer 
to any two materials of contrasted colours inlaid with the saw, and which, in 
France, would be called by the general name of marqueterie. 




It in ( I fTEa's SAWING HORSE. 






w, and springs open when left to itself, hut is closed by a 
strut, which is loosely 1 to the stool by a tenon and 

mortise, and rests in a groove in the moveahle jaw. When the 
strut is pulled downwards, by a string leading to tin? treadle, it 
closes the flexible jaw of the vice. In the plan the jaws are 
inclined some twenty degrees, so as to be at right angles to the 
path of the workman's right hand. 



Fig. 716. 




In the following descriptions of counterpart sawing, the several 
methods will be noticed in that order which appears to offer the 
most facility of explanation, regardless of other considerations. 

In buhl-work the patterns generally consist of continuous lines, 
of which the honeysuckle ornament may be taken as a familiar 
example. To make this, two pieces of veneer of equal size, say 
of ebony and holly, are scraped evenly on both sides with the 
toothing-plane, and glued together with a piece of paper between, 
for the convenience of their after separation.* Another piece 
of paper is glued outside the one or other veneer, and on which 

* Veneers, like other thin plate*, we pinched by one corner with screw clamp 
to the table or bench ; the tooU are applied from the fixed end, in order that ttx-y 
may pull the material and keep it straight Instead of forcing it up in a ware. 



734- ORDINARY PRACTICE OP BUHL-CUTTING. 

the design is sketched; a minute hole is then made with a 
sharp-pointed awl or scriber, for the introduction of the saw, 
that spot being selected in which the puncture will escape 
observation. 

The buhl-cutter being seated on the horse, the saw is inserted 
in the hole in the veneers, and then fixed in its frame; the work, 
held in the left hand, is placed in the vice, which is under 
control of the foot, and the saw is grasped in the right hand, 
with the fore-finger extended to support and guide the frame ; 
the medium and usual position of which is nearly horizontal 
and at right angles to the path of the saw. 

The several lines of the work are now followed by short quick 
strokes of the saw, the blade of which is always horizontal ; but 
the frame and work are rapidly twisted about at all angles, to 
place the saw in the direction of the several lines. Considerable 
art is required in designing and sawing these ornaments, so that 
the saw may continue to ramble uninterruptedly through the 
pattern, whilst the position of the work is as constantly shifted 
about in the vice, with that which appears to be a strange and 
perplexing restlessness. 

When the sawing is completed, the several parts are laid flat 
on a table, and any removed pieces are replaced. The entire 
work is then pressed down with the hand, the holly is stripped 
off in one layer with a painter's palette-knife, which splits the 
paper, and the layer of holly is laid on the table with the paper 
downwards, or without being inverted. 

The honeysuckle is now pushed out of the ebony with the 
end of the scriber, and any minute pieces are picked out with 
the moistened finger, these are all laid aside : the cavity thus 
produced in the ebony is now entirely filled up with the honey- 
suckle of holly, and a piece of paper smeared with thick glue, 
is rubbed on the two to retain them in contact. They are 
immediately turned over, and the toothings or fine dust of the 
ebony are rubbed in to fill up the interstices ; a little thick glue 
is then applied, and rubbed in, first with the finger, and then 
with the pane of the hammer, after which the work is laid aside 
to dry. 

"When thoroughly dry, it only remains to scrape the bottom 
with the toothing-plane or, when the work is small, with its 
iron alone, and then the buhl is ready to be glued on the box 



Hfll I.- WORKS, IN TURK WOODS. 735 

or furniture in the manner of an ordinary veneer, as already 
explained ; when the work is again dry, it is scraped and 
polished. Exactly the same routine is pursued in combining 
holly ground and the ebony honeysuckle, and these con- 
stitute the counter or count^r/mrt buhl, in which the pattern is 
the same but the colours are reversed. 

It is obvious that precisely the same general method would be 
pin-sued to make four satin-wood honeysuckles at the respective 
angles of a rosewood box ; the veneers for which would be then 
selected of the full size, and glued together with paper inter- 
posed. To ensure the exact similitude of the several honey- 
suckles, one of them having been cut out would be printed from, 
by sticking it slightly to the table, dabbing it with printing-ink, 
and then taking impressions, to be glued on the other angles of 
the box at their exact places. The counter would have, in this 
case, a satin-wood ground, with the honeysuckles in rosewood. 

To advance another stage, three thicknesses of wood may be 
glued together, as rosewood, mahogany, and satin-wood, and a 
center ornament added to the group of four honeysuckles. The 
three thicknesses, when cut through, split asunder, and re-com- 
bined, would produce three pieces of buhl-work, the grounds of 
which would be of rosewood, mahogany, and satin-wood, with 
the honeysuckle and center of the two other colours respec- 
tively. Such are technically known as works in three woods, 
and constitute the general limit of the thicknesses, but the 
patterns consist of many more parts than here supposed. 

In a series of three woods in the possession of the author, or 
three veneers, cut and interchanged as above explained, the 
three tablets each present forty-eight different pieces, and by 
the introduction of a broad arabesque band, the ground con- 
sists of a central panel of one colour, and a margin of another. 
It is the general aim so to arrange the design as to have about 
nn equal quantity of each colour, to make every combination 
effective, or without the predominance of any one colour. 

Before glueing such works together, it is sometimes required 
to take off a printed impression for future use; in such cases 
one thickness is entirely stripped off, and those pieces of this 
thickness which best display the character of the pattern, are 
slightly glued on their corresponding places on the two thick- 
nesses, and project therefrom in the manner of type ; so that 



736 



BUHL-WORKS IN BRASS AND PEARL SHELL. 



they alone receive the printing-ink, and return it to the paper 
pressed upon them with the hand, or with a tool handle used as 
a burnisher. 

Brass borders, technically known as Vandykes, are worked in 
narrow slips, and in other respects as above, except that unless 
a small hole is drilled through the brass and wood for the saw, 
it is allowed to cut its own path from the outside edge of the 
materials, and which is more usual. The true buhl, or the wood 
ground with brass scrolls, is laid down in four or more pieces 
around one box or panel ; and the counter, or the brass ground 
with wood scrolls, upon another. 

When the material is small and costly, as pearl-shell, it 
becomes necessary to use two or several pieces, accurately placed 
edge to edge, to cover the entire surface to be ornamented ; and 
the joints are placed where least observable in the pattern. 
The paper knife, from part of which fig. 718 was drawn, required 
eight pieces of pearl shell; in using this material, a hole is 
made in the wood close against the pearl, and the saw is sent in 
from the edge of the same. The counter, when glued on another 
veneer, is not inlaid of the irregular angular form of the rough 
pieces of pearl, but it is cut around the general margin of the 
pattern, as at the one part of fig. 719, which represents the 
counter to fig. 718. 

Fig. 718, the buhl or true buhl. 



Fig. 719, the counter or counterpart buhl. 




Inlaid by ordinary cutting. 



Inlaid by internal cutting. 



Sometimes, to give additional elaboration and minuteness, the 
saw is made to follow all the device of the counter, and leave a 



MAIMJI 1 IH\ UOKKK. 737 

narrow line of pearl both within and without : this is called 
internal cutting, and is represented in figure 719; but in 
general, the counter fails to present the same good effect as 
that of the true buhl, in which the drawing of the ornament 
is more eHVctually preserved ; und in the internal cutting the 
pattern presents a thready or liny appearance. 

Before concluding this part of the subject, it deserves to be 
noticed that in the more minute buhl works, the parts are not 
cut exactly square, but slightly bevilled, so that the pearl may 
be left a trifle larger than the interstices in the wood, to com- 
pensate for the saw-kerf, and make the fitting close as regards 
the true buhl. But this bevilling is prejudicial to the counter, 
as the line of junction in it becomes wider than usual ; this 
defect is, however, considered to be less observable in the coun- 
ter, and which is also the less valuable piece. The stringing* t 
or the straight and circular lines combined with pearl buhl work, 
are mostly of white metal, such as tin or pewter, and are inlaid 
with the routing gage.* 

In buhl works no part of the material is wasted, and the 
whole of the work is cut at once. The circumstances are 
entirely different with the marquetry works now to be de- 
scribed, of which a slight specimen is represented in fig. 720, 

Fig. 720. 

The frouBd BUck Ebony. Hit pen Iram. arc of Bolljr lUinrd (TM. Botrhi-d. tod rnjnurd. 




llnllV Whll*. 

MiM. Uolly. 

I. ..- 






Buhl works of brass and wood, are sometimes made by itamping instead of 
tawing. As however the action of stamps and punches will be considered in a 
subsequent chapter, it need only be here observed, that the brass inlay, whether a 
honeysuckle or other ornament, is stamped out of sheet brass, and the wood veneer 
is stamped with the name tools; the brass honeysuckle is then inserted into the 
cavity in the wood as before. This method produces, so far as the nature of the 
materials will allow, an absolute identity of form, but it must be obvious the mode 
is not applicable to small patterns, as the punches then inflict too much injury on 
the wood ; neither does the stamping admit of the unbounded choice of design 
attainable with the saw, as the punches are necessarily expensive and limited to 
their particular forms. 

3 B 



738 MARQUETRY WORKS. 

wherein the ground is ebony, and the flowers or other orna- 
ments are made of coloured woods, as denoted by the annexed 
names. The dyewoods are used so far as they are available, 
and the greens, blues, and some other tints, are of holly stained 
to those colours. Each different leaf or coloured piece is pro- 
duced one at a time, and mostly requires two cuttings, which 
may be accomplished in three several ways. 

In the first mode, an engraving of the design is carefully 
pasted on the ground or counter, and cut out entirely; after 
which the several leaves are sawn out from different veneers, by 
aid of another impression of the engraving cut into pieces, and 
the leaves are inserted in their respective places ; this mode 
requires extreme exactness, but admits of complete success. 

In the second mode, the design is also pasted on the counter, 
which is then left entire : the leaves are cut out from woods of 
appropriate colours, and are then glued on the respective parts 
of the paper pattern on the counter. The projecting leaves are 
cut in, either singly or in groups, with the saw, which is just 
allowed to graze their external margins. The leaves are then 
all parted from the ground, and inserted in their respective 
apertures in the counter. By this, or the counterpart method, 
the fitting becomes more easy, and the cuts may be slightly 
bevilled, to improve the closeness of the joints. 

In the third mode, the separate leaves to constitute the inlay, 
are cut out from the different coloured veneers, and glued in 
their appropriate positions on a sheet of paper. A sheet of 
white paper is also glued or pasted on the veneer to be used for 
the counter or ground ; and further, a sheet of the blackened 
or camp paper, such as that used in the manifold writers, is also 
required. 

The three are assembled together at the bottom, the veneer 
with the paper upwards, then the camp paper, and at the top 
the leaves, the backs of which are then struck at every part, with 
several blows of a light mallet, so as to print their own impres- 
sions on the white paper. The printed apertures are then cut 
in the counter one at a time, so that the outer edge of the saw- 
kerf falls exactly on the margin of every aperture. 

In this, or the third mode, the fitting of the parts may bo 
made unexceptionably good, as the operation is not prejudiced 
by the unequal stretching of the paper, which is liable to occur 



< III IM.VR, OR l<: \ll\0, 8AW MACHINES. 739 

\\ l.rn t\vu copies of the engraved design arc employed, as in the 
tii-t and second modes.* 

Tin- ribs and markings of the leaves in marquetry work, are 
made by cuts of the saw, or scratches of the graver, which 
-.( tilled \\ith the fine wood dust and glue. 

Occasional assistance is derived from the judicious disposition 
of the grain of the wood ; and the shading of the leaves, to give 
them roundness, is obtained by scorching their edges by holding 
them near a heated iron before they are laid down. In this 
manner white roses and other flowers with many leaves are most 
successfully imitated in holly; the several leaves being cut out, 
scorched on the edge, and grouped together to form the flower, 
before incision. Ivory is used for very white flowers ; and ivory, 
either white or stained, and also pearl shell, and other materials, 
are used for insects, and parts requiring additional brilliancy of 
effect. 

SECT. IV. RECTILINEAR, OR RECIPROCATING, SAW MACHINES. 

Rectilinear sawing machines are for the most part derived 
from, saws used by hand for similar purposes ; and under these 
circumstances it appears desirable that the machines to be 
noticed should, so far as practicable, be introduced in the order 
adopted in the last section ; namely, machines derived from the 
felling, cross-cutting, and pit saws, and those from the frame, 
bow, and buhl saws. 

Few sawing machines have been made for felling timber, 
because the labour of removing the machines from tree to tree, 
in general outweighs any mechanical advantage to be derived 
from their use. In the most simple machine of this kind, the 
saw is formed as the arc of a circle, attached to a wooden sector 
moving on its center, and worked with reciprocating motion by 
a horizontal lever.f 

Aa a more expeditious mode of transferring the pattern than with the mallet, 
the three parts above described, havo been squeezed in a fiat screw press, this fails 
to bring up the impression, from the unequal thicknesses of the Tcneers ; the hydro- 
static press does not produce the required effect, and is liable to crush the wood 
from its enormous force ; but tho rolling press, such as that for copper-plate 
printing, was tried by Holtzapffel and Co., and found to succeed in all respects in 
transferring the pattern. 

t Another construction for A felling and cross-cutting saw, which is more 
elaborate, is described in the Mechanics' Mag. vol. ii. p. 49-50 ; and at vol. iii. p. 1 
of the same Journal, is a proposition for a pit-aaw, which, as well aa the above, it 

I -2 



740 



CROSS-CUTTING SAW MACHINES. 



In cross -cutting .taw-machines erected in the Portsmouth Dock- 
yard and Woolwich Arsenal, the timber is laid as through a 
doorway, the posts of which are double, so as to form two nar- 
row grooves for the guidance of the saw; this resembles the 
ordinary cross-cut saw, except that it has two guide-boards 
riveted to it, in continuation of its length, and the boards work 
freely through the grooves in the posts. The saw is actuated by 
a vertical lever, or inverted pendulum, moved by the steam en- 
gine, and the workman bears down the opposite end of the saw 
with any required degree of force ; the saw is guided in its first 
entry by a board with a saw-kerf, which then rests upon the 
timber, and when not in use the saw is turned up on its joint, 
leaving the doorway free for the reception of other timber.* 

A cross-cutting saw machine of a more exact kind is erected 
at the City Saw Mills : the saw-blade is strained in a rectangular 
frame, which both reciprocates and descends in a vertical plane. 
The machine has a large double cross ; the two horizontal arms 
have grooves that receive the rails of the saw frame, and which 
is reciprocated by a crank and connecting rod ; the vertical arms 
of the cross fit in a groove formed by double vertical beams. 

The cross and saw frame are 
almost counterpoised, so that a 
moderate psessure alone, and not 
their whole weight, falls on the 
saw teeth, and the timber is 
clamped on a railway or slide, 
which is at right angles to the 
plane of the saw's motion. 

A cross-cutting saw machine 
worked by hand, that is much used 
on the Continent and in America, 
for cutting firewood, is repre- 
sented in fig. 721. The wood is 
laid in an X form sawing horse, 
and fixed by a chain and wooden 
lever, which latter is brought 
under a peg. The frame saw is suspended by its lower angle in 

is proposed to work by means of the oft-repeated scheme, of a heavy pendulum 
put in motion by manual power. 

See Roes's Cyclopaedia, Art. Machinery for Manufacturing Ships' Blocks, 
Vol. xxii. ; also Encycl. Metrop. Part Manufactures, Art, 532. 



Fig. 721. 




VKRTK M. -\\\ M\( MINIS HIU\I.\ 11^ POf 741 

the elrft of a lever that swings as a pendulum when the saw 
frame is moved. Tl. iipports and guides the saw frame, 

the action of which is assisted l>y the momentum of an adjust- 
able weight, built out at right angles to the suspending lever. 
The saw always rests on the timber, and cuts both ways; and 
being guided in its required position, a person but little experi- 
enced in the use of the ordinary frame saw, can exert his whole 
strength in the act of cutting, and accomplish the work expcdi- 
tiously, especially as the saw is longer than that shown on page 
726, and employed in the ordinary manner for the same purpose. 
Upright or reciprocating saw machines, are largely employed 
to perform that kind of sawing which is usually done at the 
saw-pit ; the larger upright or frame saws are used for cutting 
large round or square timber into thick planks and scantling, 
the smaller for cutting deals into boards. The earlier of these 
machines appear to have been those for round timber: they 
were mostly built of wood and driven by water power, these 
have been repeatedly described.* 

The vertical saw mills now used in England are made almost 
entirely in iron, and driven by steam power, and as the several 
constructions differ but little either in respect to principle or 
general arrangement, the modern frame-saw for deals, fig. 722, 

The reader interested in the practical details of the earlier saw-milk, is 
directed to Gregory's Mechanics, 1807, vol. ii., p. 321 ; and, in addition to tho 
authorities there quoted, he will find useful matter on the subject in Hassenfratz'a 
Traitf de FArt du Charptntier, Paris, 1804, in Evan's Young Millwright, and 
Miller's Quide, Philadelphia, 1821, and more particularly in the reprint of Belidor's 
work, Architecture I/ydrauliqve, avec Notct, par M. Navier, Paris, 1819. 

In Season's lAttrumcntarum, published in 1578, at Plates 13 and 14, are two 
very curious and graphic drawings of saw -machines driven by manual power; tho 
one by a crank and winch-handle ; tho other by a pendulum pulled as a church 
bell, and acting through the medium of a right and left-handed screw, and a system 
of diagonal links, as in the so-called " lazytongs." One of the saws has curvilinear 
teeth, of which 1, 3, 5, 7, cut during the descent, and 2, 4, 6, 8, during the ascent 
of the blade. 

In the saw invented by Lieutenant J. W. Hood, for cutting through ice, the 
blade is suspended from the end of a lever, like that of an ordinary hand-pump, 
and has a heavy weight beneath the ice. The axis of the lever is in a wooden 
frame, or sledge, the progression of which is caused by the end of a rod or paul- 
that sticks into the ice ; the rod being jointed to the lever a little in advance of its 
pivots, thrust* the frame and saw some three or four inches forward during the act 
of cutting. This ice-saw is worked by two to four men, whereas the previous 
methods used in the Greenland fisheries, with a triangle and pulley blocks, required 
from twenty to thirty men. Trans. Soc. of Arts, 1827, voL xlv., p. 96. 



742 



VERTICAL SAW MACHINES, DRIVEN BY POWER. 



will be principally spoken of. In this drawing the whole of the 
mechanism has been brought into view, by supposing the floor 
to have been removed, and some unimportant alterations to 
have been made; in reality the pedestals F F rest upon the 
floor, and the machine occupies considerable length. 

The stationary frame work in fig. 722 consists of two standards 
or vertical beams, in front of which are fixed two accurate square 




bars, by means of six loops. The sliding saw frame shown 
geometrically in fig. 723, has four vertical and two horizontal 
bars and is cast in one piece, or as a rectangular frame, which is 
attached to the stationary square bars b b, by appropriate bear- 



VEKi IMS l>K I'oWER. 

ings at the tour angles. One central crank is in general used, 
hut for greater di-tim -tur->, t lie drawing is inailr from a machine 
having two exterior cranks, although one only is represeir 
the crank rods are not attached uuvetly to the saw-frame, hut 
to a floating lever, which is jointed at its center to the saw- 
frame; so that even supposing the two cranks to be a little 
: nnlar in length or angular position, they nevertheless move 
the platform equally, without straining or racking it. 

\Vhen only one crank placed beneath the floor is emp! 
it is needful, both to avoid excessive height in the machine, and 
the disadvantage attending the action of a short connecting rod, 
that the latter should pass freely through an oval loop in the 
lower cross rail of the saw-frame, and be united to the upper 
rail ; sometimes the crank shaft is fixed to the ceiling of the 
Imilding, but this construction is the least in estimation. The 
crank shaft, in addition to the driving pulley, has always a heavy 
fly-wheel to equalise the action of the machine, but which is not 
shown in the drawing. 

Two deals are usually sawn at once ; the parts now to be 
described are therefore in duplicate, although in the figure, one 
deal is supposed to be removed for the purpose of showing the 
mechanism more distinctly. Generally each deal has to be cut 
into three boards, and two saws are then employed on each side 
of the frame ; but sometimes as many as eleven thin saws or webs 
are used, then producing twelve thin boards or leaves from each 
deal. The saws, of which one is shown at * #, have buckles 
riveted to them, and these pass through mortises in the top and 
bottom rails of the sliding frame ; the buckles at the bottom are 
solid and shaped like an inverted T, those at the top have mortises 
and thin steel wedges ; the T pieces and wedges bear on the 
outsides of the frame. 

The distances between the blades are adjusted by interposing 
pieces of wood, and pressing the whole together by the side 
us, after which the saws are separately tightened by the steel 
wedges : these details are sufficiently manifest in the gcomctrieal 
\ie\v, l'i. 7~-'i. It is to be further ob-rm-d that the edges of the 
saws are not quite perpendicular, hut have a little lead, or then- 
upper ends overhang the lower about J or J inch, to extend the 
cut throughout the descent of the blade, and to carry the *a\\s a 
little distance from the cuts, in mling or back stroke. 






744 VERTICAL SAW MACHINES, DRIVEN BY POWER. 

The two deals lie on a series of rollers built on pedestals, of 
which two only are shown at F F; the rollers also support a 
long rack, which, at the left of the figure, has dogs or nippers, 
that grasp the end of the deal by means of a side screw. The 
weight to the left of the figure, pulls the longer end of a 
horizontal lever, the shorter end of which (not seen), has a 
roller that presses the part of the deal contiguous to the saw, 
against a fixed vertical plate or fence, so that the cuts become 
exactly parallel with the side of the deal, whether it be straight 
or crooked. 

The deal is advanced by means of the rack and pinion, which 
are actuated by a ratchet movement as follows : an eccentric on 
the main shaft alternates the shorter end of the lever I, and to 
the longer end of the same is fixed the ratchet or paul, which 
according to its distance from the center, slips over two or three 
teeth in its descent, and in rising thrusts the ratchet-wheel round 
the same distance, and by its connexion with the pinion for 
the rack, advances the rack and wood a proportionate quantity. 
The retaining pauls or detents on the top of the wheel pre- 
vent its retrogression ; when they are turned back, the wood 
ceases to advance, and the slide may be run quickly back by 
a winch. 

The plank frame by the late Mr. Benjamin Hick, of Bolton, 
(of which a model is deposited in the Museum of the Inst. Civil 
Engineers) has no long rack. Each deal is grasped between 
two grooved feeding rollers ; the one fixed to the framing 
of the machine, the other pressed up by a loaded lever, and 
moved a small step at a time, by a ratchet as usual. 

The single saw frames above described make about 100 to 120 
strokes, of 18 or 20 inches long, in the minute, and cut two 
12 -foot deals in from five to ten minutes ; the saws require to be 
sharpened about every tenth round, or journey, for hard deals, and 
every twentieth for pine. Similar frame saws are made double, 
so as to operate on four deals at a time ; the crank is then 
double, and so contrived that the saws in one frame descend, 
whilst those of the other ascend. By this arrangement the 
vibrations of the machine are somewhat lessened, so that the 
velocity may be increased to about 160 or 200 strokes in the 
minute ; but the time occupied in fixing and adjusting is also 
greater, so that but little if any real advantage is obtained. 



\IKII. VI. ^V\\ MV(IIIM>, IKIV|\ IIV TIIK FOOT. 



Sawing mat-nines for round timber, an larger, stronger and 
somewhat dillrivnt from the deal fi-aim-.. The timber-slide moves 
on tillcts or V. V.' s , which are fixed to tbe floor, and panel 
between the standards of tbc saw frame; the timber slide has 
strong vertical end plates, through mortises in which stout iron 
spikes or dogs are driven like nails, into the ends of the required 
nlauks. The dogs are then secured by side screws or wedges in 
the dog plates, from which they project sufficiently, to allow t la- 
saw blades to stand between the end of the timber and the dog 
plate, at the commencement of the sawing. 

The sliding frames carrying the saws for timber frames are 
longer than for deal frames, and those in the Government saw 
mills at Woolwich rest in contact with rectangular fillets on the 
standards, against which they arc pressed by powerful springs, so 
that the square bars bb, fig. 723, are dispensed with. In these 
machines the blades are strained one at a time by a loaded lever, 
like a Roman steelyard, which gives to each the tension of about 
one ton, and whilst under this tension, the wedges are driven 
just home, but without violence ; each blade becomes therefore 
tense alike. Various contrivances are added to vertical saw 
machines driven by power, so that, when the saws have arrived 
at the end of the timber, the motion of the wood or that of the 
entire machine may be arrested automatically. 



Rectilinear sawing machines are not much used for those 
kinds of work that arc performed with the ordinary hand saws, 
back saws, and frame saws, used in carpentry; but two useful 
sties mecaniques suited to works of this scale are described in the 
Manuel du Tourneur, and fig. 724 is reduced from one of these. 

The saw frame has a central wooden rod, and a blade on each 
e.lu r e, which are stretched by clamps, screws and nuts, much as 
usual. The saw is guided perpendicularly by fixed wires ; these 
pass through holes in the cross heads of the saw frame, which 
are sometimes fitted with rollers to relieve the friction. The saw 
frame is suspended from a bow spring attached to the column 
erected on the bench ; and the lower end conimnnieates by a 
double-ended hook with a light treadle. The spring, when left 
to itself, raises the saw frame and treadle some 8 or 10 inches, 
and the pressure of the foot gives the cutting motion. 



746 SCIE MECANIQUE FROM THE MANUEL 1>E TOURNEUR. 

For straight pieces a wide saw is used, and the work is guided 
agaiust a square fence, which overlaps the front edge of the 
bench, and is fixed by a binding screw passing through a mortise. 
For bevilled pieces a chamfered bar c, is fixed to the right hand 
side of the bench, and carries a square sliding block, surmounted 
by an angular fence, with graduations and a clamping screw ; 
the work is laid against the angular fence, and moved upon the 
chamfer slide past the saw. For circular works a narrow blade 
is employed, and the popit head or center point connected with 
the stationary frame work, serves as the axis of motion for the 
piece of wood to be cut. 




In order to leave the bench unobstructed, so that large pieces 
may be sawn, the guide rods upon which the saw frame works 
are discontinuous ; the lower parts terminate beneath the bench, 
the upper are fixed to cross pieces, connected with a dovetail bar, 
itself attached in front of the column, so that the group of pieces 
carrying the upper wires may be fixed at a greater elevation to 






MA 'I UK HAW MM II 

admit of thicker work. The back edges of the blades run in 
aw-ki riV in tin- lower rail of the guide frame.* 

Tlnvr .small reciprocating saw machines, fitted upas adjmn-t- 
to the latin-, \\ill now be described; their constructions 
rntuvly ilitlViviii, and they were planned by their respe< 
inventors quite independently of each other. The one first de- 
scribed was especially contrived for buhl cutting ; this appears 
however, to be far the least valuable application of these machines, 
as they may be much more efficiently used for various works 
similar to those done by the slender bow or sweep saw. The 
i \trcme delicacy of buhl work, is incompatible alike with tin 
encumbrance arising from the mechanism, and the friction of tin- 
work upon the supporting platform. 

In Mr. Mac Duffs buhl cutting machine, the saw is stretched 
in a frame about 1 to f> inches high and 10 to 14 inches wide ; 
t IK- frame reciprocates vertically upon small fixed 
wires, by the modification of the crank shown in 
fig. 725. The pulley e, beneath the lathe bearers b, 
receives continuous motion from the foot- wheel, the 
lower end of a cord r, is fixed to a pin about an 
inch from the center of e, passed around the fixed 
pulley />, then between the bearers to the saw 
frame, which is raised by a spiral spring j by this 
arrangement, the parallelism of the cord is obtained. 
The work is supported upon a table or platform, 
midway between the path of the saw frame. f 

* A machine on a somewhat larger scale was erected by Mr. Brunei, at the 
Woolwich dockyard, and worked by the peculiar but expensive parallel movement 
of the interior epicycloid. There is a fixed wheel, aay of 16 inches diameter, with 
internal teeth, and a corresponding pinion of 8 inches diameter, carried round by, 
and revolving upon the end of a crank of 4 inches radius ; the pinion carries 
a stud by which it is connected with the saw frame. The velocities of the crank 
and pinion are as 2 to 1, and in the tame direction ; the stud, if attached to the 
center of the pinion, would move in a circle of 8 inches, but when attached to the 
edge or pitch line of the pinion, it reciprocates in a right line, 16 inches long ; the 
.:* placed in any intermediate position, would travel in an ellipsis, 

A reciprocating saw machine for sawing, boring, and manufacturing bavilled and 
curvilinear works in wood, was patented in 1833, by Mr. Samuel Hamilton, and 
is briefly noticed in the foot note following the application of the circular saw to 
curvilinear works. 

t Mac Duff's buhl saw received the prize of 102. awarded by Dr. Fellowes : 
and is fully described in the Mech. Mag. 1830, voL ziii. p. 129 ; at page 285 of the 
same volume Mr. Mac Duff has described a larger and more simple machine of 
the same kind. 




748 LUND'S VERTICAL SAW MACHINE. 

In the two following machines the saw is unprovided with the 
frame, by which, under ordinary circumstances, it is stretched 
and guided, these functions being fulfilled by the motive parts of 
the respective apparatus. 

Mr. Lund's vertical saw machine, which is represented from the 
back in fig. 726, consists of a bench with foot wheel and treadle, 
surmounted by a rectangular frame, the lower rail of which is 
rebated to fit the bearers ; the center rail is extended into a plat- 
form about three feet square, which, for the sake of portability, 
consists of two wide flaps with hinges and brackets, somewhat 
as in an ordinary pembroke table. To the extremities of the 
upper rail are fixed two long and narrow springs, made of ham- 
mered steel, that spring downwards when left to themselves. 
The ends of the saw are grasped in screw clamps, formed at the 
ends of square wires, working rather freely in the two outer rails, 
within holes fitted with metal. The lower saw clamp is connected 
by a cat-gut with an eccentric and guide pulley, as in Mac Duff's, 
but the eccentric shown detached in fig. 727 has more range, the 
traverse being sometimes 4 or 5 inches. 

The upper saw clamp is connected with the straight springs 
by means of a catgut line, reeved in the manner shown more at 
large in fig. 728 (one of the side frames being removed), the 
catgut proceeds from the springs, over the two fixed pulleys, and 
under the pulley on the top wire or clamp ; this arrangement 
equalises the actions of the springs, and gives a parallel motion 
to the blade, the back edge of which lies towards the operator, 
and works in a notch on the edge of a hardened steel disk, inlaid 
in the platform. One end of the catgut has a small circular 
button, which is passed through a round hole in the spring, and 
then sideways into a notch, so as to be readily detached for the 
removal of the saw. 

Mr. Lund's machine is simple and effective for inlaid and fret 
works, and a variety of thin curvilinear pieces, which occur in 
cabinet work and pattern making. For cutting parallel and 
bevilled pieces, appropriate guides are added to the platform, 
similar to those elsewhere described. For circles, a brad-awl is 
passed through the center of the work into the platform, or rather 
into a subsidiary and common platform then added. And to 
shorten the length of stroke during the working of the machine 
as required in sawing around small curves and rounded angles, 
a sliding bolt beneath the platform, is thrust across the path 



LUND'S AM) MUM. \\ II 1 IS*S VBftTICAL SAW MAC1IINK8. 749 



lie saw, 80 th:it the HMVIU >f the saw to the full height 
i- thru i>iv\eutnl b\ the temporary increase of thickness in 



Fig*. 726. 




the platform, as the saw clamp strikes against the sliding-bolt 
or slide.* 

Fig. 729 is copied from Professor Willis's sketch of a vertical 
saw for curvilinear works, constructed by himself in 1837. The 
frame of the machine is elevated above its true position to 
show the details, and is clamped on the bed of a lathe or 



* Mr. Land makes an ingenious use of this machine for inlaying the instrument* 
in drawing-cases lined with velvet. The bottom of the trays are glued up in three 
thicknesses, the grain of the inner piece being crossways, of the outer lengthways, 
a piece of white paper is added to receive the outlines of the instrument*, the spaces 
for which are then cut in the saw machine, with a saw thinned away at the back, 
and very much set to cut a wide path. 

The inner pieces having been removed, are split through the joint and glued flat 
down on a piece of velvet; each inner piece is then cut round with a penknife, 
leaving the face alone covered. The principal piece, or skeleton, is then glued and 
laid on another piece of velvet, which covers the holes as in a drum ; the velvet 
is cut through at various parts of each aperture, and folded round the edges of the 
hole*, and lastly, every removed and covered inner piece, is pushed into its place, 
i stretches and smooths the edges of the velvet, and completes the work. 
As the central pieces are in three layers, the cells may be either of one-third or 
two-thirds the entire depth, at pleasure. 

Mr. Lund's saw machine was constructed and used in 1828. 



750 



PROF. WILLIS'S VERTICAL SAW MACHINE. 



grinding frame, and the saw derives its motion from an eccen- 
tric carried by one of the ordinary grindstone spindles. This 
eccentric is a pulley of hardwood cut in half and screwed against 
the face of the mahogany pulley. A loop of wire embraces it, 
and connects it with the lower spring, so that when the spindle 
revolves the spring is thrown into rapid vibration ; the springs 
are of wood, 21 inches long and 2|- inches broad. 

The saw is clamped at each end in a small iron clamp ; the 
lower clamp is joined to the lower spring by the same steel pin 
that carries the loop of wire. The upper clamp has several 
hooks filed in its edge, any one of which can be hooked on a 
steel pin fixed to the upper spring. Thus the saw is carried 
and stretched at the same time by the two springs, and can be 
readily disengaged, either by unhooking the upper clamp or by 
uuclamping either end. The lower spring is fixed to the frame, 
the upper is fixed to a separate piece of wood that can be ad- 
justed to different heights, and the platform is 12 inches above 
the bearers. 

The only point that requires further consideration is the 
adjustment of the saw in the springs, so that it may traverse as 
nearly as possible through one and the same point of the platform, 
notwithstanding that the ends of the springs nearly describe arcs 
of circles, and therefore carry the extremities of the saw slightly 

to and fro during its move- 
729. vS,, ments. 

The vertical distances 
between the springs at their 
roots, where they are fixed 
to the framing, and at their 
pins where they carry the 
saw, must be so adjusted, 
that when the saw is at the 
top of its stroke, the lower 
spring is horizontal; and 
when at the bottom of its 
stroke the upper spring 
must be horizontal, and the 
platform midway between 
the two horizontal lines. 

In this condition, \\ith a range of two or even three inches, the 
one curvature will neutralise the other at the platfozm, as in 











MM MINES FOR SMALL WOlu 

some of tin- p:ir:illel motions, which may be proved by ;i diagram 
carefully drawn on paper. 

Professor Willis has used this machine extensively for cutting 
<>ut in thin wood, models of (Jothir ti so mathcm.v 

runes in illustration of the teeth of wheels and other elements 
of mechanism. To adapt the machine to take cither short or 
long strokes as required in buhl cutting, without discontinuing 
the motion of the foot- wheel, Prof. Willis proposes to apply a 
contrivance to the eccentric, analogous to that explained in hU 
Treatise on the Principles of Mechanism, p. 1 1.". 

A very curious sawing machine, the connecting link between 
ilincar and circular saws, was patented by Mr. Newbury in 
1808, and is thus described . " Nr. Newbury's engine is formed 
by a long and very flexible blade of a similar nature to a clock- 
spring, which passes over two rollers of considerable diameter, 
placed in the same plane, and whose extremities are united so]as 
to form a band round the two rollers. When this blade is intended 
to act as a saw, one of its edges is cut into teeth of the usual 
shape, and the substance to be sawed is placed on a stage, 
through which the blade passes, and is pressed against the blade 
with the necessary force, and in the direction proper to produce 
the shape required for it."* Guides for cutting rectilinear, 
curvilinear, and circular pieces are alluded to, the description 
does not however state the most difficult point of the construction, 
namely, the mode adopted in joining the ends of this elastic 
blade, or ribbon saw. 

SECT \. COMMON APPLICATIONS OP CIRCULAR SAWS TO 
SMALL WORKS. 

The remainder of the present chapter will be devoted to the 
consideration of machinery for circular saws ; and in treating 

See Retrospect of Philosophical Discoveries, 1*06, vol. IV., p. 222. Tho 
following paragraph respecting Newbury's flexible saw, appears on page 527 of tho 
last edition of Belidors Architecture I/ytlraulIque, arec A'ote*, par M. Navier, 
Pant, 1819.- 

it a lame jlex'Me el tant Jin." " Ctttt intention a M propotte en AngUterre, 
MOW it paratt qn'on y dontait de *OH lucre*. EUe a itt employee arte arantaye en 
Fraud par M. Tonrondt pour refendn let lUemue q*i competent let tuyatuc det 
vittfArckimUt. (BuUetindeloSocUtc'd'EnvnragemeHt.JuilUtUlS.) Lt modMt 
de ta machine at dtpott an Oontenattirt det Artt et Mftiert." 



752 ARRANGEMENT; SAWS FIXED ON LATHE CHUCKS. 

this extensive subject, it is proposed to present the matter in 
the following sections. 

V. Common applications of circular saws to small works. 
VI. Common applications of circular saws to large works. 
VII. Less common, or specific applications of circular saws. 
VIII. Circular saws and machinery for cutting veneers. 

It is further to be observed that in the present or fifth section, 
in speaking of the construction and application of small sawing 
machinery, or that which may be conveniently used by the 
amateur, the matter will be arranged under the following sub- 
divisions. 



1. Lathe chucks for very small saws. 

2. Spindles for saws of medium size. 

3. Platforms, or tables and benches, for saws of medium size. 

4. Stops to prevent the vibration of flexible saws. 

5. Parallel guides. 

6. Sawing the sides of rectangular pieces. 

7. Sawing grooves, rebates and tenons. 

8. Sawing or cross cutting, the ends of pieces, either square 
or bevilled ; or those works in which the angular variations are 
in the horizontal plane. 

9. Sawing bevilled edges, and prismatic pieces ; or those 
works in which the angular variations are in the vertical plane. 

10. Sawing geometrical solids and irregular pieces; or those 
works in which the angular variations are in both the horizontal 
and vertical planes. 

The sub-divisions 1 to ] 0, when a little modified, denote also 
the arrangement followed in Sections VI. and VII. 



1. Lathe chucks for very small saws. Circular saws not 
exceeding one or two inches diameter, are occasionally mounted 
on lathe chucks, similar to that represented in fig. 730, which is 
not only the most simple, but probably one of the earliest modes 
in which the circular saw was used. The chuck should be of 
moderate length, with a tenon to fit the hole in the saw, and a 
central screw or nut to fix the same, as represented. 

Opticians use this mode for the small thin saws with which 
they cut the notches in the tubes serving as springs in pocket 



SAWS FIXED DN I V I II I. 01 

-copes. Carvers in ivory and similar materials employ .small 
In if thick saws, the edges of which are of round, angular, or 
other sections. In each art tin- objects are mostly applied ly 
the hands alone. 

rutting the notches in the heads of screws for mcch 
tmetion, thirk saws are similarly employed. The screw is 
held in a socket, fig. 731, the end of which is tapped ti- 
the thread of the. screw, and in cutting the notch, the socki 
supported an inch or more from its extremity, upon the edge of 
the rot for the turning tool. The socket in wriggled up and 
down as a lever, to make the bottom of the notch tolerably 
straight, instead of concave, and the precautions to make the 
cut diametrical will be found at the beginning of page 723. 

The gas-burners designated as bat's iriny burners have a narrow 
slit through which the gas issues : these are cut in a similar 
manner by thin circular saws; and Mr. Milne, gas-fitter of 
Edinburgh, serrates such saws with a screw-cutter or tap, as in 
making the teeth of a worm-wheel (see pages 591-2), but the 
cutter should for the present case have one side of the tin 
perpendicular, to produce saw teeth of the customary form. 



733 - 




V 



In cutting the knuckles and tenons for joints, fig. 732, the 
work is usually supported on a small iron platform, fig. 733, the 
surface of which is horizontal, with a notch to receive the saw, 
and a cylindrical stem to adapt the platform to the bed piece of 
the common rest. The platform is fixed a little below the axis, 
to place the knuckles exactly central to the saw, so as to make 
the notches equally deep on both sides; and if the surface of 
the platform is parallel with the axis of the spindle, the notch is 
sure to be perpendicular or square to the side of the work. 

Sometimes two saws are used upon the same chuck or spindle, 

3 c 



754 



SAW SPINDLE. 



to ensure parallelism in the sides of the middle piece or tenon ; 
and similar methods are commonly used in sawing, notching, 
and drilling the small wooden mechanism of piano-fortes. For 
some of these works, especially those in metal, the saws are not 
always mounted on lathe chucks, but occasionally on small spin- 
dles similar to that drawn in the next figure. 



2. Spindles for circular saws of medium size. For sawing 
ordinary works in wood, the above arrangements are mostly 
insufficient; as the saw should be further removed from the 
pulley or lathe head, to enable pieces of moderate width to be cut 
off, and also larger in diameter to serve for thicker pieces. The 
saw is then mounted on a spindle such as that shown in section 
in fig. 734 : the saw plate fits upon the cylindrical neck of the 
spindle, and is grasped between the two flat surfaces of the flange 
and loose collar, (which latter is shaded) and pressed forward 
by the nut. A steady pin, or a small wire (represented black) 
is inserted obliquely in the spindle, and passes through a cor- 
responding notch in the saw. The steady pin constrains the saw 
always to travel with the spindle, without depending on the 
grasp of the nut alone. 



Fig. 734. 





The saw spindle, fig. 734, is frequently squared at one end, 
and has a center at the other, to admit of being supported in the 
lathe at its extremities, by the square hole chuck and popit head 
respectively, so as to revolve together with the mandrel. When 
the saw spindle is used independently of the lathe, it has a 
center at each end for the center screws then employed, and also 
a pulley to receive the band from the foot wheel or other motive 
apparatus. In regard to the proportions of circular saws and 
some other particulars concerning them, the reader is referred 
to the table on page 784, near the commencement of the follow- 
ing or sixth section of this chapter. 



WOODEN PLATFORM FOR SAWS. 






8. Platform* or tablet, and benches. "Wooden platforms em- 
ployed for supporting the work have sometimes iron stems, and 
are in ; itsions of fig. 733, except that they are placed 

abovr tl , so th:it one-third the saw-plate protrudes per- 

pendicularly through the center of the platform. But a large 
platform thus constructed is very weak, from being attached 
only at one point; and every time the platform is fixed, there 
is the trouble of placing the sa\v-kcrf exactly parallel with the 
saw, otherwise great friction ensues. 

The saw platform and apparatus in fig. 735, arc made almost 
entirely in wood; they are applicable to the ordinary turning 
lathe, and to saws not exceeding about 8 to 10 inches in 
diameter. The wooden platform is supported at the front and 
back, nearly throughout its width, upon the edges of the 
wooden box, the position of which is defined by a tenon fitting 
between the lathe bed, and secured by a bolt passing through 
the same. The platform is hinged to the back of the box, 
thus constituting as it were, a large and overhanging cover. 
The lost process in the construction of the apparatus, is to fix 
it upon the lathe bearers, and to allow its own circular saw 
to cut the saw-kerf or slit in the platform, which thence 
becomes exactly parallel with the saw. 



Fig. 735. 




In refixing the apparatus ready for work, the wood frame is 
first placed loosely on the bearers, and the platform is turned up ; 
the saw spindle is then adjusted between the centers, and lastly, 
the platform is shifted sideways until the saw enters the kerf, the 
entire wood frame is then secured by its bolt and nut ; but on in- 
to the tenon beneath, there is no risk of the groove being other- 
than parallel with the saw. Occasionally that part of the 
3c 2 



756 



SMALL SAW MACHINE OF 1ROX. 



platform which is contiguous to the saw, is covered with a thin 
plate of brass to increase its durability. 

The sawing apparatus, fig. 735, although made principally in 
wood, will be found a very convenient appendage to the turning 
lathe ; or the same parts may be used independently of the lathe, 
upon a wooden bench or frame with a wheel and treadle, much 
the same as that partly represented in the succeeding figure, 
except that the wooden standards are then required to extend 
above the bearers, so as to carry the center screws for the saw 
spindle. The back board for receiving any parts of the work 
under progress, and the drawer for the saws, are convenient for 
their respective purposes, but by no means important. 

The sawing machinery represented in fig. 736, although 
generally similar to the last, is made entirely in metal, except 
the wooden frame. The principal piece in fig. 736, or the bed 
piece, is planed flat on its underside, and has a fillet to adapt it 
to the lathe bearers or other frame ; the ends of the casting are 
formed as popit heads, and are tapped for the reception of the 
center screws, which support the saw spindle. The middle of 
the bed piece is formed as the box or trough, to which the plat- 
form is hinged by two center screws, tapped into projections on 
the underside of the platform, the front part of which rests 
upon the supporting screw, fitted into the bed piece. 

Fig. 736. 




In general construction the iron machine fig. 736 is a great 
improvement on that in wood, fig. 735, in respect to strength 



STOP! POR FLEXIBLE SAW!. 

and permanent accuracy ; ami an the supports for the spindle 

and platform, are all unhid in >m- iron ca-tin-, the inechaiiiMn 
is not subject to derangenx nt, and is quite independent of the 
frame or bench, which may br i-ithcr that partly represented in 
tin- li.u'inv, or the frame of an ordinary loot lathe after the removal 

iie headstocks; or on any bench w hat>or\er, pro\ided nn 
power from any source can be conveniently applied to the saw 
spindle. And in the course of the following descriptions it will 
be seen, that the latter machine, with certain additional mechan- 
ism, is capable of performing, within the limitation of its size, 
almost any kind of work to which the circular saw is applied. 



4. Slops to prevent the vibration of flexible saws. When the 
diameter of the circular saw is considerable, compared with the 
diameter of the flange on the spindle, the blade becomes very 
flexible, and may be easily diverted sideways from the true 
plane; the prevention of this is accomplished in many ways. 

The saws used for slitting the thin wood of wbich cedar pencils 
are made, are from about 4 to 6 inches diameter, and very thin, 
so as to act rapidly and with little waste ; such saws have fre- 
quently supplementary collars, or thick flat plates of brass, fitted 
to the cylindrical neck of the spindle, and extending to within 
\ or \ of an inch of the edge of the saw, which thereby nearly 
acquires the stiffness of the collars themselves. But as saws are 
in general required for thicker wood, such large flanges are 
mostly inadmissible, and other methods must be employed. 

For small saw machines having wood platforms, it is generally 
considered sufficient, that the saw should work in a narrow cut or 
groove made by the revolving blade in the platform, and which 
allows the saw but very little lateral play ; as the teeth can no 
.rcr cut when the smooth part of the blade rubs against the 
slit. The friction will in time wear away the wood until the 
slit becomes inconveniently wide, but a fresh piece of wood can 
IK- thru inlaid, and another notch made by the saw as at fii>t. 

Metal platforms are sometimes made in two parts for the 
convenience of forming the slit for the saw, but friction again-t 
the metal would blunt the t th, and should be avoided. In 
such cases, the inner edges of metal platforms made in two 
pieces are usually tapped for small screws, which are adjusted 
nearly to grasp the smooth part of tin thin the 



PARALLEL GUIDES FOR SMALL CIRCULAR SAWS. 

line of its teeth. The platform fig. 736, is made in only one 
piece, with a wide shallow groove in its upper surface, which is 
again filled up flush with a bar of iron, in the end of which is a 
deep notch to admit the saw, and at right angles thereto the 
stop screws are inserted laterally in the bar. The latter can be 
adjusted in the groove, to place the stop screws just within the 
line of the teeth, after which they are twisted by their capstan 
heads until they nearly touch the saw plates. 

But stop screws, howsoever constructed, give rise to noise, 
and are somewhat liable to wear the saw into grooves. A 
preferable mode for small saws, is to inlay a piece of ivory or 
hard wood in the groove on the top of the platform, and allow 
the saw to cut its own slit ; or else to fit two pieces of ivory 
into dovetail grooves, made transversely in the under sides of 
the platform, and to advance them to the saw by adjusting 
screws, but which, although a more costly method, is no better, 
as in every case the stops should be as nearly as possible flush 
with the platform; various other stops will be described in 
speaking of large sawing machinery. 



5. Parallel guides for small circular saws. Saw machines of 
every kind, depend very materially for their usefulness on the 
various guide principles introduced into their several constructions, 
and upon the advantage of which principles, as applied to cutting 
tools generally, some preliminary observations were offered in 
pages 463 to 471 of the volume now in the reader's hands. 

In circular sawing machinery, the table or platform being a 
flat surface, and the saw-blade at right angles thereto, all pieces 
that lie tolerably flat on the saw-bench are sure to be so guided 
as to be cut out of winding, and square with the face on which 
they lie. But to guide them across in a right line, it is requisite 
to have some kind of rectilinear guide parallel with the saw ; 
the width of the piece sawn oft' then becomes equal to the dis- 
tance between the saw and guide, and any number of succeed- 
ing pieces may be produced exactly of the same width. 

The guides for parallelism are constructed in many ways, 
three of which, available for small sawing machines, will be 
noticed at this place ; the jointed parallel rules are also used, 
and will be described in subdivision 5 of the next section. 

The most simple parallel guide, is a straight bar of wood fixed 



SAWING RECTANGULAR PIECES. 759 

to the platform by a screw clamp at each end, or by two screws 
passing through transverse mortises iu the cuds of the bar; but 
two sets of guaduations are then required on the platform, to 
place the straight fence or bar exactly parallel with the saw. 

Sometimes A shallow groove, inclined 30 to 40 degrees with 
the saw, is made in the top of the platform, and fitted with a 
slide, the overhanging edge of which is also inclined 80 to 40 
degrees, so as to be always parallel with the saw; the variation 
of width arises from placing the guide in different parts of the 
groove. ThU may be considered a modification of the principle 
employed in the Manjuois scales and parallel rule, but as a 
saw-guide the range is rather too limited. 

A more convenient guide was suggested by Professor "Willis 
of Cambridge, and is shown iu figs. 735 and 736. The first is 
simply a square, the two bars of which are not in the same 
plane, as the one bar lies upon the platform, the other is flush 
with it, and fitted to the back edge of the platform by a groove 
and tongue joint : a screw-clamp is there situated, to fix the 
one bar of the square to the platform, after the position of the 
other bar has been adjusted to the width required in the works. 
This parallel guide may be allowed to extend altogether beyond 
the sides of the platform, so as to have fully twice the range 
of the jointed parallel rules, to be described hereafter, and is 
besides steady alie in every position, provided the surfaces 
by which the two bars are united are sufficiently large, and 
firmly joined. The parallel guide in fig. 736, is made iu iron, 
and also after Professor Willis's plan; but the back bar, then 
lies in a rebate in the platform, and is secured by a small clamp 
and screw, partly seen. 

6. Sau-iny the fides ofrectumjular pieces. Before commencing 
to saw a piece of wood with the circular saw, it is desirable, in 
order to ensure accuracy in the result, that two neighbouring 
of the work should be moderately straight, to serve as the 
basis from which to commence; otherwise as the work is thrust 
past the saw with the hand, it may assume different positions 
in its course, and thereby give rise to enormous friction against 
the saw, and may also present, when finished, curved instead of 
flat surfaces. 

Round wood is in general too large to be cut up with the 



760 SAWING RECTANGULAR PIECES. 

small saw-machines here referred to, but particulars of the mode 
adopted iu large machines, are given iu the corresponding sub- 
division of the next section. It may however be observed, that 
when the first cut is diametrical, small round wood may be held 
with tolerable facility to the saw, and it is sometimes sawn at 
twice, or with two radial cuts, from opposite sides, but which 
cannot be expected exactly to meet. When the first cut is 
required to be on one side the center, it is much the best plan 
to flatten some part of the wood with the hand-saw or plane, to 
serve as the bed on which the work may rest upon the platform. 

In sawing up pieces of plank-wood, the broad surfaces left by 
the pit-saw will in general be found sufficiently accurate for 
their guidance in that plane, so that the edges alone then require 
examination, and one of these is sometimes corrected with a 
jack-plane, for greater exactness. 

When the saw has been put in rapid revolution, and so that 
the teeth near the operator descend, the work is laid flat on the 
platform and against the parallel guide, and is then gradually 
advanced towards the saw. If the work be thrust forward too 
quickly, the saw may be altogether stopped from the excessive 
work thrown upon it, and if it be not advanced at an uniform 
rate, the markings left by the saw will present corresponding 
irregularities. 

In dividing a piece of wood that is long* compared with its 
width, it occasionally springs open as a fork when sawn, so that the 
outside or guiding edge of the work, from having been originally 
straight becomes a little concave. This is sometimes allowed 
for by making the face of the parallel guide to consist of two 
straight lines, a little distant one from the other, instead of one 
continuous line, by fixing a thin plate to the principal piece by 
countersunk screws. The set-off in the guide usually occurs a 
little behind the cutting edge, and allows the work to escape the 
saw, so as not to be scored by the ascending teeth at the back 
part of the plate, and which are otherwise apt to catch up the 
work, if small, and throw the pieces in the face of the operator. 

It usually happens that many similar pieces are cut in imme- 
diate succession; in such cases, the succeeding piece is frequently 
made to push forward that which is nearly sawn through, by 
which mode the risk of hurting the fingers with the saw is 
avoided ; otherwise the piece is thrust towards the conclusion 
with a stick of wood, having a rectangular notch at the end. 



BAWINQ GROOVES, REBATKS, AND TENONS; CROSS-CUTTING. 7CI 

The jointed platforms arc very convenient, aa they can be 
turned up to shoot off an\ ae. mnuliitiun of work or sawdust, 
niul also for the removal of any little pieces of wood, which may 
occasionally In-come wedded in the cleft beside the saw. 



7. Satring grooves, rebates, and tenons. When the platform of 
;i circular saw machine docs not admit of any change of elevation, 
as in that shown on page 765 and many others, the quantity the 
taw projects through the table can only be varied by select 
saws of different diameters, or by placing supplementary beds of 
different thicknesses upon the platform ; the latter method 
generally interferes with the action of the parallel rule. But 
in the machine, fig. 736, constructed in iron, the hinged plat- 
form may be adjusted by the regulating screw in front, so that 
the projection of the saw through the table may, if required, 
barely exceed the thickness of the wood to be operated upon, or 
the saw may be only allowed to cut to a limited depth, and to 
form a groove either in the side or edge of the work. 

By making two incisions on the contiguous faces of the wood, 
the solid angle may be removed, as in the formation of a rebate, 
fig. 787, the same cuts again repeated would form the tenon, 
fig. 788; but this process requires that the end of the wood 
should have been previously cross-cut exactly square, in the 
mode explained in the following subdivision of this chapter. 



8. Saicing or cross-cutting the ends of pieces, either square or 
devilled ; or those in which the angular variations are in the hori- 
zontal plane. The most general guide for cutting the ends of 
work either square or oblique, is shown in fig. 7ol>, and also iu 
plan in figs. 7H', 111, and 712; it is applicable to every angle. 
An undercut L'PM.U is made iu the platform parallel with the saw, 
for the reception of a slide that carries a semicircular protractor, 
is graduated, and may he fixed at any angle by the 
thumb-screw parsing through its semicircular mortise into the 
slide beneath. The slide has sometimes V grooves made in its 
two sides, and the platform is then in two parts with bevilled 
edges, corresponding with the V grooves. The work to be sa\\n 
i> held hy the fingers in contact with the straight fence of the 
guide, and the t\u> thus grasped are slid together past the saw. 



762 



SAWING PIECES INCLINED HORIZONTALLY. 



The guide for angles is represented in fig. 740, in the position 
for cutting rectangular pieces from the end of a long bar, and the 
edge p p of the parallel guide, then serves as a stop for the width 
of the blocks thus removed. By the similar employment of an 
oblique position, such as that shown in fig. 741 ; rhomboidal 
pieces of any angle and magnitude, may be as readily produced. 



Figs. 737. 



739. 




IAAAA71* 



740. 



741. 



742. 



When the pieces are not cut from the end of a long rod, but 
are small, and only require to be reduced to any exact size, it is 
more convenient, to affix the stop for width upon the fence or the 
semicircular protractor, as in fig. 741, and in this manner small 
pieces can be easily sawn into regular or irregular polygons of 
any particular angles and numbers of sides. 

In cutting mitres, as for picture-frames, the once piece would 
be cut by placing the semicircular fence in the position, fig. 741, 
but for the other piece of the mitre, it is necessary to place the 
semicircle as in fig. 742, so that the guide may precede the work 
that is to be sawn ; consequently, unless the slide will admit of 
being withdrawn from the groove, and replaced the other end 
foremost, there should be two holes for the thumb-screw, and 
two indexes for the graduations. 

Although the oblique fence may be placed at the smallest 
angle, and even parallel with the saw, yet when the pieces are 
required to be thin and acute, it is more generally convenient to 
prepare with the apparatus, fig. 740, a wooden guide of the parti- 
cular angle, and of the form shown in fig. 739; p, being the 



v \\SIM, iMl.il.v IMCUMU VERTICALLY. ~ "> 



llcl rule-; g, the guide or bevilled block, and w, the work. 
A separate wooden block is necessarily required for every angle, 
and the parallel guide is still available in determining the general 
width or thickness of the works. 

\\lirn pieces arc parallel in one direction and bevilled in the 
other, they nmy be cut out without any waste beyond tha; 
from the passage of the saw. In such cases the work is prepared 
M a parallel piece equal in thickness to the parallel measure of 
the objects, and the work is turned over between every cut so a* 
to saw the pieces " heads and tails/' or the wide end of the one 
from the narrow end of the other, as shown by the dotted lines 
in fig. 739. This mode is employed for ivory knife-handles, and 
for the thin slips for covering the keys of pianofortes, which are 
made thicker in front, where the principal wear occurs. 

Triangles may be sawn out of parallel slips in a similar 
manner; thus, by using guides at the angle of forty-five degrees, 
and turning the work over each time, right-angled triangles, r, 
are produced exactly of one size; with sixty degrees, equilateral 
triangles, e, and so on for all others having two equal sides, a 
half triangle at each end being the only waste. In manufactories 
where large quantities of bevilled works are sawn, it is usual to 
employ a wooden bevil guide for every different angle required; 
both from motives of economy, and also to prevent the acci- 
dental misadjustmeut of variable guides; and sometimes the 
unchangeable guides are made in metal. 






9. Sauriny bevilled edges and oblique prisms ; or those in which 
the aiiyulur variations art in tlit vertical plane. In cutting pieces 
with bevilled edges, a supplementary bed of metal, the hinge of 
which is quite close upon the saw-platform and against the saw, 
is occasionally employed ; this may be set at all angles by a stay 
and binding-screw. But the more simple and usual plan is to 
employ supplementary wooden beds planed to the definite angles 
m-d, and through which beds, the saw is allowed to cut a 
thin kerf as usual. 

A i in pie of the use of inclined saw-beds is seen in 

the so-called mosaic works, consisting of groups either of 

nglcs, rhombuses, or of squares, cut in different coloured 

woods, and arranged so as to constitute various patterns, which 

it is proposed to distinguish as triangular mosaics and square 



764- MOSAIC WORKS IN WOOD. 

mosaics. Mr. James Burrowes, of Tonbridge Wells, informs the 
author that nearly every sort of wood is used, both English and 
foreign, and also many sap-woods, but principally holly and ebony 
for white and black ; and bar-wood, barberry, beech, cam-wood, 
cherry, deal, fustic, green ebony, king-wood, laurel, laburnum, 
lilac, mulberry, nutmeg, orange, partridge, plum, purple, ye\v, 
and walnut, for various colours. Mr. Burrowes adds, that he 
was the first to introduce this work in Tonbridge-ware turnery, 
boxes, and toys, although striped, feathered, and tesselated works 
somewhat of the same kind, were used long prior, in the band- 
ings and stringings of ornamental cabinet-work. 

For the triangular mosaics, beds of the angles of 45 and 22^- 
degrees are principally used, but others of 15, 30, 60, and 75 
degrees are also occasionally employed; they require guides for 
parallelism, either to be applied to the inclined beds themselves, 
or to be added to the parallel rule, with the power of adjustment 
vertically as well as horizontally ; very thin saws are used, and 
they project but little through the beds. 

Figs. 743. a 6 c 744. 




o <] < 




The wood is cut in pieces six or seven inches long, first into 
veneers of appropriate thickness, the formation of which into 
slender squares requires no explanation. Figure 743 shows 
that a bed of 45 degrees, will at one cut for each piece, convert 
the veneer into rhombuses figured separately at a, the acute 
angles of which measure 45, the obtuse 135 degrees each; and 
when the wood is turned over between each cut, right-angled 
triangles b, are produced, with the same bed. When, as in the 
dotted line fig. 743, the bed measures 22 degrees, and the work 
is also turned over, triangles are produced such as c, and from 
which three figures, a, b, c, almost all the work is compounded. 

Such of the pieces as are required to form the pattern, are 
selected and carefully arranged in groups on the bench: one 



MOSAIC WORKS IN WOOD. 



768 



man picks up a small group, brushes them over quickly with 
thin glue, and ha n to another workman, who dexterously 

arranges them in their required positions ; ami further quantities 
of the pieces are handed up by the first workman, until all that 
constitute the first glueing are arranged. The stick, or faggot, 
is then tightly bound with string, and before the last coils are 
-trained around the mass, any pieces which stand out beyond 
their true positions, arc rapped with the hammer along the side 
of the faggot. 

Genenilly, eight rhombuses, a, constitute the central group, as 
in fig. 7-H-, and the eii;ht angles are then filled up by ri_ht- 
angled triangles, b, thus producing an octagon, which is allowed 
to dry. At other times, the eight rhombuses, a, are combined 
for the central star, the hollow angles of which are filled in by 
eight squares, which themselves produce eight new angles, A B, 
fig. 745, each measuring 135 degrees. Sometimes each angle 



Fig. 745. 



746. 







A B, is filled by the obtuse angle of one rhombus, a, and this 
also produces an octagon. At other times, each angle, A' B', is 
filled by the three acute angles of three rhombuses, a, which 
together measure 135 degrees also (one group being striped, the 
others only dotted), and afterwards 16 right-angled triangles, b, 
complete a nearly eirenlar figure. The whole of the latter group 
would be combined at one glueing by dexterous workmen ; 
except when the squares or other pieces are themselves com- 
pounded of little bits, which is a preparatory process. 

The central octagon, fig. 744, when dry, is often surrounded 
by other sectional groups, as in fig. 746, either eight compounded 



766 MOSAIC \VORKS IN WOOD. 

triangles, such as c, with the new spaces filled by eight right- 
angles, b, to reconstitute the octagon, or else eight wedge-form 
pieces, d, are alone used. The edges of the sections are glued, 
and quickly placed around the octagonal nucleus, after which the 
whole is sometimes fixed between powerful clamps, or wedged 
within external rings ; at other times, string is again used to 
bring the parts together. 

The blocks, when finished, are allowed to dry for some weeks, 
and are ultimately cut into thin veneers, and glued upon round 
boxes. Octagons of different patterns are united side by side, 
and the spaces filled in with right-angled triangles, so as to con- 
stitute straight patterns for the centers and borders of rectangular 
boxes. Small round sticks are occasionally turned into little 
ornaments, and the curvilinear surfaces so obtained, present 
various pretty effects when the intersections are accurate. 

The compounded sections of the wooden mosaics are generally 
prepared beforehandof small triangles, as adistinctprocess, andare 
frequently screwed fast in cauls of their appropriate angles, or they 
are built up as laminated sheets, and cut into form with the saw. 

The chequered squares are prepared from slips of veneer one 
inch or more wide, so as to avoid handling the little squares, 
which could scarcely be tied up in true rectangular arrangement. 
The pieces of veneer are glued together, either white and black 
alternately, or in any arrangement that the pattern may require ; 
strips cut off the edges of the laminated pieces and reversed as 
at a, fig. 747, produce the chequered squares, cut obliquely and 
alternated they produce rhombuses b; and striped rhombuses c, 
triangles d, and squares, can be also readily obtained, and the 
author suggests that b, c, d, and similar pieces, should as in the 
diagrams, figs. 745 and 746, be mingled with the present patterns, 

a Fig. 747. f> c d 



many of which are much elaborated, principally from small 
triangles alone, without a sufficient regard to the general design 
or drawing of the figure. The author possesses however, a very 
good specimen of mosaic work composed almost entirely of 
triangles, which in a diameter of 3 inches, contains no less thnn 
808 separate pieces of wood, combined with very good effect. 



MOSAIC WORKS IN W- 7 ''7 

The square wood mosaics, called also Hrrlin mosaic*, from 
thoir assimilation to worsted works, arc more recent than the 
triangular. Figures of vases, animals, and running patterns, are 
composed entirely of little squares of various coloured woods, 
which are glued up like the chequered works. Supposing the 
iv pattern to constitute a rectangle composed of 20 squares 
in \\itiih, ami -'50 in length, 30 slips of veneers of appropriate 
colours and an i:i< li \vi.ie, are first glued together, and this is 
repeated 19 times, making one laminated block A, for every line 
of the figure. A veneer B, is then cut off from each of the 20 
blocks A ; and these striped veneers B, are glued side by side to 
constitute the group c, of 600 slender squares ; the thin leaves cut 
off from the end of this last constitute the mosaic pattern D. 

The accuracy of the work greatly depends on the exact simi- 
litude of the veneers as to thickness ; and as the blocks A, will 
each produce some 15 or 20 repetitions of B and c, the perse- 
vering care required in the formation of a single specimen, will 
also effect a vast extent of repetition of the same pattern or D. 

The small square mosaics for borders and other works are 
usually inlaid in slips of holly as running patterns, by aid of the 
buhl saw. Very large mosaics are usually made in 6, 9, or 12 
sections, glued up separately into squares, and then combined. 
One example, thus formed by Mr. Burrowes, represents the 
Prince of Wales's feathers, arms, and motto ; it measures 3 by 
2^ inches, and consists of between 8000 and 9000 squares ; the 
block was prepared in 12 sections, that were afterwards united.* 



From the researches of Winkclmann, Wilkinson, and others, there appears to 
be no doubt but that, 3300 years ngo, the ancient Egyptians were wonderfully 
successful in making mosaics of minute cylinders, squares, and filaments of glass, 
united by partial fusion ami pressure ; and that from the end of the mam, slices, 
about one-sixth of an inch thick, were cut off and polished, much the same as 
above described. 

Various specimens are referred to, in which the pictures are said to be very 
perfect sod exactly alike on opposite sides, showing them to run through ; the 
modo of construction is apparent, from the joinings being just visible in a strong 
light, and from the colours having in some places run into one another, from the 
partial excess of the brat employed in uniting them. 

The Egyptian* also appear to have made other mosaics, by cementing pieces of 
glass, stone, and gems on backgrounds, just the same sa nince practised by the 
ancient Romans, and by the artists of Italy and other countries in our own times. 
See Wilkinson's Manners and Customs of the Ancient Egyptians, 1885, Vol. iii. 
pages 9497, ftc. 



76S 



SAWiN'G PRISMATIC PIECES. 



Iii sawing the regular prisms of from 3 to 12 sides, it is neces- 
sary the inclined beds should meet the saw-plate, at the same 
angle as that at which the sides of the polygon meet, or their 
exterior angles. It is therefore proposed as an example for all 
prisms, to trace in fig. 748 the formation of the hexagon, or 
6-sided prism, from a round or irregular piece of wood, upon 
which, as a preparatory step, one plane surface has been cut in 
any manner, either by the saw or plane. The following table 
contains the several angles required. 



In regular prisms of . 3 


4 


5 6 


7 


8 


9 


10 11 


12 sides. 


Their external angles 1 , 
measure . . . . J 


90 


108 120 


128J 


135 


140 


144 147& 

i 


150 deg. 


The supplements to 1 
















the external angles, 
















or what they fall ) 120 


90 


72 60 


51? 


45 40 


36 32 


30 deg. 


short of 180 de- 














grees, are . . . J 















Referring to the above table it is seen the external angle 
of the hexagon is 120 degrees (represented by the dotted arc A), 

Figs. 748. 





O CO 



A 




d e f 9 

and that the supplement to the latter is 60 degrees, therefore 
the inclined bed should also meet the saw at an angle of 60 
degrees (represented by the dotted arc, B,) by means of this bed 
alone, the second side of the prism would be cut on the piece 
of wood. But in cutting the remaining four sides, it would be 
required to introduce some guide, to ensure the parallelism and 
equality in width of the sides ; and this is done by laying a second 
angle upon the first, also equal to the supplementary angle of 
60 degrees (represented by the dotted arc, C,). Then B, and C, 
which are of the same angle, together constitute a trough, and 
the width of the side of the trough near the saw, must be equal 
to the side of the required hexagon ; but the second piece C, is 
not adjusted to its position, until after the first two sides of the 
prism have been sawn. The angle of the inclined beds must be 
very exact ; as any error that may exist, becomes accumulated, 
or is six times multipled in producing a hexagon. 



SAU NTALLI \M) VERT1CAI.1 ^ . ?'' 



.iihir poly^o'.. :n <|iiently the angles alike, hut tin: 

sides dissimilar; thus it may be consult n d that in a, fig. 749, a 
parallel piece is added between the halves of the regular hexagon, 
whereas in b t a piece is abstract i -d, and in r, two of the sides dis- 
appear. These and the entire group, a to y t fig. 749, may be 
sawn with the bed B, fig. 748, of 60 degrees. 

It is most convenient, especially when many pieces are wanted, 
to prepare fora, a rectangular prism, and then to cut off the four 
dotted triangles at four cuts, leaving the stop *, in the same 
position throughout ; b may he treated in the same manner 
as fl, or else as in r, the two exterior cuts may be made on the 
edge of a wide piece of board, and then two interior cuts remove 
the rhombus c, and leave a hollow angle of 120 degrees, as 
explained by the dotted In 

The several inverted angles of the piece ff, may be also pro- 
duced in tliis manner by two cuts each; two of the cuts in ff, 
are however made on the horizontal table, and not the inclined 
bed, B. The inverted angles are convenient as troughs, to support 
prismatic pieces on their angles, instead of their surfaces. 

Pieces analogous to those, a to ff, may be cut on beds of any 
other angles; but when the prismatic pieces have dissimilar 
angles, unless they are complementary one to the other, separate 
inclined beds are generally required for every angle.* 



10. Sawinff geometrical solids and irregular pieces, or those in 
which the angular variations, are in both the horizontal and vertical 
planes. It is proposed to illustrate this part of the subject, by 
some remarks on the formation of various solids illustrative of 
geometry, and crystallography ; such as erect and oblique prisms, 
pyramids, double pyramids, the five regular solids or platonic 
bodies, (namely, 1st, the tetrahedron, 2nd, the hexahedron, 3rd, 
the octahedron, 1th, the dodecahedron, 5th, the icosahedron,) 
and some other polyhedra. And, although in the formation of 
tin- models of these solids, various modes are employed, those 
methods will be selected, in which all, or nearly all the work, 

It will to shown in the succeeding section that, in some cases, prismatic worka 
are mounted upon an axis, placed at various angles by a dividing plate, and 
then applied to the saw. And in the subsequent volumes, it will to likewise 
explained that most lathes for ornamental turning, possess very ready means'of 
producing, both iu wood and metal, an infinite variety of polygonal and polyhedral 
works, with great precision and smoothness. 

3 D 



770 SAWING PYRAMIDS. 

may be performed by the saw machine alone, independently of 
the various other means. 

The models above referred to, are generally made in sycamore, 
maple, or horse chesnut, and in the majority of cases, the wood 
is prepared as prisms, the sawing of which has been fully 
described. Sometimes, before the subsequent processes, the 
prisms are very carefully planed in angular beds, mostly so 
arranged, that the surface to be planed is horizontal. 

A long prismatic rod, carried to the saw at right angles, is 
readily cut into short erect prisms of various heights j and the 
same prisms, carried obliquely to the saw, become oblique prisms. 

For pyramids of 3 to 12 sides, long prisms should be first pre- 
pared also of 3 to 12 sides, the sections of which are exactly equal 
to the bases of the required pyramids. 

The prisms are usually cut into short pieces equal to the 
vertical height of the pyramids, and one guide-block suffices for 
making all pyramids the sides of which meet at the same angle. 
The ordinary guide or gage-block, is simply a piece of wood 
having at the end a rectangular and perpendicular notch BCD, 
fig. 755, which may be made at the saw machine by aid of 
the protractor. For pyramids, the sides of which meet at 60 
degrees, as in fig. 750, the side B C, of the notch in fig. 755, 
measures 30 degrees with the principal edge A B, of the guide; 
for pyramids of 40, 50, or 70, the angle of the guide is respec- 
tively 20, 25, and 35 degrees, or half the angles at which the 
sides meet. 

The side A B, of the guide is placed in contact with the 
parallel rule, and the short prism is placed in the nook, so that 
in every case the base of the prism rests against the face C D, 
and one of its sides, whatsoever their number, touches the vertical 
face B C; the parallel rule is then adjusted to direct the saw s s, 
through the dotted line proceeding from the apex to the base of 
the pyramid. One cut having been made, the guide and work 
are quickly withdrawn, the waste piece removed by the saw, is 
thrown away, and the block is shifted round until the succeeding 
face of the prism, (or so much of it as remains,) touches the face 
B C, and so on to the last face of the pyramid. 

Sometimes, as in fig. 751, a pyramid is cut at each end of a 
prism, the method is almost the same ; but the wood and guides 
are each longer, as in fig. 756. The square end of the prism is 



- \ U 1 M. 



l'\ H \MI1S. 



771 



placed against the stop, and the fir>t pyramid having been cut, 
piece is changed end fur end, and the process is repeated ; 
in cuttiiiu'tlic M-rond pyramid, tlie point of the first touches the 
stop, or a notch \n-.\\ be made in the stop to prevent the extreme 
point of tin- priMii from being bruised. 

\Vhen tin- pyramids meet base to base, as in fig. 752, 
other mi tiioiU are pursued, dependent on the parallelism of the 
opposite sides or angles of equal pyramids. Sometimes the 
prism is cut off to the exact length of the double pyramid ; and 
the first pyramid having been cut as shown in fig. 756, the 
second pyramid is produced as is fig. 753, by laying the sides of 
the first pyramid against the parallel rule, and placing a wedge 
beneath the point of the first pyramid, to support the axis of 
the piece horizontally. 



Fig. 750. 




A 755. 



7SU. C 



758. 



A much ea>ier and more accurate way of cutting the second 
pyramid, is suggested by the author in figs. 757 and 758. The 
prism is in all cases to be left longer than the two pyramids, 
the first of which is cut as in fig. 756. Then leaving all matters 
as before, for pyramids of 4, 6, or 8 sides, simply to remove the 
parallel guide sideways, so as to change the position of 756 
into 757, in order that the saw may enter the opposite side of 
the prism, at the base of the first pyramid, and proceed into the 
solid prism as far as its center. In a 4, 6, or 8-sided prism, the 
4, 6, or 8 cuts release the double pyramid in 757, from its hollow 
bed, or inverted pyramid, or that which is sometimes termed, by 

8 D 2 



77- SAWING MACLED OR TWISTED PYRAMIDS. 

mineralogists, its pseudo-morphous crystal. It is needful the 
saw should penetrate slightly beyond the apex, and the crystal 
will jump out of its bed when the last side is nearly cut through, 
leaving a, trifling excess on the last side, just at the point; but 
if the inverted cuts are extended much beyond the apex, the 
model will be released before the last side is completed. 

For double pyramids of 3, 5, or 7 sides, meeting base to base, 
as in fig. 752, the position of the saw in fig. 757, cannot be 
employed in cutting the second pyramid ; because in a pyramid 
with uneven sides, the saw then would enter at one of the angles 
instead of at one of the faces of the first pyramid. Conse- 
quently the angular guide, fig. 756, is changed end for end, as 
in fig. 758, and all the sawing is done on the same side of the 
axis of the prism. The position fig. 758, might be used for all 
second pyramids, whether of odd or even sides, but for the latter 
the guide fig. 757, is more conveniently placed. 

Sometimes, however, it is required that the face of one pyra- 
mid should meet the edge of the opposite, as in fig. 754, thus 
producing what is termed in mineralogy, a macled or twisted 
crystal. Macled double pyramids with 3, 5, or 7-sides, are cut 
by pursuing throughout the method prescribed for ordinary 
double pyramids with 4, 6, or 8 sides; namely, using the one 
guide, after the mode fig. 756 for the first, and after the mode 
fig. 757 for the second pyramid, and then with pyramids of 
uneven sides the required displacement is obtained. 

Macled double pyramids, with 4, 6, or 8 sides, require the face 
B C, of the first guide, fig. 757, to be perpendicular as in the 
reduced figure a 758, and the face B C, 757, for the second 
pyramid, to be inclined 22^, 30, or 45 degrees respectively, as 
at b, or half the supplement to the external angle of the respec- 
tive polygons. For macled hexagonal pyramids, the side B C, 
may continue perpendicular, provided that in sawing the second 
pyramid, the edges, and not the faces, of the 6-sided prism are 
placed against B C, fig. 757. 

Irregular prisms may be sawn into irregular pyramids, but 
certain corrections are sometimes required. Thus, the prism 
beneath fig. 759, which is more, and fig. 760, which is less than 
a regular hexagon, produce the irregular pyramids respectively 
annexed ; the sides of each of which meet on one base line. In 
the first pyramid, fig. 759, the plain ridge is equal to the central 



\ui\-. IRREGULAR PYRAMIDS. 






M added to the hexagon : in the second pyramid, li^'. '. 

ral face that corresponds to the narrow side of the* hexa- 
gon, terminates below the extreme point. The six faces mi^ht 
iu cither case be made to converge exactly to unr \> <\\\\, by 
employment of a second guide adapted to the irregular aide. 
Fig. 759. 780. 761. 703. 




A 



O o 




Irregular pyramids, having as in fig. 7G3, equal sides, but ////- 
equal angles, produce pyramids, that converge exactly to a point. 

Thus fig. 761 shows the result when the rhombic prism is cut 
into a pyramid, the bases of the sides also meet on one plane, 
and when the piece is released by cutting the inverted pyramid by 
the method shown in fig. 757, the solid that results is an irregular 
octahedron, the section of which is rhombic in both planes. 

To produce an irregular octagonal pyramid from a regular 
octagonal prism, a wedge is placed beneath the prism, as in 
fig. ? 62, which now represents the guide; the point of the wedge 
is to the left, in cutting the sides 1, 3, 5, 7, of the octagon, and 
the point of the wedge is to the right, in cutting the sides 2, I . 
6, 8. By thi> twisting of the axis, the regular prism yields an 
irregular pyramid of the section shown at fig. 763, and the 
departure of the latter from the true polygon, is shown by the 
angular space, between the true polygon, and the vertical face in 
fig. 702, which space represents the piece removed in vii 
of the subjacent wedge, the angle of the two being alike. 

\Vhen the inverted irregular pyramid is similarly cut, the line 
of junction of the two is in one plane when the more obtuse 
edges of both pyramids meet; but the line of junction becomes 
zig-zag or macled, \\hen the more obtuse angles of the one octa- 
gon meet the less obtuse of the other. 

thud pursued with the 1 or ii-sidcd prisms pro- 
duces similar results, subject, however, to certain displacements 
of the edges and point ., the modes of correcting which will 
ly manifest to those ho take up these matters 
practically. 



774 SA\VIXG THE TETRAHEDRON, HEXAHEDRON AND RHOMBOID. 

It is now proposed to show how, by pursuing the methods of 
cutting various pyramids, the five regular solids, and many 
others, can be obtained with the saw-machine. 

The tetrahedron, with 4 planes each an equilateral triangle, is 
cut from a regular triangular prism, inclined 19| degrees,* and 
it is best to cut it at the end of a long piece, as in fig. 756, and 
then to remove it by one cut of the saw at 90 degrees, which at 
any distance between the apex and base, produces the true 
tetrahedron. 

The hexahedron or cube, with 6 planes each a square, is cut 
off from a square prism held at 90 degrees; the length of the 
piece removed, must necessarily be the same as that of the 
sides of the prism. 

The regular hexahedron or cube, may be also viewed as two 
triangular pyramids, the faces of which are interposed or macled, 
or so placed, that the face of the one pyramid meets the angle 
of the opposite, as before explained in fig. 754. And pursuing 
this method, the cube may be sawn from a triangular prism by 
the positions figs. 756 and 757, provided the prism is inclined 
exactly 35 degrees to the saw.f The cube, when produced in 
this manner from the triangular prism, is however very small, as 
viewed diagonally, (and in which direction it is cut,) the cube 
appears as a hexagon, three angles of which touch the centers of 
the triangular prism. It is better to use the hexagonal prism, 
and to place its alternate sides, 1, 3, 5, successively upon the plat- 
form, both for the first and second processes, figs. 756 and 757; 
in which case the hexagonal outline of the cube, may be as large 
as the section of the hexagonal prism from which it is sawn. 

Any other inclination than 35 degrees produces an oblique 
hexahedron, or rhomboid, with six equal rhombic faces. For 
instance, the very dissimilar figures 764, 765, and 766, were 
cut from hexagonal prisms of the same size, and respectively as 
large as the prisms would permit. In fig. 764, which is an acute 
or elongated rhomboid, the angle at which the prism met the 
saw was 10 degrees; and in fig. 766, an obtuse or compressed 
rhomboid, the angle was 80 degrees. Viewed along the dotted 
line or through tlieir common axis, the three figures all appear 
as equal hexagons, and show the three pyramidal planes of each 
solid as equal rhombuses, as in the figure 767 ; but the axis of 

Mathematically, 19. 28'. 17". t Mathematically, 35. 15'. 52". 




AWIXO THE OCTAHEDRON 

about four time* as long as that of the cube, 705, the 
axis of 766 is only about one eighth as long as the cube, and its 
edge is acute like a knife. 

Figa. 74. W. 77. 




The octahedron, with 8 planes, each an equilateral triangle, 
may be viewed as a double square pyramid, cut off at an angle of 
35 J .* and is produced in that manner with very little 

clilliculty from a square prism. When the prism meets the saw 
at a smaller angle than 85J degrees, the octahedron is said to be 
acute or elongated ; and when the angle is greater, the octa- 
hedron is obtuse or compressed, as recently explained in regard 
to the rhomboids figs. 764 and 766. 

It has been considered unnecessary to represent the regular 
tetrahedron, hexahedron, and octahedron, which are simple, and 
fr.miliarly known; and the subsequent figures 76S to 771, of 
the dodecahedron, the icosahedron, and trapezohedron, are to be 
viewed as explanatory diagrams, and not as faithful representa- 
tions of these respective polyhedra. 

The dodecahedron, fig. 768, with 12 planes each an equilateral 
pentagon, may be viewed as frusta of two pentagonal pyramids, 
the sides of which are interposed or raacled, and the pyramids 
being truncated form the two remaining pentagons. The double 
5-sidrd pyramids, are first cut at the angle of 26| degrees,t and 
discontinuous!}', by means of the positions shown in figs. 756 and 
757, the sides of the pyramids will then be found to meet at 36, 
the angle made by the first and third sides of a pentagon. The 
outer plane is obtained by cutting off the point of the pyramid 
at right angles to the prism, and extending it by trial, until the 
terminal pentagon itself, and the 5 pentagons near it, become 
equilateral. The second pyramid, not having been cut so far as 
the c. -liter, the solid is now remove, 1 from its matrix or prism, by 
one cut at right angles to the prism, and so far removed from 

Mathematically 35*. 15'. 52"., or half the upplemnt to 109*. 28'. 16"., the 
angle at which the pyramidal plinea of the octahedron meet Soo Brooke'* 

illograpby, page 118. 
f Mathematically 26V 83'. 54". 



776 SAWING THE RHOMBIC DODECAHEDRON AND ICOSAHEDRON. 

the angles of the zig-zag line oil which the pyramids join, as the 
corresponding pentagon, at the outer end of the solid. 

The above, or the pentagonal dodecahedron, is also called the 
Platonic dodecahedron ; but there is another kind named the 
rhombic dodecahedron, which is more referred to by minera- 
logists. The rhombic dodecahedron, fig. 769, has 12 faces, each 
an equilateral rhombus, and may be viewed as a hexagonal prism 
with a shallow triangular pyramid at each end. 

The rhombic dodecahedron may be therefore sawn from the 
hexagonal prism, provided, that first three pyramidical planes are 
cut at the angle of 54f degrees,* and that the solid is then 
released from the prism, by three similar but inverted cuts on the 
intermediate angles of the hexagon, so much of the central prism 
being left, as will make six rhombuses equal to those terminating 
the original prism. 



Figs. 7 




V\ "./>' 

V 



The rhombic dodecahedron may be also viewed as a square 
prism terminating in two square pyramids cut off at an angle of 
45; but as these planes run on to the angles of the prism, it is 
needful the bed should be inclined 45 horizontally, for the 
pyramids, and also 45 vertically, for their displacement. 

The icosahedron, fig. 770, with 20 planes each an equilateral 
triangle, may be viewed as two obtuse pentagonal pyramids, 
united by frusta of two other pentagonal pyramids a to b, the 
sides of which are very acute and interposed. The icosahedron 
may be sawn from the pentagonal prism nearly in the manner of 

Mathematically, 54. 44'. 8". 



THE ICOs \lll Pllox \M. IKAPEZOHKDl: 

the 1 -irst guide is the au_'lo of 10} degrees,* and suitable 

itting the two central frusta. This guide is first employed as 
in tig. 750, antl then shifted as in fig. l'>7, the 1U cuts produce 
tin- 10 angles, each of 00, constituting the central zone of the 
figure. The extreme end of the piece is then sawn at five cuts 
on a bed of 52$ degrees,t so that the five planes of the outer 
pyramids constitute equilateral triangles exactly terminating on 
the line a, or on the sides of one series of five triangles, and the 
points of the other series, constituting the central zone of the 
solid. The icosaliedroii is removed from the prism by placing 
the guide block as in ~i->l , and cutting the second pentagonal 
pyramid, which similarly to the first, falls on the line b, and just 
meets both the sides and angles of the 10 central triangular 
faces ; when the work is accurately performed, every point is the 
center of a group of five equilateral triangles. 

The solid fig. 771, with 24- equal trapezoidal planes, may be 
viewed as two frusta of octagonal pyramids, joined base to base 
with continuous edges, and surmounted by two obtuse four-sided 
pyramids. This solid belongs rather to mineralogy than geometry, 
and occurs with various angles; its usual name is an icositessera- 
hedron ; but it has been sometimes termed a trapvzuhedron, from 
the shape of its faces : three of its varieties will be noticed. 1 u 
the first, the three quadrantal sections, namely, through A o E, 
through C o G, and through A B C D E F G H, are all regular 
octagons, and the angles of the solid are throughout alike; this 
variety may be therefore called the regular trapezohedron. In 
others the three sections are irregular octagons, and the alternate 
angles dissimilar ; these may be called irregular trapezohe<lra, 
and two of these varieties that occur in mineralogy are referred 
to in the annexed table. 

The reynlar Impezohedron may be sawn from the regular 
octangular prism, by means of two beds, one of them inclined in 
two directions. The first bed for the frusta of the two central 
pyramids, is inclined 21 degrees horizontally, or on the line B C, 
ii_'. 756. The second bed for the two exterior four-sided pyra- 
mids, is inclined .V. 1 decrees horizontally on the line B C, fig. ', 
and '2~2 ;eally, as at b, in the same group, in onh r 

to twist the prism on its axis, because the four terminal planes 
run on to the angle of the octagon. 

Mathwiuiittlly, 10*. 48'. 44". t lUthematioiJly, W. 37'. 21". 



773 



SAWING THE MIXERALOGICAL TRAPEZOHEDRA. 



The four planes of the terminal pyramid produce trapeziums, 
and which are increased, by trial, until they just equal the eight 
trapeziums formed by the partial obliteration of the central 
pyramidal faces. The second four-sided pyramid, which com- 
pletes and releases the solid, is merely an inversion of the first. 

The irregular or mineralogical trapezohedra, may be produced 
from the regular octangular prism, nearly in the manner just 
explained, by the employment of different angles, that are stated 
exactly in the annexed table, which shows the comparison of the 
three varieties of this solid selected for illustration.* 





Alternate angles of 
the solids. 


Beds for the central 
parts. 


Beds for the ter- 
minal parts. 




A. C. E. G. 


B. D. F. H. 


Hor.aiigles. 


Wedge. 


Hor. angles 


Vert, 
angles. 


Reg. Trapezohedron 


135. 0'. 
126. 52'. 
143. 8'. 


135. 0' 
143. 8'. 
126. 52'. 


20. 5V. 
24. 6'. 
17. 33'. 


none 
8. 8'. 
8. 8'. 


59. 38'. 
54. 44'. 
64. 46'. 


22. 30'. 
22. 30'. 
22. 30'. 







The table supposes the regular octangular prism to be in every 
case used, but to produce the irregular pyramid from the regular 
prism, requires the use of a wedge, as explained in page 773, and 
the angle of the wedge is half the difference between the two 
external angles of the prisms, which are simply the reverse one of 
the other. The wedge becomes unnecessary, if prisms are pre- 
pared, having the same irregular section that occurs in the second 
and third solids, and which is the preferable mode. If the lathe 
with revolving cutters and dividing plate is used for preparing 
the prisms, as hereafter recommended, instead of stopping the 
lathe at eight equal spaces, or taking 45 each time, the angles 
taken alternately, are the supplements to the two external angles 
of the prism, common to the second and third solids, namely 
53. 8'. and 30. 52'., which together are equal to 90. t When 

* The irregular trapezohedron, in another of its sections is a regular hexagon, as 
Fig. 772. illu>ti-ated by the figure 772; six of the trapeziums then con- 
stitute parts of tlie original prism, three trapeziums at an 
obtuse angle form the summit of the crystal, nnd three jmirs 
>f trapeziums are situated more acutely and intermediately, 
The trapezohedron might be therefore also worked from the 
hexagonal prism, by aid of two beds of the particular angles, 
one of them having a double inclination, 
t The angles for the dividing plate are consecutively as follows : 

153% 8'. 3143, 8'. 5233. 8'. 7323. 8'. 

2 90. 4180. 6270. 8360. 

Unless the lathe has an index with an adjusting screw, the 8' must in each case be 
neglected, but it is an admissible error. 




vl. REMARKS ON THE MODELS OF SOLIDS. ",',.> 

the wedge is thus dispensed with, the vertical angle 22. 30'., suit- 
able to the regular prism, becomes 18. 20'. for the second, and 
26. 3V. for the third solid in the tnhlc, or half the supplements. 



The order of procecdm- -ivc -\\, in reference to producing the 
various solids with the circular saw.namely, first tosaw the central 
parts of the solids, and then the terminal planes or pyramids, is 
in all cases advisable when only one or two solids of a kind are 
made, as the equality of the faces is then arrived at by two 
adjustments in place of four. The two central portions arc 
simply inversions one of the other, and necessarily agree without 
trial ; the central part thus produced, serves as the base from 
which to determine the two adjustments for the terminal parts. 

As however, every step of this process depends on the primary 
accuracy of the prism, which serves as the means both of guiding 
and holding the pieces whilst under formation, it is desirable, as 
regards the more complicated polyhedra, that those who possess 
the lathe with revolving cutters, for ornamental turning, should 
make, or at any rate finish the prisms therewith, which will 
thence acquire an unexceptionable degree of accuracy. The 
trouble of preparing the wooden prisms, may be entirely saved, 
if metal prisms of the several sections, each with a conical hole 
to serve as a driving chuck, are prepared. The pieces of wood 
for the solids are then roughly turned, as cylinders with conical 
stems, which arc driven into the prisms for their attachment. 
The metal prisms may be used for an indefinite number of pieces ; 
they save much trouble and uncertainty, and are especially 
desirable in the more complex polyhedra. 

There are other and very different ways of making the 
geometrical and crystallographical solids. Sometimes the wood 
is prepared with the plane alone, into prisms of unequal sides and 
angles, so arranged, that two or four of the sides of the solid, 
may be parts of the surfaces of the original prism, and that some 
of the edges of the solids may fall on the remaining faces of the 
prism. The plane is then used subsequently to the saw machine, 
in perfeetinir and smoothing all the fan 

The- Jo not admit ui'thesa: ili-ation or facility 

of method as that described, which the author believes to be 

mal, and that may be called the method of double pyramids ; 

and which he was led to work out practically to the extent set 



780 SAWING VARIOUS CRYSTALS AND SOLIDS THAT ARE 

forth, in order to show how much may be done by the saw-machine 
and various simple adjuncts. 

The author has now the pleasing duty to acknowledge the 
kindness of Professor Willis, who has examined the several 
details mathematically, and furnished the corrected angles that 
are given in the notes and table. 



Many crystals that occur in mineralogy are considered to be 
derived from the primary solids, especially from the tetrahedron, 
cube, octahedron, and the rhombic dodecahedron, by the oblitera- 
tion of some of their edges and angles in various ways ; or as it 
is said in mineralogy, the edges are bevilled or replaced, the points 
or angles are truncated. By way of general illustration of .the 
method of producing these secondary crystals from their prima- 
ries, a few of those derived from the cube are demonstrated by 
figs. 773 to 778, but numerous other crystals, from this and other 
primary solids, might be advanced. 

The cubes are first prepared as described on page 774, and 
their faces are rubbed smooth ; in cutting their edges and 
angles, beds similar to fig. 779 are required. The latter may be 
made entirely with the saw ; for example, the rectangular block 
is supported on the face A, and two incisions a b, each at 
45 degrees, are made by means of the saw and protractor ; then 
the piece being placed with B downwards, and with the face A, 
against the parallel rule, the perpendicular notch c, is sawn ; the 
three cuts release a piece of wood, leaving a cubical matrix. 



Figs. 773. 774. 775. 77<3. 777. 778. 




Fig. 773, the cube with bevilled edges, requires that the edges 
of the cube should be parallel with the saw, and the guide is then 
placed, as in fig. 781 ; that is, before the protractor, which is set at 
zero, and * is the stop for the quantity each of the 12 edges is 
bevilled or truncated. Cubes with two bevils or planes on each 
edge, may be bevilled with the position 781, provided the guide 
is tilted up some 20 degrees, by fixing a wedge of 20 degrees 



DERIVED FROM TIIK I in:. 781 

tin- ^uidr, as dottrel in fig. 779; or otherwise by making 
n similar bed, fig. 780, with the angles 25 and 65 instead of 45, 
which will make a rectangular notch, inclined 20 degrees, as iu 
fig. 780, so that the wedge may be dispciiM-d with. 



Fig. 779.^^ c 780.^- 







774, the cube with three bevilled planes at each angle of 
the cube, (one angle only being shown,) is obtained with the 
:ion of fig. 781; but the protractor is then set about 10 
degrees from 90, so as to cut off every edge of the cube by 
two cuts slightly inclined. The square face of the cube then 
becomes an octagon, if the facets meet as represented in dotted 
lines, or a dodecagon when the bevils do not meet. The bed, 
if also inclined vertically, as by the wedge in fig. 779, will 
duplicate the angular chamfers, and it is clear this elaboration 
may be carried systematically to any required extent. 

Fig. 775, in which the angles of the cube are truncated on 
the diagonal, require that the bed, fig. 781, should be placed at 
85J degrees,* and then the angles of the cube will be cut off 
nearly at 3 \ \ degrees to every plane, or at right angles to the 
diagonal, and this little facet, in like manner to the above, may 
be converted into three planes, somewhat after the manner of 
fig. 774, if so required. 

When, as in fig. 776, the angles of the cube are so far oblite- 
rated, that the eight little triangular planes exactly meet, the 
rube is converted into the cubo-octahedron, a solid having six 
square faces and eight triangular faces, the whole of which are 
equilateral ; one only of each is represented, to avoid confusion. 

By pursuing the last method a little further, so that the trian- 
gular faces encroach upon each other, they first produce a little 
ridge intermediate to the neighbouring facets, and carried to the 
proper extent, convert each of the triangular faces, in fig. 776 

Mathematically, 85*. 15'. 52*. the wine angle as that employed to produce the 
cube from the regular prism with 8 or 6 sides, by six pyramidal cuts ; and also 
the regular octahedron from the square prism. 



7S2 CONCLUDING REMARKS ON THE MODELS OF SOLIDS. 

into equilateral hexagons, in fig. 777 ; the six little square faces 
are all that remain of the original cube, and these squares are 
united by eight hexagons, all equilateral. The name of fig. 777 
when perfected, is the ex-octahedron, and which implies that this 
solid may be also obtained from the regular octahedron, by 
obliterating its six points, which develope the six squares, and 
the hexagons are then consequently parts of the octahedron. 

If, as in fig. 778, all the angles of the cube could be truncated 
by planes extending from angle to angle, the cube would descend ' 
to the octahedron. With the circular saw this is impracticable 
to the full extent, although some of the planes may be deve- 
loped ; but the mineralogist produces the octahedron from cubes 
of fluor spar, which splits diagonally from every point of the 
cube with great facility. 

"When the octahedron is produced by the cleavage of fluor, 
further reduction only makes a smaller octahedron, which form 
is thence described as the primary crystal of this mineral. In 
other minerals, the cube is the primary to the octahedron. 

It is expected that enough has been said to show that, with a 
little contrivance in the carrying out of the methods advanced, 
a vast number of even the most complex models of geometrical 
and crystallographical solids, with plane surfaces, may be pro- 
duced with comparative facility and great exactness, by the 
saw-machine; and the mechanical amateur will find it a some- 
what fascinating study, especially if he be likewise interested 
in geometry or crystallography. 

The circular saw should be rather stiff, and have fine teeth, 
as then the planes developed by the instrument will be tolerably 
smooth, and merely require to be rubbed slightly on a sheet 
of fine glass-paper, laid on a flat board or metallic surface; they 
are sometimes cleaned off on a wooden face wheel, on which 
powdered glass or flint is glued after the manner of glass-paper. 

In concluding this section, the author begs to add that the 
whole of the various works described, subsequently to page 766, 
may be executed by the amateur with the machine represented 
on that page, aided by the simple additions described. The 
remainder of the chapter refers to larger sawing machinery, 
principally used by manufacturers. 



CIRCULAR SAWS FOR LARGE WORKS. 733 

SECT. VI. COMMON APPM- \Ilu\s Of CIRCULAR SAWS 
TO LARGE WORKS. 

Iii the present section, it is proposed to devribp the principal 

,-s of con i in large circular nwing-benchet, such ns 

in general driven by steam power, and used for various 

manufacturing purposes. Sonic remarks are first offered on the 

conditions and proportions of the circular saws themselves and 

the subsequent matter is arranged under the sub-divisions 

employed in the last section and enumerated on page 7 

1. Conditions and proportions of circular saws. It appears to 
be uncalled tor to enter into particulars on the manufacture of 
circular saws, especially after the remarks already offered (pages 
683 698 of this Volume,) on the modes of constructing, sharpen- 
ing, and setting rectilinear saws, as the methods are nearly 
similar for both kinds; and some remarks on the circular saw in 
particular, are given on the first and last of the pages quoted. 

As regards the methods of hammering and blocking circular 
saws, to give them the right degree of flatness and tension, a 
point of considerable importance, the reader is referred to the 
section, " On the principles and practice of flattening thin plates 
of metal with the hammer/' (vol. i., p. 414 422,) and particularly 
to the remark, (p. 419 20,) on the propriety of keeping the edge 
of the saw " rather tight or small " prior to its being set to work. 
So that the heat communicated to the edge in the course of 
work may, by stretching the edge, render the blade tense alike 
throughout ; whereas had the saw been at first rather large or 
loose on the edge, the expansion at that part would render it 
so loose or flaccid on the edge, as to cause it to vibrate when 
at work, which is a great di>advantage. 

The teeth of both circular and rectilinear saws have been 
considered at some length, both as regards their outlines, (pages 
683 6K7,) and in respect to the modes of sharpening and setting 
them (pages 688 698), but on the whole it may be said that the 
teeth of circular saws are more distant, more inclined, and more 
let, than those of rectilinear sa\\s. 

The teeth of circular saws are more distant than those of straight 

<, because their jri iocity causes the teeth to follow in 

such rapid succession, that their elleet is almost continuous; the 

distance is carried to the extreme in Mr. R. Eastman's circular saw, 



784 



TABLE OF THE DIMENSIONS OF CIRCULAR SAWS. 

Tlit columns, " Gage of Plate," refer to the Birmingham sheet-iron gage : for the 
comparison of which, tcith ordinary linear measure, see Appendix, page 1013. 

The columns, " Form of Tooth," refer to the diagrams on page 684. 

The columns, " Revolutions per Minute" and "Horses' Power," required for the 
maximum of effect, are from the expedience of Mr. Ovid Topham, Engineer. 



(1.) SINGLE PLATES OF EQUAL THICKNESS THROUGHOUT. 


Generally called Bench Saws, and used either for'tbick or thin Wood. 
Intermediate sizes used, and also thick Saws for cutting Grooves. 


Diameter. 


Gage of Plate. 


Form of Tooth. 


Space of Tooth. 


Revolutions Horses' 
per Minute. Power. 


2 inch 
3 
4 
6 
9 
12 
15 
18 
24 
36 
48 
60 


23 to 28 
21 27 
20 26 
19 24 
17 22 
15 21 
14 20 
13 18 
12 16 
10 14 
8 12 
69 


644 to 646 
644 to 653 


^ to ^fein. 

5 
IB S 

A - i - 

i - f- 

s i 

i a 

4 4 

~ 1' ~ 

I 5 2 2 
H - 3 - 
2 4 


2000 
1800 
1600 
1400 
1200 
1100 1 
1000 1J 
900 2 
750 2 
500 3 
393 3J 
330 4 


(2.) SINGLE PLATES BEVILLED ON THE EDGE. 


Generally called Bevilled Saws, and used for Veneers. 
The largest, medium, and smallest of the ordinary sizes alone are given. 


Diameter. 


Width of Gage of Gage of 
BeviK Plate. Edge. 


Form of Space of Revs, per Horses' 
Tooth. Tooth. Minute. Power. 


8 inches 
22 
36 


2 to 3 in. 12 to 15 22 to 28 
3 - 5 - 10 - 13 20 - 25 
4 - 6 . 8 - 11 18 - 22 


644 or 645 | to J in. 1300 
j 5 - 800 1 
- - i - f - 550 2 


(3.) SEGMENTS FIXED TO A DISK, AND BEVILLED ON THE EDGES. 


Generally called Segment or Veneer Saws, and used for Veneers and thin Wood. 
The largest, medium, and smallest of the ordinary sizes alone are given. 


Dia- ^- of Width of 
meter - mente. **gm e ut*. 


Width of Gage of 
Bevil. Plate. 


Gage of Form of 
Edge. Tooth. 


Space of R ^f Horses' 

* tb - EL Power - 


5ft 10tol5 5 to Sin. 
12- 15-2054- 9- 
18- 20-306 -10- 


2 to34in. Iltol2 

24-44- 10-11 

3 -5 - 9-10 


24to28 644or645 
22-26 
20-24 


'. t . > .| in. 320 3 
130 5 
I - f - 85 6 



Bench saws, below about oiie foot diameter, are usually mounted on spindles 
running on conical steel centers, and driven by catgut bands ; those above one 
foot on spindles running in cylindrical brass bearings, and driven by leather straps. 

Compared with the diameter of the saw, and speaking generally, the hole or eye 
may be considered to measure from J to T ^ part of the diameter ; that of the flange 
of the spindle, from J to J part of the diameter ; of the pulley for leather straps, 
about | ; and for the catgut, } the diameter of the saw. 

The velocity of the edge of the saw varies from about 4500 feet to 5000 feet per 
minute; and the greatest thickness of work done can scarcely exceed | the diameter 
of the saw, and is generally below J the diameter. 



CIRCULAR SAWS FOR LARGE WORKS. 7S5 

!i only eight sectional teeth (see fig. 791, p. 797). The 

ular saws are more inclined, because such teeth cut 

more keenly, and the additional power they require is readily 

applied, by the great velocity and momentum that may be 

n to circular saws. The teeth of circular saws are more set, 
to make a wider kerf, which is required, because the large 
circular plate can neither he made nor retained, so true as the 
narrow straight blade. The general proportions of circular saws 
are given in the annexed table. 

It is generally politic, to use for any given work, a saw of as 
small diameter as circumstances will fairly allow, as the resist- 
ance, the surface-friction, and also the waste from the thickness, 
rapidly increase with the diameter of the saw. But on the other 
hand, if the saw is so small as to be nearly or quite buried in the 
work, the saw-plate becomes heated, the free escape of the dust 
is prevented, and the rapidity of the sawing is diminished. 

Hassenfratz, Emy, and other French writers on carpentry, 
have described the mode of cutting thick logs of timber, as in 
fig. 782, by means of two comparatively small saws, each extend- 
ing alone to the center of the log. The saws are in the same plane, 
but one above and the other below the log, and a little removed 

Lto avoid the contact of their teeth ; but from the reasons above 
stated, and some others, the plan is but rarely if at all adopted. 
Fig* 782. 78S. 




: 






I'nder iiHt cimim-tanee.s, it is \)e&t to employ that part of 
the saw which is nearest to the center, and it may be stated 
generally that, as in fig. 783, the diameter of saw *, should 
be about four times the average thickness of the wood w, and 
that the flange on the spindle, should be as nearly as prac- 
ticable flush with the saw table or platform p p. 

1 dit ion to various other particulars in the table on circular 
saws, an attempt has been made to tabulate the velocities proper 
for different Haws, and the amount of power severally required, 
but , iibei. s must be received with some latitude, because 

3 E 



786 CIRCULAR SAWS FOR LARGE WORKS. 

they are very much influenced by accidental circumstances. 
Amongst these are the particular quality of the wood or other 
material, as to its hardness and grain, its greater or less freedom 
from moisture, or from gummy or resinous matters, also its 
magnitude, and the degree of smoothness desired in the surfaces 
left by the saw; all these circumstances demand certain variations 
in the porportions and conditions of the saws used. A few words 
will be therefore added respecting each of these conditions. 

The harder the wood, the smaller and more upright should be 
the teeth, and the less the velocity of the saw ; hence it follows 
that the rate of sawing is proportionally slow. 

In cutting with the grain, or lengthways through the fibres, 
the teeth should be coarse and inclined, and the speed moderate, 
so as rather to cut the removed wood into shreds than to grind 
it into powder ; as the more minute the sawdust, the greater 
the power that must be expended in its production. 

In cutting across the grain, the teeth should be finer and 
more upright, and the velocity should be greater than in the 
last case ; so that each fibre of the wood may be cut by the 
passage of some few of the consecutive teeth, rather than be 
torn asunder by one tooth only. 

Wet wood is softer than dry, and is therefore more easily cut, 
but the saw is required to be keener and more coarsely set ; the 
waste is consequently greater. 

For gummy or resinous materials, and for ivory, the saw teeth 
are required to be very keen, and the velocity comparatively 
slow, to avoid the dust becoming softened and rendered adhesive, 
as it will then stick to the blade. This disposition is lessened 
by lubricating the saw either with a tallow candle, solid tallow, 
lard, or oil applied with a brush. 

When the object is to get through as much work as possible, 
the rapidity with which the wood is then advanced, will prevent 
regularity in its progress, and consequently likewise in the saw 
marks on the wood. The saw is then liable to be overloaded; 
if so, it vibrates rapidly sideways with great noise, requires 
greater force, but nevertheless proceeds through the wood 
.slowly and leaves it full of coarse ripple marks. 

Smooth sawing requires the work to be regularly advanced 
towards the saw, and the latter must be keen and very uniformly 
set; as one tooth projecting beyond the general line, is sufficient 



IP1NOLM i'>R LARGE CIRCt'LAR BAWi. 



787 



to score or scratch the work. It is a proof that the saw wns in 
most excellent onlt-r ami well applied, when the portion cut in 
every revolution of the saw, cannot be detected by the c 
marks left on the wood or other material. 



taws exceedm;/ nlxmt one foul diameter. 
Saws of this magnitude are seldom used on spindles mounted 
In 'tween pointed centers, as represented on page 754, but on 
those resembling the sections figs. 784 and 785. These spindles 
revolve in hearings or brasses b b, made in halves, and secun ly 
united to the stationary framework of the saw bench. The end- 
play, or end-long motion of the spindle, is usually prevented 
alone by the two collars or projections c c, which embrace the 
one bearing; sometimes, however, the one collar c', fig. 7t>5, is 
screwed on the spindle to admit of adjustment, and has a side- 
screw to retain its position ; or else the collar c', is in the solid, 
as usual, and a fixed screw *, exterior to the pulley, is made to 
bear on the end of the spindle. 

Each spindle has a wooden or iron pulley of about one-third 
the diameter of the saw, for the driving strap, but in mills driven 
by power, a fast and a loose pulley of equal diameter are placed 
on each spindle, as in fig. 786, so that the spindle may be dis- 
connected with the engine by throwing the strap on the host, 
free, or lire pull. 




Saws below about 20 inches diameter, are commonly held like 
those previously described, between the fiat surfaces of the collar 
or projection r, that is forged in the solid with the spindle, and 
the surface of the loose collar or washer u>, as in fig. 7S4 ; one 

3 E 2 



788 BENCHES, PLATFORMS AND STOPS, FOR 

steady pin then suffices, and which is fixed near the periphery 
of the flange. Large saws require flanges, say from 5 to 10 
inches diameter, and which are then added to the spindle, as in 
fig. 785; the one is fixed by a feather or parallel key, and car- 
ries three steady pins ; all the steady pins are represented black 
in the figures. 

The loose flange is sometimes pressed up by only one screwed 
nut n, but it is preferable to have two, of different threads, that 
the second may prevent the first from being accidentally loosened; 
as the two then unwind at different rates, and check each other's 
motion. Either the one nut is right and the other left-handed, 
as in Collinge's patent axletrees, or else both nuts have right- 
handed threads, which differ in pitch as well as diameter. 



3. Benches and platforms for large circular saws. These are 
in general framed together very strongly in wood, in the ordi- 
nary manner of carpentry; they measure from about 4 to 12 
feet long, 2^ to 4 feet wide, and 2^ to 3 feet high. The bear- 
ings for the saw are placed close beneath the platform, and at 
about the middle of its length ; the central part of the bench is 
represented in plan in fig. 786. 

To arrive at the saw spindle for the purpose of changing the 
saw, there is frequently inlaid in the platform a rectangular 
frame of cast iron with a rebate on the inner edge, fitted with a 
loose iron panel in two pieces to form the cleft for the saw. The 
panel is supposed to be removed to show the nuts and stops for 
the saw, and before the saw can be changed, it is also needful 
to lift out the wooden bar, which lies across the end of the 
spindle and against the saw; the bar is added for the purpose 
of carrying the stops * *, to be explained. 

Sometimes the bench is nearly covered with plates of iron to 
lessen the friction of the timber upon it ; and in benches for 
heavy work, the half of the platform in front of the saw is occa- 
sionally made as a slide, with a rack, pinion and winch handle, 
by which it is moved endlong. The work is in such cases placed 
against a ledge or cross piece on the slide, and is carried to the 
saw with great facility. A few saw benches, for some specific 
kinds of work, are constructed entirely in iron. 



4. Stops to prevent the vibration of large saws. These are in 



I.AIUJK CIIUII.MI 



MM MINES. 



781 



many cases inl-iid in the wooden bed of the machine, beneath 
tin- nun plate l>y which access is obtained to the saw, as shown 
in tig. 786. The two grooves * , nearest the periphery of the 
saw, are in some instances each entirely Tilled with a block of 
hard wood, kept in position by the top plate, and set forward 
from time to time by pieces of card or veneer placed behind 
them, to compensate for the portion worn away by the saw. At 
other times, the grooves are fitted with blocks of wood or metal, 
which have mortises for fixing screws, as shown on a larger 
scale at *' *' ; these admit of adjustment and fixation. Screwed 
holes are also used, especially in the iron framings, cylindrical 
wooden plugs from f to f inch diameter are then screwed into 
the holes and set forward to meet the saw. 







Large saw machines have sometimes wedge-form pockets 
beside the saw plate, which are filled with greasy hemp ; the 
downward motion of the saw carries the hemp into the narrow 
part of the pocket, and pressing it against the saw, checks the 
vibration. This method, although it causes more friction, is 
nevertheless much approved of, as the elasticity of the packing 
enables the saw to be at all times closely gripped ; which on 
account of its small irregularities, cannot be the case when rigid 
metallic or wood stops are used; but hemp is less suitable than 
wood for small saws. Frequently the stops are applied to both 
the front and back edges of large saws, as shown in the figure. 



790 PARALLEL GUIDES FOR LARGE CIRCULAR SAWS. 

5. Parallel Guides for circular saws. The parallel guide 
mostly added to large saw benches, closely resembles the ordi- 
nary parallel rule used for drawing, as will be seen on the 
inspection of fig. 786. The principle requires that the four 
centers of the parallel rule should constitute the four angles of a 
parallelogram, or that the four sides should be exactly two pairs, 
with which view the two radius bars are clamped together and 
drilled as a solid bar, and so likewise are the long bars. Unless 
the centers or pins fit accurately, it will be found that when 
the bars lie very obliquely, that the front bar or fence will 
have a rolling motion, as on a center, instead of being firm and 
parallel. 

In some few cases the long metal bars are dispensed with ; 
iron ears or plates, for two of the centers are then fixed to the 
wooden fence or rail, and the back centers are similarly attached 
to the platform itself, through which a circular mortise, parallel 
with the paths of the radius bars, is sometimes made for the 
clamping screw that fixes the rule. It is, however, better the 
rule should be constructed as in the figure 786, and quite inde- 
pendently of the platform, to admit of ready detachment. The 
long back rod is then essential, and also a fixing bar, placed as 
a chord to the arc described by the radius bars, and retained by 
a screw and nut passing through a mortise in the bar. 

In the above construction, the long fence moves in an arc, 
like those described by the radius bars, and shown by the dotted 
lines, but the three-bar parallel rule is sometimes employed, 
because it may be opened in a right line, and therefore moves 
simply sideways to the saw ; its path is directed by a pin in the 
long bar or fence, which enters a straight groove made trans- 
versely in the platform. The construction of the three-bar 
parallel rule is nearly a duplication of the former, and as it is 
equally important that the centers of the similar parts should 
be equidistant, the four radius bars are drilled together, to 
ensure their similitude, and so are also the three long bars. 
In the two and three-bar parallel rules, two slit clamping bars 
are occasionally used, which entirely restrain any wriggle, as 
they secure both ends of the fence ; the perpendicular height 
of which varies from two to ten inches, according to the nature 
of the work to be sawn. 



RAWING THE 8IDK8 Of RECTANOUI \K MICE*. 

6. Sairiny the tides qf rectanffular pifCff. In both small and 
sawing machines, the work. i < applied much in the snme 
manner ; hut in saw-mills two individuals are commonly em- 
ployed, one to hand np and thrust forward the work, and another 
to assist by dragging and afterwards removing the work from tin; 
bench. \Yhen the pieces are short, the person who pulls com- 
monly uses a tomahawk, \\ hich is like the half of a small pickaxe, 
tin* point of which is struck into the wood to serve as a handle. 

When a log or round piece of wood is applied by the hands 
alone to the circular saw, it is difficult to get the first cut exactly 
true, ns the wood is apt to roll on the two or three points at 
which it may touch the platform ; but when the saw has pene- 
trated a little way, the blade itself materially assists the holding 
of the work. One cut having been made, the flat side is placed 
downwards, and a second cut is made from either of the ed_ 
and provided the first side is moderately true, the second will 
become at right angles to the first; the third and fourth sides 
will he found to present no difficulty. 

As a ready means of adapting the parallel guide to works of 
different widths, a parallel piece of wood is often placed along- 
side the object to be sawn. Thus in cutting the blocks for 
wood-paving, the round larch timber is first cut into pieces 
about 3 feet 6 inches long, and these are, for the most part, 
sawn into pieces six inches square; but should any of them fail 
to hold that size, a parallel board half an inch thick, is placed 
alongside the work, which is then reduced to the next following 
size, or 5 inches square. And in the same manner, pieces of 
two dimensions, as of 2 by 1 inch in section, are in some cases 
cut by setting the parallel rule to 2 inches, and packing the 
work the thin way, with a piece 1 inch thick.* 



In reality, the standard size of the squared timber for the blocks of the 
Metropolitan Wood-Paving Company, is 54 by 6 inches ; but the round logs are 
cut as large as they will respectively hold, the one measure being always half an 
inch more than the other. The wood is used very soon after it is felled, and is 
so wet, that the men find it needful to suspend a board over the saw and at right 
angles to it ; this arrests the saw-dust, which if allowed to drive against the 
attendant, soon wets him to the skin. 

In some wood-cutting proems*, a screen of wire-game is placed between the 
work and the workman, that he may be enabled closely to watch the operation 
without risk of the shavings entering his eyes. 



702 LARGE CIRCULAR SAAV MACHINES FOR SPECIFIC WORKS. 

SECT. VII. LESS COMMON OR SPECIFIC APPLICATIONS OF 

CIRCULAR SAWS TO LARGE WORKS. 

It may be considered that in the last section, the remarks on 
the structure and use of the circular saw-bench, were concluded, 
so far as concerns its ordinary application to the conversion of 
timber into scantling, or squared pieces of various sizes. But 
it still remains to notice, in continuation, some of the miscella- 
neous and large applications of circular saws, which so far as 
admissible, will be introduced in the order formerly adopted, as 
the subdivisions 7, 8, 9, and 10, will be repeated, to which will 
be added the sawing of curvilinear works, and some other less 
classifiable matters. 

Part of the contrivances for these works, are merely additions 
to the ordinary saw-bench, others are machines expressly con- 
structed for their respective purposes ; but to save unnecessary 
subdivision, they will be collectively and briefly noticed ; as the 
principles rather than the mechanical details will be advanced, 
together with references to such published descriptions of them 
as have come under the author's notice. Two contrivances for 
obtaining an accurate base to work from, in pieces not originally 
straight, will be first referred to. 

The late Mr. Smart, in obtaining the first true side in irregular 
pieces three or four feet long, intended for the staves of casks, 
attached the pieces to an external fence or guide. The wood 
was grasped by its extremities, somewhat as between the centers 
of a lathe, in a kind of trough made of two boards united at 
right angles ; one end of the trough had a solid block of wood, 
that could be fixed at variable distances ; the other end had an 
iron bar, roughened at its extremity, and brought up by a rack 
and pinion, so as to stick into the ends of the wood, the grasp 
being secured by a ratchet. 

The trough was considerably longer than the length of the 
wood to be sawn, and two studs projected from its extremities 
beyond the side of the work. These projections were made 
to rub against the face of the parallel rule, and avoiding the 
saw, to direct the cut exactly in a right line, and produce, 
on the irregular wood, one flat surface that might serve as 
the base for the subsequent operations.* The same end is 

* See Trans. Soc. of Arts, Vol. 47, plate 8. 



CIRi I I 

iliflPmmawi 



CIRCULAR SAW M \ in s KS FOR GROOVES, RKBATKS AND TENONS. 793 

differently obtained, and on larger pieces of timber, in the 
following method. 

In the Ravensbourne wood-cutting mills at Deptford, battens 
10 or 12 feet long, and intended to be sawn and plain 
flooring-boards, are grasped by their upper and lower edges, and 
without strain, by screw-teeth or dogs built out from a carriage 
which runs in V bearings; tbe slide is carried by a self-acting 
rack and pinion movement, past a circular saw revolving in a 
vertical plane, which skims the side of the batten, and leaves it 
as straight as the V slide itself. The traversing carriage or drag 
of this machine, is closely analogous to that of the veneer saw 
to be hereafter noticed. 






7. Sawing grooves, rebate*, and tenon*. These works may be 
accomplished in the large way, in the modes already described 
on page 761. The flooring boards of the warehouses in the St. 
Katherine's Docks, London, were grooved on each edge upon 
an ordinary saw-bench, for the reception of strips of hoop-iron 
used as tongues to prevent dust falling through the joints; and 
the frames for doors are occasionally grooved for the panels in the 
same manner, but with thick saws. The still wider rectangular 
grooves in the blocks for wood pavement, are cut out with 
two ordinary saws on the same spindle, having two or more 
intermediate chisels, to cut the bulk of the removed wood into 
chips. 

The mortises in the shells of ships' blocks, for the reception 
of the sheaves, are cut by small double circular saws ; a hole is 
first bored through the shell at each end of the mortise, and the 
saws are then made to penetrate from each side, and nearly 
complete the mortise, in a less expensive manner than with the 
mortising engines in Portsmouth Dockyard. 

The squares or tenons of the steel pins for harps, by which the 
strings are tuned are also cut by means of two thick saws, sepa- 
rated to the extent of the side of the square; the pin is presented 
twice to the saws, the second position being at right angles to 
the first. The equality in size of the squares is also ensured by 
this method, so that they all fit the same tuning key. 

Rebates may of course be cut upon the ordinary saw bench 
at two processes, as before explained, but they are also made by 
two saws mounted on separate spindles, and placed in the exact 



794 SAWING TENONS AND COMBS; COMB MACHINE. 

directions of the two cuts required ; one saw spindle is a little 
before the other, to avoid the contact of the teeth. The angular 
grooves or rebates in the blocks for wood pavement, are thus 
made at one operation, in a machine with two saws at right 
angles to each other. 

The combination of two saw spindles was first employed by 
the late Mr. Smart, in cutting the tenons for the construction 
of his patent hollow mast. The small pieces of wood were first 
squared on all sides to the proper measures, each small block 
was then rebated, first on the one angle, it was then turned 
over, and the formation of the second rebate completed the tenon. 
Another part of the same machine carried a mandrel and center 
bit, so that by the aid of a guide, the holes in the tenons could 
be also made exactly true and alike.* 

Two saws mounted on the same spindle are used in cutting the 
teeth of combs, which may be considered a species of grooving 
process. One saw is in this case larger in diameter than the 
other, and cuts one tooth to its full depth, whilst the smaller saw, 
separated by a washer as thick as the required teeth, cuts the 
succeeding tooth part way down, on the same principle as in the 
stadda, and rack saws, figs. 703 to 706, page 723. 

A few years back, Messrs. Pow and Lyue invented an inge- 
nious machine for sawing box wood and ivory combs. The 
plate of ivory or box wood, is fixed in a clamp suspended on two 
pivots parallel with the saw spindle, which has only one saw. By 
the revolution of the handle, a cam first depresses the ivory on 
the revolving saw, cuts one notch, and quickly raises it again ; 
the handle in completing its circuit, shifts the slide that carries 
the suspended clamp to the right, by means of a screw aud 
ratchet movement. The teeth are cut with great exactness, and 
as quickly as the handle can be turned ; they vary from about 
30 to SO teeth in the inch, and such is the delicacy of some of 
the saws, that even 100 teeth may be cut in one inch of ivory; 
the saw runs through a cleft in a small piece of ivory, fixed ver- 
tically and radially to the saw, to act as the ordinary stops, and 
prevent its flexure or displacement sideways. Two combs are 
usually laid one over the other and cut at once; occasionally the 
machine has two saws, and cuts four combs at once. 

* See Gregory's Mechanics, 1807, Vol. II, pige 328, plate 2G. 



i I \R SAW M \( MINKS FOB CROSS-CUT! 7M 

8. Sawing or cro**-cutting the end* of piece*, either *quare or 
bevillfd; or those in which the angular variation* are in the hori- 
zontal plane. The saw-bench is not much employed in cross- 
cutting tlu- ends of long timber for the general purposes of 
lit iy ; but short pieces are sometimes guided to the saw, as 
in the small machines, by the intervention of either a wooden 
square or bevil, the one edge of which rests against the parallel 
rule, the other thrusts forward the work. In cutting the square 
scantling for wood pavement into oblique prisms, a wooden 
slide is sometimes added to the saw-bench, with a trough exactly 
at the required angle, and in this case, as well as the last, the 
parallel rule serves as the guide for the length of the blocks. 

The Metropolitan Wood- Paving Company employ for this pur- 
pose, an iron machine which has a slide running in V bearings 
or angular grooves, planed in the bed of the machine and parallel 
with the saw : the cast-iron slide is constructed to serve as the 
inclined trough to receive the squared wood, and has an adjust- 
able stop to determine the length of the blocks.* 

The three following diagrams are intended to show the prin- 
ciples of different circular saw machines for cross-cutting; the 
wood is shaded in each of the examples, and the arrows denote 
the movements for following up the cuts of the revolving saws. 

In cross-cutting the round logs of lignum vitae for the sheaves 
of ship blocks, Messrs. Esdailes use a wooden saw-bench, the 
sliding platform of which is inclined, and has at its lower end a 
perpendicular rail, as in fig. 787. The log of wood is laid in the 
nook, and the entire platform is then thrust by the hands past 
the saw, which revolves on a fixed axis as usual, and thus the 
log is sliced into pieces, their thickness being determined by a 
wooden stop ; but it is necessary, in this machine, that the saw 
should have rather more than twice the diameter of the log. 

In the block machinery at Portsmouth, a somewhat elaborate 
machine is used for the same purpose, which is so constructed 
that the saw *, need only be large enough to penetrate to the 

* The angle specified in the Count de LiUSt Patent u 6J* 2G' 6% every block is 
afterward* chamfered on three edges, grooved on the face, and drilled with four 
holes for the dowels, in appropriate machines, nearly the whole of which are con- 
structed in iron and driven by two steam-engines, each of twelve hones' power. 
The thirteen various machines, are managed by sixteen men and fifteen boys, and 
in one week of seventy-two working hours, produce on the average 80,000 blocks, 
or 800 square yar.ls of paving. 



796 



CIRCULAR SAW MACHINES FOR CROSS-CUTTING. 



center of the log, as explained in fig. 788. A short log of 
lignum vitae is mounted on a kind of lathe mandrel ; the saw 
spindle is then traversed sideways until the teeth cut to the center 
of the wood, and the mandrel is afterwards rotated once on its 
axis by a wheel and pinion, to extend the cut around the log. 
One slice having been removed, the saw is withdrawn sideways 
to the dotted position s', and the mandrel and wood are set for- 
ward through the collars, as much as the thickness of the sheave, 
by a screw at the back of the mandrel, preparatory to the next 
slice being removed. 

Figs. 787. 788. 789. 








Another cross-cutting machine, after the manner of fig. 789, 
and also contrived with a view of using a saw for work of nearly 
its own diameter, is used at Portsmouth, for cross-cutting the 
butts of round elm timber, into short pieces used for the wooden 
shells of the blocks. In this latter case, the timber is fixed hori- 
zontally and immoveably, and the saw is carried in one plane, first 
down the one side of the timber and then the other. To accom- 
plish this, the saw spindle is mounted at the end of a double 
swing frame, near the centers of which are placed guide pulleys, 
for the strap that connects the saw with the steam-engine. The 
parts of the wooden swing frame, are double and strongly braced 
with iron bars, and the angular movements of the frame are 
governed by racks and pinions, but the various details are alto- 
gether omitted in the diagram.* 



9. Sawing devilled edges and prismatic pieces; or those works in 
which the angular variations are in the vertical plane. The most 

* The two machines, figs. 788 and 789, were invented by Mr. (now Sir M. I.) 
Brunei, and are fully described and figured in Rees's Cyclopaedia, article "Machi- 
nery for Manufacturing Ships' Blocks;" and also in Encycl. Metrop., part 
Manufacture?, articles 533 and 535. 



EASTMAN'S SAW MACHINE FOR WEATHER BOARDS. 797 



Ir niul usual method of accomplishing this class of work, is 
by the employment of oblique supplementary beds, as explained 
in fig. 748, page 768; the hexagonal blocks for wood paving 
have been cut on the common (taw-bench, precisely in the mode 
t lie re described for small hexagonal and other prisms: indeed, 
the whole of the remarks already given on bevilled or prismatic 
works, are applicable alike to the small saw machines and the 
full-sized saw-benches. 

In the sawing machine invented by Mr. Robert Eastman, of 
America, for cutting feather-edged or weather-boards, &c., (as in 
fig. 790,) the round log of timber is held horizontally, between 
centers inserted in the end of a long rectangular frame or 
carriage, which has rollers that run on fixed bars or rails. The 
round timber is placed above the revolving saw, which makes a 
vertical and radial incision into the timber; the slide then runs 
quickly back, and the wood is afterwards shifted on its axis 
for a new cut, by means of a dividing plate and appropriate 
mechanism. The machine is automatic, or self-acting, so that, 
the primary adjustments having been first made, the entire tree 
is cut into radial feather-edged boards without further atten- 
tion. The rough exterior edges of the board are also cut away 
by tappers, or chisels c, screwed near the center of the saw-plate, 
which cut away the sap or waste wood, and reduce the tree to 
the cylindrical form ; sometimes, if the tree is large, two series 
of radial boards are cut. 



Up It <. 



791. 



792. 




g 



The account further states that ordinary steel saws, toothed 
all round as usual, were found to heat and choke when thus em- 
ployed, on account of their being so deeply buried in the wood, 
the inventor, therefore, contrived what he termed sectional teeth, 



798 SAW MACHINES FOR HEXAGONAL PAVEMENT, ARCHITECTURAL 



shown in fig. 791. An iron plate of one-eighth of an inch thick 
had four dovetail notches, fitted with four pieces of steel, each of 
which constituted two teeth in the form of the "hawk's bill/' 
the paucity of teeth was compensated for by giving the spindle 
a velocity of 1000 to 1100 turns per minute, and the saw is said 
to have penetrated with facility eight inches deep into white 
Canada oak. The radial boards are described to be, (as explained 
in the former volume,) much less liable to split in shrinking than 
those cut out in the ordinary way.* 

A mode, somewhat resembling the above, for cutting hexago- 
nal blocks for wood pavement, has been recently proposed by 
Messrs. Randolph, Elliot, & Co., of Glasgow, and is illustrated 
by fig. 792. In this case, two saws are employed on the same 
horizontal spindle, and the headstocks, which are of iron and just 
like those of a lathe, pass exactly between and beneath the saws, 
which thus produce two parallel cuts at once. The round timber 
being shifted twice, and one-third of the circle each time, becomes 
an exact hexagonal prism, three or four feet long, and is after- 
wards cross-cut into the proper lengths.f 

Professor Willis is in the habit of using the circular saw for 

blocking out Gothic and othermould- 
ings, for the illustration of architec- 
tural science. For example, if in the 
moulding, fig. 793, the several cuts 
are made that are denoted by the 
surrounding lines, the fillet and cham- 
fers are definitively produced, and 
the margins of the curvilinear parts 
are accurately blocked out or defined, 
so that the mouldings may be easily 
and faithfully finished by moulding 
planes. 

The wood in such cases, is marked at one end with the sectional 
and formation Hues, as in the figure, and then mounted between 
centers in a species of lathe, with a dividing plate, so that the 
line a, first becomes horizontal. The saw, which is also horizontal, 

* The full description of this machine, with figures, is transcribed from Pro- 
fessor Silliman's American Journal of Science and Art, into Gill's Technological 
Repository, 1822, vol. ii. page 217. 

+ Practical Mechanic and Engineer's Magazine. Glasgow, 1843, p f>7. 



Fig. 793. 





MOULDINGS, AND WORKS OF TWO 1S< I I NATIONS. 799 

is attached to :i kind of slide-rest, witli three adjustments ; a 
aid a lateral adjust incut, to adapt the saw also to the 
I'M- a ; and a longitudinal adjustment, by which the saw is then 
ti;i\crscd the entire length of the moulding. The work is then 
adjusted on its axis by the dividing plate, until b becomes 
/ontal, and the saw having been as before adjusted to b, is 
swept tin- 1. ii-th of the moulding, and the two incisions remove 
the angle of the square block. The cuts c and d, similarly treated, 
remove another portion of the wood that is in excess, and so on 
to the end ; all the cuts thus made become strictly parallel, or 
in prismatic relation to one another. 

When the mouldings run on to a chamfered base or plinth, 

which commonly occurs in Gothic architecture, the plinth is 

of all removed by a transverse and oblique incision of the 

saw, after which the mouldings are made, and finally the removed 

plinth is replaced without alteration, and the work is complete. 



10. Sawing works, in which the angular variations are in both 
the horizontal and vertical planes. All the observations and 
i n >t ructions given in the former and corresponding subdivision, 
are in truth applicable to large saw-benches ; but the machine 
now to be described is more suitable to large works of this class. 

In Mr. Donkin's saw-bench, fig. 7 9i, the half of the platform 
in front of the saw is hinged like the flap of a table, and has 
quadrants, somewhat after the manner of the sketch, by which 
it may be fixed for cutting any bevils within its range. The 
parallel rule is available for setting out the widths of the works ; 
and the saw is mounted upon a swing-frame of cast-iron, shown 
separately in fig. 795. So that the quantity the saw projects 
through the table, as for sawing rebates, can be regulated by a 
cam ', upon which the one end of the swing-frame rests. 

In cutting small bevilled works, such as those for the wooden 
cogs of cast-iron mortise wheels, and various other pieces, Mr. 
Doukin employs a supplementary carriage, running upon three 
iron rollers, and guided by the hands against the parallel rule. 
b carriage is also conveyed by fig. 71H. It is made 
in cast-iron, and rectangular, but deficient of the half of the 
lower side ; and carries a center screw, a dog or prong chuek, 
and a dividing plate, much as in a lathe; but the axis of these 
parts, although sometimes horizontal, is generally vertical. 



800 



DONKIN'S SAW MACHINE. CURVILINEAR SAWING. 



The small pieces of wood are cut out square as usual, but 
somewhat too large ; they are then grasped between the dog 
and center screw. If the pieces are parallel or prismatic, the 
saw-table remains horizontal as usual ; if the pieces are taper or 
pyramidal, the table is inclined, and which throws the guiding 
carriage to any required obliquity. The parallel rule is next 
adjusted to enable the saw to cut the first side; and should the 
object have four, six or more sides, the dividing plate is brought 
into requisition, for giving the four or more angular positions. 
The parallel rule determines the respective distances of each 
side from the axis on which the work is shifted. 



Fig. 794 



795. 




In this ingenious manner, by the changing of the horizontal 
and vertical angles, by the adjustment of the parallel rule, and 
by the projection of the saw through the platform, almost any 
piece, having plane surfaces, may be sawn ; and the settings once 
adjusted, an unlimited number of similar pieces may be produced, 
as it is only necessary to make the first cut, throughout every 
piece of the entire number, then the second cut throughout the 
whole, the third, and so on. This is accomplished by leaving 
every adjustment undisturbed whilst the first cut is repeated 
throughout all the pieces, except the removal of the one block 
of wood from between the centers and the insertion of the next, 
and so on with each of the succeeding cuts. The indentations 
made by the center screw and dog, ensure the similitude of 
position throughout the entire operation. 

11. Sawing Curvilinear Works. The trephine-saw used in 
surgery, and represented nearly full size in fig. 796, appears to 
have been by far the earliest of the circular saws of this kind. 
It consists of a thin tube of steel, with teeth cut on the edge, 
of the peculiar form represented, and at the opposite end of the 
tube is fixed, by small side screws, the stem by which it is 
attached to the mechanism whereby it is worked. 



Mil H riiM \M> OTHER SURGICAL S.vWi. 801 

The motive apparatus of the trephine-saw, is usually a cross 
"He like that of a corkscrew, or a revolving brace like that 
used in carpentry. To guide the first entry of the trephine- 
saw, the shaft is drilled and fitted with a drill-point p p, which 
is fixed by a side screw *. In the commencement, the point 
makes a small central hole, and when the saw has once fairly 
penetrat <>mt is loosened and allowed to fall back into 

the stem of the saw. 

In another modification the center of the trephine-saw is dis- 
pensed \\ith, as the " guide principle" is effectually introduced, 
saw is fixed at the one extremity of a cylindrical stem, 
which ut the other has a winch handle; the stem works freely 
in a vertical tube or socket with three legs, constituting a tripod 
stand, therefore the axis is kept steady and vertical by the left 
hand; and \\hilst the teeth fulfil their office, the saw advances 
through its fixed collar by the pressure of the right hand, with 
which the winch-handle is turned.* 

* The art of surgery baa given rise to an enormous variety of instruments, a 
most complete collection of the representation of which, both of the earliest and 
latest times, was published by A. W. H. Seerig, in a work entitled Armamentarium 
Chirur<jic*m ; oder moylichitc volUtandigt Sammlung row Albildunyen ehiruryitcher 
InttrwmenU Ultcrer u*d newrer Zeit. The work contains 145 large and crowded 
lithographic plates, and was published at Breslau, in 1835. 

It appears from plate 75 of this collection, that the trephine-saw was known in 
the time of Hippocrates, and that both the blades and the mecbaui&m for moving 
them, have since assumed numerous varieties of form. 

The amputating saws set forth in this work as having been contrived or used by 
various eminent surgeons, are modifications of the bow, frame, and piercing saws 
for metal, and the tenon and dovetail saws for wood ; they vary from about 14 to 
4 inches in length. Some of the small saws analogous to the dovetail saw, have 
edges more or less curved, and the smallest of these dwindle down to a'nearly 
ar plate of steel lew than one inch in diameter, serrated around the edge, 
except where a slender wire, terminating in a wooden handle, is rivetted to the 
edge of the saw-plate. These last are known as Hey's saws, and are principally 
used for the cranium and the metacarpal bones. 

A saw intended for dividing deeply-seated bones, is formed like the chain of a 
table clock, but with the one edge serrated ; it is worked with two cross handles 
by the alternate motion of the two hands. One of the bandies is detached, whilst 
the end of the chain-saw is passed beneath the bone, by a kind of semicircular 
needle. The chain saw was invented by Dr. Jeffrey of Glasgow. 

A nearly similar chain-saw is arranged as an endless band, passing around the 
grooved edge of a taper staff like the blade of a poniard, but terminating in a small 
semicircle. There ar* guards to cover up portions of the edge, and a prop or 
strut to steady the instrument, whilst the endless chain is put in motion by a winch 
hau.il* attached to a pin-wheel, around which also the chain circulates. Thin 

3 r 



802 



ANNULAR OR CROWN SAWS FOR LARGE WORKS. 



The trephine-saw has given rise to various larger applications 
of the same kind of instrument, having teeth of the ordinary 
form, and known as crown saws, annular, curvilinear, drum, and 
even as washing-tub saws, the respective merits of which names 
it would be useless to discuss. Small saws of this kind, when 
mounted upon the lathe, are often employed for cutting out 
disks of metal and wood ; the material is in general thrust against 
the saw, by a block of hardwood fitted to the front center of the 
lathe, and frequently, as in making buttons, the cutting out is 
combined with the shaping of the two faces of the button. 



Fiys. 796. 





In the block machinery at Portsmouth the crown-saw is used 
for rounding the sheaves, which are cut out of transverse slices 
of lignum vitse ; the wood is held at rest by its margin whilst the 

singular instrument is ascribed to S. Heine, and is figured on plate 60 of Seerig's 
work, which also contains several schemes for using small circular saws, but some 
of the mechanical arrangements are not clearly defined in the figures. 

A circular saw proposed for cutting deeply-seated bones, and as an occasional 
substitute for the trephine-saw, was invented by Mr. Thomas Machell of Durham, 
surgeon, and is accurately described in the Trans. Soc. of Arts for 1812, Vol. xxx., 
page 150. In Mr. Mach ell's saw the axis of rotation is constructed within the thick- 
net* of the blade, so that two thirds the area of the circular saw may be depressed 
in the saw cut. The saw is worked by a phi-wheel, the pins of which enter 
notches in the edge of the saw-blade, the pin-wheel has teeth, and is itself moved 
by a larger and more distant toothed wheel, having a small winch-handle. 

The great difficulty encountered in almost all the surgical saws, arises from the 
removed particles of bone becoming mixed with the fluids, and forming a thick 
paste which clogs and nearly stops the action of the blades. To remedy this 
inconvenience, Mr. Weiss suggested that slits terminating in round holes should 
be cut in the edges of such blades as admit of these receptacles being made. See 
Weiss on Surgical Instruments, page 10, plate 18 ; and figure 796 in the text. 
Small bones are now more frequently cut by strong nippers than by saws, and 
many nippers are drawn on Seerig's plate 134. 



TROTTER'S SPHERICAL SAW. H :', 

unu r mandrel, \\ln.-h carries the crown-saw and also a drill, 
is advanced through its collars, and rounds and bores the 
sheaves a, at the oue operation, ready for the coaking-eu^ 
turning-lathe, &C.* 

Crown-saws, as large as 5 feet diameter and 15 inches deep, 
constructed somewhat after the manner of fig. 797, arc employed 
Messrs. Esdailes' saw-mills. The three or four pieces of steel 
tii' n constituting the hoop, are rivcttcd to the outride of a strong 
ring, and very carefully hammered, so that the plates exactly 
constitute one continuous cylinder; although the ends of the 
plates are not united, but simply make butt-joints. The ring 
is fixed to the surface-chuck of a kind of lathe-mandrel, by 
means of hook-bolts A, and the work is grasped in a slide-rest, 
which traverses \\itliiu the saw, and parallel with its axis. 

The saws of about 2 feet diameter are used for cutting the 
round backs of brushes b t and the larger saws are employed for 
felloes of wheels d, and similar curved works. If the wood is 
applied obliquely, the piece also becomes oblique, in the manner 
explained by the diagram c, which represents the sloping and 
hollowed back of a chair thus produced. It is, however, much 
more usual to saw curvilinear works of the kinds referred to, 
with the felloe or pit-turning saw (see page 707), the chair- 
maker's and wheelwright's saw (p. 725), aud the turning sweep, 
or bow-saw (p. 728), the respective applications of which have 
been already noticed at the pages referred to. 

Mr. Trotter proposed for curvilinear sawing, the employment 
of a saw-plate , fig. 798, which instead of being a flat plate, as 
u-ual, was dished as the segment of a large sphere. The fence/, 
which was made as the arc of a circle, had a conductor c, to 
receive the work w ; the circular fence was attached to a three- 
bar parallel rule, so as always to keep the curvatures of the fence, 
conductor, and saw, which were equal, truly parallel with each 
other. The construction of the spherical saw-blade is difficult, and 
its advantage questionable, especially as the edges of the pieces 
when Irtt from the saw, would be curvilinear in width as well as 
length, or part of a spherical surface, of the same radius as the 
taw. This form is seldom required in the arts, and its conversion 
into the simple arch-like form with square edges (proposed to be 



Cyclopedia, art. " Machinery for Manufacturing Shipe' Blocks." 
. c. Metropolitan, rol. Mechanic*, art. 870. 

3 i 



804 



SAWING THE CURVILINEAR STAVES OF CASKS. 



approached by inclining the work), would fully cancel the intended 
economy of the spherical saw, which is however curious, as one 
of the links in the chain of contrivances under consideration.* 

Much ingenuity has been displayed in cutting the curvilinear 
and bevilled edges of the staves of casks by circular saws. The 
late Sir John (then Mr.) Robinson, proposed many years back that 
the stave should be bent to its true curve against a curved bed, 
shown in two views in fig. 799, and that whilst thus restrained 
its edges should be cut by two saws s s, placed as radii to the 
circle, the true direction of the joint, as shown by the dotted circle 
representing the head of the cask. The principle is perfect, but 
the method has been found too troublesome for practice. 



Figs. 70S. 



800. 




Mr. Smart cut the edges of thin staves for small casks on the 
ordinary saw-bench, by fixing the thin wood by two staples or 
hooks to a curved block, fig. 800, the lower face of which was 
bevilled to give the proper chamfer to the edges. One edge having 
been cut, the stave was released, changed end for end, and refixed 
against two pins, which determined the position for cutting the 
second edge, and made the staves of one common width. The 
curved and bevilled block, was guided by two pins p p, which 
entered a straight groove in the bench parallel with the saw. 

This mode of bending was from various reasons found inap- 
plicable to large staves ; and these were cut, as shown in three 
views in fig. 801, whilst attached to a straight bed, the bottom of 
which was also bevilled to tilt the stave for chamfering the edge. 
To give the curve suitable to the edge, the two pins on the 
under side of the block then ran in two curved grooves g g, in the 



* Trans. Soc. of Arts, 1805. Vol. xxiv., p. 114. 



CIECC 






I \H -\\w \ M) M \flll\CK\ roil CtTTINO VENEERS. 805 

saw-bench, which caused the staves to sweep past the saw in the 
arc of a very large circle, instead of in a ri^rlit line, so that the 
ends were cut narrower tli.-m the middle. Mr. Smart observes, 
tluit in staves cut whilst straight, the edges become chamfered at 
the same angle throughout, which although theoretically wrong, 
is sufficiently near for practice ; the error is avoided when the 
staves are cut whilst bent to their true curvature.* 

SECT. VIII. CIRCULAR SAWS AND MACHINERY FOR CUTTING 

VENEERS. 

Valuable and beautiful woods are seldom used in the solid 
state for decorative furniture, but are cut into veneers or thin 
plates, to be glued upon fabrics made of less expensive woods, an 
art successfully practised by the Romans, as formerly adverted 
to (Vol. i., page 64). Until of late years the cutting of veneers 
was generally accomplished, either at the saw-pit with very thin 
plates strained in the ordinary pit-saw frame, (see Vol. ii., page 
703), or by the cabinet-maker with the smaller frame-saw, 
(page 726). In this latter mode, which is still much practised on 
the continent, the wood is fixed perpendicularly, and the saw is 
also guided by two men. Expert pit-sawyers could cut six 
veneers out of each inch of wood, and cabinet-makers seven or 
eight from smaller pieces, but the difficulty of these methods 
rapidly increases with the size of the veneer-. 

Small veneers for the backs of brushes and other works, have 
been split or planed from small pieces squared to the respective 
sizes. Pine, willow, and other woods, are planed into thick con- 

* See the original paper, Trans. Soo. of Arts, Vol. xlvii., pp. 121-7. In the 
year 1833, Mr. Samuel Hamilton took out a patent for "certain machinery for 
aawing, boring, and manufacturing wood for various purposes, such aa bevilled 
timber for ship-building, tenon cheeks, felloes of wheels, the circular rails of 
chair backs, choir legs, and other works of the same description, either square on 
the face, or bevilled to any required angle, or in any required radius or dim 
of a circle." 

The specification is Tory complex, but it may be said briefly, that the felloes are 
cut by a vertical reciprocating saw worked by a crank, and the edge of the work 
is guided either by a fixed circular fence, or by radius ban ; for bevilled works 
the table of a similar machine is tilted to any angle. For other classes of work, 
the saw-frame is jointed, and may be brought down by a swing-frame in the arc of 
a circle, to penetrate to any assigned depth. The work is grasped by numerous 
arrangements of parts, that hold any successive number of pieces exactly in the 
same position. Set Newton's London Journal and Repertory, A--:, Vol. viL, p. 1. 



806 BRUNEI/S MACHINE 1'OR SPLITTING VENEERS. 

tinuous shavings called scale-boards^ for making hat and bonnet 
boxes (Vol. ii., p. 504). And of late years oak, when softened by 
steaming, lias been split into staves for casks (foot-note, Vol. i., 
page 32). All these processes are accomplished without waste of 
the materials, but they are only applicable to pieces of limited 
dimensions. 

In 1806, Mr. Brunei took out a patent for splitting veneers, 
of considerable size, by means of a horizontal knife, the length 
of which exceeded the length of the block to be converted. 
The knife was composed of several pieces of steel, placed exactly 
in a line on their lower surfaces, but with edges faintly rounded 
and very keen. The compound knife received a short recipro- 
cating or sawing action, and the block of mahogany or other wood 
was carried slowly sideways, and beneath the knife by a strong 
screw slide, worked with a spoke wheel, like that by which a 
ship is steered. After one veneer had been cut off, and the 
log brought back again to its first position, it was raised in exact 
parallelism, by a system of two right and two left-handed screws 
at the four angles of the frame, which were simultaneously moved 
with one winch-handle, by aid of appropriate mechanism.* 

This machine for cutting or splitting wood into veneers, the 
precursor of the segment veneer-saw, is said to have answered 
moderately well with straight-grained and pliant woods, such as 
Honduras mahogany, but there were serious objections to its 
use for woods of irregular, harsh, and brittle grain, such as 
rosewood; as the veneer curled up considerably on removal, 
and the wood if harsh and brittle had a disposition to split and 
become pervious to the glue.f This is to be regretted, as the 
splitting-machine converted the whole of the wood into veneer 
without waste, whereas the veneer-saw, on the average, cuts 
one-third of the wood into saw-dust. 

As already explained, the ordinary circular saw will not, in 
general, serve for work exceeding in thickness about one-third 
the diameter of the saw, and the larger the saw, the thicker it 
is required to be, to give a proportionate degree of stability. 
These two conditions, joined to the impracticability of obtaining 

* See the drawing and description in the Rep. of Arts for 1810, Vol. xvi., p. 257. 

t The Russian machine for cutting the entire tree into one spiral veneer, (see 
Vol. i., p. 154,) seems open to the same objection in regard to brittle woods, neither 
does it expose the most ornamental section of the tre*. 



SINGLE-PLATE VENEER-8AW8 POR 1VC WOOD 807 

plate* of steel exceeding some 4 or 5 feet diameter, limit the 
application of the rin-ular >a\v under ordinary circumstance*. 

Hut when this instrument is employed for veneers, advantage is 
taken of the pliancy of the thin h at* or veneer, and the saw is con- 
sequently made thick and strong towards the center, to give it the 
required stability, but towards the edge it is thinned away almost 
to a feather edge, as at * *, in the diagram, fig. 802. Therefore 

Fig. 802. 




the solid block of wood or ivory tc, which is unyielding, can pass 
along the parallel guide y, and across the flat face of the saws* 5, 
whil>t the thin pliant veneer v, separates so much as to form an 
opening that admits the wedge-formed edge of the blade, and the 
veneer proceeds along the conical back of the saw without frac- 
ture or interruption ; circumstances that would be impracticable 
were both parts of the material when sawn, alike unyielding. 



In the small application of this principle, as for sawing blocks 
of ivory into leaves for miniatures, and small square pieces of 
wood into veneers for brushes and small works, the veneer-saw 
is made as a single plate of steel, from 6 to 86 inches diameter. 
In the large application of the principle, as for cutting logs of 
square or round wood into veneers, the saw is composed of many 
segments or plates, and commonly varies from about 5 to 1 ^ 
feet diameter. But as the segment-saws are occasionally made 
at small as 20 inches diameter, the two kinds constitute an 
unbroken series, and their principal applications will now be 
described, beginning with the smallest. 

The single-plate veneer-saw (described in section 2 of the 
table, on page 781), is thick and parallel at the center for about 
one-half its diameter, the edge is ground away, as a cone, 
almost to a feather edge; at other times the edge is thin, and 
nearly parallel for about an inch, and is then gradually coned, 
making the section somewhat concave. The edge is required to 
run exceedingly trur, and the teeth must be sharp and very 
faintly set. 






808 SAWING IVORY VENEERS FOR MINIATURE LEAVKS. 

Saws of six to ten inches, are sometimes used in machines such 
as that shown on page 756, for very small pieces of ivory veneer 
and for slicing up wooden mosaic works, but it is more usual to 
employ larger saws for miniature leaves, say those from fifteen 
to twenty inches diameter, and consequently larger machines 
are also required, which are driven either by a hand fly-wheel 
or other motive power. The principal variations between veneer 
saw -benches, and those for ordinary and thicker works, is in the 
parallel guide, which, for veneers, is made fully as high as the 
width of the block to be sawn, by screwing a parallel piece of 
wood or metal against the vertical face of the parallel rule, and 
cutting it off in a circular arc, exactly to agree with the curvature 
of the saw, and without extending at all behind it. In many 
cases the parallel guide is constructed \vith a set-screw, that it 
may be adjusted for distance very minutely, after which it is fixed 
as usual. When, therefore, the block of ivory or wood is placed 
against the parallel rule, and pressed towards the saw by hand, 
the thin leaf bends away as cut from the block, or yields 
sufficiently to pass behind the saw without impediment. 

In bevilled or veneer-saws for ivory, the teeth should be finer, 
and the rate of motion slower than for wood, say, three-fourths 
the speed, as when a considerable velocity is used the saw 
becomes heated, and this, from the gelatinous nature of the 
material, causes the sawdust to adhere to it; the heat also 
tends to split the thin leaves of ivory. These sources of mis- 
chief are avoided by giving to the saw-blade a subdued rate of 
motion, and keeping it moderately anointed with tallow or lard. 
Some idea of the delicacy of veneer-saws for ivory, will be 
given by the inspection of the annexed scale, which shows the 
average numbers of veneers or leaves cut from each solid inch 
of ivory: 

When the width of the ivory is 1 2 3 4 5 6 7 inches, 
Each inch of ivory is cut into 30 27 24 22 20 18 16 leaves. 

The leaves from 1 to 2 inches wide and 2 to 3 inches long, 
are used for memorandum-books, the larger sizes for miniature 
leaves, the lengths of which are about one-third more than their 
widths. When scraped and prepared ready for the artist, the 
30, 27, or 16 leaves, respectively measure about half an inch in 
total thickness, showing the waste in sawing and scraping to be 
equal to about one-half the original material. The leaves might 



LARGE SEGMENT-SAW, OR V KN C tR-SA WM ILL. ^09 

be cut still thinner, hut this would be objectionable as regards 
r intentleil purposes. 

lu-villr.l or vcncer-saws, when used for wood, 
greater diameter, coarser teeth, are used without grease, and 
at a higher velocity thau for ivory ; hut the single-plate ven 
saws are not frequently made of the full-size named in the table, 
nor are they used for wood exceeding about six inches wide, or 
that has not been previously squared into small pieces.* 



In the larger applications of the veneer-saw, it is built up of 
segments or separate plates of steel, screwed to the edge of a 
metal disk or chuck. Some few of the smallest segment-saws 
are even less than two feet diameter, and those not exceeding 
about four feet diameter are generally used in the ordinary 
saw-benches, with fixed horizontal platforms, the work being 
then fed by hand as usual. 

But when the segment veneer-saw exceeds about four feet 
diameter, the horizontal platform or table is rejected, and the 
guidance of the wood is entirely effected by machinery, called 
the drag ; the arrangement of this construction, which is known 
both as the veneer-mill and the segment-saw, is shown in the 
perspective figure 804, page 812. The veneer almost always 
proceeds from the edge of the saw, through a curvilinear trough 
parallel with the back of the saw; but in the figure the veneer 
is represented as if bent almost at right angles, so as to quit the 

A manufacturer, experienced for thirty yean in cutting miniature leave*, 
generally employs single-plate saws from sixteen to twenty inches diameter. He 
also uses a segment-saw, measuring the larger diameter, when new, and composed 
of six segments, attached to a gun-metal chuck, the edge of which is very thin. 
and the center enlarged into a boss cut with a hollow screw, for its attachment to 
the saw-spindle, which runs in a collar and center, exactly after the manner of a 
lathe-mandrel He prefers about eight to ten points per inch, and an average 
Telocity of about 000 to 700 revolutions per minute ; in topping the teeth, he use* 
a steel turning-tool, and sets the teeth before sharpening them. 

He adds, that when the blocks of ivory are cut into lengths, prior to being sawn 
into veneers, loss occurs, because the central and wider leaves require to be longer 
than those from the same block, which are exterior and narrow. Sometimes the 
entire tooth, or a large portion of it, U cut into veneers with the large segment-taws, 
Laving the drag (to be describe' 1) ; this is better as regards the cutting of the leaves 
into squares ; but the apparent economy ia again lost, a* these saws being intended 
for wood, have coarser teeth, and will not leave such smooth surfaces as the saws 
exclusively used for ivory, neither will they produce more than about fourteen or 
fifteen veneers from each inch of ivory. 



810 CONSTRUCTION OF THE SEGMENT-SAW. 

saw in front; this construction is far less common, but was 
selected for the present illustration, as it affords a more con- 
spicuous view of the entire process. 

In the veneer-saws furnished with the drag, the axes run in 
massive brass bearings, which are fixed on brick or stone piers ; 
the edges of the larger saws dip below the ground into a pit 
lined with brickwork or masonry. 

The axis of the saw is connected or disconnected with the 
steam-engine at pleasure, by means of a fast and loose pulley ; 
and in bringing the saw to a state of rest, the brake-wheel at 
the end of the axis is strongly grasped by a friction-hoop, as in 
some cranes. Between the driving pulleys and the cone for the 
saw is placed a bevelled pulley, for a catgut band or rope that 
is used in feeding the cut, as will be hereafter explained. The 
saw, which is the all-important part of the machine, is made of 
great strength, and consists of three parts, shown in the section 
of the edge, fig. 803, of which the shaded part c to c is of cast- 
iron, the white part * to * of soft steel, and the black h to h of 
hardened steel. 

Fig. 803. 

~> Log of wood. 

J h shea 





The saw is composed, first, of a cast-iron wheel or chuck, with 
from six to eighteen arms, which are taper, so as to constitute a 
cone, the thickness of which at the center is about one-twelfth 
the diameter. The rim of the wheel c c, is flat and turned smooth 
on the face to receive a series of 6 to 18 segments of soft steel, 
about one-quarter of an inch thick, marked s s, which are fixed 
to the cast-iron by strong rivets ; the segments project from 5 to 
8 inches beyond the cast-iron, and are chamfered at the edge. 
To the soft-steel segments * s, are affixed a second series h h, 
consisting of about twice the number ; these are hardened and 
serrated, so as to constitute the cutting edge of the saw. 

The tempered plates are technically called the hard, and are 
attached to the soft segments by numerous countersunk copper 



Ml . I NEm-.SAWMIH . 11 

screws, tapped into * *. \Vhen ni-\v, the hard segment* pr" 
from 4 to 6 inches beyond the soft; so that the angle then 
he three parts, h to c, con-iden -ively, is 

only alxmt 4 to degrees with the flat face of the saw, and the 
i-r will readily yield to more than that extent from the log 
without splitting. To prevent the risk of accident from the 
exposed spokes of the wheel or chuck, and also the current 
of wind caused by their rapid rotation, the spaces intent-inn.; 
between them are filled up on the face with wood, and an entire 
cone of thin boards is attached to the back of the chuck. 

The log to be sawn sometimes requires to be previously adzed 
all over, to remove the sand and dirt that would soon blunt the 
saw ; it is then partially levelled with the adze or plane, to adapt 
it to the vertical face of the drag. The drag has three long bars 
of wood, in order that the revolving saw may cut or prepare for 
itself the surface against which the log is fixed. The sharp 
ends of the iron dogs are driven a little way into the log, and 
the dogs arc then drawn down by screw-bolts as represented. 

Sometimes the log is only temporarily held by the iron fasten- 
ings or dogs, whilst its surface is partially levelled with the saw, 
after which it is glued on a wooden frame, that is full of trans- 
verse and oblique bars, and has been also levelled with the saw ; 
the log and frame are afterwards bolted to the drag. In this case 
the entire body of the wood can be cut into veneer without inter- 
ruption from the fastenings, and the glue joint is safe so long as 
the log does not project more than the width of the glued surface. 

The timber requires two motions to be impressed upon it; the 
one motion, longitudinal, to carry it across the face of the saw ; 
the other motion, lateral, to advance it sideways between each 
cut, the exact thickness of the intended veneer. 

For the first or cutting motion, a long railway extends across 
the face of the saw, and supports the drag, which is carried past 
the saw by means of a rack and pinion, actuated by a cord pro- 
ceeding from one of the grooves of the cone pulley on the man- 
drel, down to the pinion axis, which is beneath the surface of the 
ground, and not represented. On the pinion axis there is a 
double train of toothed-wheels, and a clutch-box, by the three 
positions of which latter, the draj: is left at rest, or it is carried 
slowly past the saw in the act of cutting, or quickly back pi 
ratory to the succeeding cut. The gearing lever, by which the 



812 



CONSTRUCTION OF THE DRAG AND MODE OF 



three positions of the clutch-box are given, is perpendicular, and 
passes downwards through a trap-door, situated close behind the 
little stool on which the attendant is seated. 



Fig. 804. 







The second motion of the log, or its lateral adjustment, is thus 
effected. The slide that runs on the railway has a horizontal 
plate, which carries three or more triangular standards, like but- 
tresses, to the perpendicular faces of which are fixed the three 
wooden bars against which the wood is clamped. 

The horizontal plate that carries the triangles, is united at 
each end to the lower piece of the drag, by a chamfer slide with 
an adjusting screw and nut, one of each alone being seen. The 
adjusting screws have worm-wheels at the one end, and are simul- 
taneously moved by means of a winch-handle w, at the extremity 
of a long rod, having two worms taking into the two worm- 
wheels fixed on the adjusting screws. From 50 to 60 turns of the 
handle are required to advance the log of wood one inch ; the 
attendant can therefore determine with great facility, the number 
of veneers cut out of each inch of wood, or he can cut the 
veneers to any particular pattern for thickness. 

There is no impediment to the passage of the log across the 
rectilinear face of the saw ; but for the guidance of the veneer 
around the back of the cone, some particular arrangements are 









US I SEGMENT VENEER-SAWMILL. 813 

required. To enable the veneer to avoid the edge of the soft 
steel segments, to winch the s. nated blades an i feather- 

edged guide. plate, usually of brass, and extending around about 
one-sixth or eighth of the circle, is fixed almott in contact u-ilh the 
blade, by screw-bolts and nuts, which, as seen in fig. 804, unite 
the stationary framing of the machine; the guide is repre- 
sented black in the sectional view, fig. 803. As the vencc: 
awn off, the attendant leads the veneer on to the guide, by 
means of a spud, or a thin blunt chisel, the veneer then slides 
over the guide, as shown, and proceeds through a curvilinear 
wooden trough, usually extending round the back of the cone, 
and the veneer is pulled out on the other side by an assistant, 
and stacked on the heap. Sometimes the veneer is bent nearly 
at right angles, and quits the saw in front, as in the figure : this 
arrangement is less usual, but was selected for the illustration, 
as it offers a more comprehensive view of the several parts. 

Before running back the drag, preparatory to a new cut, the 
handle IT, is unwound two or three turns, to remove the log beyond 
the reach of the saw, and prevent its being scratched by the saw 
teeth, these turns are afterwards moved in addition to those 
required for the new thickness : the handle is managed by a boy, 
who stands outside the railway. 

Whilst the saw is in the act of cutting, the principal attendant 
applies a soft deal freeing -stick, on the right and left of the 
blade beneath the timber, in order to clear the sawdust out of the 
teeth. The speed at which the table is fed is easily adjusted, by 
the selection of an appropriate groove of the cone pulley on the 
main shaft, which communicates with the driving pinion beneath 
the floor ; and this adjustment of the feed is jointly dependent on 
the condition of the saw as to sharpness, and the general quality, 
hardness, and size of the wood. 

The veneer-saw may be used for logs of wood measuring as 
much as 24 feet in length and 5 feet in breadth, but which sizes 
are rarely or never met with in the same log. It may be added, 
that the number of veneers cut out of each solid inch of wood, 
varies with the width and the intended purpose of the veneers ; 
but that on the average 

When the width of the wood te 12 18 24 30 36 48 inohw, 
Each inch of wood i cut into 15 14 13 12 11 10 9 8 renew* ; 

and, as about one-third of the wood is wasted in sawdust, the 



814 VENEER-SAWMILL ALSO USED FOR THIN BOARDS. 

respective veneers are about two-thirds the 15th, 14th, &c. of 
aii inch in thickness. 

The veneer-saw is also applied to cutting cedar wood for 
making pencils ; bead stuff, or thin wood for making the headings 
in cabinet work ; quarter stuff, or wood j inch thick ; and occa- 
sionally also to wood nearly ^ inch thick ; and this may be con- 
sidered the point of meeting, between the veneer-saw and the 
upright frame-saw, page 742, in which ten or a dozen saw-blades 
are occasionally used for deals. But the veneer-saw works with 
greater accuracy, and is almost always used for such thin boards 
of mahogany as are not cut by hand at the saw-pit. 

For sawing thin boards, the segments should be nearly new 
or very wide, in order that the angle made by the removed board 
may be slight. But as the board in riding over the guide, (page 
81 0,) near the edge of the saw, is nevertheless somewhat strained 
open, it becomes needful to apply a contrivance called a guard, 
to prevent the thin board from being at all split off, instead of 
being entirely separated by the saw. This is accomplished 
by a curvilinear arm, equal in size and form to the feather- 
edged guide which lies against the hardened saw-plates, but the 
guard is very much thicker and stronger, and is covered with a 
thin plate of brass. 

It will be further perceived in the perspective figure, page 812, 
that the guard is attached to a column, and is represented turned 
back, or out of work, which is the case whilst veneers are being 
cut ; but in sawing boards, the guard is placed parallel with the 
edge of the saw, just external to its teeth, (as dotted,) and is ad- 
justed by set-screws to rest in hard contact with the face of the 
wood which is sliding past it, the removed board is consequently 
held securely unto within half an inch of the saw teeth, or 
the line of separation, as shown by the diagram, fig. 803. 

In sharpening the veneer-saw, the workman first applies a 
lump of grindstone very cautiously upon a proper support, 
against the edge of the teeth as the saw revolves, so as to reduce 
the few points extending beyond the circle. The saw having 
been stopped, he then stands on a stage and rests his left arm, 
which is guarded by a wooden board, or leather shield, upon the 
teeth of the saw, whilst he manages the triangular saw-file with 
both hands. . The saw teeth are afterwards set by a hammer 
and a small flat stake held in the left hand. The necessity for the 






SO REMARKS ON CIRCULAR SAWS. - 1 .~i 



recurrence to sharpening and setting depends much on the bard- 
nets of the wood, but it is commonly needed several times each 

hat the saw is in constant work. 

\\ hcu the edge becomes too thick and wasteful, it is ground 
ans of revolving laps of lead or iron fed with emery, one 
lap on the face, another on the back of the saw ; the laps are 
placed one below the other, to prevent their faces touching, and 
are kept in rapid motion, whilst the saw traverses between them, 
as in cutting, so that all parts of the circumference, of this most 
stupendous and accurate of saws, may be ground alike. 4 ' 



Notwithstanding the very considerable length to which the 
chapter on saws has been extended, the subject may be considered 
as very far from exhausted. Thus the great majority of the 
applications of the saw hitherto noticed have been for manufac- 
tures in wood, but toothed saws are also employed for many other 
purposes, and different materials, some few of which will be 
glanced at by way of conclusion. 

Both reciprocating and circular SHWS are occasionally employed 
in cutting off piles beneath the surface of water, when to draw 
them (by the aid of the hydrostatic press,) would endanger the 
safety of the foundations. Two methods of thus using rectilinear 
saws have been described, to which the render is referred.f 

The circular saw, when used for piles, is commonly placed at 
the bottom of a long vertical shaft, the top of which is driven by 
a winch, through the medium of a pair of mitre-wheels. The 
shaft is attached to a swing-frame, like a gate, or to a traversing 
platform, connected with such of the piles as may with safety be 
ultimately drawn up ; in every case the erection of machinery 
for sawing piles is troublesome, and the process tedious. 

In the American steam pile-driving machine, intended princi- 
pally for constructing the foundations of railways, two piles are 
driven at the same time, in the respective track. After which, they 

The author U greatly indebted to Hewn. Eadaile and Margrave, of the Citj 
Saw-Hills, for the free access they permitted him to their establishment, which 
contains eleven veneer-sawn, from 17 ft 6" in. to 6 feet diameter, and also nearly 
every kind of machine-saw and shaping-engine for wood that is extensively used. 

Many of the practical details, on sawing ivory veneers, were derived from the 
experience of Mr. Donald Stewart. 

t See EncycL Metro. Part Mechanics, article 536 ; also, Civil Eng. and Arch. 
Journal, 1843, voL vi , page 439. 



816 CONCLUDING REMARKS ON CIRCULAR SAWS. 

are sawn off by a circular saw four feet in diameter, tlie spindle of 
which is mounted on the end of a strong horizontal frame, moving 
on a joint, so as to cut first the one pile and then the other. 
Notwithstanding the irregularities of the ground, the piles may 
be cut either to a dead level or to any particular inclination.* 

Circular saws areusedin cutting sheets of slate into rectangular 
pieces, many of which are afterwards planed by machinery (vol. i. 
page 165). Slate is also grooved with thick circular saws, for 
making a particular kind of roofing, the joints for cisterns, and 
other works ; and more frequently two thinner saws are used, 
and the intermediate substance is chiselled or tooled out. Recti- 
linear toothed-saws, driven both by hand and machinery, are 
likewise used for blocks of slate and soft building stone. 

A saw machine is used at the Butterley Iron Works, Derby- 
shire, in cutting off the ends of railway bars whilst red hot ; in 
fact, the moment they leave the rollers. The two saws are exactly 
like those for wood, of three feet diameter, with flanges of two 
feet, they travel at upwards of 1000 revolutions per minute, 
and their lower edges, dip into water. The bar is brought up 
to the saws by machinery, and both ends are cut off simul- 
taneously, in twelve to fifteen seconds, to the precise length 
required, f 

If the customary applications of the saw machine to works in 
metal had been touched upon in this chapter, they would almost 
inevitably have trenched upon the fifth volume; as it would have 
been difficult, to avoid proceeding from the circular saw, used 
simply for dividing works, to circular cutters with plain edges, 
used in cutting grooves, and to cutters with curvilinear or figured 
edges, used for the teeth of wheels, and various other analogous 
works, subjects that are for the present held in reserve. 

By analogy, it might also have been shown, that in some of 
the various apparatus employed in ornamental turning, revolving 
cutters of all kinds, with plain or figured edges, are likewise 
used. But in reference to these, it will be explained in the 
fourth volume, that the many teeth of the circular saw, or figured 
cutter, dwindle down to a single radial tooth; and that the 
solitary cutting edge makes up for its apparent deficiency, by 
the extreme rapidity with which it is in general driven. 

* Civil Eng. and Arch. Journal, vol. v., page 1. 
t Trans. Inst. Civil Engineers, vol. iii., p. 197. 



617 



U [AFTER XXVIII. FILES. 

SECT. I. GENERAL AXD DESCRIPTIVE VIEW OF FILES Of 
USUAL KINDS. 

file is a strip or bar of steel, the surface of which is cut 
into fine points or teeth, that act by a species of cutting, closely 
allied to abrasion. When the file is rubbed over thr material to 
be operated upon, it cuts or abrades little shavings or shreds, 
which from thrir iiiimiti-ness arc called file-dust, and in so doing, 
the file produces minute and im ^ular furrows of nearly equal 
depth, leaving the surface that has been filed more or less smooth 
according to the size of the teeth of the file, and more or less 
accurately shaped, according to the degree of skill used in the 
manipulation of the instrument. In treating this subject, it is 
proposed to divide the matter into the following sections : 
I. General and descriptive view of files of usual kinds. 
II. General and descriptive view of files of less usual kinds. 

III. Preliminary remarks on using files, and on holding works 

that are to be filed. 

IV. Instructions for filing a fiat surface, under the guidance 

of the straight-edge, and of the trial-plate, or planometer. 
\ Instructions for originating straight-edges and trial-plates, 

or planometers. 
VI. Instructions for filing rectilinear works, in which several 

or all the superficies have to be wrought. 
\ 1 1. Instructions for filing curvilinear works, according to the 

three ordinary modes. 

Y I II. Comparative sketch of the applicatious of the file, and of 
the engineer's planing machine, &c. 



The files employed in the mechanical arts are almost endless 
in variety, and which is to be accounted for by there being some 
four, five, or six features in every file, that admit of choice, in 
order to adapt the instrument to the several kinds of work for 
which the file is used; and most of the names of files express 



818 GENERAL CHARACTERS OF FILES. 

these different features, for instance the three following files are 
in common use : 

6 inch, blunt, single-cut, Sheffield, saw-file, 

9 inch, taper, smooth, Lancashire, half-round-file, 

12 inch, parallel, rough, Sheffield, safe-edge, cotter-file. 

From the perusal of these compounded names it will be seen, 
that six sources of variation have been noticed, and upon which 
several characters a few observations will be offered. 

1. Length. The length of files is always measured exclusively 
of the tang or spike, by which the file is fixed in its handle, and 
the length and general magnitude of the file require to be pro- 
portioned to the work to be performed. When the works are 
both large and coarse, the file should be long and strong, that 
the operator may be able to exert his entire muscular force in 
using the instrument; when the works are minute and delicate, 
the file should be proportionally short and slender, so that the 
individual may the more delicately feel the position of the file 
upon the work ; as the vigorous employment of force, and the 
careful appreciation of position or contact, are at opposite ex- 
tremes of the scale. Thus, it may be said, the watchmaker 
frequently uses files not exceeding three quarters of an inch in 
length, and seldom those above 4 or 5 inches long ; artisans in 
works of medium size, such as mathematical instrument makers 
and gunmakers, employ files from about 4 to 14 inches long ; and 
machinists and engineers commonly require files from about 8 
to 20 inches long, and sometimes use those of 2, 3, feet and 
upwards in length. 

The lengths of files do not bear any fixed proportion to their 
widths ; but, speaking generally, it may be said the lengths of 
square, round, and triangular files, are from 20 to 30 times their 
widths, measured at the widest parts ; and the lengths of broad 
files, such as flat files, half-round files, and many others, are 
from 10 to 12 times their greatest widths. 

2. Taper, blunt, and parallel files. Almost all files are required 
to be as straight as possible in their central line, and are distin- 
guished as taper, blunt, and parallel files ; a very insignificant 
number of files are made curvilinear in their central line, as in 
the rifflers used by sculptors and carvers, and some other files. 

The great majority of files are made considerably taper in 
their length, and to terminate nearly in a point, such are called 



OEN I it OF PILES. v 1 l 

taper files; others are mad parallel, and known as "blunt 

ly as blunt files; but in each of these kinds tin- 
section of the iilr is the largest towards the middle, so that all 
sides are somewhat arched or convex, and not absolutely 
straight. A very few files are made as nearly parallel as pos- 
sible, and have, consequently, nearly straight sides, and an equal 
section throughout ; such are designated as parallel files, and by 
some, as dead parallel files, just as we say "dead level" for a 
strictly level surface, but it is very far more general for the so- 
called parallel files to be slightly fuller in the middle. 

3. Lancashire and Sheffield files. In England the principal 
seats of the manufacture of files, are Sheffield and Warrington; 
th.se made at the latter place being more generally designated 
.-hire files. The Sheffield files are manufactured in very 
much the larger quantity, and for nearly every description of work, 
both large and small. The Lancashire files are less used for large 
than for small works, including watch and clock-work, some parts 
of mathematical instruments, and the finer parts of machinery. 

Formerly all the Lancashire files bore a great pre-eminence 
over the Sheffield, in respect to the quality of the steel from 
which the files were made, their greater delicacy of form, the 
perfection and fineness of their teeth, and the success with which 
they \\erchardcned; these circumstances rendered the Lanca- 
shire files more expensive, but also much more serviceable than 
the Sheffield. Of later years, this superiority is generally con- 
sidered more particularly to apply to the smaller Lancashire 
files, not exceeding about 8 or 10 inches in length, as from the 
steady improvement amongst the best of the Sheffield file manu- 
faeturers, in respect both to the quality of the steel, and the 
Ixinanship, it now results, that the larger files made both in 
Lancashire and Sheffield, assimilate much more nearly in their 

6 qualities than formerly. 

1 . Tin- tfttli of files. Many files that are in all other respects 
alike, differ in the forms and sizes of their teeth. Three forms 
of teeth are made, those of double-cut files, those of floats, or 
tingle-cut files, and those of rasps. The floats and rasps are 
scarcely used but for the woods and soft materials ; the double- 
files are used for the metals and general purposes; and 
when the tile is spoken of, a double-cut tile is always implied, 
unless a single-cut tile, or a rasp, is specifically named. 

3 G 2 



820 



TEETH OF FILES. 



In a double-cut file, the thousands of points or teeth occur 
from two series of straight chisel-cuts crossing each other ; in a 
single-cut file or float, the ridges occur from the one series of 
chisel-cuts, which are generally square across the float ; and in a 
rasp the detached teeth are made by solitary indentations of a 
pointed chisel or punch, a subject that will be further noticed 
when the cutting of files is adverted to. 

Double-cut files are made of several gradations of coarseness, 
and which are thus respectively named by the Lancashire and 
Sheffield makers : 



LANCASHIRE FILES. 



SHEFFIELD FILES. 



1. Rough. 

2. Bastard. 

8. Second-cut. 

4. Smooth. 

5.* Dead-smooth. 



1. Rough. 
2.* Middle-cut. 
8. Bastard. 
4.* Second-cut. 

5. Smooth. 

6. Superfine. 

The sizes marked with asterisks are not commonly made, and 
this reduces each scale of variety of cut to four kinds, of which 
the Lancashire are somewhat the finer. The above names afford, 
however, but an indifferent judgment of the actual degrees of 
coarseness, which, for all the denominations of coarseness, differ 
with every change of length ; but the numbers in the annexed 
table may be considered as pretty near the truth : 

Approximate Numbers of Cuts in the Inch, of Lancashire Files.* 



Lengths in Inches. 


4 


6 


8 


12 


16 


20 


Rough-out . 


56 


52 


44 


40 


28 


21 


Bastard-cut . . 


76 


64 


56 


48 


44 


34 


Smooth-cut . 


112 


88 


72 


66 


64 


56 


Superfine-cut . . 


216 


144 


112 


88 


76 


64 



Of floats and rasps, but two denominations are generally made, 
and which are simply distinguished as coarse and fine ; the fine 
are also called cabinet floats and rasps ; and as with the files, the 

* The numbers in the Table, were counted from the engravings of the teeth of 
files in Mr. Stubs' pattern book. These engravings were laid down with great care 
from the files themselves, and it is somewhat curious the numbers should so nearly 
fall in regular series. The second courses of teeth were in each case counted, and 
which are somewhat finer than the first course, as explained on page 829. 

One of the smallest and finest Lancashire files, was found by the author to con- 
tain from 290 to 300 cuts in the inch, which is confirmatory of the above numbers. 



SECTIONS OP PILES. 



621 



two nominal sizes of the t, < th of floats and rasps, differ for every 
variety of length in tin- instrmni i 

5. Safe-edge*. Some files have one or more edges that an l.-l't 
uncut and these are known as naft-tdgtu, because such edges are 
not liable to act upon those parts of the work againat \\ hieh 
are allowed to rub, for the purpose of guiding the lustrum 
The safe-edge file is principally required in making a set-off, or 
shoulder, at any precise spot iu the work, and in filing out r 
angular corners; as whilst the one side of the notch is being 
filed, the other side can be used to direct the file. Occasionally 
the edges alone of files are cut, and the sides are left safe or 
smooth, as in some warding files, which nearly resemble saws. 

6. The name* qffile*. These are often derived from their pur- 
poses, as iu saw files, slitting, warding, and cotter files ; the names 
of others from their sections, as square, round and half round files. 



Figs. 805. Sections derived from the Square. 
B C D F 



G 



H 



Figs. 808. Sections derived from the Circle. 

L M N P 




R 



Fig*. 807. Sections derived from the Triangle. 
S T V \V X Y 




Ml 



Files of all the sections represented in the groups, figs. 805, 
806, and 807, are more or less employed, although many of them 
are almost restricted to particular purposes, and more especially 
to the art of watchmaking, for which art indeed, very many of 
the files have been originated. The sections may be considered 
to be derived from the square, the circle, and the equilateral 
triangle, as will be detected by the eye without description. 

To avoid wearying the reader by attempting to describe all 
the various tiles that are made, the eight or nine kinds which are 
of most extensive application, will be briefly adverted to, nud 
these will be placed in the supposed order of their usefulness 
as derived partly from the author's observation, aud partly from 



822 FILES COMMONLY USED. 

the relative quantities considered to be manufactured of each 
kind in two large establishments. After this, a few remarks will 
be given on some of the files to which the sections 805 to 807 
refer, and this, or the first division of the chapter, will be con- 
cluded by a short account of the mode of forming the teeth of 
files, and some other particulars of their construction. 



It may be considered that in nearly every branch of art in 
which the file is used, that the following constitute the basis of 
the supply ; namely, taper files, hand files, cotter and pillar files, 
half-round, triangular, cross, and round files, square, equalling, 
knife and slitting files, and rubbers ; a short explanation will be 
given of all of these varieties, in the course of which, reference 
will be occasionally made to the sections A to Z just given. 

Taper files, or taper flat files, are made of various lengths from 
about 4 to 24 inches, and are rectangular in section as in B 
fig. 805 ; they are considerably rounded on their edges, and a 
little also in their thickness ; their greatest section being towards 
the middle of their length or a little nearer to the handle, whence 
these files are technically known to be "bellied;" they are cut 
both on their faces and edges with teeth of four varieties, namely, 
rough, bastard, second-cut, and smooth-cut teeth. Taper flat 
files are in extremely general use amongst smiths and mechanics, 
for a great variety of ordinary works. 

Hand files or flat files resemble the above in length, section, and 
teeth, but the hand files are nearly parallel in width, and some- 
what less taper in thickness than the foregoing. Some few of 
them are called parallel-hand-files, from having a nearer equality 
of thickness, and parallelism of sides. Engineers, machinists, 
mathematical instrument makers and others, give the preference 
to the hand file for flat surfaces and most other works, except in 
filing narrow apertures and notches, as then the small end of the 
taper file, first described, may be employed in the commence- 
ment, gradually the central and wider part, and then the entire 
length of the instrument, as the space or notch to be filed becomes 
wider; the taper form thus enables a larger and stronger file to 
be used in the commencement, but for other and accurate pur- 
poses the hand file is esteemed preferable to the taper. 

Cotter files are always narrower than hand files of the same 




PILES COMMONLY USED. 

h ami thickness ; they are nearly flat on the side* and edge*, 
so as to present almost the same section at every part of their 

.tli, in which regret they \.iry IV. nn 6 to 22 inches. Co 1 
files are mostly used in filing grooves, for the cotters, keys or 
wedges, used in fixing wheels ou their shafts, whence their n; 
The taper cotter files, or as they are also called entering files, are 
entirely dillerent from the above, as they arc taper both in width 
and thickness, and almost without any swell, or pyramidal, in 
which respect alone they differ from ordinary taper files that are 
usually much swelled or bellied. 

Pillar files, also somewhat resemble the bund files, but they 
are much narrower, somewhat thinner, as in C, and are used for 
more slender purposes, or for completing works that have been 
commenced with the hand files. Pillar files have commonly one 
safe edge, and vary from 3 to 10 inches in length. 

Half round files, are nearly of the section L, notwithstanding 
that the name implies the semicircular section ; in general the 
curvature only equals the fourth to the twelfth part of the circle, 
the first being called full half round, the \&stflat half round files. 
The half round files, vary from about 2 to 18 inches in length, 
and are almost always taper. The convex side is essential for a 
variety of hollowed works, the flat side is used for general 
purposes. 

Tringular files, commonly misnamed "three-square" files, are 
of the section R, and from 2 to 16 inches long; they are used for 
internal angles more acute than the rectangle, and also for clear- 
ing out square corners. One of the greatest uses of triangular 
files from 3 to 6 inches long, is the sharpening of saws, the 
greater number of which have teeth of the angle of 60 degrees; 
an aiiL'li- doubtless selected, because it appertains to all the angles 
of the equilateral triangular file, the three edges of which are 
therefore alike serviceable in sharpening saws. In the southern 
parts .. f Knjaud, saw-files with single-cut teeth, are in more 
general nse.from the idea that they "cut tweeter;" in the midland 
and northern ,. the double-cut files of the same dimensions 

are more in vojjue, being esteemed more durable. Small saws 
for metal, which are harder than those for wood, are always 
K in (1 with double cut files, the Lancashire being preferred. 

Cross files, or crossing files, sometimes called double half- 
rounds, are of the section M, or circular on both faces, but of 



824 FILES COMMONLY USED. 

two different curvatures, they are used for concave or hollowed 
forms the same as the convex side of the half-round ; but cross- 
ing files are on the whole shorter and less common than half- 
round files, and are probably named from the files being used 
in filing out the crosses of arms or small wheels, as in clock- 
work, in which ease the opposite sides present a two-fold choice 
of curvature in the same instrument, which is convenient. 
Those cross files which are principally known as double half- 
rounds, are fuller or more convex on both faces than ordinary 
cross-files, and are employed by engineers. 

Round files, of the section I, range from the length of 2 to 18 
inches ; they are in general taper, and much used for enlarging 
round holes. The round file is better adapted than the so-called 
half-round file, to works the internal angles of which are filled in 
or rounded, as the round file is much stronger than the half-round 
of the same curvature. Small taper round files, are often called 
rat-tail files, and the small parallel round files, are also called 
"oint files, as they are used in filing the hollows in the joints of 
snuff-boxes and similar objects, for the reception of the pieces of 
joint wire (vol. i. page 429), that are soldered in the hollow 
edges of the work for the joint pin or axis. 

Square files, are used for small apertures, and those works to 
which the ordinary fiat files are from their greater size less 
applicable. The square files measure in general from 2 to 18 
inches long, and are mostly taper ; they have occasionally the 
one side safe or uncut. 

Equalling files, are files of the section D ; in width, they are 
more frequently parallel than taper, in thickness they are always 
parallel. They are in general cut on all faces, sometimes, as in 
the warding files for locksmiths, the two broad surfaces are 
left uncut or safe, and they range from 2 to 10 inches long. 

Knife files, are of the section T, and in general very acute on 
the edge, they are made from 2 to 7 inches long, and are as 
frequently parallel as taper. The knife files are used in cutting 
narrow notches, and in making the entry for saws, and for files 
with broader edges ; knife files are also employed in bevilling 
or chamfering the sides of narrow grooves. 

Slitting files, called also feather-edged files, resemble the last in 
construction and purpose, except in having, as in section V, two 
thin edges instead of one ; they are almost always parallel. 



"illl-R FILES OF DIFFERENT SECT I 

, are strong heavy files generally made of an inferior 
kind <>:-(,!, they measure from 12 to 18 inches long, from f to 
uches on every side, and are made very convex or fish- 
bellictl ; tlu van- frequently designated by their weight alone. 
which varies from about 4 to 151bs. Rubbers are nearly re- 
stricted to the square and triangular sections A and R. Some 
few rubbers are made nearly square in section, but with one side 
roiiiuit -d, as if the sections K ami B were united, these are called 
half thick. Rubbers are scarcely ever used by machinists and 
engineers, but only for coarse manufacturing purposes, where 
the object is rather to brighten the surface of the work, than to 
give it any specific form. Rubbers were formerly made only of 
bar or common steel, but are now also made of cast-steel, and in 
a more careful manner. 

Many arti/aus, and more particularly the watchmakers, require 
other files than those described, and it is therefore proposed to 
add the names of some of the files to which the sections refer, 
premising that such names as are printed iu Italics, designate 
small files especially used in watchmaking. 

Names of some of the Files, corresponding with the Sections 
A to Z, (represented on page 821). 

A. Square files, both parallel and taper, some with one safe 
side ; also square rubbers. 

B. When large, cotter files ; when small, verge and pivot files. 

C. Hand files, parallel and flat files; when small, pittance 
files ; when narrow, pillar files ; to these nearly parallel 
files are to be added the taper flat files. 

D. \Vhcu parallel, equalling c/ocAr-/>i/iio and endless-screw files ; 
\vhen taper, slitting, entering, warding, and barrel-hole 
til.-. 

E. French pivot and shouldering files which are small, stout, and 
have safe-edges; when made of large size and right and 
left they are sometimes called parallel V tiles, from their 
suitability to the hollow V V's of machinery. 

F. Name and purpose similar to the last. 

G. Flat file with hollow edges, principally used as a nail file 
for the dressing case. 

H . Pointing mill-saw file, round-edge equalling file, and round- 
edge joint file ; all are made both parallel and taper. 



S2l> OTHER FILES OF DIFFERENT SECTIONS. 

I. Round file, gulleting saw file, made both parallel and taper. 

K. Frame saw file, for gullet teeth. 

L. Half round file. Nicking and piercing files, also cabinet 
floats and rasps ; all these are usually taper. Files of this 
section which are small, parallel, and have the convex 
side uncut, and have also a pivot at the end opposite the 
tang, are called round-off files, and are used for rounding 
or pointing the teeth of wheels, cut originally with square 
notches. The pivot enables the file to be readily twisted 
in the fingers to allow it to sweep round the curve of 
the tooth to be rounded. 

M. Cross, or crossing files, also called double half rounds. 

N. Oval files; oval gulletting files for large saws, called by the 
French limes a double dos. Oval- dial file when small. 

O. Balance-wheel or swing-wheel files, the convex side cut, the 
angular sides safe. 

P. Swaged files, for finishing brass mouldings ; sometimes the 
hollow and fillets are all cut. 

Q. Sir John Robison's curvilinear file, to be hereafter described. 

R. Triangular, three-square, and saw files, also triangular 
rubbers, which are cut on all sides. Triangular files 
are also made in short pieces, and variously fixed to 
long handles, for works that are difficult of access, as 
the grooves of some slides and valves, and similar works. 

S. Cant file, probably named from its suitability to filing the 
insides of spanners, for hexagonal and octagonal nuts, 
or as these are generally called, six or eight canted 
bolts and nuts ; the cant files are cut on all sides. 

T. When parallel, flat-dovetail, banking and watch-pinion files ; 
when taper, knife-edged files. With the wide edge round 
and safe, files of the section T, are known as moulding 
files, and clock-pinion files. 

V. Screw-head files, feather-edge files, clock and watch-slitting 
files. 

W. Is sometimes used by engineers, in finishing small grooves 
and key ways, and is called a valve file, from one of 
its applications. 

X. A file compounded of the triangular and half-round file, and 
stronger than the latter; similar files with three rounded 
faces have also been made for engineers. 



MANUFACTURE OF FILES. V.'7 

N I> >i,i,|. ,,i :i filet, used by cutlers, gun-makers 

and others. The tiles are made separately and r. 
together, with the edge of the one before that of the 
dtlu-r, iu order to ^i\c the equality of distance and 
parallelism of ehecki n <! works, ju-t as in the double saws 
for rutting the teeth of racks and combs, see p. 7~ 

Z. Double file, made of two flat files fixed together in a wood 
or metal stock; this was invented for filing lead pencils 
to a fine conical point, and was patented by Mr. Cooper 
under the name of the Styloan/non. 



The manufacture of files. The pieces of steel, or the blanks 
intended for files, are forged out of bars of steel, that have been 
either tilted or rolled as nearly as possible to the sections 
required, so as to leave but little to be done at the forge ; the 
blanks are afterwards annealed with great caution, so that in 
neither of the processes the temperature known as the blood-red 
heat may be exceeded. The surfaces of the blanks are now 
rendered accurate in form and quite clean in surface, either by 
filing or grinding. In Warrington, where the majority of the 
files manufactured are small, the blanks are mostly filed into 
shape as the more exact method ; in Sheffield, where the greater 
number are large, the blanks are more commonly ground on 
large grindstones as the more expeditious method, but the best 
of the small files are here also filed into shape : and in some few 
eases the blanks are planed in the planing machine, for those 
called dead-parallel files, the object being in every case to make 
the surface clean and smooth. The blank before being cut is 
slightly greased, that the chisel may slip freely over it, as will 
be explained. 

The file cutter, when at work, is always seated before a 
square stake or anvil, and he places the blank straight before 
him. witli the tang towards his person, the ends of the blank 
are fixed down by two leather straps or loops, one of which is 
held fast hv each foot. 

The largest and smallest chisels commonly used in cutting 
files are represented in two views, and half size in figs. 808 and 
809. The first is a chisel for large rough Sheffield files, tin- 
length is about -'3 inches, the width :2| inches, and the angle of 



8-28 



CUTTING THE TEETH OF FILES. 



the edge about 50 degrees, the edge is perfectly straight, but 
the one bevil is a little more inclined than the other, and the 
keenness of the edge is rounded off, the object being to indent, 
rather than cut the steel ; this chisel requires a hammer of about 
7 or 8 Ibs. weight. Fig. 809 is the chisel used for small super- 
fine Lancashire files, its length is inches, the width inch, it 
is very thin and sharpened at about the angle of 35 degrees, the 
edge is also rounded, but in a smaller degree; it is used with a 



810. 




hammer weighing only one to two ounces, as it will be seen the 
weight of the blow mainly determines the distance between the 
teeth. Other chisels are made of intermediate proportions, but 
the width of the edge always exceeds that of the file to be cut. 

The first cut is made at the point of the file, the chisel is held 
in the left hand, at an horizontal angle of about 55 degrees, with 
the central line of the file, as at a a fig. 810, and with a vertical 
inclination of about 12 to 4 degrees from the perpendicular, as 
represented in the figures 808 and 809, supposing the tang of 
the file to be on the left-hand side.* The blow of the hammer 
upon the chisel, causes the latter to indent and slightly to drive 
forward the steel, thereby throwing up a trifling ridge or burr, 
the chisel is immediately replaced on the blank, and slid from 
the operator, until it encounters the ridge previously thrown up, 
which arrests the chisel or prevents it from slipping further 

" A foreman, experienced in the manufacture of Sheffield files, considers the 
following to be nearly the usual angles for the vertical inclination of the chisels : 
namely, for rough rasps, 15 degrees beyond the perpendicular; rough files, 12 
degrees; bastard files, 10 degrees; second-cut files, 7 degrees; smooth-cut files, 
5 degrees ; and dead-smooth-cut files, 4 degrees. 



Ct 1 KB TEETH OF FILES. 

back, and the T. 1\ K -ti nuines the succeeding position of the 
rhivl. The heavier tin- blow, the greater the ridge, and the 
greater the distance from tin- pn -ceding cut, at which the chisel 
is arrested. The chisel having been placed in its second posi- 
tion, is again struck with the hammer, which is made to give 
the blows as nearly as possible of uniform strength, and the pro- 
cess is repented with considerable rapidity and regularity, GO to 
80 cuts being made in one minute, until the entire length of the 
file has been cut with inclined, parallel, and equi-distant ridges, 
which are collectively denominated the first course. So far as 
this one face is concerned, the file if intended to be single-cut 
would be then ready for hardening, and when greatly enlarged 
its section would be somewhat as in fig. 81 1.* 

Most files, however, are double-cut, or have two series or 
courses of chisel-cuts, and for these the surface of the file is now 
smoothed by passing a smooth file once or twice along the face 
of the teeth, to remove only so much of the roughness as would 
obstruct the chisel from sliding along the face in receiving its 
successive positions, and the file is again greased. 

The second course of teeth is now cut, the chisel being 
inclined vertically as before or at about 12 degrees, but horizon- 
tally, only a few degrees in the opposite direction, or about 5 to 
10 degrees from the rectangle, as at b b, fig. 810 ; the blows are 
now given a little less strongly, so as barely to penetrate to the 
bottom of the first cuts, and from the blows being lighter they 
throw up smaller burrs, consequently the second course of cuts 
is somewhat finer than the first. The two series of courses, fill 
the surface of the file with teeth which are inclined towards the 
point of the file, and that when highly magnified much resemble 
in character the points of cutting tools generally, as seen in 
fig. 811, for the burrs which are thrown up and constitute the 
tops of the teeth, are slightly inclined above the general outline 
of the file, minute parts of the original surface of which still 
remain nearly in their first positions. 

If the file is flat and to be cut on two faces, it is now turned 
over, but to protect the teeth from the hard face of the anvil, a 
thin plate of pewter is interposed. Triangular and other files 



The teeth of tome ingle out file* are much lea inclined than 55 degree*, thoee 
of float* are in general equare arrow the instrument. 



830 



CUTTING THE TEETH OF FILES AND RASPS. 



require blocks of lead having grooves of the appropriate sections 
to support the blanks, so that the surface to be cut may be 
placed horizontally. Taper files require the teeth to be some- 
what finer towards the point, to avoid the risk of the blank being 
weakened or broken in the act of its being cut, which might 
occur if as much force were used in cutting, the teeth at the 
point of the file, as in those at its central and stronger part. 

Eight courses of cuts are required to complete a double-cut 
rectangular file that is cut on all faces, but eight, ten, or even 
more courses are required, in cutting only the one rounded face 
of a half-round file. There are various objections to employing 
chisels with concave edges, and therefore in cutting round and 
half-round files, the ordinary straight chisel is used and applied 
as a tangent to the curve, but as the narrow cuts are less 
difficult than the broad ones, half-round and round files are 
generally cut by young apprentice boys. It will be found that 
in a smooth half-round file one inch in width, that about twenty 
courses are required for the convex side, and two courses alone 
serve for the flat side. In some of the double-cut gullet-tooth 
saw files, of the section K, as many as 23 courses are sometimes 
used for the convex face, and but 2 for the flat. The same diffi- 
culty occurs in a round file, and the surfaces of curvilinear files 
do not therefore present, under ordinary circumstances, the 
same uniformity as those of flat files, as the convex files are 
from necessity more or less polygonal. 

Hollowed files are rarely used in the 
arts, and when required it usually becomes 
imperative to employ a round-edged chisel, 
and to cut the file with a single course of 
teeth. Sir John Robison's curvilinear 
file will be hereafter noticed, in which the 
objections alluded to in both hollowed 
and rounded files are nearly or entirely 
removed. 

The teeth of rasps are cut with a pecu- 
liar kind of chisel, or as it is denominated a 
punch, which is represented also half size, 
and in two views in fig. 812. The punch 
for a fine cabinet rasp is about 3 inches long, and f square at its 
widest part. Viewed in front, the two sides of the point meet at 




! KTII OF RASPS. 831 

mglc of about 60 degrees, viewed edgeways, or in profile, the 
edge forms an angle of about 60 degrees, the one- face being 
only :i lift!.' inclined to the body of the tool. Different si 
rasps necessarily require different sized punches, tin- ends of 
h would luiu-li resemble the ordinary point tools for turning 
wood or i\ory. hut that they are more obtuse, and that the edge 
of the punch is rounded, that the tool may rather indent than cut . 

In cutting rasps, the punch is sloped rather more from the 
operator than the chisel in cutting files, but the distance between 
the teeth of the rasp cannot be determined as in the file, by 
placing the punch in contact with the burr of the tooth previously 
made. By dint of habit, the workman moves or, technically, 
hops the punch the required distance; to facilitate this move- 
ment, he places a piece of woollen cloth under his left hand, 
which prevents his hand coming immediately in contact with, 
and adhering to the anvil. 

The teeth of rasps are cut in rather an arbitrary manner, and 
to suit the whims rather than the necessities of the workmen 
who use them. Thus the lines of teeth in cabinet rasps, wood 
rasps, and farriers' rasps, are cut in lines sloping from the left 
down to the right-hand side ; the teeth of rasps for boot and 
shoe-last makers and some others, are sloped the reverse way; 
and rasps for gun-stockers and saddle-tree makers are cut in 
circular lines or crescent form. These directions are quite 
immaterial; but it is important that every succeeding tooth 
should cross its predecessor, or be intermediate to the two before 
it ; as if the teeth followed one another in right lines, they would 
produce furrows in the work, and not comparatively smooth 
surfaces. Considering the nature of the process, it is rather 
surprising that so much regularity should be attainable as may 
be observed in rasps of the first quality. 

In cutting files and rasps, they almost always become more 

or less bent, and there would be danger of breaking them if they 

were set straight whilst cold, they are consequently straightened 

whilst they are at the red heat, immediately prior to their being 

l and tempered. 

Previously to their being hardened, the files are drawn through 

beer grounds, yeast, or other sticky matter, and then through 

,mou salt, mixed with cow's hoof prc\ loudly roasted and 

pounded, and which serve a* a defence to protect the delicate teeth 



832 HARDENING AND STRAIGHTENING FILES. 

of the file from the direct action of the fire. The compound 
likewise serves as an index of the temperature, as on the fusion 
of the salt, the hardening heat is attained; the defence also 
lessens the disposition of the files to crack or clink on being 
immersed in the water, see vol. i. page 253. 

The file after having been smeared over as above, is gradually 
heated to a dull red, and is then mostly straightened with a 
leaden hammer on two small blocks also of lead ; the tempera- 
ture of the file is afterwards increased, until the salt on its 
surface just fuses, when the file is immediately dipped in water. 
The file is immersed, quickly or slowly, vertically or obliquely, 
according to its form ; that mode being adopted for each variety 
of file, which is considered best calculated to keep it straight. 

It is well known that from the unsymmetrical section of the 
half-round file, it is disposed on being immersed, to become 
hollow or bowed on the convex side, and this tendency is com- 
pensated for, by curving the file whilst soft in a nearly equal 
degree in the reverse direction ; by this compensatory method, 
the hardening process leaves the half-round files nearly straight. 

It nevertheless commonly happens, that with every precaution 
the file becomes more or less bent in hardening, and if so, it is 
straightened, not by blows, but by pressure, either before it is 
quite cold, or else after it has been partially reheated in any 
convenient mode ; as over a clear fire, on a heated iron bar, over 
a hooded gas flame, as in tempering watch-springs, or in any 
other manner. The pressure is variously applied, sometimes by 
passing the one end of the file under a hook, supporting the 
center on a prop of lead, and bearing down the opposite end of 
the file ; at other times by using a support at each end, and 
applying pressure in the middle, by means of a lever the end of 
which is hooked to the bench, as in a paring-knife. Large files 
are always straightened before they are quite cooled after the 
hardening, and whilst the central part retains a considerable 
degree of heat. When straightened, the file is cooled in oil, 
which saves the teeth from becoming rusty. 

The tangs are now softened to prevent their fracture ; this is 
done either by grasping the tang in a pair of heated tongs, or by 
means of a bath of lead contained in an iron vessel with a per- 
forated cover, through the holes in which, the tangs are immersed 
in the melted lead that is heated to the proper degree ; the tang 




MEANS OP GRASPING PILES. '''> 

is afterwards cooled in oil, and when the file has beeii wiped, 

ami the teeth brushed clean, it is considered fit for use. 

i 

The superiority of the file will be found to depend on four 
points, the primary excellence of the steel the proper forging 
and annealing without excess of heat the correct formation of 
the teeth and the success of the hardening. These several 
processes are commonly fulfilled by distinct classes of work- 
people, who are again subdivided according to the sizes of the 
files, the largest of these being cut by powerful muscular men, 
the smallest by women and girls, who thereby severally attain 
great excellence in their respective shares of the work. 

The manufacture of files, especially the cutting of the teeth, 
has been entered into much more largely than was at first 
intended, but it is hoped this may not be without its use ; as 
notwithstanding the suitability of ordinary files to most purposes, 
still occasions may and do occur, in which the general mechanist 
or amateur may find some want unsupplied, which these hints 
may enable him to provide for, although less perfectly, than if 
the file in question had been manufactured in the usual course. 
The process of cutting teeth, is also called for in roughing the 
jaws of vices and clamping apparatus.* 

Means of grasping the file. In general the end of the file is 
forged simply into a taper tang or spike, for the purpose of 
fixing it in its wooden handle, but wide files require that the 
tang should be reduced in width, either as in fig. 813 or 814. 
The former mode, especially in large files, is apt to cripple the 
steel and dispose the tang to break off, after which the file is 
nearly useless; the curvilinear tang, 814, is far less open to this 
objection, and was registered by Messrs. Johnson, Cammell, and 
Co., of Sheffield. Some workmen make the tangs of large files 
red hot, that they may burn their own recesses in the handles, 
but this is objectionable, as the charred wood is apt to crumble 

There is perhaps an equal mixture of philosophy and prejudice in the harden- 
ing of file* : some attach very great importance to the coating or defence, other* to 
the medication of the water, and all to the mode of immersion bent calculated for 
each different file, in order to keep it as straight as possible, question* of opinion 
which it is impossible to generalise. Mr. Stube's process of manufacture ] 
pretty much as above described, and although he has experimented with mercury 
at 8 F., as the cooling medium, as well as various fluids, he has arrived at the 
conclusion, that the salt principally acts ai an antiseptic, and that fresh spring 
water at 45* is as effective as any fluid. 

3 H 



834 



VARIOUS MEANS OF GRASPING FILES. 




away and release the file : it is more proper to form the cavity 
in the handle, with coarse floats made for the purpose. 

In driving large files into their handles, it is usual to place the 
point of the file in the hollow behind the chaps of the tail vice, 



Figs. 



813. 



814. 



81 5.. 1 



and to drive on the handle with a mallet or hammer. Smaller 
files are fixed obliquely in the jaws of the vice, between clamps 
of sheet brass, to prevent the teeth either of the vice or file, from 
being injured, and the handle is then driven on. The file, if 
small, is sometimes merely fixed in a cork, or in a small piece of 
hazle rod, but these are to be viewed as temporary expedients, 
and inferior to the usual wooden handles turned in the lathe. 
Very small watch files are fixed in handles no larger than drawing 
pencils, and some few of them are roughened on the tang, after 
the manner of a float, and fixed in by sealing wax or shell lac. 

Several of the small files have the handles forged in the solid, 
that is, the tang is made longer than usual, and is either parallel, 
or spread out, to serve for the handle, as in a razor strop ; many 
of the watch files are thus made. In the double-ended rifflers, 
or bent files, fig. 815, used by sculptors and carvers, and in 
some other files, there is a plain part in the middle, fulfilling 
the office of a handle ; and in several of the files and rasps made 
for dentists, farriers, and shoemakers, the tool is also double, but 
without any intermediate plain part, so that the one end serves 
as the handle for the other. 

In general the length of the file exceeds that of the object 
filed, but in filing large surfaces it becomes occasionally neces- 
sary to attach cranked handles to the large files or rubbers, as in 



US MEANS OF ORASPIN'; FILK*. 



336 



fig. 810, in order to raise the hand alx.\e the plane of the work. 

ad of the file is simply inclined, ns in fig. v 
or bent at right angles, as in 818, for the attachment of the 
wooden handles represented ; hut the last two modes 

Mvond >ide of the file from hen until the tang is 1 

the reverse way. The necessity for bending the file is : 
by employing as a handle, a piece of round iron $ or $ J'<'h in 
diameter, hent into the semicircular form as an arch, the one 
extremity (or abutment), of which is filed with a taper groove to 
fit the tang of the file, whilst the opposite end is flat, and r 
upon the teeth ; in this manner, both sides of the file may be 
used without any preparation. 

Pig. 819 represents, in profile, a broad and short rasp with fine 
teeth, used by iron-founders in smoothing off loam moulds for 
iron castings, this is mostly used on large surfaces, to which the 
ordinary handle would be inapplicable, and the same kind of tool 
when made with coarser teeth, will be recognised as the baker's 
r.-'.-p. For some slight purposes, ordinary files are used upon 
large surfaces, without handles of any kind, the edges of the file 
itself being then grasped with the fingers. 

Cabinet-makers sometimes fix the file to a block of wood to 
serve for the grasp, and use it as a plane. Thus mounted, the 
file may also be very conveniently used on a shooting board, in 
filing the edges of plates to be inlaid. 

Fig. 820 represents a very good arrangement of this kind by 
Mr. W. Lund, a a is the plan and b the section of the file-stock, c c 

Fig. 820. 




is the plan oft lie shooting board and r/its section. Two files fl 

' (1 hlack), are screwed against the sides of a straight 
3 n 2 



VARIOUS MEANS OF GRASPING FILES. 

bar of wood, which has also a wooden sole or bottom plate, that 
projects beyond the files, so that the smooth edge of the sole may 
touch the shooting board instead of the file teeth. The shooting 
board is made in three pieces, so as to form a groove to receive 
the file dust, which would otherwise get under the stock of the 
file; the shooting board has also a wooden stop s, faced with 
steel, that is wedged and screwed into a groove made across the 
top piece, and the stop being exactly at right angles, serves also 
to assist in squaring the edges of plates or the ends of long bars, 
with accuracy and expedition. Mr. Lund prefers a flat file that 
is fully curved on the face, as nearly half the file then comes 
into action at every stroke. 

Short pieces of files (or tools as nearly allied to saws), are 
occasionally fixed in the ends of wooden stocks, in all other 
respects like the routing gages of carpenters, as seen in two 
views in fig. 821 ; the coopers' croze, page 488, is a tool of this 
description. 

Files intended for finishing the grooves in the edges of slides, 
are sometimes made of short pieces of steel of the proper section, 




) 823. 







a>i ) MB. 



"I- a fell )82T. 







(see fig. 822,) cut on the surfaces with file teeth, and attached in 
various ways to slender rods or wires, serving as the handles, and 
extending beyond the ends of the slides. Or the handle is at 
right angles to the file, and formed at the end, as a staple, to clip 
the ends of the short file, as in reaching the bottom of a cavity. 
Files intended to reach to the bottom of shallow cavities are 
also constructed as in figs. 823 and 824, or sometimes an inch or 
more of the end of an ordinary file is bent some 20 or 30 degrees, 
that the remainder may clear the margin of the recess. 

To stiffen slender files, they are occasionally made with tin or 
brass backs, as in figs. 825 and 826 ; such are called dove-tail 






>S USUAL M 

ti!i *, c\idcntly from tln-ir similitude to dove-tail saws; and thin 
equalling files, are sometimes grasped in :i brass frame, fig. v 
exactly like that used for a metal frame-saw, by which the risk of 
breaking tin- instrument in the act of filing is almost annulled. 
equivocal analogy, both to the file and saw, is to be 
observed in Mime ut the delicate circular cutters, used in cutting 
watch u heels and other small works. The teeth of such cutters 
are in many instances formed by cuts of a chisel, the same as 
the teeth of files, and the axis of the cutter becomes, by corn- 
on, the handle of the circular file. 

SECT. II. GENERAL AND DESCRIPTIVE VIEW OF FILES OF 
LESS USUAL KINDS. 

Notwithstanding the great diversity in the files alluded to in 
the foregoing section, it is to be remarked that all those hitherto 
noticed are made entirely of steel, and their teeth are all pro- 
duced in the ordinary manner by means of the chisel and hand 
hammer ; in the present section, a few of the less usual kinds 
of rasps, floats, and files, will be noticed, the teeth of which are, 
for the most part, produced by means differing from those 
already described. 

The rifflers, fig. 815, used by sculptors, are required to be of 
numerous curvatures, to adapt them to the varying contour of 
works in marble. In general the rifflers are made of steel in 
the ordinary mode, but they have also been made of vrrought- 
iron, and slightly case-hardened, in which case the points of the 
teeth become converted into steel, but the general bulk of the 
instrument remains in its original state as soft iron; conse- 
quently such case-hardened rifflers admit of being bent upon a 
block of lead with a leaden mallet, so that the artist is enabled 
to modify their curvatures as circumstances may require. 

Several kinds of floats are made with coarse, shallow, and 
sharp teeth, which are in section like fig. G4G, page 684 ; these 
ii could not be cut with the chisel and hammer in the ordinary 
manner, but are made with a triangular file. Figs, a to /, 828, 
represent the sections of several of these floats, which have teeth 
at the parts indicated by the double lines ; for instance, a is the 
float, b the yraille, c the found, d the carlet, e the topper, used 
by the horn and tortoiseshell comb-makers; parts of the names 
of \\hieh floats are corrupted from the French language, indeed 



888 



FLOATS FOR TORTO1SESHELL, IVORY, ETC. 



the art was mainly derived from French artizans. The floats, 
/ to i, are used by ivory carvers for the handles of knives, and in 



Figs. 828. 



829. 




f 



the preparation of works, the carving of which is to be com- 
pleted by scorpers and gravers ; k and I are used in inlaying 
tools in their handles; k is made of various widths, and is 
generally thin, long, and taper; / is more like a key -hole saw. 
When the teeth of these floats have been formed with the 
triangular file, and made quite sharp, the tools are first hardened 
and very slightly tempered, just sufficiently to avoid fracture in 
use ; but, when after a period the tools have become dull, they 
are tempered to a deep orange, or a blue, so as to admit of being 
sharpened with a triangular file. 

The larger of the floats, such as those a to e, used by the 
comb -makers, are kept in order principally by the aid of a burn- 
isher, represented in two views in fig. 829, the blade is about 
2 inches long, 1 inch wide, and -^ inch thick ; the end is mostly 
used, and which is forcibly rubbed, first on the front edge of 
every tooth, as at a, fig. 830, and then on the back, as at b, by 
which means a slight burr is thrown up, on every tooth, somewhat 
like that on the joiner's scraper; but in this art the burnisher is 
commonly named a turn-file. When the teeth of the floats have 
become thickened from repeated burnishing, the triangular file 
is again resorted to, and then the burnisher for a further period ; 
by these means the floats are made to last a considerable time. 

The quannet is a float resembling fig. 819, but having coarse 
filed teeth, of the kind just described ; it may be considered as 
the ordinary flat file of the horn and tortoiseshell comb-makers, 
and in using the quannet, the work is mostly laid upon the knee 
as a support. An ingenious artizan in this branch, Mr. Michael 



WHITE'S IM i FILE. 8 /.' 

y, invented the i|ii:uiuet represented in figs. 830 and 831. 
stock consists of a piece of beech- wood, in which, at inter- 
vals of about one quarter of an inch, ruts inclined nearly 80 
degrees with , arc made with si thin saw; every cut is 

tilled with a piece of saw-plate. The edges of the plates and 
wood, are originally tiled into the regular float-like form, and 
the burnisher is subsequently resorted to as usual. The n 

mtage results from the small quantity of steel it is necessary 
to operate upon, when the instrument requires to be restored with 
the file. From this circumstance, and also from its less weight, 
the wooden quannet, fig. 830, is made of nearly twice the width 
of the steel instrument, fig. 819, and the face is slightly rounded, 
the teeth being sometimes inserted square across, as in a float, 
at other times inclined some 30 degrees, as in a single-cut file. 

A more elaborate, but less available, instrument was invented 
by Mr. White, probably daring his residence in France, about 
the time of the Revolution (1793). It consisted of numerous 
parallel plates of steel, which were placed vertically and in con- 
tact, something like a pack of narrow cards, and were fixed in 
that position in an appropriate frame, and as the edges of the 
plates were all bevelled, they constituted a single-cut file. The 
most curious part of the contrivance was, the ingenious mode of 
chamfering the edges, as for this purpose the plates were loosened 
and arranged in a sloping direction, so that the chamfers then 
lay collectively in one plane, which was ground either on a 
grind-stone, or a lead lap fed with emery ; the plates were re- 
placed perpendicularly before use. Means were also described 
for placing the steel plates square across the instrument as in a 
float, or inclined to the right or left as in a file, according to 
the material to be wrought; and. a drawing is also given of a 
circular float of similar nature for cutting dye-woods into small 
fragments. "White's "perpetual" file, with movcable plates, is 
however scarcely known, and it is very questionable if it ever 
obtained more than the experimental application which led to 
its description having been published.* 

The cutting of files by machinery is an operation that has 
engaged the attention of many persons, and the earliest attempt 

Publiihed in Diicnptimu da Mackina tt Proe^de$ tpccijiit dam let Hrtrtti 
<T/uu, i '', Ac. Par M. Chrittian. Parii, 4to, 1824. Tome 8, p. 99. Patent 
dated 6 Jan. 1795. 



840 THE CUTTING OF FILES BY MACHINERY. 

at the process that has come under the author's notice is that 
of Thiout aine, which was figured and described in a work by 
his son in 1740; and this machine being based on the manual 
process, in all probability differs but little in its general features 
from most of those of more recent projectors. 

According to the drawings referred to, the file is attached to a 
screw slide, Avhich is suspended at the ends by pivots, and covered 
with a thin plate of tin ; the slide rests upon a stationary anvil, 
and is actuated by a guide screw, which is moved at intervals, 
the space from tooth to tooth by a pin wheel, for which the 
ratchet wheel would be now substituted. The chisel is held by 
a jointed arm, beneath which is a spring to throw up the chisel 
from off the file, the moment after a drop hammer, which is also 
fixed on a joint, has indented the tooth. The movements of the 
slide and hammer are each repeated at the proper intervals, in 
every revolution of the winch handle, by which Thiout's machine 
is represented to be worked.* 

The practical introduction of machinery for cutting files 
appears to be due to a Frenchman of the name of Raoul, at 
about the close of the last century, but the description of the 
machine has not been published, and the manufacture is now 
carried on by his son, some of whose files are in the possession 
of the author. They are certainly beautiful specimens of work- 
manship, being more strictly regular, and also less liable to clog 
or pin when in use, than files cut by hand, as usual. 

His manufacture is principally limited to watch files with flat 
sides, and measuring from f of an inch, to 5 or 6 inches long. 
When magnified, the teeth of the files, cut either by hand or 
machinery, appear as nearly as possible of the same character.f 

Machines have been recently constructed in England for 



* See Thiout's TraH6 de I 'Horlogerie. Paris, 1740. Vol. 1, page 81, plates 33 
and 34. 

+ Mr. Raoul was rewarded for his files by the Lyce'e desArts,im institution that 
no longer exists, but which was founded soon after the French Revolution, for the 
reward of national discoveries and improvements. From the Report of the Lyceum 
of Arts it appears, that on the 1 Oth Thermidor, year 8 of the Republic (July, 1800), 
an honorary crown was decreed to Citizen Raoul for the perfection of his files. 
And on a subsequent page of the report, is given the opinion of a Committee 
appointed to examine into the comparative merits of Raoul'a files, from which 
report it appears, they were pronounced by tho Committee to be equal, and even 
superior, to the best English files. 



UY. 

.)_' both large and small filet, and half a dozen or more at 
>r. I lie details of the machines display great intimity 
and skill, especially in the arran-eiiu 'tit for holding the blanks 
and the chisels, and also in the intruduetiuu of templets and 
other mechanism, by which, in cutting taper files, the hammer 
is leas raised in cutting the ends of the file than at the middle, 
so as to proportion the force of the blow to the width and depth 
of the cut, at different parts of the file. Two machines u 
used for double-cut files, the bed of the one inclined to the right, 
of the other to the left, to give the different horizontal inclina- 
tions proper to these teeth; and a machine with a straight bed 
was used for single-cut floats, and for round and half-round files. 

Considerable difficulty was at first experienced in the manage* 
ment of the chisels, which were then very frequently broken, 
but with more dexterous management it is ultimately considered 
that the chisels last for a longer time in the machines, than 
when used by hand. The machines make about 24-0 strokes 
in the minute, or three times as many as the file cutter, with the 
advantage of nearly incessant action, as unlike the arm of the 
workman, the machines are unconscious of fatigue ; moreover, 
to save the delay of adjustment, two beds for the files are 
employed, so that the one may be filled whilst the blanks in the 
other are being cut, and two frames for the chisels are also 
alternately used. Taking all these points into account, each 
machine is considered by the proprietors, nearly to accomplish 
the work often men, but there are various drawbacks that prevent, 
under ordinary circumstances, any great commercial advantage 
in the machine over the hand process, from which considerations, 
the patent file cutting machines, are not at present used. 

In concluding this section, there remain to be introduced, two 
propositions for the manufacture of files, suggested by a very 
talented and philanthropic member of the scientific world, the 
late Sir John Robisou, K.H., F.R.S.E., late President of the 
Royal Scottish Society of Arts, &c., namely, his methods of 
making curvilinear files, and of cutting flat files with very fine 
h. The subjects cannot be better stated than by quoting 
Sir John's correspondence with the author; speaking of the 

Captain Lriocton* Patent File Cutting Machines, specified 1836, constructed 
by Meters. BraKhwatte* of London, and carried into practical effect by Me 
Turton & Sons, of Sheffield. 



SIR JOHN ROBISON'S CURVILINEAR FILES, AND 

curvilinear files of the Section Q., page 821, lie introduces the 
subject as follows : 

" I have just entered on a new project, of which I should be 
glad to know what you think. Having always found difficulty 
in filing hollow surfaces, from the scratches which the irregular 
cutting of even the best half-round, or round files, leave in the 
work, in spite of every care, I was lately led to consider whether 
half-round, or even round files, might not be made as perfect in 
their cutting as flat ones. It has occurred to me, that this object 
may be attained by cutting flat strips of rolled steel plate on one 
side, and then squeezing them into the desired curve by a screw 
press, and a block-tin or type-metal swage, and in the case of the 
round file, by pressing the plate round a cylindrical mandrel. 

" I do not think that the files made in this way should cost 
more than those now made, as the surface would be cut by two 
courses of cuts (as flat files are), instead of the numerous courses 
required to cover the surface of round files, the saving in this 
respect would make up for the time required in bending the 
plates." * * * * 

A valuable addition to Sir John's proposal occurred inciden- 
tally ; Messrs. Johnson and Cammell, to whom the scheme was 
communicated, in the haste of putting it to trial, took a thin 
equalling file that had been previously cut on both faces. The 
equalling file was softened, bent, and re-hardened, and this pro- 
duced a file, the convex and also the concave surface of which 
were both useful additions to thetools of the general mechanician. 

But it was found that with a plate of equal thickness, the 
central part bent more easily than the edges, making the curve 
irregular. This was successfully obviated by making the blank 
thinner and more flexible at the edges, somewhat as a half-round 
file, and in which case the bending was quite successful, and the 
section became truly circular.* 

Sir John Robison's second project in respect to the manufac- 

* The Society for the Encouragement of Arta, of London, bestowed its silver 
medal on Sir John Robison for his invention of the curved file, which distinction 
it is to be regretted arrived as a posthumous honour. (See Trans. Soc. of Arts, 
vol. liv., p. 128.) And the Royal Scottish Society of Arts presented, in November, 
1843, a silver medal to Messrs. Johnson, Cammell, and Co., for the skilful manner 
in which they had carried out and perfected the above scheme, and introduced the 
curved files as a regular article of manufacture. (See the official report in the 
Edinburgh New Philosophical Journal for January, 1844, p. 86.) 



HIS MODE 07 CUTTING PINE PLAT FILE*. s 1 "> 

tore of files, refers to a new mode of forming the teeth of 

herwisc than by percussion; and without delay 
tin render by referring to tin earlier correspondence on the 
subject, the author jjives a short extract from a letter recehrd 
v days before Sir John's death, and also the contents of the 
packet tli 1 to. 

" Lest my medical friends should be mistaken, ami this malady 
.case so as to prevent my communicating my project for cut- 
ting fine files, I shall now make out a memorandum of my ideas 
on the subject, and making a scaled packet of it shall enclose it 
to you. If I get better and reach London, we can discuss the 
matter together, and if I am put hors de combat, you will con- 
sider it your own. * 

" It appears to me that the graver may be applied with good 
cllect in cutting the teeth of the finer classes of flat files, and that 
if a number of steel blanks were firmly embedded on a platform 
similar to the bed of a planing table, and made to move forward 
in their own plane by a micrometer screw, then if an equal num- 
ber of gravers were to be fixed in a frame to lie over the plat- 
form, so that each graver point should be in a certain relative 
tion to one of the blanks, on motion being communicated 
to the frame in a proper direction, and to a distance a b'ttle ex- 
ceeding the breadth of the blank, a line would be ploughed out 
of the surface of each blank. If the frame were then brought 
back to its first position, and the platform advanced or receded 
by the micrometer screw, a second movement of the cutter frame 
would produce a line parallel to the first, and so on in succession. 

" If the points of the gravers, instead of being set to cut 



equilateral grooves as at A, were inclined so as to cut them as 
at 15, then, by a proper proportioning of the depth of the cut, 
and the progressive movement of the platform, a regular cutting 
tooth of great sharpness may be given to the file. 

ic movement to be given to the graver frame may be an 
oscillating one round a distant center, so that the short arc of 
the teeth may be sensibly a straight b'ne. 

" It is evident that the sharpness and smoothness of the 



PRELIMINARY REMARKS ON USING TILES. 

engraving must depend mainly on the way in Avhich the cutter 
is presented to the work, and experience shows that the position 
of the tool in the hand of the engraver is the most favourable, 
both to the production of clean lines, and the preservation of the 
point of the tool ; the graver must be supported endways, and 
not alone by fastenings in its middle, like the tool of a planing 
machine, or a slide rest cutter. 

" The means of regulating the depth of the cut, and the other 
arrangements of the parts of such a machine, would of course 
require consideration by engravers and practical mechanics. 

" (Signed) JOHN ROBISON. 

" EDINBURGH, 17th February, 1843." 

The author much regrets that the multiplicity of his engage- 
ments, and especially those connected with these pages, should 
have prevented him putting the above project to experimental 
proof, but he would be well pleased to hear that the subject had 
been brought to successful issue, by any person more favourably 
situated for carrying out the suggestion.* 

SECT. III. PRELIMINARY REMARKS ON USING FILES, AND ON 
HOLDING WORKS THAT ARE TO BE FILED. 

The use of the file is undoubtedly more difficult than that of 
the generality of mechanical tools, and the difficulty arises from 
the circumstance of the file possessing, but in a very inferior 
degree, the guide principle, the influence of which principle, in 
all tools, from the most simple cutting tool used by hand, to the 
most complex cutting machine or engine, formed the subject- 
matter of the introductory chapter of the present volume. The 
comparative facility of the manipulation of turning-tools, was 
shown to depend on the perfection in which the guide principle 
exists in the turning lathe. It was further stated at page 468 

" The guide principle is to be traced in most of our tools ; in 
the joiner's plane it exists in the form of the stock or sole of the 
plane, which commonly possesses the same superficies that it is 
desired to produce. For instance, the carpenter's plane used for 

Since writing the above, the author learns that Captain Ericcson tried some 
experiments on cutting file teeth as with a graver, but that he was led to con- 
aider the modeless practical than that of cutting teeth by percussion. The subject 
appears, however, to deserve more extended trial. 



PREMMINMIY REMARKS ON' V8INO FILES. 

surfaces is itself flat, both in length nnd width, nml therefore 
furnishes a double guide. The flat file is somewhat under the 
same circumstances, but as it cuts at every part of its surface, 
from thousands of points being grouped together, it is more 
!n TOMS than the plane, as regards the surface from which 
it derives its guidance, and from this nnd other reasons it is far 
more difficult to manage than the carpenter's plane." 

These points are recalled not to impress the amateur with the 
idea that the successful use of the file will be to him unattain- 
able, but rather to call forth such a measure of perseverance, as 
may enable many to arrive nt a practice which is confessedly 
difficult. It is proposed in the present section to notice certain 
preliminary and general topics, before attempting, in the next 
three sections, to convey the instructions for manipulating the file. 

Commencing with the position of the work, it is in all cases 
desirable that the surface to be filed should be placed horizontally, 
and the general rule for the height of the work above the ground 
is, that the surface to be filed should be nearly level with the 
elbow joint of the workman, and which may be considered to 
range with different individuals from forty to forty-five inches 
from the ground. Some latitude is, however, required in respect 
to the magnitude of the works, as when they are massive, and 
much is to be filed off from them, it is desirable that the 
work should be a trifle lower than the elbow ; when the work is 
minute and delicate, it should be somewhat higher, so that the 
eye may be the better able to add its scrutiny to that of the sense 
of feeling of the hand, upon which principally the successful 
practice depends. The small change of height is also in agree- 
ment with the three different positions of the individual in the 
act of filing ; for instance. 

Firstly. In filing heavy works, or those which require the 
entire muscular effort, the file varies from about 12 to 2t inches 
long, and the length of the stroke is from about 10 to 20 inches, 
or nearly the full length of the file. The operator stands a 
little distant from his work, with the feet separated about 30 
inches, which somewhat lowers his stature ; he grasps and thrusts 
the handle of the file with his right hand, and bears forcibly near 
the end of the file with that part of his left hand which is conti- 
guous to his wrist, so as to make the file penetrate the work, or 
hamj to it. The general mou'inrnt of the person is then an 



846 PRELIMINARY REMARKS OX USING FILES. 

alternation of the entire frame upon the knee and ankle joints, 
the arms being comparatively fixed to the body, the momentum 
of which is applied to the file. 

Secondly. In filing works of medium size, the file varies from 
about 6 to 12 inches, and the length of stroke is from about 4 to 
9 ; the operator then stands nearer to the work and quite erect, 
with his feet closer together. The right hand grasps the file 
handle as before, but the extremity of the file is now held between 
the thumb and the first two fingers of the left hand, and the 
general movement is that of the arms, the body being compara- 
tively at rest. 

Thirdly. In filing the smallest works the file is less than 
6 inches long, and the stroke does not exceed 3 or 4, and some- 
times is not one-tenth as much. When the work is fixed, the file 
is still usually held in both hands as last described, but frequently, 
in fact more generally, the file is managed with the right hand 
alone, the forefinger being stretched out as in holding a carving 
knife, and the work is held upon the support or filing block with 
the left hand, as will be explained. The act of filing is then 
accomplished by the movement of the elbow, or even of the 
fingers alone, but so little is the body moved, that the workman 
is usually seated as at an ordinary table. 

It is apparent, and also true, that the most direct way of pro- 
ducing a flat surface with the file, would be to select a file the 
face of which was absolutely flat, and that should be moved in 
lines absolutely straight ; but there are certain interferences that 
prevent these conditions being carried out. First, although it is 
desirable to employ files that are as nearly straight as possible, 
and that are also fixed straightly in their handles, yet very few 
files possess this exactitude of form, and although in the attempt 
to attain this perfection, some files are planed in the engineer's 
planing machine before being cut with teeth, still the cutting 
and the hardening so far invalidate this practice, that few even of 
these planed files can retain their perfect straightness, and either 
both sides become in a small degree irregularly tortuous, or the 
sides become respectively concave and convex. Therefore, as 
for the sake of argument, it may be almost taken for granted 
that no files truly possess the intended form, it is better purposely 
to adopt that kind of irregularity, which the least interferes 
with the general use of the instrument. 




PRELIMINARY REMARKS ON USING FILES. 



M7 



'1 In file, if concave or hollow in respect to its length, in the 
manner coarsely exaggerated in fig. VJ2, might be used for 

nwily ; but it would be impossible 
n flat surface therewith, as the concave file would only 



r - . 



- !. 




touch the surface at its edges, but the convex side of the same 
file might, as in fig. 833, be made to touch any and every part 
of the surface if moved in a right line. On this account most 
files arc made thicker and wider in the middle, or with both 
faces convex, and the error of hardening will then rarely make 
cither side concave, but will leave both faces convex, although 
differently so ; and consequently, both sides, notwithstanding 
some irregularity, are useable upon flat works, provided the 
operator can move them in a right line across the work. 

In reference to the manipulation of the instrument, it is to 
be observed that the most natural movements of the hand and 
arm are in circular lines, the several joints of the limbs being the 
centers of motion ; but, as in filing a flat surface, it is needful 
the hands should move very nearly in right lines, a kind of 
training becomes necessary. 

If, however, the file were carried quite straight across a wide 
surface, the central part of the file would be alone used ; but as 
the continual effort of the individual is to feel that the file lies in 
exact contact with the surface being filed, the hands imperceptibly 
depart so much from the exact rectilinear path as to bring all 
parts of the file from point to heel into use. 

Again, it might be urged that the file, from being itself in the 
form of the arc of a large circle, \\nuld reduce the work to the 
counterpart form, or make it hollow in the opposite degree; it is 
true this is the tendency, and may by dexterity become the 
result, even on narrow pieces; but the contrary error is more 






PRELIMINARY REMARKS ON USING FILES. 

common, so that the surface of the work becomes rounded instead 
of concave or plane. 

If the surface to be filed is four or five inches or more in 
width, the risk of departing from the true figure becomes 
reduced, as the file has then a wide base to rest upon, and the 
pressure of the hands readily prevents any material departure 
from the right position of the file ; but the difficulty becomes 
greatly increased when the surface to be filed is narrow. 

The file held in the two hands upon the narrow work, may 
be then viewed as a double-ended lever, or as a scale beam 
supported on a prop ; and the variation in distance of the hands 
from the work or prop gives a disposition to rotate the file 
upon the work, and which is only counteracted by habit or 
experience. 

Assuming, for the moment, that in the three diagrams the 
vertical pressure of the right hand at r, and the left at /, to 
be in all cases alike, in fig. 834, or the beginning of the stroke, 
the right hand would, from acting at the longer end of the lever, 
become depressed; in fig. 835, or the central position, the 
hands would be in equilibrium and the file horizontal ; and in 
fig. 836, or the end of the stroke, the left hand would prepon- 
derate; the three positions would inevitably make the work 
round, in place of leaving it plane or flat. 

It is true the diagrams are extravagant, but this rolling action 
of the file upon the work is in most cases to be observed in the 
beginner ; and those practised in the use of the file have, perhaps 
unconsciously, acquired the habit of pressing down only with the 
left hand at the commencement, and only with the right hand at 
the conclusion of every stroke ; or negatively, that they have 
learned to avoid swaying down the file at either extreme, and 
which bad practice will necessarily result, if the operator have 
not at first a constant Avatch upon himself, to feel that the file 
and work are always in true contact, throughout the variable 
action of the hands upon the instrument. 

When the work is fixed in the bench or table-vice, the file is 
almost always managed with both hands, as above described ; but 
when the file is held in the one hand only, all the circumstances 
are altered, except the continued attempt to keep the work and 
file in accurate juxta-position; and to assist in this, the work 
when so small as to be filed with the one hand only, is almost 



i: I MtllAL ROTATION OP nil I ll.E OR WORK. 840 

imariahlyheld on tlir tilinir-block with the h ft hand, occasionally 
through the intrr\< nt'ou of a hand-vice, as in fig, 858, page v 
In this case the two hands act in concert, the right in moving the 
file, tin- h-t't in adjusting the position of the work, until the indi- 
vidual is conscious of the agreement in position of the two parts. 
Sometimes indeed the partial rotation of the work, in order 
to adapt the x work to the file, is especially provided for, so as 
to compensate for the accidental swaying of the file ; such is the 
case in the various kinds of swing tools, used by watchmakers in 
filing and polishing small flat works. A similar end is more 
rarely obtained, on a larger scale, when the file is required to 
he held in both hands. For example, filing-boards resembling 
fig. 837, and upon which the work is placed, have been made 



Figs. 837. 8S8. 839. 




to move on two pivots, somewhat as a gun moves on its trunnions ; 
consequently the works, when laid upon the swinging bonrd, 
assume the same angle as that at which the file may at the 
moment be held. 

A more common case is to be seen in filing a rectangular mor- 
or key-way, through a cylindrical spindle, as in fig. 888; 
the hole is commenced by drilling three or four holes, which are 
thrown into one by a cross-cut chisel, or small round file; and 
the work, when nearly completed, is suspended between the 
centers of the lathe, so that it may freely assume the inclination 
of the file. At other times, the cylinder is laid in the interval 
between the edges of the jaws of the vice, that are opened as 
inue.h as two-thirds the diameter of the object, which then simi- 
larl uithesupporting edges; this mode is shown in fig. 839. 
i Implications are objectionable in some instances, 
as the file is left too much at liberty, and the works are liable to 
be filed hollow instead of flat, especially if the file be rounding, 
because the unstable position of the work prevents the file from 
beinu' constrained to act on any particular spot that may require 
to be reduced. 



850 ON PREPARING WORKS FOR FILING BY 

Some general remarks will be now given on certain practices 
in respect to economising the wear of files ; and these will be 
followed by other remarks on the modes of holding works that 
are to be filed, prior to giving, in the next sections, the practical 
instructions upon filing. 

The exterior surfaces of iron castings are usually more or less 
impregnated with the sand of the foundry moulds, which is very 
destructive to the tools; and this is in many cases removed 
by pickling them with dilute sulphuric acid, which dissolves a 
little of the metal, and undermines and loosens the sand, as 
explained in vol. i., p. 375. Iron castings become moreover 
superficially hard from coming in contact with the moist sand of 
the foundry mould ; so that a thin but hard skin envelopes the 
entire object to the depth of the twentieth or thirtieth of an 
inch, and as this is very injurious to the files, it is usually 
chipped off with a chisel and hammer ; the pickling is then less 
required. 

The ordinary chipping chisel is about six or eight inches long, 
and three-fourths of an inch broad on the edge, which is a little 
convex, that the corners may not be liable to dig into the work. 
The bevils are ground to meet at an angle of about 80 degrees, 
and the hammer used with the chipping chisel varies from about 
two to three pounds in weight. Before commencing to chip the 
work, it is usual to rub both the face of the hammer and the end 
of the chisel upon the bench or floor, to remove any grease and 
leave them bright and clean, as were either of them greasy there 
would be risk of the hammer glancing off and striking the 
knuckles. A blow is first given with the hammer upon the angle 
of the work, to make a little facet upon which the first chisel-cut 
is made, about the thirtieth of an inch below the general sui'face 
of the casting, the chisel being then only raised some 30 degrees 
above the horizontal line. In continuing the cuts the chisel is 
elevated to about 45 degrees, the blows are given in quick suc- 
cession, and the cuts are led gradually over the entire surface, 
the advance being always upon a line that is convex to the chisel. 

Provided the casting is moderately flat, the edge of the chisel 
is kept at one uniform distance below the general surface of the 
work, which is occasionally examined with the straight-edge. 
Should the surface of the casting present any lumps or irregu- 
larities of surface, a thicker chip or two thin chips are removed 




CHIPPING, PICKLING, GRINDING, ETC. 851 

such high parts, to lessen the suhsi <juent labour of filing, 
hut which process is much less destructi\c to the file after tin- 
hard sand-coat has been removed by acid from the iron. 

In some massive works, and also in cases where large quanti- 
ties have to be chipped off certain parts of castings, much larger 
chipping chisels are used, which are called flogging chisels ; tin y 
commonly exceed one foot in length, and are proportionally stout ; 
one man holds the chisel in both hands, sometimes by means of 
a chisel-rod for greater security, whilst another strikes with a 
lijrht sledge-hammer. Where much has to be removed, it is also 
usual to employ cross-cutting chisels ; these are about seven or 
eight inches long, a quarter of an inch wide on the edge, and an 
inch broad in the other direction; the cross-cut chisel is first 
used to cut furrows, half or three-quarters of an inch asunder, to 
the full depth of the parts to be removed, and the intervening 
ridges are then easily broken off with the ordinary chipping 
chisel; but since the general employment of the planing- 
machinc, and others of the engineer's tools, the chipping chisels 
are scarcely required. When iron castings are so near to their 
required dimensions, that chipping would remove too much, they 
are either cleaned with a nearly worn-out file, or the outer coat 
is removed on the grindstone, means that are much less wasteful 
of the material. 

\Vrought iron is but seldom pickled previously to being filed, 
but is either cleaned with an old file, or is ground on a stone to 
remove the outer scale or oxidised surface ; the chipping cl i 
is only in general required when the nature of the work pre- 
vents it from being forged so nearly of the required form as to 
bring it properly within range of the file. 

Brass and gun metal are, as already noticed in the first volume, 
75, sometimes pickled, but with nitric acid, instead of the 
sulphuric acid which is employed for iron; and brass is com- 
monly hammered all over to increase its density, unless a minute 
quantity of tin is added, say a quarter or half an ounce to tin- 
pound, which materially stiffens the alloy, so as to render ham- 
mering as unnecessary as it is with good gun-metal. 



After a file has been used for wrought iron or steel, it is 
leas adapted to filing cast iron or brass, which require k -u 
files, therefore to economise the wear of the instrument, it is used 

3 i 2 



852 DRAW-FILING AND CURLING. 

for a time on brass or cast-iron, and when partially worn, it is 
still available for filing wrought iron or steel ; whereas, had the 
file been first used on these harder materials, it would have been 
found comparatively ineffective for brass and cast-iron. 

As a further measure of economy, the pressure on the file 
should be always relieved in the back stroke, which otherwise 
only tends to wear down or break off the tops of the teeth, as 
their formation shows that they can only cut in the ordinary or 
advancing stroke ; the file should, in consequence, be nearly 
lifted from the work in drawing it back, but it is not usual 
actually to raise the file off the work, as it then becomes needful 
to wait an instant before the next stroke, to ensure the true posi- 
tion of the file upon the work being resumed : whereas, if it is 
brought back with inconsiderable pressure, the file is not injured, 
and the hand still retains the consciousness of the true contact 
of the file and work, without which the instrument is used with 
far less decision and correctness than it otherwise would be. 

Some workmen smooth the work by the method called draw- 
filincj, or by drawing the file sideways along the work, using it 
in fact, as a spoke-shave instead of a file : this certainly has the 
effect of smoothing the work, because in that position the file can 
only make slight and closely congregated scratches, but the teeth 
will not cut in this manner. Another mode sometimes employed 
is to curl the work with the file, by describing small circles with 
the instrument as in grinding or polishing, but neither of these 
practices employs the file teeth in the mode in which they are 
legitimately adapted to cut, and no great reliance should be 
placed upon them. When smooth surfaces are required, it is a 
better and quicker practice, as the work advances towards com- 
pletion, to select files that are gradually finer, but always to use 
them from point to heel. 

When it is desired to make the smooth files cut wrought-iron, 
steel, and other fibrous metals very smoothly, the file is used with 
R little oil to lubricate the surface, so that it may not penetrate 
to the same degree as it would if used dry ; the oil also lessens 
the disposition to the scratching and tearing up of the particles, 
which, should it happen, mostly produces a furrow or scratch, 
especially if the file be pinny, a circumstance now to be explained; 
but the oil should not be used on the coarser or preparatory files. 

The particles removed from the materials operated upon, are 






REMOVING THE FILE-DUST FROM FILES. 

always more or less liable toclug the tile, but which particularly 
win n the instrument is dry, nre partially removed by giving the 
edge of the file a moderately smart blow on the chaps of the vice 
or the edge of the bench ; but particles of wrought iron, at 
and other tibrous metals, arc apt to pin f fie file, or to stick i 
hard as to require to be picked out with a pointed steel u ire, 
which is run through the furrow in which the pin is situated. 
The marking point, used in setting out works, is commonly 
employed for the purpose. 

riles are sometimes cleaned witli a scratch-bruxh, which is a 
cylindrical bundle of tine steel or brass wire, bound tightly in 
its central part, but allowing the ends of the wire to protrude 
at both extremities as a stiff brush. Occasionally also, a scr< 
is used, or a long strip of sheet brass, about an inch wide, a 
small portion of the end of which is turned down at right angles, 
and thinned with a hammer; the thin edge is then drawn 
forcibly through the oblique furrows of the file, and serves as 
a rake to remove any particles of metal that lodge therein. 

But the best and most rapid mode of cleaning the file, is to 
nail to a piece of wood about two inches wide, a strip of the so- 
called cotton card, which is used in combing the cotton-wool 
preparatory to spinning; the little wire staples of the card that 
are fixed in the leather constitute a most effective brush, and 
answer the purpose exceedingly well. Some workmen, to lessen 
the disposition of the file to hold the file-dust, or become pinny, 
rub it over with chalk ; this absorbs any oil or grease that may be 
on the file, and in a considerable degree fulfils the end desired. 

To remove wood-dust from files, floats, and rasps, some per- 
sons dip them for a few moments into hot water, and then brush 
them with a still' brush; the water moistens and swells the wood, 
thereby loosening it, and the brush entirely removes the par- 
ticles ; the heat given to the file afterwards evaporates the trifling 
quantity of moisture that remains, so as to avoid the formation 
of rust. This plan, although effective, is neither general nor 
import;:. 

.il methods of fixing works, in order to subject 

them to the action of the file, will be now noticed. .Many of 

the in:ii\e parts of machinery are MI heavy, that gra\ity alone 

, p them steady under the action of the file, and 



854 



TAPER-VICE. 



for such as these, it is therefore only needed to prop them up 
in any convenient manner, by wedges, trestles, or other supports, 
so as to place them conveniently within reach of the operator. 
But the great majority of works are held in the well-known 
implement, the smith's bench-vice, or tail-vice, the general form 
of which is too familiar to require description : but the annexed 
figures represent the front and side views of a less-known modi- 
fication of the same, called a taper-vice, which presents some 
peculiarities, and is occasionally employed by engineers. 

The taper-vice, figs. 840 and 841, is made principally of cast- 
iron, and to include within itself the base whereon it stands, that 
has at the back two small iron trucks or rollers, so that when 
the vice is supported upon them alone, it may be easily rolled 
from place to place notwithstanding its weight. The front limb 
of the vice moves on the joint a, the back on the joint b, so as to 



Figs. 840. 







grasp either wide or narrow pieces ; but it is by this arrangement 
adapted alone to objects that are parallel, which condition, it is 
true, is more usually required. But in the present apparatus, if 
the jaws are closed upon a taper object, a form that frequently 
occurs in steam-engines and similar works, the two parts of the 
vice swivel horizontally on a joint, the axis of which is on the 
dotted line c, so as to place the jaws at an angle corresponding 



uuniN.uiY I \ll-\HK AND VICE-BENCH. 

with that of tin- work ; in tact, the lower part or pedestal of the 
mted somewhat like the front axlctree of a carriage. 

Under ordinary circumstances, however, the screw and nut of 
such a vice would bear very imperfectly upon tin- moving j: 
owing to tlirir obliquity ; hut this objection is met by cutting a 
spherical recess in the outside of each half of the vice, and 
making the collar of the screw, part of a sphere to constitute a 
ball-and-socket-joint, and also by making the nut a perforated 
sphere, adapted to a spherical cavity or seat, but with a feather 
to prevent it from turning round. The two bearings of the 
A thus accommodate themselves at the same time, both to 
the horizontal and vertical obliquities of the jaws. To constrain 
the two parts of the vice to open in an equal degree, there are 
two links that are jointed to a collar that slides freely on a 
cylinder, which latter is in fact the continuation of the joint pin 
c : and to the collar are also attached the two springs that open 
the limbs of the vice when the screw is relaxed. This useful 
apparatus is well adapted to its particular purpose, such as the 
larger pieces of steam engines, and similar machinery. 

The ordinary tail-vices, or standing-vices for heavy engineer- 
ing and large works, sometimes exceed 100 Ibs. in weight; but 
the average weight of tail-vices, for artizaus in general, is from 
40 to 60 Ibs., and of those for amateurs, from 25 to 35 Ibs. 

The bench for the vice usually extends throughout the length 
of the engineer's shop, or vice-loft, and is secured against the 
windows. The tail-nee is strongly fixed to the bench at the 
required height, and the tail that extends downwards is fixed 
in a elect nailed to the floor, or against one of the legs of the 
bench, which latter mode is desirable, as the vice is then in 
better condition to resist the blows of the chisel and hammer, 
which give rise to much more violence than the act of filing. 

Amateurs sometimes employ portable vice-benches, having 
nests of drawers for containing the files and other tools ; or the 
is attached to the right-hand side of the turning-lathe; less 
frequently the tail-vice is attached to the plauing-bench, but it i> 
then requisite it should admit of ready attachment and detach- 
ment, to have the planing-hcnch at liberty fur its ordinary 
application. 

rq>rescnts a very convenient mode of mounting the 
t ail- \ ice upon a tripod stand of cast- irou, which indeed i> in 



856 



Til I POD VICE-STAND, ETC. 



Fig. 842. 



many cases preferable to the wooden benches; as although small, 
it is sufficiently heavy to ensure firmness, especially as from 
having only three points of support, all are sure to touch the 
ground. The tripod readily admits of being shifted about to 
suit the light, and also of temporary change of height, by lifting- 
pieces added to the feet, when 
the work is required to be 
nearer to the eye of the ope- 
rator. The tripod pedestal 
serves additionally for the 
occasional support of a small 
anvil (when not required 
for forging), and also for a 
paring knife, fig. 8, page 
26, Vol. I.), when an appro- 
priate wooden cutting-block 
is added to the tripod. 

The table-vice mostly used 
by watch-makers and similar 
artizans, resembles that 
shown in figs. 843 and 814. 
It is attached to the table by 
a clamp and screw, which are 
armed with teeth to give a secure hold ; but it is usual to glue a 
small piece of wood on the table to receive the teeth, and also 
to prevent the lodgment of small pieces of the work at that part, 
and the work-table has also a ledge around it, to prevent the 
work or tools from rolling off. It will be also perceived, that 
the clamp is surmounted by a small square projection a, used 
as a stake or anvil ; and that the jaws of the vice have center 
holes on one or both sides for the employment of small center 
drills, that are too delicate for the breast-plate, after the mode 
described in page 553 of the present volume. 

It is in all cases desirable that the jaws of vices should be 
exactly parallel, both with the edge of the bench and with the 
ground, in order that the position of the work maybe instinctively 
known ; but the tail-vice and bench-vice are liable to various 
objections that arise from their opening on a center, or as a 
lunge; for although the jaws are almost parallel when closed, or 
then nip in preference at the upper edge, when opened widely, 




i.\ini:-\JCK FOR SMALL \\oliKs. 






ie nuliiil position <>t' the jaws causes the lower edges alone to 

grasp tli.- \\urk, and as in addition, the front jaw moves in .1 




844. 




circular arc, a wide object, on being fixed, is necessarily thrown 
out of the horizontal into an inclined position ; each of which 
imperfect conditions is shown in fig. 844. 

The inclination of the two limbs of the vice, likewise depre- 
ciates the contact of the screw and nut; this is sometimes 
remedied by a modification of the ball and socket already de- 
scribed. A more simple mode is the employment of a washer of 
the form represented at w, fig. 842, which is placed beneath the 
screw; the fork embraces the lower extremity of the curved jaw 
of the vice, and the washer being thickest in the center, rolls, so 
that the flat side always touches the entire surface of the shoulder 
of the screw, and the central and bulged part of the washer 
touches the limb of the vice, and causes the pressure to be nearly 
central upon the screw, instead of, as in fig. 844, against the 
upper edge of the collar of the screw, which is then liable to be 
bent and strained. The box or internal screw, b, fig. 8 1 2, in which 
the screw-pin works has also a power of adjustment or hinge-like 
rotation, which eiiMires, here likewise, centrality of pivure. 
This mode is extremely simple, and worthy of general adoption. 

The inconveniences common to vices opening radially on a 
joint pin, are completely removed in those opening on straight 
islides ; these are called parallel rices, because the surfaces of their 
jaws or chaps, and also the bearings of their screws and nuts, 
alwuvN retain their parallelism; consequently whether the work 
be wide or narrow, it is always firmly grasped by the chaps 
provided the work be itself parallel. One of these vices is repiv- 
ted in fig. 815. The front jaw is forged in continuation of 
the body of the vice, the whole being of a rectangular form, and 



858 



PARALLEL VICES. 



receiving at its upper parts the extremities of the pinching 
screw, which has a semi-cylindrical cover to protect it from the 
file-dust. The back or sliding jaw of the parallel vice fits accu- 
rately upon the upper surface of the principal bar at a, and also 
upon a square bar b, placed above it. 



846. 




Parallel vices are sometimes attached to the table or bench, 
by clamps that only allow them one fixed position, namely, with 
the jaws parallel with the bench, as in the bench-vice, fig. 843 ; 
but more generally the clamp of a parallel vice, c c c, fig. 845, 
has a vertical socket or hole, and the principal piece of the vice 
terminates in a round stem that fits the socket, and has a nut n, 
by which means any horizontal inclination may be given to the 
jaws ; they are represented inclined, or they may even be placed 
at right angles to the bench. 

Some parallel vices are attached to the table by ball and 
socket joints, as shown detached in fig. 846; and various similar 
schemes have been proposed. The screw-clamp is attached to 
the table by a thumb-screw , and the clamp terminates in a 
portion of a sphere ; the lower part of the vice has two shallow 
spherical cups adapted to the ball, so that by turning the thumb- 
screw b } the ball is grasped between the two cups. It is true 
this kind of parallel vice may be inclined both horizontally and 
vertically, and therefore offers much choice of position ; but it 
is too unstable in any to serve for more than very light works, 
which require but a small application of force. 

The jaws of vices are faced with hardened steel and cut like files, 
so as to hold securely; but works that are nearly finished would 




s.VJ 

he injured hy the indentation of the teeth, and are therefore 
.i-il by various kinds of shields or vice-damp*, aa they are 
generally called ; several of these are shown in figs. 847 to 857. 
-clamps, such as fig. 847, are often made of two detached 
pieces of stout sheet-iron, brass, or copper, of the length of the 
chape of the vice, and nearly as wide. The two pieces are 
pinched between the jaws, and then bent closely around the 
shoulders of the vice to mould them to the required form, and 
make them easily retain their positions when the work is removed 
from between them. 




BUT 3 



Iff. 



849. 



Sometimes sheet lead an eighth of an inch thick is used ; but 
such clamps answer better when cast in the rectangular form, ns 
. 8 18, and then bent as at b; the lead should be hardened 



n a, 



with a little antimony, to resemble a very soft type metal (Vol. I., 
page 277), and, previously to bending the clamps, they should be 
heated to about 300 to 400 Fahr., to avoid fracture. This alloy, 
although harder than lead, is still sutliciontly soft to adapt its ( -If 
to irregularities in the objects IK Id, and the clamps being thick, 
last longer, and more readily admit of being restored to form 
by the hammer or rasp, than those made of sheet lead 



860 VICE-CLAMPS. 

Spring or jointed clamps of the several forms, figs. 849 to 857, 
are also made. Fig. 849 represents tAvo stout rectangular pieces 
of metal, united by two springs which pass on the sides of the 
vice-screw ; these open to a considerable distance, and from the 
flexibility of the springs, readily adapt themselves either to 
thick or thin pieces. 

The clamp, fig. 850, is made in two pieces of cast or wrought 
iron, jointed like a wide door hinge, and with a spring to separate 
the two parts to a small extent ; this clamp has a piece of soft 
steel or iron attached to each half, to make a fine close mouth, 
suitable to delicate works and thin plates. 

Fig. 851, is a narrow spring clamp made of one piece of steel, 
to which are attached pieces of wood or brass, that may be 
renewed when worn out of shape; the clamp, fig. 852, is made 
of one piece of steel, and formed with a crease to hold small 
wires horizontally; 853 and 854 are detached clamps, one 
plain, the other with an angular notch, that serve for holding 
round and other pieces vertically; 852 and 853 are each useful 
in holding round bars whilst they are being tapped, and not 
unfrequently their inner edges are cut with file teeth, after 
which they are hardened and tempered. As shown in fig. 855, 
some of the vice-clamps are made with jaws inclined at about 30 
degrees to the perpendicular, to serve for holding chamfer bars 
for slides, and various bevilled works; these clamps have the 
effect of placing the chamfered edge nearly horizontal, which 
latter is the most convenient position for the act of filing. 

Fig. 856 are the long sloping clamps, consisting of two pieces 
of wood bevilled at their extremities, and united by an external 
strap of sheet iron or steel, which is riveted to them ; should 
they fail to spring open sufficiently, a stick is thrust between the 
two parts, as shown by the dotted lines ; fig. 857 are upright 
wooden clamps, which are forked so that the tails proceed verti- 
cally, one on each side of the screw of the vice. The sloping 
wood clamps commonly used by gun-makers, are made long 
enough to rest upon the floor, and when the one end of the 
^un-barrel is pinched between them, the other end is supported 
either by a vertical prop, called a horse, or by a horizontal 
wooden horse, fixed to the bench at about the same height as 
the jaws of the vice. 

Wooden clamps, although of great convenience, are open to a 



ll \\li-vicu. sill 

tliut is sometimes acutely frit, as when small pieces 
briskly tilcil \\liilst lirld in wooden clamps, owing to the slow 
inctin^ power of the wood, the works become so hot as to be 
inconvenient to be held in the lingers, but which is continually 

i. MS it is necessary at short intervals to remove the v 
from the vice, for the purpose of testing, by the straight ad 
square, or other measuring instruments, the progress made. 
Sometimes the work is grasped between slips of leather or card, 
that are simply held to the vice by the penetration of its teeth. 
Leather and card are, however, partly open to the same objec- 
tion as wood clamps, from which the metal clamps, owing to 
their superior power of conducting heat, are nearly free. 



A great number of small works are more conveniently filed, 
whilst they are held with the left hand, the file being then 
managed exclusively with the right; this enables the arti/an 
more easily to judge of the position of the file. In such cases, a 
piece of wood/, fig. 858, called 9.jiHi>y-l>l<>ck, is fixed in the table 
or tail-vice, and square, round, and similar pieces, are rested in 
one of several notches made in the block with a triangular file. 
If the works are rectangular, or have flat surfaces, they are held 
quite at rest ; if they are circular, they are continually rotated, 
as will be explained, and it' they are wide and flat, they are laid 
on the flat surface of the filing-block/, against a ledge or projec- 
tion represented on the lower side of the block, which is then 
placed upwards. 

Pieces that are suHiciently long and bulky, are held upon the 
filing- block by the hand unassistedly ; but small and short 
works arc more usually fixed in some description of hand-\ 
and applied in the position shown in fig. 858, and the vice b, 
larger than the work, serves as a handle, and affords a better 
grasp. 

For works of larger size the hand-vices are progressively 
larger, as in 859 and 860 ; some of them have wooden handles. 
Almost all the hand-\ ices have fly-nuts to be t\\ isted v> ith the 
fniL'ers l>nt the most powerful, \\hicli sometimes wei^'h as much 
as about three pounds, have square nuts that are fastened by a 
or spanner *. Occasionally, to ensure a strong grip, one 
ear of the ordinary fly-nut is pinched in the tail-\iee, \\lulst 
the hand-vice is twisted bodily round; but unless due caution is 



862 



HAND-VICES AND PIN-TONG3. 



used, either the vice may be strained, or the screw broken, from 
the great purchase thus obtained. 

Hand-vices are not, however, in all cases employed ; but small 
wires and other pieces are also held in a species of pliers, 
fig. 861, called pin-tongs or sliding-tongs, which are closed by a 
ferule that is drawn down the stem. Fig. 862 shows another 
variety of this kind, that has no joint, but springs open by 
elasticity alone when the ring r is drawn back. 



Figs. 858 




061. 




The small pin-vice, fig. 858, is used by watchmakers in filing 
up small pins and other cylindrical objects ; the jaws are not 
united by a joint, but are formed in one piece with the stem of 
the vice, the end that constitutes the jaws being divided or forked; 
the screw and stem are each perforated throughout, that the 
ends of long wires maybe filed; and the stem is octangular 
that the pin-vice may be readily twisted to and fro between the 
fingers and thumb of the left hand, whilst the file is reciprocated 
by the right hand, and in this manner a considerable approach 
to the cylindrical form is obtained. 

Independently of the rapid movement of the hand-vice to and 
fro on its axis, simultaneously with the strokes of the file, the 
two hands being moved together, the hand-vice is thrown pro- 
gressively forward with the fore-finger about a quarter of a turn 



MODES OP HOLDING PLAT WORKS. M ',.'', 

at nearly every alternation, so as to bring all parts of the work 
alike under the operation of the file. Hut as it is in this case 
important that the work should In- pinched exactly central in the 
, or so that the axis of the work may pass through the axis 
or central line of the vice, a central angular groove is frequently 
made in each jaw of the hand-vice, to give the work, without 
trial, a nearly axial position. This is more usual in the nan 

S fig. 859, known as dog-note or piy-nose hand-vices, than in 
those with wide or cross chaps, 858 and 860. 

Many circular works that were formerly thus filed, are now, 
from motives of expedition and accuracy, more commonly exe- 
cuted in the turning-lathe, since the great extension in the use 
of this machine, which has become nearly as general as the vice 
or the file itself; but frequent occasions still remain in which 
the hand-vice and file are thus employed, and it is curious to see 
how those accustomed to the rotation of the different kinds of 
hand-vice with the wrist, will in this manner reduce a square or 
irregular piece to the circular section. 

In the pin-tongs, fig. 862, besides the facility of turning the 
instrument round with the fingers, from the reverse end having 
a center and pulley, the same spring tongs serve conveniently 
as forceps for holding small drills to be worked with the drill- 
bow, and also for other purposes in watch-work. 



Numerous flat works are too large, thin, and irregular in their 
superficies to admit of being fixed in the various kinds of bench 
and table-vices that have been described, and if so fixed, there 
would he risk of bending such thin pieces by the pressure of 
the vice applied against the edges of the work, consequently, 
di tie rent methods are employed in fixing them. 

The largest flat works are simply laid on the naked surface of 
the work-bench, and temporarily held by half a dozen or more 
pins or nails driven into the bench. The pins should be as close 
to the margin as possible, and yet below the surface of the work, 
so as not to interfere \\itti the free application of the file; it is 
frequently necessary to lift the work out of its temporary bed 
for its examination with measuring instruments, /ind advantage 
is taken of these opportunities for sweeping away with a 
small brush (like a nail-brush for the dressing-table,) any loose 



SGI FILING BOARD AND FLATTING VICE. 

filings that may have got beneath the work, and prevent it from 
lying flat. 

For thin flat works of smaller size, the filing-board, fig. 863, 
is a convenient appendage; it measures six or eight inches square, 
and has a stout rib on the under side, by which it is fixed in the 
vice. Such thin works are required to be frequently corrected 
with the hammer, and also to be turned over, in order that their 
opposite sides may be alternately filed, so as to follow and com- 
pensate for, the continual changes they undergo in the act of 
being filed. In some instances the work is held down with one 
or more screw clamps or hand-vices as represented ; this is need- 
ful when pins would bruise the margins of nearly-finished works, 
and a card or a few thicknesses of paper are then interposed to 
protect the object from the teeth of the vice. 



Figs. 863. 864. 





In filing thin flat works, such as the thin handles or scales 
of penknives and razors, and the thin steel plates used in pocket 
knives, the Sheffield cutlers generally resort to the contrivance 
represented in fig. 864, and known as a flatting-vice. A hand- 
vice is fixed, in the ordinary tail-vice or table-vice, by the one jaw 
with the screw uppermost, so that the jaws of the hand-vice are 
horizontal. The thin scale to be filed is then placed on a flat 
piece of metal not less than a quarter of an inch thick, and the 
two are pinched together by the one corner, so that all the remain- 
ing surface may be free to the action of the files, and the work 
is readily shifted about to allow all parts to be successively ope- 
rated upon. The facility of changing the position is particularly 
useful in working on pieces of tortoiseshell, buckhorn, and other 
materials of irregular form and thickness, to which the filing 
boards with pins or clamps would less conveniently apply. 

As before observed, the one face of the small filing-block/, 
fig. 858, is also used for very small thin works, and which are 



INS ..it IIIIM. \ FLAT SURFACE. 



prevented slipping from by the wooden Icd^'e, or by 

pins drnen in. In many instances, also, thin works OTC held 
upon a piece of cork, such as the bnn- f..r a large cask, beneath 
which i.s Allied a square piece of wood, that the cork may be held 
in the \ice without being compressed. The elasticity of the 
. allows the work to become somewhat embedded by the 
pressure of the file, between which and the surface-friction, it is 
sufficiently secured for the purpose without pins. 

SECT. IV. INSTRUCTIONS FOR FILING A FLAT SURFACE, UNDER 
TIIK GUIDANCE OF THE STRA IUHT-EDGE, AND OF TIIK TRIAL- 
PLATE, OR PI. ANoMl I I R 

In following out the subject of the instructions for the use of 
the file, it is proposed, first to explain that which may be called 
the manual process of producing a true or plane surface on 
a piece of cast iron of moderate dimensions, say four or five 
inches wide and eight or ten inches long; and although the 
entire routine is only required for surfaces of the most exact and 
finished kind, the same general treatment, when discontinued at 
certain stages, is equally suited to various other works in me- 
chanism, that only demand by comparison an inferior degree of 
precision : the routine is also nearly the same for surfaces larger 
or smaller than that referred to. 

Before any effective progress can be made in filing Hat works, 
the operator must be provided with the means of testing the 
\e advance of the work, he should therefore possess a 
true strai^ht-ed^c, and a true surface-plate. The straight-edges 
used by smiths are generally of steel, and although they have 
sometimes a nearly acute edge, it is much more usual to give 
them moderate width : thus, in steel straight -edges from one to 
four feet in length, the width of the edge is from one-sixteenth to 
one-fourth of an inch, and in cast-iron straight-edges from six to 
nine feet in length, the width is usually two to three in 

The straight-edge is used for trying the surface that is under 

cornet ion, along its four margins, across its two diagonals, and 

ii-ions intern. which respective lines, if all exact, 

denote the surface to be correct ; but the straight-edge alone is 

a tedious and scarcely suflicicnt test, and when great accuracy is 

red. it is almost imp > have at least one very exact 



866 INSTRUCTIONS FOR FILING A FLAT SURFACE. 

plane metallic surface, or surface-plate, (the piano-metre of the 
French,) by which the general condition of the surface under 
formation may be more quickly and accurately tested at one 
operation : and to avoid confusion of terms, it is proposed in all 
cases, when speaking of the instrument, to employ the French 
appellation piano-metre or rather planometer, which is exact and 
distinctive. 

The flat piece of cast-iron, intended to be operated upon, 
having been chipped all over, as described in page 850, a coarse 
hand-file, of as large dimensions as the operator can safely 
manage is selected, and in the commencement, the rough edges 
or ridges left by the chipping-chisel are levelled, those parts how- 
ever being principally filed, that appear from the straight-edge 
to be too high. 

The strokes of the file are directed sometimes square across as 
on a fixed line, or obliquely in both directions alternately ; at 
other times the file is traversed a little to the right or left during 
the stroke, so as to make it apply to a portion of the work 
exceeding the width of the file. These changes in the applica- 
tions of the file are almost constantly given, in order that the 
various positions may cross each other in all possible directions, 
and prevent the formation of partial hollows' The work is tried 
at short intervals with the straight-edge ; and the eye directed on 
a level with the work to be tested, readily perceives the points 
that are most prominent. After the rough errors have been 
partially removed, the work is taken from the vice, and struck 
edgeways upon the bench to shake off any loose filings, and it is 
then inverted on the planometer, which should be fully as large 
or larger than the work. As, however, it cannot be told by the 
eye which points of the work touch the planometer, this instru- 
ment is coated all over with some colouring matter, such as pul- 
verised red chalk mixed with a little oil, and then the touching 
places become coloured. 

In all probability the work will at first assimilate so imper- 
fectly with the planometer, that it will only rest thereon at its 
two highest points, most likely at the two corners of the one 
diagonal, and when pressure is applied at the two other corners 
alternately, the work will probably ride or rock on the two points 
of temporary support. The work is slightly rubbed on the sur- 
face-plate, and then picks up at its highest points some of the 



INSTRUCTIONS FOR FILING A PLAT SURFACE. "", 

red ID tin- fiee, .MM! the file is principally 

used in the \icinity of thr coloured parts, with the occnsi 
test of the v dgc, :ni(l nfti i a short period the work is 

gain tried on the planom< 

Should the same two points still become reddened, they are 
reduced with the file, but it is probable the work may 
be found to rest upon larger portions of its surface, or upon 
three or four points instead of two only; and if so, nil the 
marked places are reduced in a small degree before the suc- 
ceeding trial. This process is continually repeated, and if 
watchfully performed, it will be found that the points of con- 
tact will become gradually increased, say from two to four, to 
six or eight, then to a dozen or more, and so on. 

In this, or rather an earlier stage of the work, the smith's 
plane for metal is often advantageously used in connexion with 
the file. The general structure of the plane is shown by the 
figure and description on page 483, and it is employed much after 
the manner of the joiner's plane, but it may be used at pleasure 
lengthways, crossways, or diagonally, without any interference 
from grain or fibre as in wood work. The grooved or roughing- 
out cutter is employed in the commencement because it more 
readily penetrates the work, and a few strokes are given to crop 
off the highest points of the surface, the furrows made by the 
serrated cutter are then nearly removed with the file, which acts 
more expeditiously although less exactly than the plane, and in 
this manner the grooved plane iron and the coarse file are alter- 
nately used. In the absence of the planometer, the metal plane 
assumes a greatly-increased degree of importance. 

As the work becomes gradually nearer to truth, the grooved 
cutter is exchanged for that with a continuous or smooth edge, a 
second-cut, or bastard hand file, is also selected, and the same 
alternation of planing and filing is persevered in, the plane s< 
ing as it were to direct the file, until it is found that the plane 
iron acts too vigorously, as it is scarcely satisfied with merely 
scraping over the surface of the cast-iron; but when it acts it 
>ves a shaving having a nearly measurable thickness, and 
efore, although the hand-plane may not injure the gen 
truth of the surface, it will prevent the work 1'roin bring so deli- 
cately acted upon, as the continuance of the process now demand - : 

3 ic 2 



868 INSTRUCTIONS FOR FILING A FLAT SURFACE. 

a smoother hand file is consequently alone employed in further- 
ing the work. 

If the piece of cast-iron should have been turned in the lathe, 
or planed in the planing machine, instead of having been 
wrought entirely with the chipping chisel, plane and file, the 
former instructions would be uncalled for, as the remaining 
steps alone would remain to be followed. Unless, indeed, the 
work had been so imperfectly fixed as to have been strained, and 
thence become distorted on being released from the machine : 
on the latter supposition the grosser errors would probably re- 
quire correction with the bastard file, before the smooth file 
could be judiciously used. 

The necessity of the convex form of the file will now be ren- 
dered most striking, as were the file absolutely flat on its face, 
it would be scarcely possible to reduce with it any small and 
isolated spot that might become coated with the red chalk from 
off the planometer; but as the file is a little rounded, any pre- 
cise spot on the work may be acted upon, as the end of the file 
may be pressed with the fingers of the left hand on the exact 
spot to be reduced, whilst the remainder of the file is held just 
out of contact with the rest of the surface. 

When, however, the points of bearing become numerous, the 
file cannot even thus be managed with sufficient discrimination, 
and notwithstanding the best efforts it will act on too large a 
part, and thereby lengthen, or it might be said altogether to 
prevent the complete correction of the work, because the file is 
not sufficiently under control. Before the file has assumed this 
questionable tendency, it is politic and usual as a measure of 
economy, to discontinue the use of the file, and to prosecute the 
work with a scraper, which having a sharp edge, instead of a broad 
and abrading surface, may be made to act with far more decision 
on any, even the most minute spot or point. A worn-out triangu- 
lar file, ground at the end on all the faces, so as to make thin keen 
edges, is generally used as the scraper; this should be keenly 
sharpened on an oil-stone, so as to act without requiring much 
pressure, which would only fill the work with striae or utters. 

The continual reduction of all the points, which are sufficiently 
prominent to pick up the colouring matter from the planometer, 
is now persevered in with the scraper instead of the file, and pre- 



INSTRUCTIONS foil MUM; \ i RPACB. 

y in the same manner, except as regards the change of the 
tool ; ami if the process have been carefully performed through- 
out, it will be found nt the i on. IUMUM that it' the work and piano- 
meter are both wiped clean, and ruhhed hard t>_'i-:ln-r, that the 
high points of the work will he .somewhat burnished, giving to 
>rk a finely mottled character. 



In producing metallic surfaces, the constant effort should bo 
n-duee all the high places with as much expedition as circum- 
stances will admit, but avoiding, on the other hand, that energetic 
UM- di the tool, which may too hastily alter the condition of the 
surface, and in expunging the known errors, induce others equal 
in degree but differently situated. Throughout the work, attempt 
should be made to keep the points of bearing, whether few or 
many, as nearly equidistant as may be, instead of allowing them 
to become grouped together in large patches. 

In respect to the tools, there should be a gradual diminution 
in their cutting powers, and also of the vigour with which they 
are used, as although energy is wise at the commencement of the 
work, it should gradually subside into watchfulness and caution 
towards the conclusion. The periods of alternation between the 
hand-plane and the file, and also the times when these are suc- 
cessively rejected, in favour of the scraper as the finishing tool, 
must be in great measure left to the judgment of the operator. 

There should be a frequent examination of the work by means 
of the straight-edge and planometer, which latter should at all 
times be evenly tinted with the colour. At the commencement it 
is necessary the coating of red stuff on the planometer should be 
moderately abundant, so as to mark even those places which are 
minutely distant, but with the continued application of the work, 
the colouring matter will be gradually removed from the piano- 
meter, and which is desirable, as towards the conclusion tho 
quantity of red should be small, so as but faintly to mark tho 
summits of each little eminence, the number and equality of 
which are dependent on the perfection of the planometer, and 
the >teady persevering watchfulness of the operator. 



It is not to be supposed that it is in every case needful to 
proceed in the careful and progressive mode just described, as. 
the parts of different works require widely dill', -rent degrees of. 



870 RELATIVE DEGREES OF ACCURACY REQUIRED IN FLAT WORKS. 

perfection as to flatness. For instance, in many it is only neces- 
sary they should be clean and bright, and have the semblance of 
flatness, with such even the straight-edge is little if at all used as 
a test. Those surfaces by which the stationary parts of framings 
are attached, require a moderate degree of accuracy, such as may 
be comparable with the perfection in the hewn stones of a bridge 
or other massive edifice, which require to be flat, in order that 
they may bear fairly against each other, as without a certain 
degree of truth the stone might break from the unequal strain 
to which it would be exposed. 

The flat parts of metallic works, if similarly imperfect, would 
bend, and perhaps distort the remainder ; but although it is of 
great importance that bearing surfaces should be out of winding, 
or not twisted, it is by no means important that such bearing 
surfaces should be continuous, as a few equally scattered bearing 
points frequently suffice. Thus it was the common practice before 
the general introduction of the engineer's planing-machine, to 
make fillets or chipping places around the margins of the bearing 
surfaces of castings, which fillets alone were corrected with the 
chisel and coarse file, for the juxtaposition of the larger pieces 
or frame work of machines, the intermediate spaces being left 
depressed and out of contact. This mode sufficed, provided the 
pressure of the screw-bolts could not, by collapsing the hollow 
places, distort the castings, with which view chipping places 
were also generally left around the bolt holes of the work, this 
method greatly reduced the labour of getting up such works by 
hand ; but fillets and chipping places are now in a great measure 
abandoned. Smaller and more delicate works, requiring some- 
what greater accuracy than those just described, are left from 
smoother files, but in most cases without the necessity of 
scraping ; but the rectilinear slides and moving parts of accu- 
rate machinery, and the trial or surface-plates of the mecha- 
nician, require beyond all other works, the most dexterous use 
of the file and other means, from which it is again repeated, 
grinding should be entirely excluded. 



Until very recently, when the points of bearing had been so 
multiplied by the file and scraper, as not to exceed about half 
an inch in average distance, and that a still higher degree of 
accuracy was desired ; it was the ordinary practice to attempt the 



IMPOLICY OF GRINDING i IIPACE8. 

obliteration of these miii I, oil of grinding. 

Supposing only o e or surface t< luivc been required, it 

then became necessary to grind the work uj>on the planoin 

If, but to avoid the necessity of so injurious a practice, it was 
usual, when practicable, to make three similar pieces at one 
time, in order that, when all three had been separately filed and 
scraped to agree pretty nearly with the straight-edge and piano- 
meter, the three pieces might then he mutually employed in the 
correction of one another, by grinding the faces successively 
together with emery-powder and water. 

1 lie one piece was laid down horizontally, wetted all over with 
water, and then strewed with emery powder, after which, one of 
the other surfaces was inverted upon it, and rubbed about in 
various ways with longitudinal, lateral, and curling or circular 
strokes, on the supposition that as the two pieces came into contact 
respectively at their highest points, these highest points became 
mutually abraded, with a tendency to reduce them to the general 
level. After a short period, the top surface was removed, fresh 
emery and water were applied, and the third surface was rubbed 
upon the first ; after which, all three were variously interchanged, 
by placingeveryone in succession as the lower surface, and rubbing 
the two others upon the lower until it was considered from the 
uniform but deceptive grey tint thus produced, that the errors 
in all were expunged, and that the three surfaces were all true. 

It is, however, considered quite unnecessary to enter more into 
detail on a process that may be considered to be nearly obso! 
as regards the production of plane metallic surfaces, especially 
as at a future part of this Volume, the practice of grinding will 
be noticed, in reference to surfaces requiring inferior exactness, 
and consisting of materials that do not admit of the employment 
of the file and scraper. 



That two surfaces which are very nearly accurate, if ground 
together for a very short time, do in some degree correct each 
other, is true, but it has been long and well known, that a con- 
tinuance of the grinding is very dangerous, and apt to lead the 
one surface to become convex, and the other concave in a nearly 
equal dl id on this account, three pieces were usually 

operated upon that the third might act as an umpire, as although 
two pieces possessing exactly opposite errors may appear quite 



872 INSTRUCTIONS FOR ORIGINATING STRAIGHT EDGES, 

to agree, the third cannot agree with each of these two, until 
they have all been made alike, and quite plane surfaces. 

But the entire process of grinding, although apparently good, 
is so fraught with uncertainty, that accurate mechanicians have 
long agreed that the less grinding that is employed on rectilinear 
works the better, and Mr. Whit worth has recently shown in the 
most satisfactory manner,* that in such works grinding is 
entirely unnecessary, and may with the greatest advantage be 
dispensed with, as the further prosecution of the scraping process 
is quite sufficient to lead to the limit of attainable accuracy; the 
only condition being, that the mode of continually referring the 
work to the planometer, and scraping down the points sufficiently 
high to be coloured, should be steadily persevered in, until the 
completion of the process, and works thus treated assume a much 
higher degree of excellence than is attainable by grinding. 

Mr. Whitworth stated a further and equally important advan- 
tage to result from the discontinuance of grinding, as regards 
the slides arid moving parts of machinery. Some of the grinding 
powder is always absorbed in the pores of the metal, by which 
the metallic surfaces are converted into species of laps, so that 
the slides and works carry with them the sources of their depre- 
ciation and even destruction. The author's previous experience 
had so fully prepared him for admission of the soundness of these 
views, that in his own workshop he immediately adopted the 
suggestion of accomplishing all accurate rectilinear works by the 
continuance of scraping, to the entire exclusion of grinding. 

SECT. V. INSTRUCTIONS FOR ORIGINATING STRAIGHT-EDGES AMI 

TRIAL-PLATES, OR PLANOMETERS. 

The remarks hitherto offered on producing a flat surface were 
based upon the supposition that the operator is in possession of 
a good straight-edge, and a good surface or planometer, and 
.vhich is usual under ordinary circumstances; but it may be con- 
sidered necessary that the more difficult case should be placed 
before the reader, of originating the planometer itself, by which 
alone can he render himself independent of external assistance ; 
the previous observations will greatly abridge the description. 



* In a Paper read before the British Association for the Advancement of Science. 
Glasgow, 1840. 







\M> I ill \l I'LATES, OR PLANOMETBE*. 873 

/*/, to on straight-edge. In originating a straight- 

edge, it is judicious to prepare thr ground, so far as possible, 
\\ith the means possessed by every joiner; and accordingly, 
throe pieces of hard straight -^niined mahogany should he : 
pi mod as straight as possible with the joiner's pi me. Calling the 
three pieces, for distinction, A B and C, when they are c<> 
pared. A and B may appear to agree everywhere, even when 
of them is changed end for end : this shows A and B to be either 
both straight, or else the one concave, the other convex ; but C 
may he unlike either of them. C is then adjusted also to A, and 
will therefore become a duplicate of B ; but when the duplicates 
l> and C are compared, it may be found that they touch in the 
middle, and admit lijjht between them at the ends, showing each 
to be convex. The central parts both of B and C, which are 
erroneous in the same direction, are then each reduced in a nearly 
equal degree, until in fact, the transmission of light is prevented 
throughout their length, even when they are reversed, and by 
which the condition of each will be somewhat improved. 

Next, to ascertain whether B and C, when thus improved, are 
each pretty near to the truth. The third, or A, is fitted to B, 
making A and B as nearly as may be, counterparts of one 
another; and if A, when thus altered, should also agree with the 
third or C, all are true : but this can scarcely yet be strictly the 
case. And the routine is therefore continually repeated of 
redueini: in an equal degree the two which may show evidence 
of being nearly alike, (either both convex or both concave,) and 
then by titting the third to one of the corrected two, as a test by 
wh ifh to try, if they not alone agree with each other but like- 
wise agree with the third, or the test ; as the work can only be 
perfect when all three admit of being compared without any 
want of contact being observable in any of the three comparisons. 

If the trying-plane is carefully manipulated, the three pieces 
will, in three or four repetitions of the series of operations, 
<>me as nearly accurate as the nature of the tools and of the 
method will admit; and then, either the best of the three 
wooden straight-edges, or all three of them, may be used as the 
preliminary test in making the steel straight -edges.* 

The more common practice of the joiner it to operate upon only two piece*, 
each of which U first planed until they agree together when placed edge to edge in 
the ordinary manner, or in one plane. The two piece* are now placed tide by tidt, 



874 INSTRUCTIONS FOR ORIGINATING STRAIGHT EDGES, 

Sometimes the metal straight-edges are wide strips cut off 
from a sheet of steel of hard quality ; if forged from a bar of 
steel, the hammering should be continued until the metal is 
quite cold, to render it hard and elastic ; and in some instances, 
the straight-edge, when partly finished, is hardened and tempered 
before its edges are completed. In all cases, if the one edge is 
to be chamfered, this should be done in an early stage, as it is 
very apt to throw the work crooked ; and the sides are always 
filed, or otherwise finished, before any great progress is made in 
correcting the edges. When three straight-edges are made at 
one time, the three are generally united by temporary pins 
through their ends, to make one thick bar, and are then corrected 
in the mass as the first stage. 

The work having been thus far prepared, the wooden straight- 
edge is rubbed with a dry lump of red chalk, that it may leave 
evidence of the points of contact. A coarse file is first used, and 
it may for a time be assisted by the hand-plane ; the size rnd 
length of the file are gradually decreased, and after a time, it 
will be found that the wooden straight-edge is no longer suffi- 
ciently delicate to afford the required test. When all three of 
the steel straight-edges have been brought collectively to a state 
of approximate truth, they are separated, and wrought the one 
from the other, precisely in the same order that was described 
in reference to the wooden straight-edges; but as on the steel a 
very small and smooth file may be used, the process of correction 
may be carried with the file much higher upon steel straight- 
edges, than upon metallic surfaces. In addition to the mode of 
examining straight-edges by the transmission of light, they are 
also compared by laying them two at a time upon a true bench 
or surface, and rubbing them together without colouring matter ; 
the high places will then mutually rub each other sufficiently to 

aud their edges are placed in agreement at the extremities, so that the fingers, 
passed transversely across their ends, cannot feel any want of continuity of surface; 
in other words, cannot feel the joint. If, whilst thus placed, the joint is also in- 
appreciable to the sense of touch at various intermediate parts of the length of 
both pieces, the work is correct, and the two are straight. 

From the very precise action of the trying-plane, the wooden straight-edge may 
perhaps be equally well produced by the methods requiring either two or three to 
be made ; but the method of making three at once is given in the text, because it 
is always followed in metal works, in consequence of the different nature of the 
\\orking tools, and of the abstract superiority of the method 



IB, OR I' 



875 



leave a small degree of brightness, that may be easily observed 
on a careful scrutiny ; and as both edges of every straight-edge 
are commonly wrought, the investigation becomes amplified and 
impt a there bring six comparisons instead of three. 

tic ^muling is sometimes resorted to in completing steel 
straight-edge* : it is less objectionable with steel, than \\itli cast 
iron and other metals which arc softer and also more pomu- than 
steel, but the process of grinding being very difficult of control 
is not desirable; and as very small files may be used, and with 
discrimination, in correcting straight-edges, the scraper 
although useful here likewise, does not present the same 
importance as in correcting wide surfaces or planometers. 

Secondly, to originate a surface-plate or planoraeter. This 
process requires that the operator should be in possession of at 
least one very good straight-edge; one of a series of three tnat 
have been accurately tested in the manner just described. The 
present case also demands, like the last, that three pieces should 
be operated upon, in order that the same correctional method 
may be brought into effect. 

The planometer should be a plate of hard cast-iron, having ribs 
at the back to prevent its bending, either from its own weight, or 
from taking an unequal bearing on the bench or other support. 
Generally a deep rib extends around the four margins of the 
planometer, and one, two, or more intermediate and shallower 
ribs are added, which divide the back into rectangular compart- 
ments, as in fig. 865 ; this plauometer would rest upon the bench 
around its edges, or on four prominent points at the corners 
represented black. It has been recently proposed by Mr. \Ylut- 



Kigs. 865. 



867. 




worth, that the ribs should be placed obliquely and made to con- 
_'<? to three points of bearing, as in fig. 866, which is a much 
better plan, as the planometer is then at all times supported on 
precisely the same points, notwithstanding the inequality of the 
bench, which can scarcely be the case when tour feet are used. 



876 INSTRUCTIONS FOR ORIGINATING PLANOMETERS. 

The handles are added at the ends, that the planometer may be 
readily inverted ; in order that it may be applied upon such 
heavy works as it would be inconvenient to lift, and then imme- 
diately replaced on its feet when returned to the work-bench. 

In the absence of the planing-machine, the three castings for 
the planometers would be chipped all over and roughly filed, and 
in this case the smith's plane for metal would render most 
important service for a considerable period. A good wooden 
straight-edge is now convenient, as when rubbed with red chalk 
it denotes the high places very effectively, and should be applied 
at various parts of the length and width, and also obliquely ; and 
indeed a small thick block of beech-wood or mahogany, planed 
very flat as a surface and rubbed with chalk, will serve to hasten 
the process of obliterating the coarser errors. 

In due time, the plane, the coarse file, and the wooden 
straight-edge, would all be laid aside, and the work would be 
prosecuted with a smoother file, under the direction of a metal 
straight-edge, and which if coloured must be also greased to 
make the red matter adhere. This part of the work may be 
carried to no mean degree of perfection, as a very correct judg- 
ment of a plane surface can be obtained from a good straight- 
edge applied in all directions, as the eye readily measures the 
comparative width of the line of light transmitted, and the 
fingers also appreciate, when the straight-edge is slightly rotated 
or rubbed sideways, which points of the work are the highest, 
and give rise to most friction. 

One surface, which may be called A, having been corrected 
very carefully with the file and straight-edge, may be now 
smeared with red stuff and oil, and employed to hasten the 
correction of the second piece, or B, and the third, or C, until 
these two are about as near to truth as the first, or A ; the three 
are afterwards mutually operated upon under the guidance of 
colouring matter. At this stage of the work it will soon become 
necessary to discard the file in favour of the scraping-tool, in 
using which it will be found very convenient to remove by a 
paper screen, the glare of the bright metallic surface, so as to 
enable the little patches of colour to be more readily observed. 
The screen, fig. 867, consists of a small frame of wood, eight to 
ten inches square, covered with writing-paper, and attached to a 
small board ; the paper is inclined some ten degrees towards the 




INSTRUCTIONS FOK OBIOINA'MM. i 877 

itor, and nt night a short piece of candle is placed in tin 
center of the I HI: ilcstal as shown. 

three plates having been, as before observed, brought into 
ly ilit- same preparatory state, it is to be now judged of by 
the straight-edge, whether all three are nearly alike, or lean to 
the same kind of error. Tims, supposing the pieces A and B 
to have a tolerably equal disposition to convexity, or tbnt when 
plaeed in contact they n t in the eenter, but fail to touch around 
the margin, then A and B are each a little reduced in the middle 
until the tendency to rotate in the center is gone; A and B will 
be then each a shade nearer to truth than before. The third 
piece, or C, is fitted to A, after which, supposing for a moment 
A and B to be each a true, or a plane surface, C would become 
also a plane surface, and the task would be then completed. 
Perfection is not, however, nearly so easy of attainment, and it 
is almost certain that although A and B may be counterparts, 
they will not be planes; presuming therefore that C has been 
fitted to A, it is almost certain that C will not fit B. (This may 
be called routine One.) 

Considering, therefore, that now A and C are the two most 
nearly alike, or that both are proved to be convex, these are 
the two upon which an equal amount of correction is this time 
attempted, until they become counterparts, or fit well together; 
and the third piece, or B, becomes the arbiter in this stage of 
the work. (This may be called routine Two.) 

We will lastly assume that B, when altered until it fits C, does 
not quite fit to A, but that B and C present an equal departure 
from truth, and arc still both convex; then B and C are altered 
in an equal degree until they appear to be perfect counterparts, 
and this time A, when fitted to one of them, shows whether the 
whole three are planes, or that two of the pieces are convex and 
one concave. (This may be called routine Three.) 

The method of comparison will probably be rendered somewhat 
more evident, by the following tabular view of the processes. 

Routine Two. -: ne Three. 

A. B. Counterpart* A. C. Counterpart*. B. C. Counterpart!*. 

C. Arbiter. B. Arbiter. A. Arbit 

The inspection of the letters in three routines will farther 
show, that every one of the three surfaces admits of comparison 
with the two others, and that the abstract method is to fit together 






878 INSTRUCTIONS FOR FILING FLAT WORKS. 

those two which appear to have the same error, by altering those 
two in an equal degree, after which, the third piece, when fitted 
to one of the other two pieces, incontestably proves whether all 
three are planes ; as this cannot be the case until all three agree 
together in every comparison. The attainment of true planes 
will be found to require several repetitions of the three routines, 
but towards the conclusion increasing care will be continually 
required, in order that no degeneration may insidiously occur, 
to disappoint the hope of the progress towards perfection being 
steadily on the increase. 

This correctional process, which is precisely analogous to the 
mutual correction of three straight-edges, is somewhat familiar 
to mechanicians, but the process is obviously very much more 
tedious than the origination of straight-edges, on account of 
the great increase of the surface to be operated upon, and the 
circumstance that the quantity taken in excess from any part, 
must be amended by reducing every other part of that surface 
in an equal degree. 

For the sake of simplicity it has been supposed throughout the 
description that the two convex pieces were in each case selected 
for correction ; but this is immaterial, as the result would be the 
same if the two concave pieces were wrought, or the one and other 
pair alternately, as circumstances may accidentally suggest. 

The three planometers having been made as perfect as the 
skill and patience of the operator will admit, one of them should 
be carefully laid aside, and only used in the most guarded manner 
in the reproduction of other planometers, or the correction of 
those in general use ; which latter process will be found occasion- 
ally requisite, but the less frequently so, if the instrument is 
equally worn by rubbing the work to be examined, at all parts 
of the planometer, instead of upon the central part alone. And a 
true surface or standard having been once obtained, it should be 
most scrupulously preserved, as it will be found very considerably 
less troublesome to copy a good standard, than to originate the 
three standards themselves from which the one is to be reserved. 

SECT. VI. INSTRUCTIONS FOR FILING RECTILINEAR WORKS, IN WHICH 
SEVERAL OR ALL OF THE SUPERFICIES HAVE TO BE WROUGHT. 

The former instructions have been restricted to the supposition 
that only one of the superficies of the work was required to be 




Mf-vn 



IBC1 Ml NEAR SURFACKH. 

e plane or flat ; hut utly happens in rectangular 

8, such an the piece A I*. < ,11 six surfaces, 

namely, the top and hottmn A, a, tin- t\u> Miles B, b, and ti 

ill require to be corrected and made in rectangular 
arrangement (the surfaces a, b, c, heiu.u necessarily concealed 
>m view), and therefore some particulars of the ordinary 
method of producing these six surfaces will he added; and the 
former remarks on pages 500 to 503 on squaring thick and thin 
works in wood may be also consulted. 

The general rule is first to file up the two largest and principal 
faces A and a, and afterwards the smaller faces or edges B b, and 
Figs. 868. 

869. 870. 




r .1 p 

C e. The principal faces A a, especially when the pieces are 
thin, must be proceeded with for a period simultaneously, 
because of the liability of all materials to spring and alter in 
their form with the progressive removal of their substance, and 
on this account the work, whether thick or thin, is frequently 
prepared to a certain stage at every part, before the final correc- 
tion is attempted of any one part. 

The straight-edge and surface-plate are required, to prove that 
each of the faces A and a is a plane surface, and the callipers or 
a similar gage is also needful to prove them to be in parallelism. 
Callipers, unless provided with set screws, are very liable to be 
lentally shifted, and it is needful to use them with caution, 
otherwise their elasticity, arising from the length of their legs, is 
apt : . There are gages, such as fij;. ^I'l'.t, with short 

parallel jaws that open as on a slide, and arc fixed by a side 
screw ; and a still more simple and very safe plan, is to file two 
ilar notches in a piece of sheet-iron or steel, as in fig. 
870, the one notch exactly of the finished thickness the work is 
required to possess, the other a little larger to serve as the coarse 
or preliminary gage. 



880 INSTRUCTIONS FOR FILING WORKS. 

Sometimes the one face of the work, or A, having been filed 
moderately flat, a line is scored around the four sides of the work 
with a metal moving-gage, the same in principle as the marking- 
gage of the joiner, fig. 342, page 487. At other times the 
corrected face A, is laid on a planometer larger than the work, 
as represented, (neglecting the inversion,) and the marginal 
line is scribed on the four edges, by a scribing-point p, fig. 868, 
projecting from the sides of a little metal pedestal that bears 
truly on the surface-plate. 

Chamfers or bevelled edges are then filed around the four edges 
of the face a, exactly to terminate on the scribed lines, the central 
part of a can be reduced with but little watchfulness, until the 
marginal chamfers are nearly obliterated. This saves much of 
the time that would be otherwise required for investigating the 
progress made ; but towards the last, the callipers and planometer 
must be carefully and continually used, to assist in rendering A 
and a, at the same time parallel and plane surfaces. 

The two principal edges, B b, are then filed under the 
guidance of a square ; the one arm of the square is applied on 
A, or a, at pleasure, as in joinery work : or if the square have a 
thick back, it maybe placed on the planometer, as at s, fig. 868 ; 
if preferred, the work may be supported on its edge B upon the 
planometer, and the back square also applied, as at s, in which 
case the entire length of the blade of the square comes into 
operation, and the irregularities of the plane B, are at the same 
time rendered obvious by the planometer. 

Another very convenient test has been recommended for this 
part of the work namely, a stout bar, such as r, fig. 8G8, the 
two neighbouring sides of which have been made quite flat and 
also square with each other. When the work and trial-bar, (or 
rectangulometer,) are both laid down, the one side of the bar 
presents a truly perpendicular face, which may, by the interven- 
tion of colour ing matter, be made to record on the work itself, the 
points in which B differs from a rectangular and vertical plane.* 

When the edge B has been rendered plane and square, the 
opposite edge b, may in its turn be marked either with the 
gage or scribing-point at pleasure ; the four edges of b may be 
then chamfered, and the entire surface of b is afterwards cor- 
rected, (as in producing the second face a,) under the guidance 

* See Smith's Panorama of Scieuce, Vol. I., page 30. 






HAVING \ \11IOU8 RECTILINEAR SURFACES. 



881 



of the square, callipers, rectangular bar, and surface-plate, or 
some of these tests. 

ends C <*, now claim attention, and the marginal line is 
scribed around these by the aid of the back squat < hut 

the general method so closely resembles that just described as 
not to call lor additional particulars. 

Should one edge of the work be inclined, or bevelled, as in the 
three following figures, in which the works are shaded to distin- 
guish them from the tools, the rectangular parts are always first 
\\ rouirlit, and then the bevelled edges, the angles being denoted 
by a bevel instead of a square : either with a bevel having a 
movable blade, as in fig. 871, or by a bevelled templet made of 
sheet-metal, as in figs 872, or 873, which latter cannot get 



Figt. 871. 



872. 



873. 



874. 




r 





875. 



876. 



877. 



878. 



misadjustcd. The bevelled edge of the work, is also applied if 
possible on the planometcr ; in fact the planometer and bevel 
are conjointly used as the tests. Bevelled works are either held 
in the vice by aid of the chamfer-clamps, fig. 855, page 859, or 
they are laid in wooden troughs, with grooves so inclined, that 
the edge to be filed is placed horizontally. Triangular bars of 
equilateral section arc thus filed in troughs, the sides of which 

at an angle of 60 degrees, as in fig. 874. 

The succeeding examples of works with many plane surfaces 

are objects with rebates and grooves, as represented in figs. 875 

to 878. Pieces of the sections 87.">, and 870, supposing them 

to be short, would in general he formed in the solid, either 

from furgings or castings, as the case inijrht be; the four 

;md more accessible faces would lie tiled up s.juare and 

true, and aftcr\\ard> the i. \\ ith a due regard to their 

3 L 






INSTRUCTIONS FOR FILING MORTISES. 



parallelism with the neighbouring parts, just after the mode 
already set forth. The safe-edge of the file is now indispen- 
sable ; as in filing the face b, the safe-edge of the file is allowed 
to rub against the face a of the work, and which therefore serves 
for its guidance; and in filing the face a, the side b becomes the 
guide for the file. The groove in fig. 876 requires a safe-edge 
square file. 

When however pieces of these sections, but of greater 
lengths, have to be produced by means of the file alone, it is more 
usual to make them in two or three pieces respectively, as shown 
detached in figs. 877 and 878; and which pieces are first ren- 
dered parallel on their several edges, and are then united by 
screws and steady pins ; or rather, they are united before being 
actually finished, in order that any little distortion or displace- 
ment occurring in fixing them together may admit of correction. 

In works of these kinds, which have rebates, grooves, internal 
angles, or cavities, the square, with a sliding blade, shown in 
fig. 876, is very useful, as the blade serves as a gage for depth, 
besides acting as a square, the one arm of which may be made of 
the precise measure of the edge to be tried. This instrument is 
often called a turning-square, as it is particularly useful for 
measuring the depth of boxes, and other hollowed works turned 
in the lathe. 

In making straight mortises, as at s s, fig. 879, unless the 
groove is roughly formed, at the forge, or in the foundry, it is 
usual to drill holes nearly as large as the width of the mortise, and 



Figs. 879. 




880. 




in a straight line; the holes are then thrown into one another by 
a round file, or a cross-cutting chisel, and the sides of the mortise 
are afterwards filed square and true. 






M. inii.f- \ ,tTLY WITH DKIKTS. 888 









tilar mortise r r, tin- -nine, with the 

.1 that the holes are made on a circular lino; and that, 
instead of a flat file In ing used throughout, a half-round or a 
crossiir/ tile is used lor the concave side of the mor 

Shcu ular mortises, or those which may be rather con- 

sidered to be square holes, as iu tig. 880, would if large 
pared by forging or casting the material into the form ; and then 
the six exterior faces having been corrected, the aperture would 
be filed on all sides under guidance of some of the various tests 
before rt tt rrcd to. And in such a case, it is convenient to employ 
a small square *, in the form of a right-angled triangle to which is 
attached a wire that may serve as a handle, whereby the square 
may he applied at any part within the mortise without the sight 
of the workman being intercepted by his own fingers. Some- 
times also, a cubical block filed truly on four of its faces to the 
exact dimensions of the aperture, is used as a measure of the 
parallelism and flatness of the four iuterior faces. 

These miscellaneous examples of filed works with plane sur- 
faces, will be concluded by others of somewhat frequent occur- 
rence, and in which different tools are judiciously employed in 
conjunction with files. The method first to be described, is one 
that is considerably used in thick pieces of metal, for making 
holes differing from the circular form, such as square, hexagonal, 
triangular, elliptical, and other holes, by first drilling a round 
hole, and then enlarging and changing the section of the ehvular 
hole by a taper punch, better known as a drift, which tool is 
made of steel, and exactly of the same section as that required 
in the hole; the drift is hardened and tempered before use. 

The drift for a taper square hole is made as in fig. 881, or 
simply as a square pyramid, considerably longer than the hole 
required : a round hole is first drilled in the work, just large 
enough to admit the small end of the drift, which is then drivt u 
in, its angles indent and force out the metal, making it first like 
the magnified line m, and ultimately exactly square, unless by 
ike the hole were drilled too large, when the eircnlar part^ 
would not be quite obliterated. If admissible, the endlong blows 

lie drift are mingled with a few blows on the sides of t 
work, as at bb, or parallel with the sides of the drift, which ca\ 

metal to adapt itself more readily to the tool. The drift 
must not however be used too violently, for as it aet> as a 

; 



88-t 



HOLES MADE WITH DRIFTS AND FILES. 



wedge, it may burst open the work, and which latter is therefore 
mostly left strong and rough before being drifted ; and generally, 
when the angles have been somewhat indented, they are partly 
filed out, and completed by the alternate employment of the file 
and drift, the marks made by the latter serving continually to 
indicate the parts to be removed with the file. 

Taper square holes, such as those in the chucks for drills, are 
made with some facility. The chuck is first drilled on its own 
mandrel, and the drift is put in the four different ways in suc- 
cession, that the errors incidental to its form may be scattered 
and lost; the chuck is also placed on the mandrel at intervals, 
with the drift in its place, that the drift may show as it revolves, 
whether or not the hole is concentric. When it is required 
that the drifted hole should be parallel instead of taper, the drift 
is made as in fig. 882 ; that is, parallel for a short portion in the 
middle of its length, and the extremities alone are tapered so as 
to make the tool smaller at each end ; the work is therefore first 
gradually enlarged to admit the largest part of the drift, and the 
parallel part is then driven through the work, and renders the 
inner surface of the same a true counterpart of the drift, if proper 
care have been taken. In some few cases, the sides of the drifts 



Figs. 881. 882. 



884. 




are notched with a file, so as to act as teeth ; but this is not 
general. 

"\Micn drifts are used, the process of working is often reversed, 
or the interior surfaces are completed before the exterior. The 
holes are first drifted whilst the work is larger than its intended 
size, and afterwards the exterior part is filed or turned, as the 
case may be, from the hole, that is, the hole, (sometimes filled with 
the drift,) is made the basis of the measurement of the exterior 



MAKING KEY-WAts IN \\liiiis \M 885 



ions of the work. Frequently, as in a square washer, the 
drift it-elf, or else a sqnan arbor of similar form, with a center 
lu.l<- at each end, is made to serve us the chuck hy which the 
work i> |l:ieeil u, the turning lathe for completion. 

In the concluding example of this section, that of making by 
hand the key-ways in the round holes of wheels, it is to he 
observed that it is common to turn a cylindrical plug exact 
till the hole, and to make a notch in the plug as wide as tin- 
intended key-way and parallel with the axis : the plug is shown 
at g, fig. 883. A piece of steel /, is then filed parallel, and exact ly 
to fit the notch, and its edge is cut as a file, and used as such 
within the guide-block, the latter being at the time inserted in 
the hole of the wheel. In this case the block becomes the 
director of the file, and the notches in any number of wheels are 
made both parallel and axial, and the only precaution that re- 
mains to be observed is in the depth of the notches, and this is 
not always important; the depth may however be readily deter- 
mined, by making the grooves at first a little shallower than 
their intended depth, and then, the plug having been removed 
from the hole, a stop is attached to the side of the file, parallel 
with its edge, as at *, to prevent its penetrating beyond the 
assigned depth. 

The method of cutting key-ways in large wheels, that was 
frequently employed prior to the introduction of machinery for 
the purpose was as follows. Supposing the wheel to have been 
bored with a three-inch hole, and to have required a key-way 
half-inch wide and half-inch deep. The guide-block g, fig. 884, 
of three inches diameter, would have had a groove say half-inch 
wide and one inch deep, and a cross-cut chisel c, exactly to fill 
the groove would have been made. The chisel having the same 
section as the groove, when driven through would produce no 
effect; but if a piece of sheet steel *, VTT thick, were laid at the 
bottom of the groove, the chisel would then cut a groove half- 
inch wide and T V deep ; and if two, three, four, and ultimately 
eight such strips were successively employed together, as in the 
section and detached views, fig. 88 1, the hole would be accurately 
chiselled out by the repetitions of the process. The hole would 
require to be finished with a parallel thick file, called a key-way 
or cotter-file, which has already been described on page 822 3, 
of the present volume. 



S8G lil'NKHAL KKMARKS Ul'oX 

SECT. VII. INSTRUCTIONS FOR FILING CURVILINEAR WORKS 

ACCORDING TO THE THREE ORDINARY MODES. 

The curvilinear surfaces of works are commonly of less im- 
portance than the plane surfaces, neither do they in general 
require the same skilful use of the file, especially as the more 
important curved lines and surfaces in machinery are circular, 
and are therefore produced in the turning lathe; and of the 
remaining curves the majority are introduced either to give a 
more pleasing outline to the works than would be obtained by 
straight lines, or to obliterate the numerous angles that would 
be inconvenient to the hands. 

In filing works that are convex, flat files are always used, and 
the file is necessarily applied as a tangent to the curve ; and in 
filing concave works round and half-round files are used, and in 
some cases they are selected, nearly or exactly as counterparts of 
the hollows to be wrought. 

The manipulation of the file upon curvilinear works is entirely 
different from that required to produce a plane surface, in which 
latter case the work is held at rest and the hands are moved as 
steadily as possible in right lines ; but in filing curved works an 
incessant change of direction is important, and so far as practi- 
cable, either the file, or the work, is made to rotate about the 
axis of the curve to be produced. 

A semicircular groove of half-an-inch radius, as in fig. 885, 
would be most easily filed with a round file of nearly the same 
Fi--. 885. 886. 887. 




a b t> 

curvature, and the correspondence between the file and work, 
and consequently of their axes likewise, would render the matter 
very easy ; but the file, from the irregularity of its teeth, would 
leave ridges in the work, unless in every stroke it were also 
ted to and fro axially by the motion of the wrist, and occa- 
sionally in the reverse direction, so that the furrows made by the 
teeth might cross each other. If the groove to be filed had a 
diameter of three or four inches, although the file might be 
selected to correspond in curvature with the groove, as it would 
not embrace the entire hollow, the twisting and traversing of the 






MIVKAB WORKS. 

vould be imperative in ordi-r to arrive at all parts of ' 
work. 

Under ordinary circumstances it is certainly \>< >t that the 
eunature ot tin- tile ami work should agree ; as possi! 

but it is obvious that the file it' more eoiiu \ than the work, can 
only toueli the latter at one part, as at a, fig 88(5, whereas, if 
the file is less convex, or flatter, than the work, it will act at 
places, as at b b, fig. 887. The Sheffield cutlers, in filing out 
the bows of scissors, and which they do with great rapidity, 
always avail themselves of this circumstance, and until nearly 
the conclusion, use files flatter or less convex than the work. 

In filing concave works, there is but little choice of po- 
as the file is always parallel with the axis of the curve, a* in the 
dotted line in fig. 88S, but in convex works such as fig. 889, the 
file may be applied either parallel with the axis as at p p, or 
transversely thereto as at / /. In general however the work 
would be fixed obliquely as in fig. 890, and the iile would be iir>t 



Fig*. 888. 




used transversely for some one or two strokes, at an inclination 
of about 30 degrees with the horizontal line, as at a, so as nearly 
to agree with the straight side of the object, the file would be 
successively raised to the horizontal, and depressed in the same 
degree on the other side, in fact proceeding through the positions 
a be, fig. 890, at some eight or ten intenals, and which would 

1 to make as many insignificant ridges upon the work. The 
ridges would be then melted together by swinging the hands 
from the position a to c in every stroke, to be repeated a few 
times; but as the entire semicircle could not be embraced at 
one stroke, the work would be re-fixed in two or more positions, 
so as the operation into about three stages. 

A more exact although less energetic method would be to 
place the file parallel with the axis as on p p, fig. 889, and to 
sweep round the curve principally by t ing motion of the 

>t, which joint can be more readily moved, and also with less 



888 THE THREE DIFFERENT MODES, 

fatigue, than the two hands conjointly. A third mode, frequently 
adopted in such small pieces as can be held upon the filing-block 
with the hand-vice, is to swing the work upon its axis, and to 
use the file with the right hand, as if on a flat surface, a mode 
explained in fig. 858, page 862. 

Some works are curvilinear in both directions, such as curved 
arms and levers with rounded edges ; many of these kinds are 
completed by draw-filing them, or rubbing the file sideways or later- 
ally around the curve, instead of longitudinally as usual ; but the 
changes consequent thereupon do not require any especial notice. 

The success of all the modes of filing curved works, will be 
found very much to depend on the freedom with which the several 
twisting and excursive motions of the hands are performed, and 
the work should be frequently examined, in order that the eye 
may judge of the parts in excess and that require to be reduced, 
in order to produce a pleasing outline. 

Having considered the general manipulation of the file in 
respect to curved works, it remains to be noticed that curvilinear 
objects are filed up in different modes, dependent on their 
respective forms and characters. Thus the great majority of 
curved works are moulded and formed prior to the application 
of the file, which is then principally used to smooth and brighten 
them other works are shaped almost entirely with the file, 
assisted by outlines drawn on the pieces themselves and again 
other works are shaped with the file, under the guidance of tem- 
plets or pattern-plates of hardened steel. Some observations 
will be offered on all three of these modes. 

Firstly, curved works that are moulded or formed prior to the 
application of the file. The methods employed in the prepara- 
tion and figuration of materials into curvilinear and other forms, 
by founding and forging, have been largely considered in the 
first volume, and from which remarks it will have been seen, that 
the perfection of cast works greatly depends on the perfection of 
the foundry models or patterns, and these latter greatly depend 
on the facilities offered in pattern-making by the turning-lathe, 
and the joiner's planes ; and although such castings in many 
cases do not admit of being finished in the* lathe, the per- 
fection of the pattern is a great source of embellishment and 
economy, in the configuration of the works made by moulding 
and casting. 



or rn 






tiling up metal works that have been accurately 
shaped by founding or forging, little or nothing n > be 

added to tin- remarks on the last page, as the only object is to 
act < part of curvilinear surfaces in the most expeditious 

and commodious manner, with the general aim of reducing any 
trilling errors of form that may already exist in them, and av< 
ing the introduction of new ones; which circumstances call for 
the frequent scrutiny of the eye, and an incessant yet judicious 
variation in the position of the hands. 

Secondly, curved works that are moulded or formed almost 
entirely with the file. These are blocked out square, and the 
outlines of the curves are drawn on the ends and sides of tin- 
pieces, to guide the file in a manner analogous to the routine 
pursued by carpenters, masons, and other artizans. For instance, 
to form a bead, as in fig. 891, the work is prepared of a nearly 
rectangular form, and the half-circle having been drawn at each 
end, the angles of the works are coarsely removed at about 45 



892. 



893. 




degrees, making the end a semi-octagon ; sometimes the four 
angles are farther reduced, giving to the work eight facets, prior 
to their being thrown together in making the general curve. If 
these sides are made with only a very moderate degree of exact- 
ness, they \\ill greatly tend to preserve the uniformity of section 
throughout. 

Many workmen when they have removed the two principal 
angles at 15 degrees, will make a chamfer entirely around the 
semicircle at each end, to guide the file in hastily reducing the 
principal bulk of the material, until the chamfers are nearly 
obliterated, after which the curve is f'mishrd, in exact agreement 
with the lines, with a smooth file. It is also desirable that the 
straight-edge should be frequently applied along the axis of the 
curve, at various parts, during the progress of the work. 

Should the entire piece, fig. 892, have to be made from a solid 



890 FILING WORKS, BY AID OF 

block, two cuts a and b, made with the saw, would remove the 
corner, and a little filing would then suffice to complete the 
internal angle. The round part of the bead would be made as 
before, and previous to filing the hollow, it would be chamfered 
on the line c ; a half round file, of less curvature than the hollow 
itself, would be first sunk in the middle of the chamfer, and the 
hollow would be deepened and extended sideways, always main- 
taining an easy curve, until it reached the marginal lines where 
the hollow meets the plane surfaces. This mode is better cal- 
culated to avoid the accidental obliteration of the angles of the 
work, than if the file were sunk at each margin. 

"Where hollows run on to right lines as at a, fig. 893, there is 
some risk of making a break in the junction, either from the curve 
sinking below the right line, as at b, or from the straight line, 
as at c, advancing too far and breaking in upon the curve. On 
this account a break or fillet is usually made at the part as at d, 
or else it is usual primarily to give that form, by filing the flat 
first, and then sinking down the hollow just to meet it, and at 
the conclusion letting the half-round file run a little way on to 
the right line. Some however prefer the opposite course, or that 
of sinking the hollow to its full depth, and then filing down the 
remainder with the flat file, but which mode is certainly attended 
with more risk. 

Thirdly, curved works that are shaped with the file under the 
guidance of templets or pattern-plates of hardened steel. This 
mode is much followed in works of two principal kinds, namely, 
thin works required in great numbers and precisely of one 
form, and in a variety of works that require to be exactly 
circular, although they may not admit of being so fashioned 
in the lathe. 

Many thin works of the first kind are stamped or punched out 
of the sheet-metals, as for instance the washers for machinery, 
the links of jointed chains, steel pens, parts of locks for joinery, 
and numerous other thin works; but many objects of larger 
kinds, and that are not wanted in such large numbers, are not 
stamped, but are either cast, or cut out with the shears, and after- 
wards filed between templets. Instances of such works are occa- 
sionally met with in the numerous class of machines for spinning 
and weaving, cotton, silk and wool, and also in lace and stocking 
machinery. The mathematical instrument makers likewise 



TBMPLBTS OF HARDENED MTKKI.. ^'.*\ 

rut in works th.v 

uail-uhecl of a .striking clock, fig. 894, is frequently thus 
formed, by menus of a tempi, t : it has an i . n twelve 

steps, arranged spirally, the j of wliieli <1. the 

iiuiuber of strokes of the hammer on the bell. In this case, 
which will serve as a general example, a piece of shect-sto 
cutout, ll:ittruc<l.. -ind smoothed on one side, to receive the drawing 
of the snsiil-wheel, and a second piece is also prepared. The two 

tirst drilled together with a central hole, and another hole as 
iit from the center as admissible. The two plates arc then 
united by two pins, and the outline of the work having been 
drawn on one of them, they are next filed in steps carefully t<> 
the lines, and square across the edges, and they are afterwards 
hardened and slightly tempered to lessen their liability to fracture 
on beiiii: pinched in the vice. The dozen or more snail-wheels 
having been cast, or cut out of sheet-brass, and flattened with the 
hammer, two or three at a time are pinched alongside one of the 

;ilets, whilst the two pin-holes are made with the breast-drill 
or in the lathe, with a drill that exactly fits the holes in the 
templets. It only remains to place the dozen plates between the 
t- in plets, keeping them in position by two pins extending through 
the whole number, and then all the notches are filed in the brass 
plates, until the file very nearly touches the steel patterns, as 
abolute abrasion on the steel itself would greatly injure the files. 
In this mode the several brass plates become very exact copies of 
the pattern.* 

A different application of templets is sometimes met with in 
filing up numerous similar parts in the same object, as the arms 
or crosses for the wheels of clocks and other machines. The exact 



* Templets are M much used for setting out and producing aeries of holes in 
any special arrangement, as in filing works to any particular form : the most 
complex example of the kind that occurs at the moment to the author, of templets 
being used in this manner, is in drilling the aide-plates of harps intended for the 
arbors and link-works, used in temporarily shortening the strings. The rsspeotire 
positions of the holes in these side-plates require a most exact arrangement, any 
departure from which, would prevent that precise shortening of the string re- 
quired to produce the semitones with critical accuracy, and would also cause an 
unbearable jar, unless the cranks of the harp were severally in true position, <>r 
on the lines of centers, so as firmly to support the tension of the strings under all 
circumstances. 



892 



FILING WORKS, BY AID OF 



pattern of one spoke is filed up as a templet, which is shaded in 
fig. 895, and serves for the similar configuration of every spoke; 
the position of the templet being given by a central pin, aided by 
any little contrivance which catches into the 3, 4, 5, or 6 equi-dis- 
tant teeth corresponding with the number of arms. Many other 
equally available cases of the use of templets might be cited, but 
we must now proceed to works of the second kind, or those of 
an outline partially circular. 

It frequently happens that certain forged, cast and other 
works have parts, known as bosses, swells, collars and knuckles, 
that are pierced with holes, which require their flat surfaces and 
also their margins to be made partially or entirely concentric 
with the holes. When such parts occur as bosses, they often 



Figs. 894. 



895. 



896. 





project from a flat surface, and after the central hole is drilled, 
some of the pin-drills drawn on page 550, or analogous tools 
used in drilling machines, are employed in finishing the margins : 
thus figs. 482 and 484 serve for facing the extremities of the holes, 
483 and 485 for the external faces of cylindrical bosses or collars, 
used in the guidance of arms jointed concentrically with the 
holes, and figured cutters 485 serve for bosses with mouldings 
intended for ornament. 

When the circular margins are discontinuous, files and tem- 
plets are more or less required : thus the extremity of a forged 
arm, such as fig. 896, is drilled, and in the configuration of the 
remaining parts, if but one or two such pieces are to be made, 
a boss or plug of wood is turned like a, that shall fit the hole ; the 
shoulder of the wood is then rubbed with red chalk to mark that 
part of the surface which is not at right angles to the hole, and 
the circular edge of the boss serves for the guidance of the file in 
finishing the exterior margin ; visually rather than obstructively, 
as the wooden boss would be reduced instead of the file being 



TBUPLBT8, ETC. COMPASS JOINTS. 

Led. If then fore many such objects had to be filed, two 
bosses or templets would be made of hardened steel, and n-..l 
one at each extremity of the hole, and they would be held in 
position by grasping the three pieces collectively in the tail 
. The same general method is very largely and more 
rigorously followed in making joints or hinges, of which three 
examples will be quoted in conclusion of this section. 

The brass and steel plates fig. 897, used for the joints of car- 
penters' rules are filed up to templets in all respects after the 
manner described in reference to the snail-wheel, fig. 89 i, and 
the joint-plates arc inlaid by means of the file, saw, chisel, and 
plane, by modes that do not require to be noticed. 

The joints of drawing-compasses are made somewhat differ- 
ently, and mostly as follows. The solid knuckle a, fig. 898, i^first 



$98. 




drilled and made circular by aid of a templet r, and the hollow 
side b is filed to correspond exactly with a; the two arc then 
pinched together in the vice on the line d d, and the parallel 
notches for the steel joint-plates are made in each with the saw 
fig. 712, page 729, as deep as the line e e. The parts a and b arc 
then separated, the notches in b, are completed with the frame- 
saw, and the bottom of the notches in a, are rendered circular 
with the joint-saw, fig. 713, as there explained. The middle 
plates, when filed a little larger than the templets c, are inserted 
in ft, and soldered in their places; the two parts are smoothed 
on their various internal surfaces, and united by a temporary 
joint-pin, and any little invpilaritie.s in the external or cir- 
cular curves, (which are left purposely a trifle too large,) arc 
mutually detected by their want of agreement when the joint is 



894 



CONSTRUCTING HINGES AND JOINTS, 



opened to different distances ; any parts in excess are very care- 
fully reduced with a small smooth file, principally by draw-filing, 
after which the screw-pin with its brass cheeks or bosses is 
added. 

The pin-drill, fig. 475, p. 547, is commonly used for cutting out 
the concave parts that extend to the side of small compass-joints, 
such as are represented in fig. 899, and also for inlaying the 
heads of small countersunk screws. 

Larger joints with wider knuckles, such as fig. 900, are in 
many instances cast from patterns closely resembling the finished 
works. In such cases the first process is generally to remove 
any little external errors with the file, and to clear the angles 
with a small chipping chisel ; the faces of the knuckles are then 
smoothed and inserted within one another very tightly. The 
joint-hole is afterwards drilled throughout all the knuckles, and 
which are filed up externally, sometimes under the guidance of 
templets put at the ends, but principally by the reduction of 
those high parts which get scratched or rubbed by the opposite 
parts, and thereby show their excess of height. 

But if such joints are required to be made more accurately, 
the holes are first drilled in each piece separately, and rather too 




close in the corners; the holes are broached with a parallel 
broach, so as exactly to admit a steel cylinder, fig. 901, which has 
a square end for the brace ; this rod is intended to receive the 
cutters, shown on a larger scale in fig. 902, which are cylin- 
drical pieces of steel bored to fit the rod, and cut with teeth on 
the outer cylindrical part and on one flat surface; a pin is inserted 
through both the cutter andbar,sothat thetwo may be united after 
they have been placed within the joint to be worked ; sometimes 
the back face of the cutter has only a diametrical notch to receive 






u M I ilI.f.M. ASSISTED OY OTHER TOOLS. 






driving-pin, which pmhes the cutter before it as it revolves. 
A recess must first be cleared for the rut NT with a chisel and 
hammer, or by A wide-joint saw or cutter, such as fig. 713 ; and 
the hollowed parts at a a fig. 900, are then cut throughout 
their length with the cutter, that afterwards serves to flatten 
the faces of the knuckles in exact parallelism throughout, and at 
right angles to the central hole. 

The two halves of the joint, having been separately hollowed, 
and faced until the knuckles will penetrate some distance into 
another, the external parts of the joint are next separately 
tiled under the guidance of hard steel rings, or templets, of the 
same diameter as the cutter, and placed on the cylindrical rod ; 
after which, the two parts of the joint are put together when yet 
slightly too large, and the central pin is inserted, in order that 
the rubbing of the knuckles against the corresponding hollows 
may denote the parts that are still too high or full; and by 
cautiously removing all the parts that are abraded, the joints may 
be made to fit very closely and accurately, and yet to move with 
great smoothness. 

Many joints that are at the same time wide and small, as in 
hinged snuff-boxes, could not be drilled, as above described, with 
safety, and are therefore made quite differently, by means of 
small tube, called joint-wire, the mode of drawing which was 
explained in vol. i., page 429. 

For instance, in making a snuff-box, the rims for the top and 
bottom are fitted and jointed together before the top and bottom 
plates are soldered in, and the joint is thus constructed. Sup- 
poking that five knuckles arc required for the bottom, and four 
for the top, the nine pieces of joint-wire are cut off, and filed 
square at the ends ; the rims for the top and bottom having been 
fitted so as to form the rebate, are placed together, and carefully 
filed out with a semicircular recess or groove, by means of a 
parallel round file, or a joint-file, exactly of the diameter of the 
joint-wire, which therefore leaves a hollow equal to the fourth 
part of the circle in each rim. 

of the joint-pieces are then strung on a wire, inserted in 

the hollow of the rim for the bottom of the box, and tied therein 

with tine binding-win tervals between these five knuckles 

regulated by inserting the other four between them for the 

moment, while the binding-wire is being fastened; after which 



896 COMPARISON BETWEEN THE FILE, 

this first series of knuckles is soldered in with moderately hard 
silver solder, which is usually fused with the blow-pipe. The lid 
is then treated in the same manner, and the bottom part of the 
box now serves as the gage for regulating the distance between 
the knuckles in the top rim. The same plan is also used by 
mathematical instrument makers and others, who however more 
generally turn the joint-pieces in the lathe, as the draw- bench 
forms no part of their ordinary supply of tools ; and the wide 
joint-pieces or knuckles in mathematical works are usually larger 
than could be produced in that manner. 



SECT. VIII. COMPARATIVE SKETCH OF THE APPLICATIONS OF THE 

FILE, AND OF THE ENGINEER'S PLANING-MACHINE, ETC. 

The general aim of this present section, is to show, by way 
of contrast, how several of the pieces advanced as illustrations 
of works executed with files, in sections iv. to vn. are produced 
by the planing-machine and analogous contrivances. 

The comparison of the modes of producing flat and rectilinear 
works with the file and with the planing-machine, is greatly 
in favour of the latter method, in respect to facility, expedition, 
and accuracy ; and the modes are besides entirely different. 

For instance, the laborious and tedious mode of filing a flat 
surface has been spoken of at some length, and it will be 
remembered the work is fixed, and the tool is moved in a variety 
of directions upon the surface to be filed. 

So far as the action of the smith's hand-plane for metal, (page 
483,) and carpenters' planes may be brought into comparison, 
they are used in many respects as the files, but are applied 
generally parallel with the one side of the superficies that is 
being wrought. 

But the engineer's mode of planing works in metal is entirely 
different from either of the above, and is strictly analogous to the 
mode of turning works in the lathe with a slide rest, if we 
consider the axial motion of the lathe to be replaced by the 
rectilinear motion of the planing-machine, as was briefly explained 
in general terras in the introductory chapter to the present 
volume, more particularly in reference to the " guide principle," 
see pages 468 and 469. 

The work to be planed, is there briefly described as fixed on a 



\M> NIK ENGINEER'S PLANING MACHINE. 

carriage or sledge, that is made to move to and fro in a true 
t line, a* upon a \ery accurate railway; whilst the cutting- 
which is i those used in the turning-lathe was 

supposed to he affixed to a bridge, standing across and at riht 
angles to the railway. Such a fixed tool would plough a furrow 
in the work, \\hich furrow would be accurately straight as the 
railway or guide from which the work itself received its direct 
of motion. 

If the reader will only conceive the work to be continually 
moved to and fro upon the slide or railway, a distance equal to 
its own length ; and that by a subsidiary contrivance, or another 
slide placed horizontally, the tool between each reciprocation of 
the work were moved a small distance to the right continually, a 
series of grooves would be ploughed, all individually right lines; 
and these grooves would shave off all the asperities and irregu- 
larities of the work, leaving it finely grooved in parallel furrows. 
Or provided the end of the tool were flat, and ever so little 
broader than the small interval between the successive strokes, 
the tool would leave a plane or smooth surface ; and the per- 
fection of this surface would mainly depend, on the railway or 
the cutting-slide, and the horizontal or position-slide, being 
each truly rectilinear. 

Supposing now, by means of a third slide placed exactly 
perpendicular, the tool were depressed the tenth of an inch, and 
the process were entirely repeated, the surface would be reduced 
with perfect uniformity, one-tenth of an inch all over, and the 
new surface would be mathematically parallel with that existing 
immediately previous. Pursuing this idea, let it be further 
supposed that the surface just planed is the upper surface of the 
carriage or sledge of the plauing-machiue, technically known as 
the bed or /<////<-, upon which the work that is to be planed is 
fixed by screw-bolts and clamps. 

It will now be shown how the piece represented by A, B, C, 
in fig. 868, page 879, would be treated in the planiug-machine, 
in order to make its sides strictly parallel, in pairs, ami also at 
right angles to each other, in short, to convert it into a true 
parallelopipedon. 

The side A, of the piece, would be first placed uppermost and 
correctly planed ; afterwards the side A would be inverted, and 
placed on the bed of the machine, care being taken that no 

:', M 



898 COMPARISON BETWEEN THE FILE 

shavings intervened to prevent their coming into absolute con- 
tact ; and the second face, or a, would be planed strictly parallel 
with A, and that without any especial care on the part of the 
operator. 

Next, to plane the edge B, it would be necessary the third 
slide of the planing-niachine should be placed truly vertical, 
and that between each reciprocation of the bed of the planing- 
machine on its railway, the tool should be depressed a small 
quantity by the vertical slide, so as in the end to make it slowly 
descend, by intermittent steps, down a vertical and right line, 
exactly equal to the perpendicular height of the side B. 

All things now remaining fixed as before, if the tool were 
traversed horizontally until it touched the second edge or b, this 
edge of the work would, on pursuing the same gradual depres- 
sion of the tool, be planed also vertical and in strict parallelism 
with its opposite, or B. 

Continuing the same order of work as in the hand process, 
the ends C, c, would require the work to be released from the 
bed of the machine, shifted just 90 degrees, and then refixed, 
when the ends C, c, would be treated exactly as B, b, had pre- 
viously been, and would thence be made parallel and square. 

In some instances, indeed, the analogy to the railway is strictly 
maintained for a farther stage of the work, as such a piece as 
A, B, C, fig. 868, would sometimes be mounted, as it were, upon 
one of the turn-plates by which the railway-carriage is twisted 
one quarter round, preparatory to moving it from off the prin- 
cipal to an adjoining line. In the planing-machine, the turn- 
plate on which the work is fixed, is a supplementary circular 
bed having a horizontal or azimuth motion, so that by leaving 
the tool unaltered, except in its vertical path, the several edges 
of any regular polygon, whether a square plate, or a triangle, 
pentagon, hexagon, &c., may be planed with strict accuracy. 
The sides of any irregular polygon, may be also planed, by 
moving the tool so much on the transverse or horizontal slide, 
as the differences in the radial distances of the sides of the 
unequal polygon from the center of the turn-plate. 

Supposing the piece ABC, fig. 868, to be bevelled or chamfered 
on one or all of its edges, the slide which had been previously 
fixed in the vertical line, or perpendicularly, would be inclined 
tine precise number of degrees required, so as to produce the 




TIU: r.N(i INKER'S PLANING M.\< H: 
chamfered edge with as much facility as the qqunrc or vertical 

more convenient course in small and long works of 
sections resembling figs. 871 to 874, is to place upon the bed of 
the i l.ming-machine two headstocks or lathe-head*, the one 
furnished with a dividing-plate, and so arranged that the axis 
of the headstock is strictly parallel with the path of the railway 
or main-slide of the planing-machinc. In this case the planing- 
tool is almost always made to traverse horizontally, and which 
indeed is the most generally convenient. The triangular prism 
fig. 874 would be planed with great facility and truth by placing 
it in three successive positions, one-third of the circle or 12<) 
degrees asunder, by means of the dividing-plate; and if the axis 
of the headstocks were inclined vertically, a triangular pyramid 
or wedge, instead of a triangular prism, would be produced. 
The headstocks, if horizontal and shifted four times, or ninety 
degrees each time, would plane square or rectangular prisms, and 
of course also the rectangular faces of the pieces, 871, 872, and 
873 ; and again if instead of constantly shifting the headstocks 
ninety degrees, as for the rectangular parts, the changes were 
thirty, forty-five, or sixty degrees, according to the angles respec- 
tively required in the objects represented, the bevilled or chain - 
d edges would be obtained with great facility and accuracy. 

The planing- machine almost entirely prevents the necessity 
for building up work in a dissected state, as in the figures 877, 
and 878, as such grooves may be sunk, and any fillets may In- 
planed, upon the upper surfaces of works, the vertical or lateral 
surfaces, and even the lower or inferior surfaces, by bending tin- 
tools into appropriate forms, so as to reach into the parts, after 
tin- manner of fig. 439, page 534; as such contortions of the 
instruments do not in any respect interfere with the paths of 
the slides in which the tools are fixed and guided. 

And consequently, many parts of machinery that if worked by 
hand would be very difficult of access, and also very difficult of 
proof in respect to their accuracy, are accompli>hed in the planing- 
111:11 l:in< \M-h a degree of facility most satisfactory to the mind, 
as regards their abstract truth and the parallelism of their various 
pars. h'>\\i-ver strangely situated, and also most satisfactory, as 
regards the relative economy of the method ; indeed the plauiug- 
machine may be truly considered to have cil\ cted a most enor- 

3 M 2 



900 COMPARISON BETAVEEX THE FILE 

mous and beneficial revolution in the art of metallic construction 
generally. 

The key-grooves in wheels, for the keys or wedges by which 
they are attached to their shafts, when made by machinery, are 
cut out by a modification of the planing-machine invented by 
Mr. Richard Roberts, of Manchester ; it is designated the key- 
groove engine, and may be presumed to have been derived from 
the inortising-engines in Brunei's block-mac