Build It Yourself Enlargers And Enlarging Accessories

778.6

Keep Your Card in This Pocket

Books \vill be issued only on presentation of proper
library cards.

Unless labeled otherwise, books may be retained
for four weeks. Borrowers finding books marked, de-
faced or mutilated are expected to report same at
library desk; otherwise the last borrower will be held
responsible for all imperfections discovered.

The card holder is responsible for all books drawn
on this card. t

Penalty for o^Sr-due books 2c a day plus cost of
notices.

Lost cards and chanc/e of residence must be re-
ported promptly.

Public Library

Kansas City, Mo.

Keep Your Card in This Pocket

BERKOW1TZ ENVELOPE CO., f

TT4WW836 0836

Ji 6

161949 cf

JUW1 '4

JUL2<>'40

1:

a-,- rf *4n ; -="---

- 'i''.'.l5

^4?-- OCT-U^i

BUILD IT YOURSELF

ENLARGERS

AND

ENLARGING ACCESSORIES

A complete Manual for home built Enlargers of
every variety, including miniature and portable
enlargers, enlarging accessories, etc. Profusely illus-
trated with diagrams, photos and working drawings

THE GALLEON PUBLISHERS, Inc.
NEW YORK, N. Y.

Copyright 1938

by
THE GALLEON PUBLISHERS, Inc.

No part of this volume may be reproduced in
whole or in part without the written consent
of the publishers.

CONTENTS

SECTION I.

THEORY

CHAPTER I.

OPTICAL PRINCIPLES . . 8

CHAPTER II.

ENLARGER DESIGN 12

Light House 12

Ventilation ... 13

Illumination . 17

Diffusion 17

Negative Holder 18

Lens and Assembly 21

Mounting Enlarger . 24

SECTION II.

PRACTICE 26

CHAPTER III.

SIMPLE CONSTRUCTION 27

Horizontal Enlarger using camera 27

Vertical Enlarger using camera 38

Vertical Enlarger, indirect lighting 52

CHAPTER IV.

TIN CAN ENLARGER 58

Light House, diffusion, etc 58

Lens Assembly and Negative Holder 62

Support and Easel 65

CHAPTER V.

PORTABLE ENLARGER 67

Projector 68

Case 71

CHAPTER VI.

ADVANCED CONSTRUCTION 75

Materials needed 75

General Construction . 77

Negative Carrier .... 84

Lens Assembly 85

CHAPTER VII.

METAL ENLARGERS . 86

Diffusion and Lens Assembly .89

Light House Assembly 91

BUILD IT YOURSELF

SECTION I.

THEORY

Many amateur photographers who enjoy finish-
ing their own work have been prevented from
making projection prints, or enlargements, because
of the price of the equipment. The construction of
an enlarger is not at all difficult for anyone handy
with tools. If the basic principles of projection
printing are remembered there is no reason why
the enlarger should not work satisfactorily, with
the result that the amateur can have all the bene-
fits and pleasures of low cost enlarging merely
by exercising his ingenuity.

It is outside the scope of this book to give
minute instructions in the enlarging processes,
since they may be found in many good books now
available. However, some discussion of the general
principles and theory of projection printing will
aid in the design of the apparatus.

CHAPTER I.
OPTICAL PRINCIPLES

The enlarger is based on exactly the same op-
tical principle as the camera. In both cases the
light from the object is made to pass through a lens
and the rays focused on a light-sensitive emulsion.
However, the light comes into the camera from
outside the chamber which contains the emulsion,
while in the case of the enlarger the reverse is true.

The action of the light in both cases is identical.
It comes from the source, either natural or artifi-
cial, and strikes the object. When this occurs, some
of the light rays are absorbed, some reflected and
some, if the object is not opaque, pass through
completely. These latter rays make enlarging poss-
ible. After passing through the negative, they enter
the lens. Here they are bent so that an exact re-

Figure 1

production of the object, called the image, is form-
ed on the opposite side of the lens. The image
is in focus on a plane called the focal plane
which is perpendicular to the optical axis of the
lens and at a definite distance from it for each
position of the object. This action may be seen
in Fig. 1.

When the focal length of the lens is known,
the position of the image may be calculated from
the formula

1 1 '1

- I

f p q

where / is the focal length

where p is the distance from the object to the

center of the lens
where q is the distance from the image to the

center of the lens.

Theoretically, light is reflected from an object
in an infinite number of directions. When a point of
light passes through a perfect lens, it spatters and
takes the form of a circle, called the circle of con-
fusion, in all planes except the focal plane in
which place it again appears as a point. However,
it is impossible to make a perfect lens, so that ac-
tually a point of light passing through any lens al-

ways forms a circle of confusion and in the focal
plane, a circle of least confusion. This latter has the
smallest diameter of any of the circles of con-
fusion formed by that point of light. For all prac-
tical purposes, in a good lens the circle of least
confusion is also a point. As the opening in the
lens, through which the light passes, is made small-
er, the diameter of the circle of least confusion is
decreased. Therefore, an image will appear to be
in focus even when slightly behind or before the
focal plane. The total amount of light passing
through the narrowed lens opening will be de-
creased and, consequently, in photographic work,
the exposure will be lengthened.

The comparative size of the image with respect
to the object or, in other words, the number of
times of enlargement or reduction of the object,
depends on the relative values of p and q which
may be calculated by the use of the formula.

f

where / is the desired size of the image
where is the actual size of the object
where q and / have the same significance as
previously.

10

To use this formula, for example, given a lens
of 4 inch focal length with a negative 2 inches long,
where an enlargement 6 inches long is desired, the
substitutions are

6 q 4

which gives a value of 16 inches for q. This means
that the lens must be 16 inches from the paper to
give an enlargement of the proper size.

11

CHAPTER II.

ENLARGER DESIGN

From the foregoing discussion, it can be
that, theoretically, all that is needed to make an
enlarger is a light source, a diffusing medium, a|
lens, and a board or support for the sensitized
paper, as represented schematically in Fig. 2. Ac-

LIGHT BOX

Figure 2

tually, many complications arise which must bf
taken into account if we are to construct a work-
able piece of apparatus.

In the first place, the light which comes from
the electric light bulb, which we shall consider as
our light source, does not all travel in, one direc-

12

tion, but spreads in all directions like ripples on
a pond into which a stone has been dropped. The
light, therefore, must be confined in some sort of
chamber so that there will be only one path through
which it can pass out. This chamber may be any-
thing from a simple box to a most complicated
affair, depending on the needs of the designer. In
any case, it should be light-tight.

It is always a good plan to put some sort of
reflector behind the light source, so that the light
which would otherwise be absorbed by the walls
of the box, may be used to increase the intensity
of light leaving through the aperture. The back of
the light house may itself be a reflector, as is the
case with many enlargers. The best reflecting sur-
face is provided by a light color with a dull finish,
which gives minimum absorption and maximum
diffusion of light. The internal parts of the light
house which do not serve as direct reflectors should
ftlso be finished in a light color, preferably white,
tp prevent unnecessary light absorption.

Enclosing the light produces the very serious
complication of heat. Since 90% of the power
consumed by an electric bulb is given off as heat,
some means must be introduced for allowing it

13

to leave the light house as fast as, or faster than
it is generated. If no provision is made for this,
the whole apparatus may get hot enough seriously
to damage the negative, if not the enlarger itself.
It is therefore extremely important to provide ade-
quate ventilation. Failure to do so is too common
a fault in most home-made enlargers. Since the
circulation will be entirely natural (no fan or other
mechanism forces the air through the light house),

TIN STRIP BAFFLE

Figure 3

there will be very little to impede the air flow.
At the same time, no light should be allowed to
escape through the vent openings. This necessitates
a compromise, insofar as the air path is concerned.

AtR
BENT COPPER TUBE

Figure 4
14

The simplest type of ventilator consists of holes
in the lamp house, covered with bent metal to act
as baffles. The light, since it travels in straight

Mm

SIDE VIEW
(SECTION)

TOP VIEW
TIN CAN BAFFLED HOLE

Figure 5

PAPER
LINING^

AIR

FLAPS
*-TIN CAN

PAPER
BAFFLES

A

LIGHT BOX

BAFFLED AIR PAS
Figure 6
15

BAFFLE PLATE

lines, is more or less prevented from leaving, while
the air passage is practically clear. This tin strip
baffled ventilator is shown in Fig. 3.

A comparable method for metal walls consists
in soldering a bent length of tube to the side of
the lamp house, as shown in Fig. 4. A better type,
the tin can trap pictured in Fig. 5, works very
well, while a more complicated but much more
efficient trap is the baffled passage constructed from
a tin can and black paper, according to the design
shown in Fig. 6.

The inside of the ventilators must be treated to
yield a dull black surface that will absorb light
which might otherwise be reflected. The size of the
ventilators depends on the amount of heat gener-
ated by the light source. This, in turn, is determined
by the wattage of the bulb. Therefore, the size of
the vent holes can be calculated from the rating of
the bulb used. A fairly good empirical rule to
follow in designing the ventilators is to allow at
least one square inch of inlet and one square inch
of outlet for each 100 watts consumed. The total
inlet and outlet area needed for a 150 watt bulb
would be, consequently, not less than three square
inches. To facilitate a natural circulation the in-
let should be below and the outlet should be above,
the bulb.

16

The size of the bulb which is to be used in the
enlarger depends on the speed of the lens and the
approximate length of exposure desired. Exposure
should be slow enough to permit dodging and
other printing tricks, though sufficiently fast to
prevent tedious waiting. The exact length of ex-
posure of a given bulb can be varied by the dia-
phragm opening on the lens, within the limits
imposed by the density of the negative. In most
cases a 60 or 100 watt lamp is satisfactory, al-
though for very dense negatives a No. 1 Photoflood
bulb may be used. The heat liberated by a single
Photoflood bulb in fifteen minutes, however, is
sufficient to boil one and one-half pounds of water
whose temperature initially is 70. Hence, to main-
tain a workable temperature, an extremely efficient
system of ventilation must be employed. A dimmer,
which puts additional resistance in series with the
lamp, is usually attached when a Photoflood is used
to allow focusing without excessive light and heat,
and prolong the life of the bulb.

Light emitted from a concentrated source does
not spread with uniform intensity over a flat field.
Consequently, where even illumination is desired,
as is sometimes with a camera and always with
an enlarger, some diffusing medium rmjst be used

17

between the light source and the object. By this
means the intensity of illumination over the com-
plete area can be made uniform. The diffusing
medium may be of flashed opal glass or ground
glass, either of which if placed rather close to the
bulb will still perform satisfactorily. This medium
has an advantage over condensing lens systems in
that a separate focusing of the diffuser is not neces-
sary each time the picture size is changed. How-
ever, double lens systems are out of our province
here, since the addition of a second focusing device
complicates a design altogether too much for home
construction.

To prevent damage when glass is mounted in
a support where it might be exposed to heat,
plenty of room should be allowed for expansion
of the glass.

The exit aperture in the light house is made
on a side in a horizontal enlarger, or on the bot-
tom in a vertical enlarger, and its size is deter-
mined by the maximum negative to be used. The
aperture should be slightly larger than the area
of the negative, so that the light will completely
cover the area to be projected. The negative is
held directly in front of, or below, the aperture,

18

depending on whether the enlarger is horizontal
or vertical.

All holders can be classified either as drawer
arrangements or tracks. The drawer type is simply
a frame provided with a strip around the bottom
to prevent the negative from falling through. This
frame slides into an extension below the lamp
house. The track is usually designed so that a strip
or roll of film may be slid into position, either sup-
ported by the track alone or by glass plates.

There are five main points to remember when
designing any type of carrier. First, it must be
suitable for the negative sizes most used, that
is, the amateur who intends to work with plates
should not make a carrier which is primarily in-
tended for roll film, and vice versa.

The second point to remember is safeguarding
of the film. Any small scratches on the negative
will ruin its suitability for enlarging. It is there-
fore important to remove all rough edges and
sharp corners which are likely to come in contact
with the film. No holder in which the negative is
apt to be bent, scratched, or exposed to excessive
heat should ever be used. Some provision must
also be made for supporting that part of a roll
of film which is not being projected.

19

The third specific consideration is the immobil-
ity of the negative during exposure and, in fact,
of the complete projector. If any part of the set-
up (the light, negative, lens or easel) moves dur-
ing exposure, the print will be ruined. The carrier,
therefore, must hold the negative firmly in the
desired position. This may be done by the use of
springs or by the weight of a sheet of glass rest-
ing on the negative. Out of this latter usage comes
the next point.

When an enlargement is made, all marks, both
on the negative and on that part of the carrier
within the aperture, are clearly seen on the print.
Therefore it is of the utmost importance to keep the
glass in the negative carrier clean, and free from
finger prints and dust. The ease with which the
glass may be removed for cleaning helps determine
the value of an enlarger.

The last pertinent point concerns proper nega-
tive adjustment in the carrier. This must be so
constructed that the negative can readily be shifted
about, so that the portion of the negative which
is to be projected will appear in the region of
the aperture available for exposure. It does not
matter if undesirable portions of the negative are
projected as well, since the paper can be masked

20

if a margin is desired, or simply trimmed where
a border is necessary.

The ease with which the negative may be placed
in the enlarger determines, to a large extent, how
much time will be spent in making each print. If a
drawer arrangement is to be used, that portion of
the glass which comes within the available exposure
region should be marked by lines or by a mask.
In this way the position of the negative projec-
tion on the easel can be determined immediately.
With a spring-held negative, the position may be
determined by moving the negative or glass pro-
tection plates after insertion in the carrier if care
is taken that they suffer no damage during the
process. Miniature enlargers are usually so con-
structed that the whole of one frame is in the
region of exposure, and therefore it is unnecessary
to move it once it is placed in the carrier,

The lens itself may be mounted in several ways.
Should the whole camera be used, the focusing
device already present obviates the necessity of

4/V5 HDL PER

Figure 7
21

constructing another. If only the lens is used, it
may be obtained from an old camera or purchased
separately, and fastened to a telescoping tube by
means of the flange on the lens mount, as shown in
Fig. 7. This is quite simple, since all that is needed
on the tube which holds the lens is a disk with a
hole of the proper size to accommodate the lens
mount. The material of which the disk is made
is inconsequential so long as it can be fastened
firmly in place, holds the lens securely and is
cut accurately, so that the optical center of the
lens is directly in a line drawn from the filament
of the bulb to the center of the negative. Inac-
curacy will result in an enlarger which cannot be
focused sharply.

The distance of the lens from the negative must
be determined by the formulae given previously.
This distance will not be fixed since the size of
the pictures will not be constant; but the maxi-
mum and minimum distances must be determined
before the focusing device is designed. The enlarg-
er must, therefore, be built for a lens of de-
finite focal length. To obtain enlargements of
practical size when a camera is used as the lens
assembly, the negative must be somewhat behind
its mormal position in the camera.

22

Of the lengths of tubes composing the focusing
device, the one which carries the lens should be
a little longer than that which is fastened to the
enlarger. In this way the lens may be brought
closer to the negative, with the same length tubes,
and a larger picture may be obtained.

The tubes can be held in proper focal position
either through friction or by more positive means,
such as a rack and pinion. These must be firm
enough to prevent undesirable motion, which will
ruin the print. Accurate focusing, however, must
not be sacrificed for rigidity.

The complete assembly from the light house
to the lens, forms the projector which may be
mounted with either a vertical or horizontal op-
tical axis. The suitability of either type depends
on the needs of the photographer.

Horizontal enlargers can be used where large
prints are desired, since the wall of the dark room
can serve as a support for the paper, thus increas-
ing the distance q as noted in the formulae. This,
however, is almost the only advantage of the hori-
zontal type. The vertical type of enlarger is much
better adapted to the requirements of the amateur,
since it is easier to work with and needs less room.
The paper can be put on a tablelike surface where

23

no difficulty is met with in holding it firmly in
place.

Since motion is only relative, it makes no dif-
ference whether the distance from the lens to the
negative is changed by adjustment of the easel or
of the projector. The only strict requirement is
that once the position of the movable part has been
determined, it must be secured firmly.

There are many ways in which the projector
may be mounted in a vertical enlarger. It may
either be fastened to a sliding frame or connected
by an adjustable arm to a pipe, along which it
slides. There may also be a system of horizontal
bars which are fastened to a wall or similar sup-
port, and are free to rotate in a vertical plane. In
fact, the methods of support are limited only by the
inventiveness of the builder. The same may be
said about easel mountings. It is necessary, how-
ever, to have a positive fastening in any desired
position.

To prevent motion of the projector and con-
sequent blurring of the print, the exposure should
be controlled by an electric switch, and not by the
shutter, if there is one on the lens assembly. The
switch should be on the line leading to the enlarger

24

or, preferably, controlling the outlet from which
the enlarger receives electricity. This will mini-
mize the danger of motion when starting and fin-
ishing the exposure.

25

SECTION II
PRACTICE

It is best to lay out a full scale drawing of each
part before any actual construction of an enlarger
is started, so that there will be as little waste of
materials as possible. These drawings should be
accurate, so that the method of filling together the
various parts can be easily seen. Any paper may
be used, since the drawings are not for show
purposes. Heavy wrapping paper is quite suitable.
A list of materials and tools needed also expedites
the construction.

In the following pages are plans and descrip-
tions of enlargers which have been designed and
constructed by amateurs. The principle previously
enumerated have been adhered to, except in cases
where obvious compromise was necessary.

26

CHAPTER III.

SIMPLE CONSTRUCTION
WOOD ENLARGER

The easiest enlarger to make is a horizontal
type in which the lamp house is simply a box,
and a camera is used for the lens assembly. This
avoids the construction of vertical sliding supports
and complicated focusing mechanisms.

We will start with the assumption that there
is available, a 120 Eastman camera with a re-
movable back, which we will use as the lens as-
sembly. The first things we will make, after we have
designed ihe enlarger, are the full-scale drawings
on wrapping paper. The tools and materials need-
ed are as follows:

TOOLS

hammer

screw driver

wood and metal drills

vise

saw

protractor or adjustable miter

tin snips

small paint brush

27

large paint brush
scissors

MATERIALS

1 flat hook

1 Photoflash reflector

1 frosted 100 watt bulb

1 fixture socket
electric cord
base plug
screws

tin sheet 38" x 1%"

4 angle irons (2" arms)

felt

glue

wood V 2 " x 2" x 190"

Y%" ply wood 16 x 36

drawing board 15" x 20"

2 hinges

2 C clamps
1 camera

This enlarger will have a stationary projector
and movable easel. Since the whole apparatus will
be mounted on one supporting stand, it would be
best to build the stand first. We have to make some
preliminary calculations, however, to see what
the angle L in Fig. 8 should be. This depends on

28

the focal length of the lens In the camera. By
finding the projected length of the easel track,
which we have shown in Fig. 8 as 10" (30 minus
20), we can determine the actual length. The
projected length is the distance q as given in the
lens formulae. The actual length is found by plane
geometry, using the Pythagorean principle (a 2 +b 2
=c 2 ). The angle L in Fig. 8 and B and S in Fig. 9

SIDE VIEW OF TRACK AND SUPPORT

Figure 8

are all determined from the resulting right tri-
angle. We will assume here that L is 60, which
makes B 120 and S 30, since L plus B must equal
180 and L + 5 must equal 90. It is of great
importance that these angles be accurately con-
structed, since otherwise the complete area of the
projection will not be in focus.

29

BACK VIEW
DETAIL OF EASEL ASSEMBLY

Figure 9

Construction will start with the table, which is
made of l /2 ff x 2" wood throughout. The details
for this can easily be seen from Figs. 8 and 10.
The purpose of the supports are to prevent vibra-
tion and unsteadiness. This assumes that the legs
are all cut to the same length, since no amount of

30

bracing can prevent motion if one leg is of dif-
ferent length than the others.

The easel, Fig. 9, consists of a drawing board
held in position by runners made of 2" wood,
having flanges fastened to the side to provide
added support, as may be seen in the figure. The
angle irons used will have to be bent to the pro-
per angle since they come only at 90 and 180.

Now work can be started on the projector. The
front frame which supports the camera is made

END VIEW OF TRACK
AND SUPPORT

Figure 10

of %" wood and plywood. The %" x %" bars
are cut to provide two 7" and two 4" lengths.
Grooves must be cut in the two long pieces and
in one of the short pieces to allow the camera to

31

slide in and out. These four strips are then fast-
ened together to form a frame from which the
long pieces project to provide legs, as shown in
Fig. 11. The top piece is not fastened, so that the
camera can be inserted.

Next the sheet of plywood is cut to provide
two pieces 5" x 6" and one 5" x 41/4". The
5" x 6" pieces are fastened to the sides of the frame
and the remaining piece, with the corners cut out,
to the bottom of the frame where the legs protrude.

FRONT FRAME
EXTENDED FOR
SUPPORT

S/Df VIEW

Figure 11

The negative holder which also fits in the box, is
made of two brass strips, cut to the size and shape
shown in Fig. 12 and assembled as in Fig. 13.

32

A piece of plywood 4 1 / 4" x 4", fastened to the
top of the extention box, completes the front.

The other end of the box is fastened to the
light house proper. The same screws which hold
it in position also hold the opal glass supports

Iff

i_ri^
em

r o o o~

BOTTOM GLASS SUPPORT
fMAKE

D:

5/gf gi/155 SUPPORTS
CMAKE }

BRASS SPRING

CMAKE: s)

DETAILS

Figure 12

in place, so they must be made next, according
to the dimensions shown in Fig. 12. The reason
for making the top of the box shorter than the

33

rest can now be seen, since that is where the
negative will be inserted. There is a short strip
of plywood on the other side of this opening to
make the assembly as light-tight as possible and
give a more finished appearance.

WOOD STRIP
'NEGATIVE CARRIER PUT
HERE

SECTION THRU SIDE OF JOINT

Figure 13

The lamp house proper is also a box, made of
plywood. The sides and top, which is hinged,
are 8" x 10", and the bottom is 71/4" x 10". One
side has a hole for the socket, placed so that the
light, when in position, will be on the optical axis
of the lens. This may sound difficult to do, but by
laying the dimensions out on paper first, the exact
position of the hole can be determined. This mea-
surement cannot be given here, because it depends
on the type of socket and reflector used.

34

There must be some kind of supporting frame
at the corners, since plywood is not strong enough
to make a firm joint. The support for the rear
end of the box consists of two bars of wood, l /2 f '
x y 2 " x 6 1 / 4", placed vertically in the corners.
The front frame, which will also support the

VENTILATION

a*

I
f

CM

s
CM

I 1 1
1 H ' 1 rr\WOLS FOR\

iOj ; p ; i(f / /![
! ;'/ \'!jj4i / !|

iPl ' V ll m GLASS o
j^i 1 v A / 1 | Y i SUPPORTS^

b: ;;i \l|

1 ' i > . i in-

1 lJ L.I__J .1

\

i

: \ 55 r

SPRINGS '

->' !
I

*

^

'/ I 1

* J LV ^

-- /.^ "-.,..

CAMERA
~ MOUNTS
HERE

TOP VIEW

Figure 14

extension box previously made, consists of two
bars of y 2 x y 2 x T%' and two of l / 2 x }/ 2 x 3^4 r/ ,
put together. These may be seen in Figs. 11, 13,
and 14. The back of the box is plywood, &/^' x

754".

3J

The final steps before assembly consist of mak-
ing the light traps, which are the simplest tin plate
type, and drilling the holes for ventilation in the
top and bottom of the light house. There should
be six l / 2 " holes in the top, and an equal number
in the bottom, spaced as shown in Fig. 14.

After this is done, the projector may be assem-
bled. It will be seen that there is an overlap of y<\"
where the sides of the light house extend past
the bottom. This forms the base on which the pro-
jector stands, and allows a space for ventilation.

The inside of the lamp house should be painted

TO SERIES
RESISTANCE

BARS IN POSITION

Figure 15
36

while and the inside of the extension box, black,
to prevent internal reflection. The outside may be
any color desired. The negative carrier consists of
two glass plates, between which the negative is
placed. This enlarger will not take rolls of film,
but can be used for short strips or individual neg-
atives.

For those who want a vertical enlarger with a
camera for the lens assembly, a very satisfactory
device can be made with nine double filament,,
21 and 21 candlepower, 6 to 8 volt automobile
bulbs. These are wired in series, as shown in Fig.
15. Since both filaments are connected to the brass
base, they will light when 12 to 16 volts are sup-
plied, if the base is insulated and connections are
made across the two contact points. When placed in

IT

BOTTOM VIEW OF LAMPS

Figure 17

series with 110 volts applied, there is a drop of
12.2 volts across each bulb, well below the safe
limit. The bulbs are mounted on a block of wood
" square, or any other insulating ma-

38

terial with comparable strength and the same area.
The bus bars, or electrical connections between
the bulbs, are brass strips held above the board
by washers, and arranged as shown in Figs. 15
and 16. Ventilation holes drilled in the board are
protected by tin strips to prevent light leakage
and dark spots in the field. The strips on the
opposite side of the board from the contacts, are
also held off its surface by washers.

For both the bulbs and ventilation, the holes
should be located as shown in Fig. 17. The bulb
holes should be 19/32" in diameter, and the vent
holes %" in diameter. The filament side of the
board should be covered with aluminum paint
or some other reflecting surface, but care must
be taken to see that there is no contact between
the bulb bases. The importance of this cannot be
overstressed because any path of electrical con-
duction will cause a short circuit which, in all
probability, will burn out the bulbs as well as the
house fuses.

The sides of the projector form a new type of
ventilator not previously described. A plate is fast-
ened to the top section and one to the bottom
section of the lamp house, which, when put in
position, form the ventilators as shown in Figs.
16 and 18.

39

The top ventilator consists simply of two pieces
of wood arranged in an inverted trough and held
above the roof by an extension, on two sides of
[he box, with the openings running along the other

Figure 18

two sides. The construction of this can clearly be
seen from Fig. 18.

By lifting the top ventilator, the whole top
section, consisting of the roof, the bulb board, the

40

inner light baffle and one side, lifts off. This
allows easy access to the bulbs, to replace burn-
outs. The faces where the sections come together
are covered with felt to prevent light leakage.

Since all the bulbs will go out when one filament
breaks, it will be necessary to have an extra bulb
on hand to replace any defective one. The method
of finding a defective bulb is to start with one
bulb, working around the circuit, replacing each
bulb by the one before it, and turning on the
current after each change. When the defective
bulb has been replaced, the lights will go on. If
the lights do not go on when all the bulbs have
been replaced, test each one separately with a
storage battery.

The negative carrier is of the drawer type and
consists simply of a drawer which slides into slots
below the opal glass. The camera is fastened to the
two sides, which do not lift off with the top, and
to part of the third where the negative carrier fits
in. This forms enough of a frame to hold the re-
mainder of the assembly. The camera must be
firmly fastened to the projector to insure rigidity.

Since the dimensions as given on the drawing are
intended only to give an idea of relative pro-
portions rather than to be actual fixed quantities,
there would be no sense in giving detailed in-

41

struction for cutting the parts. These must be deter-
mined hy the size of enlarger wanted, and by
the size of the camera at hand.

The projector is fastened to an automobile piston
rod which can be purchased at any junk shop. The
bolt in the small end is replaced by a wing nut and
bolt which, to a small extent, allows the diameter
of the hole to be regulated, thus clamping the rod
to ihe pipe on which it slides. The pipe is ordinary

FRONT VIEW

DETAIL OF TRACK

Figure 19
42

galvanized iron, with a floor flange fastening it
to the easel. This is a fairly common type of as-
sembly, and will be explained in more detail later,

If a permanent dark room is available, it may
be desirable to fasten a vertical enlarger perman-
ently to the wall. There are quite a few which have
been designed for this. One, which moves on roller
skate wheels, is rather easy to make. The track it-
self is nothing more than two strips of wood, 2" x
1" x 60". These are mounted on cross strips 2" x 1"
x 9", one of which contains a slot for a pulley.
The corners are braced by triangular blocks which
can be made by cutting a rectangular block in half,
diagonally. The assembly is then fastened lo blocks
2" x 4" x II", which have previously been fastened
to the wall. The method of assembly is seen in
Fig. 19.

The easel can be a table or a board fastened
to the wall below the projector. It is not movable
and therefore can easily be constructed without
further directions.

The first piece to be made is the top ventilator.
This is a tin can of about 3" diameter, with the
top and bottom cut out. A piece of this tin is cut to
form a square 6^ x e 1 /^', with a hole, in the
exact center, whose diameter is not more than y$'
smaller than that of the can. The can is then

43

ROLLER SKATE
WHEEL

WHEEL
SUPPORT

VENTILATION

HOLES

\

NEGATIVE
CARRIER

__^__.
_ _ CD

TOP
VENTILATOR

' i 7 'II

' ' / '

l.i'

" \

>{ "V TRIANGULAR \'
^^- BLOCKS X-

soldered to ihe plate. After this, a piece of ply-
wood, 1" square, is cut and drilled to allow it to
fit over the can and rest against the plate. This
forms the top of the lamp house. The sides of the
house are made from two pieces of plywood 6^"
x e 1 ^" and two 6%" x 7", which are drilled

r-L^FLAPS FOR
J L. FASTENING
N^ f >i TO CAN

\IJ^-3' t D/AM^r3 ^~

s\ r |

/*/>/? &4f71 .flWTF

r^xi/rf 4J

BAFFLE -* r:i
PLATES IN (r-\
POSITON ^"

SOLDERED^-. ri

V "o
~'///\ 1r

JOINT\ '

/~\

TIN REFLECTOR SECTIONAL VIEW
PLATE

TOP VENTILATOR

-h^

7 _Cj

L

A ^ i

J-} ^ Y- -

-r .

t u

7-" J ~ 4

1 1 /IMC*

LIGHT TRAP ' /",

(MAKE 43^.

WOOD A K/A\Trx
5r/?//= :::i! ^l p

,r-L

"IK
f M\

4 K||g

J TIN FLANGE\

SECTION THRU LOWER
VENTILATOR

DETAILS

Figure 21
45

around the bottom to provide vent holes ^4" * n
diameter and %" from the bottom, as shown in
Fig. 20. Small triangular pieces of wood, which
may be found in almost any shop, form the corner
braces by which the completed box is held together.

LAMP
HOUSE

ROLLER SKATE
WHEELS

ROLLER 6 KATE
WHEELS

SIDE VIEW

Figure 22

The tin plate is fastened firmly to the inner top of
the box to form a reflector, and the inside of the
light house is painted white.

The upper ventilator is formed by lining the

46

can on the top with black paper, and pasting in
baffles shaped as shown in Fig. 21.

Porcelain or bakelite electric sockets, of the type
used on electric signs, are fastened to triangular
blocks and put into position in the corners of the

* X

ION

KNOB ON NEGATIVE CARRIER

ALIGHT TRAP

-/H-/4

*/-"

ROLLER
SKATE
WHEELS

TOP VIEW

Figure 23
47

light house, as shown in Figs. 20, 22, and 23.
In this way, larger bulbs can be accommodated and
the light will still be uniform in intensity.

The final step necessary to complete the lamp
house consists of fastening tin strips around the
outside, just above the lower ventilation holes,
lo serve as baffles. These are cut as shown in Fig.
21, and bent at right angles down the center line.
If the angles have been cut correctly, the corners
will fit exactly. These strips should extend out for
3/4" at a distance of V from the bottom of the box.
The lamp house can now be painted.

This box is held in position by a frame 8^4"
square made from wood J^" x 1", two pieces of
which are 6 1 /4" long, and two 8>4" l n g- A small-
er frame of wood J^" x %" is fastened inside this,
flush with the top, to form a light trap and vent-
ilator. A detail of how the ventilator is formed of
these parts is shown in Fig. 21. The outer frame is
now covered on all four sides with plywood, flush
at the top but projecting below to form the box
for the negative and opal glass. The individual
pieces for this box are two pieces of plywood 3"
x 9" and two strips 3" x S 1 /^'. Centered on the
bottom edge of one of the shorter of these pieces,
a strip is cut 6" long and 1" wide, to form an
opening for the negative carrier.

48

When all but the cut section have been fastened
into position by means of corner blocks, strips
are put outside, as far up as practicable, to support
the opal glass. The front view may be seen in
Fig. 20. Since the glass will be enclosed by the
box, the side which has been notched should be
fastened by screws so that it can be removed to
allow insertion and replacement of the opal glass.

A flange of tin 1" wide is now fastened around
the inside of the frame to hold the lamp house
firmly in position. This also may be seen in Fig.
21.

The bottom of the negative support box is fast-
ened to and rests on a frame IZYz" x 11",
which has three sides of V and one side 2 T /> fr
wide. The wood used for this should be V x 2".
The individual pieces consist of three 11" and two
6 l /2" long. To make the thick side, the two short
pieces are fastened together to give an effective
width of 2". This is shown in Fig. 23. The negative;
support box is now fastened firmly to this frame.
When the camera is fastened to the underside of
the frame, the projector is completed, except for
the negative carrier which consists of a printing
frame with the back removed, and in which the
negative is held betweeen two plates of glass.

49

The support which holds the wheels and fastens
to the projector consists of two pieces of 2" wood,
24" long. Slots are cut in the bottom of each piece,
just wide enough to allow the insertion of roller
skate wheels, as shown in Fig. 20. The other ends
of each piece are fastened together by a strip of
wood 2" x 11". This overlaps at the sides for a
distance of ^'\ spacing the long bars 6" apart.

VENTILATORS

The eye for supporting the enlarger goes in the
center of this spacer, as shown in Fig. 22.

The assembly for holding the top wheels is made
from one length of wood 11" x 2" x 1", two blocks,
and two pieces 3%" x 2" x 1". The long piece
has holes inlet at each end to hold bolts. The com-
plete assembly is shown with sufficient clarity in
Figs. 20, 22 and 23 to make further description
unnecessary.

The projector is to be fastened 12" from the
top of the bar supports. It is held rigid by two
triangular braces 7" x 11" placed on the edges,
as shown in Figs. 20 and 22. All these are fastened
in place by screws.

It will be seen that the top wheel assembly.

FELT STRIPS
HINGE

which cannot be put on until after the projector
has been placed against the track, holds the pro-
jector in place. Therefore, if the connecting bolts
are not tight the projector may fall off. If all
has been done correctly, however, the only motion
possible will be in a vertical direction. A rope
from the eye on the movable support and over
the pulley on the track serves to adjust the height
of the projector, whose weight should be counter-
balanced by a bag filled with sand or similar ma-
terial so that the projector will remain stationary
at any position on the track. It is then easy to hold
the rope so that the projector will not slip during
exposure, since no weight is actually held by the
fastening.

A vertical enlarger (Plate 1,) with the same
general idea but with the advantage of indirect and
stronger lighting as shown in Fig. 24, is also easy
to construct. Indirect light is an advantage because
the light, by being reflected, is more diffused than
if a diffuser alone is used.

The light house is again a simple box, the con-
struction of which may be determined with little or
no trouble from the plans. The wood through out
is %" stock. Since all necessary dimensions are
given on the plans, Figs. 24 and 25, there is no
need for repetition here.

52

Plate 1

To form a good reflecting surface the inside of
the light house should be painted with aluminum
paint.

The ventilators, which are of the tin can type
previously mentioned, are shown in detail in Fig.
26.

,- SHORT BRADS

TOP VIEW
VENTILATOR DETAILS

Figure 26

The film holder is again a printing frame, with
the back removed. The sides, which are shown in
Fig. 24, may be either tin strips which are bent
for rigidity, or wood strips. These are fastened
far enough below the opal glass to allow the frame
to be easily inserted and removed.

54

The light aperture consists of a frame cut from
threeplywood, which supports the opal glass, and
which is inlet to prevent the glass from slipping.
If desired, a mask may be placed on the glass to
decrease the effective aperture.

V

k

^^___

1

T

O

o

O
O

o

o

\

\
STATIONARY

,

FRAME

,

[

] '

. SLIDING FR*

t<

CM

^.SAFETY QUID

i

, ^

c

3-*^"

STANDARD

-r !
_j

h

H -

~ .

METAL BATH
HANDLE

^CM

HOLDER

o

'oil

r 1
[Oi

HOLE FOl

^

-fill

[ TRIPOD SCR

V.|

'O

" '10;

^j-

,' I ' ' ' i

\

iQ 'O'
>.| ili

J

^

h

1

H

i

c

3

t

iQ iO'

TOP BOARD

*

-"

o; i , !oi

-

HANDLE B/

_j
"M

o

O

1

o

O

<

o

J

^

-*

-*

^

^

^

I"

STATIONARY AND SLIDING
FRAME ASSEMBLY

Figure 27
55

This enlarger was originally designed to take a
camera, which was fastened below the negative
carrier, but a bellows and lens may be used instead,
if the amateur is ingenious enough to construct
a practicable device.

Since the construction of the supporting frame,
Fig. 27 5 is somewhat involved, some explanation
is necessary. The light house is fastened to a cross
bar which, in turn, is part of a sliding frame of
2" x ^4" stock. A tripod screw is fastened to the
back board in the proper position, determined by
experiment, so that the camera will be held close
below the light house. The sliding frame is lock-
ed to a stationary frame immediately behind it
by means of the locking mechanism shown in

__HEAVY SHEET
METAL STRIP

WASHER

STANDARD
METAL BATH
S HANDLE

NUT

NUT HOLDER

WOOD STRIPS

BUSHING

SECTION THRU LOCKING
MECHANISM

Figure 28
56

Fig. 28. There are four of these mechanisms to
insure a firm lock. It will be seen from the figure
that the locking strip on each is fastened to the
stationary frame, so that the friction against the
sliding frame caused by tightening the handle will
prevent motion. If the handle is loosened slightly,
the pressure will be decreased enough to allow the
projector to move when desired, though still leaving
enough friction to prevent it from falling to the
bottom of the supporting track. The frames should
be lubricated with soap, not oil, since wood ab-
sorbs oil.

A pulley fastened to the top of the stationary
frame or to a ceiling rafter will permit the use
of a rope to counterbalance the weight of the pro-
jector. This can be done exactly as in the pre-
vious case by weights in a sack. The handle bar,
which aids in raising and lowering the projector,
is optional. The safety guides, shown in Fig. 29,

SAFETY GUIDE
(MAKE 4")

Figure 29
57

prevent any side motion or jamming of the sliding
frame in the locking mechanism. They consist of
an L-shaped block fastened to the sliding frame
just above or below each locking mechanism.

CHAPTER IV.
TIN CAN ENLARGER

For the amateur who can work better with metal
than with wood, quite a few designs are possible.
The easiest uses tin cans for most parts, thus
removing the necessity for making any complicated
pieces. The lens fastenes directly into a tube ar-
rangement, which makes exact calculations for the
length of the tubes necessary. For the special case
under discussion, we will assume a focal length of

FLAP BENT
DOWN

SECTIONAL VIEW

DETAIL OF LOWER LAMP HOUSE ASSEMBLY

Figure 30

about 2%". It is intended for miniature roll film,

and will not take anything larger than V x 1%".

The lamp house consists of a tin coffee can to

58

which is fastened part of another tin can. The
first step is to find the length of the bulb to he used.
Cut a hole in the side of the coffee can so that the
second can, which should have a diameter of about
3", will just fit in with the filament of the bulb
centered on its axis. The distance from the end
to the center of the hole must be determined before
the hole is cut.

When this has been done, the 3" can is cut to
fit exactly within the hole, with flaps projecting to
allow rigid fastening, as shown in Fig. 30. These

TIN COFFEE: CAN

SOCKET FOR
" IOO WATT BULB

BRASS PLATE

BOLT

WOOD FASTENED
TO STAND

BOLT

LENS MOUNT

BACK VIEW

Figure 31
59

are now soldered firmly together to provide a
light-tight joint. Holes are now cut in the bottom
of the coffee can to provide openings for the socket,
two 34" bolts and a wood screw. The position for
these can be seen in Fig. 31. When cutting the
3" can, flaps may be left which when bent, as
shown in Fig. 30, will provide opal glass supports,
or separate tin pieces may be soldered on. The
glass is inserted through the coffee can when the
enlarger is completed.

VENTILATORS

BRASS PLATE
OPAL GLASS

SPRING

ANGLE

APERTURE

PLATE __

LENS MOUNT ~7~

L ENS INSERTED HERE

SOLDERED
JOINT

FELT LINING

FRONT VIEW

Figure 32
60

The ventilators for this enlarger of the bent tube
type are made of %" copper tubing, and fastened
on the cover as shown in Fig. 32 and 33. These
should be painted dull black inside, to provide a
light-absorbing surface.

tj

ELECTRIC -
CONNECTION

SIDE VIEW

Figure 33

A piece of sheet brass thin enough to be worked
easily (about 1/16") is cut to form a rectangle
4%" x &/2 f . A rectangular piece I" x. l l / 2 " is cut

61

from the exact center, with the long dimension
coinciding with the long dimension of the plate.
An apron is now bent over on each side, as shown
in the detail in Fig. 34. Holes to take 14" holts,
placed as in the figure, are now drilled in two
corners. The distance between these holes must be
measured exactly, so that the pieces which will
fasten to it can be drilled correctly. Since the

#r-

O

DETAIL OF APERTURE
PLATE

Figure 34

plate is to serve as a mask and negative holder,
all edges must be smoothed off and all sharp
corners rounded. The apron will project down
when the projector is assembled.

To the bottom of this plate is fastened an open-
ended cylinder 2%" long, which has been cut from

62

a can of 2" diameter. This is soldered firmly to
the plate, with the vertical axis running through
the center of the aperture. Next, a brass plate 4"
square is drilled to coincide with the holes pre-

APERTURE
PLATED

SPRING*

WOOD
STRIP

////\ Y^777 ,

0)

1 WOOD
\ STRIP

OD

l f

i!

1 x

\FE
\ U

/ "~ ""*x
/ \.

\

\\

,

''

LT / f
WING \
APERTURE

L

I

i -

i

IRON
ANGLE

SPRING

SOLDERED/
JOINT

TIN

INSERT LENS'

HERE END VIEW

s LAMP HOUSE

APERTURE
PLATE
^^-

BRASS PLATE

FELT LINING
V

SECTIONAL VIEW

TOP AND END VIEWS OF LENS MOUNT ASSEMBLY
Figure 35
63

viously put in the lamp house. This should then
be fastened loosely in position, first to see if it will
fit correctly and secondly, to locate the position
of the lower holes which will support the aperture
plate and focusing assembly. To locate the center
of the holes in which the supporting bolts for the
lens holder assembly will be placed, the aperture
plate is placed on the 5" legs of two %" x 5"
x V angles so that the legs are held against the
aprons on the plate, as shown in Fig. 35. This is
then held below the lamp house so that there is a
space of about %" between the bottom of the lamp
house and the top of the aperture plate. It will be
seen from Fig. 35 that there are only two bolts
holding the aperture plate to the angles and two
holding the angles to the back plate. This is a com-
promise between positive rigidity and ease of in-
sertion of the negative. It will be firm enough,
however, if the bolts are made extremely tight,
since the weight of the lens assembly will hold the
plate against the iron strips.

A wood strip is cut to fit as shown in Fig. 32,
33 and 35, to provide a spacer for the springs and
a stop for the negative carrier. The exact size of
this will have to be determined by trial. To this
are fastened two brass strips which will serve as
springs. These are bent slightly in the center, as

64

shown in Fig. 33, to provide greater pressure
directly over the aperture and thus hold the neg-
ative firmly. Holes are drilled in all these parts so
that the same bolt will hold spring, spacer, aper-
ture plate and iron angle.

The lower section of the telescoping lens holder
is formed from the bottom of a tin can of 1%"
diameter. This is cut to a length of 2%", and a
hole drilled in the exact center of the bottom,
which has not been removed, so that the optical
center of the lens will be on the vertical light axis
of the enlarger. The space between the upper
and lower tubes is filled with felt, a layer of which
is fastened to the inner side of the upper tube.
This layer should be thick enough to prevent mo-

SHEET CUT OUT
FOR TUBS

Figure 36
65

tion of the lube during the exposure, and yet allow
accurate focusing.

The brass plate to which all parts of the pro-
jector are fastened is, in turn, attached as seen
in Fig. 33, to one end of a wood bar 12" x 3%"
x 1", both ends of which have been cut at an angle
of about 30 to the edges, so that they are parallel

JPIPE FLANGE

WOOD BASE

CD C

DETAIL OF STAND ASSEMBLY

Figure 37

to each other. This angle decreases the stress on
the support because of the force of gravity.

The other end of the supporting bar is fastened
to a tube which is cut from a piece of aluminum
or brass sheet according to the pattern in Fig. 36.
The two holes on the vertical axis of the tube

66

are for the insertion of screws which hold it to
the support bar. The tube is then bent around a
%." galvanized pipe, to give the proper shape, and
a 14" bolt is put through the other holes, which
should now be in line. A wing nut serves to hold
this in position. When all these parts have been
put together, the projector proper is finished and
may be painted.

The easel is of the type previously mentioned,
and consists of a %" galvanized pipe 3 feet long,
screwed at one end into a floor flange which is
fastened to a board which does double duty as a
supporting base and easel, as in Fig. 37. Any
type of frame or mask may be used on this, de-
pending on the needs of the builder.

Any dimensions not found in either this text or
in accompanying drawings are such that no defi-
nite value can be assigned to them and therefore
trial and error methods must be used for their
determination.

CHAPTER V.
PORTABLE ENLARGER

For those who must travel frequently, or whose
space is limited, a portable enlarger is invaluable.
It is not difficult to construct and will work admir-
ably for the minicam amateur.

67

The lamp house is a coffee can of the usual
dimensions (5" long and 4" in diameter), in which
a 60 watt bulb is mounted in a vertical position,
with the socket inserted through what was origin-
ally the bottom of the can. For ventilation, two
pieces of : J4" copper tubing are bent and soldered
over holes in the can, as shown in Fig. 38. This
is satisfactory for a 60 watt bulb, but will not be
adequate enough to prevent overheating with a

VENTILATORS
SOLDERED
ON TO LAMP
/ HOUSE

OPAL GLASS
PLATE

IRON SUPPORTS

V

BACK VIEW

larger bulb. It is therefore important to remember
that a larger bulb cannot be used.

The cover of the can and the brass and wood
plates to which it will be fastened, are drilled

i

11 *

1

FOLD

-e- /'A.

, r

NM

s -

HERE

i

c\

\

i

J_

- 1 -

NEGATIVE HOLDER

L

'/GLASS
12
GLASS HOLDER

and cut so that the holes will coincide, as shown in
Fig. 39. The wood plate is needed to add extra
strength to the assembly and insulate the lower
section of the projector from the heat generated
in the lamp house, while the brass plate provides

69

a metal surface for soldering the negative carrier
and lens assembly in place. The carrier is a track
cut from brass and folded as shown in Fig. 39,
so that a negative will just slide into the grooves.

CASE FOR PORTABLE ENLARGED
Figure 40

This is soldered firmly to the brass plate. The top
section of the lens tube is cut from a tin can 2"
long, and has a length of 2%". It is cut at the

70

top to fit around the negative track, and also sold-
ered to the brass plate. The remainder of the lens
holder is the same as in the enlarger previously
discussed.

The opal glass supports, which are soldered as
near the end of the lamp house as possible, con-
sist of three paper clips bent to the shape shown
in Fig. 39, so that the glass may be inserted and
held firmly while the enlarger is being carried.
There are three of these supports, spaced evenly
around the inside of the can. Since the sharp
points on the clips might shatter the glass, cut
a flat tin disk whose external diameter is the same
as that of the glass, making an internal opening
which leaves a width of metal of l/o". This, when
put under the opal glass, serves as a bearing plate
to distribute the pressure of the clips against the
glass. There will be just enough spring in the clips
to allow removal of the glass and plate when
necessary.

The supports for the projector and case are two
U-shaped pieces of l/^" iron of the dimensions
shown in Fig. 40. There are two identical sets:
one long and one short strap for the case, and an-
other long and short strap for the projector. These
should be interchangeable so that the motion of the
projector will be unimpeded. The holes for the sup-

71

porting rods are 14" in diameter, centered y 2 "
from the end of the straps. The straps are fastened
to the projector by bolts, as shown in Fig. 38, and
to the case by wood screws.

A wood box, 22" x 1" x 10", having the two
supporting straps placed as shown in Fig. 40,
forms the case. The cover, which is not fastened
permanently to the case, is held in position, when
carried by hooks on the sides of the case which
swing over and catch on nails in the edges of the
cover. These cannot be seen in the diagrams. When
open, the cover serves as an easel. To prevent the
enlarger from tipping over when in use, two bars
are put through the straps, which are fastened to
the cover and case as shown in Fig. 40. The bars
are 4" long and *4" thick, and the straps are made
of the heaviest sheet metal which can be worked
with ease. A wooden cleat is fastened to the inner
base of, and placed four inches from the front of
the case so that when it is closed for carrying, the
bars are held firmly to the base by the strap .and
prevented from sliding out by the cover and the
cleat. The cleat can be seen in Fig. 41. . ,

To connect the projector to the case, a system
of bars, illustrated in Fig. 41 is used. These are
YZ" x 1" x 13", and are fastened to the supporting
straps by bolts. To allow the upper set of bars to

72

DETAIL OF SUPPORTING ARMS
Figure 41

73

move freely without touching the supports for the
lower set, they are held out from the connecting
straps by ^4" washers at each bolt. To hold the
projector in any position, two rods 17" long are
bent at one end to form an eye, and fastened to
the bolts holding the lower set of bars to the long
strap in the case, as shown in Fig. 41. The other
end of rods pass through binding posts, such as are
used in electrical work, which are bolted to the
short straps and bars on the projector. These bolts
must be loose enough to turn as the projector is
moved up and down, so that the rods will not be
locked in one position. By tightening the hand
screws in the binding posts, the rods are prevented
from sliding, and thus hold the projector in a true
vertical position, these sliding rods and fastener
supports must be on both sides.

The dimensions of the supporting and bracing
bars and rods must be exactly as given, since the
slightest change in any one part will necessitate
a complete recalculation of all other dimensions,
if the system is to work correctly.

74

CHAPTER VI.

ADVANCED CONSTRUCTION

A vertical enlarger ( Plate 2.) which deserves
the title of hand-made instead of home-made be-
cause of the craftsmanship used in constructing
it, can be built by the more skilled workman. To
prevent confusion in the plans, the parts, when
mentioned in the text, have been numbered (Piece
- - ) to correspond with the list below.

1. shade holder

2. chimney

3. %" brass pipe

4. light support

5. reflector

6. double light socket

7. 60-watt lamp

8. lamp house

9. opal glass

10. ground glass

11. ventilator

12. light box

13. negative carrier

14. camera carrier

15. camera

16. heavy eye

17. Inline

18. pulley

19. wall support

20. wall spacers

21. frame

22. transom lock

23. easel

24. 6" x 8" bracket

25. sliding frame

26. wall brackets

27. sliding guide plates

28. reel brackets

29. reel pins

30. reel handle

75

Plate 2

31. carriage bolt 34. ^4" bolt, length to suit

32. rod support 35. bearer

33. retaining plates 36. sliding clips

All wood used is white pine. The vertical bars
to which the projector and extension bars are
fastened, Fig. 42, are %" x 2%" x 42" long.
They are spaced 2^4" apart on the inner edges with
a 94" x 294" x 8" cleat across the top, as shown
in Fig. 42, and fastened with 1^4" No. 8 round-
head screws. The inner edges of these vertical
bars must be perfectly parallel.

The vertical supporting bars of the extension
are similarly spaced and secured but at the bottom
end only. A y^" x 11" slot is cut down the center
of these bars, beginning 2" from the top end. These
slots are faced with a sheet metal plate which is
ll/o" x 12" x 1/32" thick with a 14" x !(%" slot
down the center (two metal strips can be substituted
for each of these plates) and secured in place with
y 2 " No. 4 flathead screws. Two %" x 2" carriage
bolts, Piece 31, are forced into holes slightly
smaller than the diameter of the bolt, 1" below the
bottom end of each slot in the bars. A wing nut is
provided for each of these bolts, which, because
of the forced fit will not turn.

The bed or easel, is 18" x 24" made with a
77

S/D SECT/OM

Figure 42

78

border frame and an additional piece across the
center opening from front to back, all of %" x
1%" strips, doweled and glued together and cov-
ered with a piece of plywood %" thick. This as-
sembly is fastened to the extension by two blocks
and an angle iron, which serve effectively to pre-
vent motion or bending of the easel because of the
weight of a printing frame on it.

L_ X /LJ - L,,

VALL BRACKET

Figure 43

Spacer bars, Piece 20, extending the enlarger
from the wall supports, are 444" x 8" x V thick,
secured to verticals with 1J^" No. 10 flathead
screws. The wall supports, Piece 19, are %." x

o

o

WALL CLIP

Figure 44
79

x 42" long, secured to the wall with two screws
in each end.

The wall brackets shown in Fig. 43, Piece 26,
are 1J4" wide by 1/16" thick, bent 90, with the
clip leg 1" long and the other 2" long. These brack-
ets hook into the wall clips, Fig. 44, which are
r x 1/16" thick, flanged to receive the 1" x 1/16"

SECTION THRU AA
Figure 45

ends of the brackets and are secured to the wall
strips with two %" No. 8 roundhead screws in
each end.

The reel, seen in Figs. 42 and 45, is %" brass

80

pipe 7" long, supported in sheet metal brackets,
Piece 28, at each end. The brackets are bent 90
and secured to the enlarger verticals with %."
No. 6 roundhead screws. ^" pins, Piece 29, are
located in the pipe as shown. The crank, Piece 30,
is a Ford car window handle riveted onto the end
of a pipe. The line, Piece 17, is ^4" braided cord.
A 5/16" diameter hole is drilled through one wall
of the pipe, about 1%" from the center, to secure
the end of the line with a knot on the inside of
the pipe. The upper end of the line is secured to
a stout screw eye, Piece 16, fastened to the wooden
lamp house support. The line runs over a pulley,
Piece 18, which has wheel about 3" in diameter.
The support which holds the lamp house from

BEND TO FORM VENT

LIGHT SUPPORT

Figure 46
81

the vertical bars, as seen in Figs. 42 and 45, is
6y 2 " x 1" x 1" thick, secured to a %" x 2%" x
16" slide and supported on two 6" x 8" iron
brackets. Piece 24, which are also secured to the
slide with screws. The slide is held in place by
four Ity" x 3%" x 1/16" thick guide plates
Piece 27, which are secured to the slide with %"
No. 6 roundhead screws. A thickness of paper
must be put under the top of the front and bottom
of the rear strap to permit the slide to operate
freely.

The lamp house, Piece 8, is 12" in diameter
and 8" high, not including the bottom of the vent.
It can be made in any shape and of any kind of
sheet metal handy, although a parabolic form is re-
commended. The light support plate, Piece 4,
shown in Fig. 46, is 4" in diameter with lugs %"
x l/o" long. These lugs are bent up to create a
vent space. The plate is soldered to the bottom end
of the ^4" brass pipe, Piece 3. The top end of
this pipe is threaded and provided with a shade
holder, Piece 1. This pipe supports the reflector,
Piece 5, which is an automobile headlight reflector.
If it is not chromimum-plated, it will have to be
lacquered to prevent tarnishing. The pipe also
supports the double light socket, Piece 6, and
two 60-watt "White Way" enlarging lamps, Piece

82

7. The wiring to the lights leads through this
pipe.

The positive, stop, Pieces 22 and 32, shown in
Fig. 47, is made from a %" x 36" Commercial

SECTION THRU 8-0*
Figure 47

transom adjuster whose length is cut to suit the
needs of the enlarger.

The light box is 9" across the front, by 7%"
x 9" high, outside dimensions. It is made of wood
%" thick with a light aperture 4" x 6" in the bot-
tom. The opal glass,- Piece 9, 4%" 6%", and the
groundglass, 4" x 6", are located 2" below the
top of the light box and spaced ^4" apart. Four
%" holes are made in the frame for ventilation,
as shown in Fig. 45.

83

The negative carrier is made as shown in Fig.
48, and located %" below the ground glass frame.
Sliding clips, Piece 36, which can be adjusted
to suit the thickness of glass used, hold in place

/H

SECTION THRU C-C
NEGATIVE CARRIER

Figure 48

the two 4" x 6" thin glass sheets between which
the negative is placed and held flat. The four ^4-"
x 2%" studs, Piece 34, are secured to l / 2 " x 1" x

1/16" plates, Piece 33, which are in turn fast-
ened to the light box by %" No. 6 roundhead
screws. Wing nuts are provided for each of the
studs. The bearer supporting the camera, Piece

35

[-< LENGTH TO SUIT *\

[CAMERA MOUNT ASSEMBLY

Figure 49

35, shown in Fig. 49, is %" 'x 6*4" x 1/16"
thick, of hard brass, with 5/16" holes in each
end spaced to match with the studs. The two venti-
lators, Piece 11, each cover two ^>" diameter
holes in the light box. They are made of thin
sheet metal and are open on the bottom end only.
The camera, Piece 15, is in this case a 3-A

85

Kodak with an / 6.3 lens. Small blocks are fitted
on the bottom end of the light box to fill the open
ends of the camera. Of course, any camera that
can be fitted to a flat surface may be used. A 4"
x 5" or 5" x 7" view camera would prove ideal,
although negatives from the latter would not fit
in the enlarger.

CHAPTER VII.
METAL ENLARGERS

A metal enlarger (Plate 3.) which is also a
demonstration of skill, can be made by the ama-
teur with the proper tools, although a tinsmith
may be needed for the more complicated parts.
It is designed for a 2^4" x 3^4" negative, and
takes a 4%" focal length lens. Instead of diffusers,
a single condensing lens is used. The condenser
is in a helical mount, which allows the lens to
move down to the negative, thus eliminating the ne-
cessity of having a piece of glass between the film
and the camera lens. This feature helps prevent
dust and lint from showing on the print.

Plate 4 shows the condensing lens and holder.
The holder is turned from a pipe coupling. The
lens is 4% // in diameter and may be purchased
from any photographic supply house for a dollar
or two. It is held in place by a small wire soldered
to the inside edge of the holder. If the edge of

Plate 3

87

the lens is beveled, the small wire ring will hold
it and allow its plane surface to project slightly
beyond the edge of the holder, thus permitting
the flat side of the lens to come in contact with
the negative. The ring or collar shown in Plate 4

>? A \-

SIDE VIEW OF ENLARGER

Figure 5

slides over the end of the lens holder. As this ring
is rotated in the spiral grooves cut in the sides
of the lamp house, the condenser moves down,
thereby holding the negative flat against the metal
mask.

88

PIPE

COUPLING

CONDENSER LENS HOLDER

SCREW
HOLDER

DETAIL OF FOCUSING ASSEMBLY
Figure 51

Plate 4

Plate 5

Plate 5 pictures the mask or negative carrier.
With this type of carrier individual films may be
used. They be left in the roll uncut and put
through the enlarger that way or else they may be
cut and used separately.

Fig. 50, the sideview of the enlarger, gives the
dimensions. The baseboard, shown in Plate 3,
is a piece of %" plywood 18" x 24". The upright
is a 1^4" 0. D. galvanized iron pipe fastened to
the baseboard by means of a floor flange. The
projector itself is made in three units: the reflector,
the lamp house and the bellows. The bellows is

SIDE VIEW OF LAMP HOUSE ASSEMBLY

Figure 52

made of two telescoping aluminum tubes. The
inner tube is threaded into a %" plate of cold
rolled steel, 6" x 8". The end of the rack, which
adjusts the focus, is also threaded and fastened

91

to this lower plate, with just enough clearance
to allow the outer tube to slide between it and the
other tube. The pinion gear and housing are fast-
ened to the outer or lower tube from the inside
by means of counter-sunk screws. This permits
the racking of the lower tube in or out, forming
the bellows. The lens holder is a *4" disk of fiber,
the inside diameter of the outer tube, fastened
to the end of the tube by four machine screws.

The lower lamp house assembly, Fig. 52, was
made by a tinsmith out of 16 gauge tin and black
iron. The inner section (Plate 6) is made to hold
the condensing lens mount, Plate 4, as shown in
Plate 7. This assembly was made to fit an old re-
flector which was picked up in a second hand store
for a dollar. To the lower part of this assembly
is soldered the other ^ f plate of cold rolled steel.
The two assemblies are bolted together at the
back with a %" spacer bar in between. The lamp
house assembly has a flange on it, allowing the
reflector to slide over it and fit snugly.

The ventilation system is shown by the dotted
lines in Fig. 50. The light socket is threaded on
a piece of %" iron pipe and is held in place,
though adjustable, by means of three set screws
at the top of the reflector. The turnbuckle serves
two purposes: first, as a brace and secondly, as

92

Plate 6

Plate 7

93

an aid to adjusting the enlarger and insuring that
the negative is in the same plane as the easel.
The arm supporting the lamp house has a hole
cut in it for the purpose of ventilation. The vent-
ilator contains baffles to prevent light leaks. The
cap on the ventilator is a lampshade holder, of the
type which is made to hold the shade to the fix-
ture. This can be purchased in any electrical or
hardware store. The bulb is a 100 watt frosted
type.

94

COST OF MATERIAL

1 %" plywood baseboard 18" x 24" $ .45
1 1^4" 0. D. floor flange and galv. iron

pipe 34" long .60

1 lamphouse assembly (made by tinsmith) 3.50

2 pieces of aluminum tubing (Aluminum

Co. of Amer.) 2.00
2 pieces }4" cold rolled steel plate 6" x 8" .50

1 turnbuckle .25
1 rack and pinion gear 20 pitch (Chicago

Gear works) 1.90

1 condenser lens 4J4" (Burke & James) 1.50

1 reflector 1.00

TOTAL $11.70

118413