CUTTING 309
as 'watered silk', imitation leather and names, designs, which in some cases
are almost indistinguishable from water marks.
Cutting.—It is very seldom now that we find a cutter attached to a making
machine, but this was once not uncommon. As the old type of cutter, known
as the 'English' or single sheet cutter, was limited in speed to under 65 feet
per minute, it was found to be uneconomical to keep back the speed of the
machine to suit the cutter.
There are still some machines, however, with this cutter attached. These
are used for making and cutting high-class writings and drawings Vaterleaf,
the sheets being subsequently hand-sized with gelatine, and as a high speed
cannot be attained with these papers the objection does not apply.
The 'English' cutter consists of the usual slitting discs or knives, which
are common to all cutters, and a reciprocating action chopper. After being
slit longitudinally, the paper is run over a large drum. This drum is moved
round, carrying the paper to the required length of sheet. The slit sheets fall
over a 'dead' knife, and are temporarily clamped as the moving blade swings
away and the action of the drum is stopped. The return swing of the table
shears off the sheets, which fall on to a moving felt or smooth inclined surface
and are 'laid' by hand by boys*
The web slackens back at each stop or clamping, and the slack is taken up
by a 'dancing roll', the tension being regulated by two krge cone pulleys.
The length of the sheet is set by a screw adjustment in the crank which moves
the drum, and slight variations are made by hanging small weights on the
'dancing roll' and by a brake which checks the momentum of the drum.
A change of gear wheels enables the crank to make two forward movements
of the drum for one chop of the knife for very long sheets.
When cutting short sheets, the speed has to be reduced to under 45 feet,
owing to the vibration and the jar of the reciprocating parts. Only one web
can be cut at a time. This type of cutter is very accurate in capable hands,
and some may still be found doing good work in cutting water-marked papers
which must be in exact register.
Under modern conditions of speed and output the revolving cutter (Fig.
13 3) is now used. The chop knife is fixed on a revolving drum, thus eliminating
the reciprocating action altogether. For very short sheets two knives may be
used on the drum, but this is seldom carried out in practice, the usual procedure
being to cut double sheets and cut them in two on the guillotine cutter.
As many as twelve or more sheets or webs may be cut at one time, accord-
ing to the thickness of the paper. If the filling is too heavy the bottom sheets
may be torn instead of being cut with clean edges. Two rolls thickened at
the centre pull the paper into the slitter discs. The tension between the feeding