3io MODERN PAPER-MAKING
rolls and the discs is maintained by two steel rolls about 3 inches in diameter.
These deliver the slit webs on to the dead knife edge.
The knife on the revolving drum, set at a slight angle so as to have a shearing
effect, chops the sheets as they pass over the dead knife, and they fall on to a
moving felt. The length of the sheet is regulated by the speed of the revolving
drum. This is set by changes of the driving pulleys, and finer adjustment is
made by expanding pulleys, enabling water-marked papers to be cut to register.
The carriage of the revolving drum and dead knife is adjustable to cut the
sheets at a true right angle to the slit sides. This device is extended so far in
the 'angle' cutter that sheets may be cut at any angle. This is essential for
reducing waste in stamping out envelopes, etc. A very useful variation of the
ordinary cutter is the Duplex cutter, which can cut sheets of different sizes from
the same web. This enables the paper-maker to make full use of the width of
the machine.
Thus, if the machine is capable of making only 72-inch deckle, and the
order is for sheets 30x40 inches, the lot may be made one sheet 30 inches and
one sheet 40=70 inches, instead of 2 sheets 30 inches=6o inches.
The Duplex cutter has two revolving cylinders and dead knives. These
may be driven independently and at different speeds, one part of the web
passing over the first revolving knife and being cut at a different length by
the second.
An invention which has reduced the labour costs of the cutter to a great
extent is the automatic 'layboy'. Formerly it was necessary to have a boy
to elay' each sheet as it came off the moving felt, so that a cutterman and
five boys was a usual cutter crew. With this device which 'lays' and jogs
up' the sheets automatically, a cutterman and an assistant can manage a
cutter.
A cutterman must be very careful and precise with his work. The setting
of the slitting discs is a very simple matter. The distance between each fixed
disc is accurately set with a good rule, preferably steel. The moving disc is
then brought into contact with the fixed disc, and this must be gently done,
otherwise the hard edges may chip each other. Indeed, to obviate any risk of
this a sheet of thin paper should be used at the point of contact.
A very common mistake is to compress the spring of the moving disc too
hard, and thus cause the cutting edges to grate on each other and wear blunt
very soon. The setting of the length of the sheet is done in accordance with
the table of sizes and pulleys issued with each cutter. The driving belt of the
revolving blade must be kept in good order, and well tightened up with the
tension pulley or pulleys provided for that purpose.
Before starting the cutter, all tools and spanners should be accounted for