Paper-Cutting Machines Part 5

To trim a pile with perfectly true corners first jog its straightest edge against the back gage, and make the first trim. Then jog this cut edge against the back gage and make the second trim, keeping the pile away from the side gage. This trimmed edge should be exactly parallel with the edge trimmed first. Then jog either of these cut edges against the side gage, and push gently (but do not jog) to the back gage, for distance. This cut will be at exact right angles to the first and second. Turn the pile and make the last cut with the trimmed edge against the back gage keeping the pile away from the side gage.

Do not try to jog a pile against both side gage and back gage at the same time, for, although these are at right angles, the attempt to force a pile against both will slue the pile.

Turn the pile on the table with the greatest care; do not lift it between cuts or jog it vertically. To test a pile for rectangularity, turn part of it one-half way around and match the edges.

_To Square a Pile_

_First_--Set the back gage about one-eighth inch further from the cutting edge of the knife than the desired dimension of the square. The extra distance the back gage is set beyond the dimension of the square will depend upon the amount necessary to trim it to a true, clean edge.

_Second_--Jog an uncut edge of the pile against the back gage and make a clean trim.

_Third_--Jog this clean trim against the side gage and just "feel" the back gage for distance. This trim is at right angles to the first.

_Fourth_--Now draw the back gage up to the exact dimension of the square desired.

_Fifth_--Jog either of the clean trimmed edges against the back gage (keep the pile away from the side gage). This trims three sides.

_Sixth_--Jog the pile against the back gage and trim the remaining uncut edge, keeping the pile away from the side gage. This completes the square.

To test a pile for squareness, turn part of the pile one quarter way around and match the edges.

_To Cut Unusual Shapes_

Any odd shapes having straight lines may be cut by the following method: Make a sample of the shape and size required; then take a piece of No. 70 strawboard a little larger than the pattern. The board must be squared up, and the odd-shaped card laid on it; then put the two pieces under the clamp and adjust the strawboard against the back gage and the sample card even with the clamp in front; then run the clamp down and draw a pencil line around the sample card on the strawboard. A piece of wood can then be glued on to the strawboard along the pencil line at the back and another at the end. If a bunch of cards is laid into this box gage and the board pushed up against the back gage of the machine, a narrow strip of wood or board must be glued on the clamp right over the card, so that a pressure may be secured on the stock.

This clamp-stick must, of course, fit into the box gage, so that it will take up the difference in thickness between the pile of stock and the height of the box gage. These gages may be made by means of a square and a pair of dividers, as well as in the machine.

Celluloid may be cut into narrow strips by using the method described above. A sharp knife and rubber bands are all that are necessary.

_Tr.i.m.m.i.n.g Books_

A common error made by printers is to make up forms nearly the full measurement of the leaf, thereby leaving the binder very little trim margin. A standing rule of every printing and binding establishment should be to allow one-eighth of an inch trim margin for the fore-edge, head, and tail of all st.i.tched tablets and quarter-bound cut-flush books. All sewed books should have three-sixteenths of an inch for the fore-edge, and one-eighth of an inch for the head and tail trim margins. The tr.i.m.m.i.n.g of letter-press work should be standardized, so that paper-covered books are trimmed a trifle larger to permit a retrim when books are returned for a substantial cover. To ill.u.s.trate this, a sheet 24 38 inches made up into thirty-two-page signatures, when folded, is 6 9-1/2 inches. The paper-covered books should be trimmed 5-7/8 9-1/8 inches; one-eighth of an inch is trimmed off the head, the balance off the tail, while the fore-edge has one-eighth of an inch trim. These books, when returned for permanent covers, as they frequently are, have one-sixteenth of an inch trimmed off the head and tail; and one-eighth of an inch off the fore-edge. This gives the standard book size, 5-3/4 9 inches for the bound volume.

When the entire edition is to be bound with a permanent cover, provision is made for three-sixteenths of an inch trim at the head.

This enables the printer to standardize forms without varying the head margins, and gives the binder sufficient margin to trim inaccurately folded sheets.

To trim books on a cutting machine, take as many as will make a pile about three inches high, and jog at the head and back. Set the back gage the exact size to which the book is to be trimmed; put the books in the machine with the head against the side and the back against the back gage. Run down the clamp, provided the machine has a hand clamp; an automatic or self-clamp requires nothing more than to pull the lever. When the cut has been made and the machine stops, remove the books and put to one side. Repeat this operation until all books are trimmed on the fore-edge and lay aside in piles with the backs out.

To trim the heads and tails, fillers must be made to take up the thickness of the back. Cut strips of straw or binders' board about four inches wide; glue them together; fan out and press. Put the books in the machine with the heads against the back gage and the trimmed fore-edges against the side; then lay the board filler on top in such a way that the fanned-out ends are sufficiently away from the back to permit an even pressure of the clamp on the books. Pull the lever, and repeat the operation for subsequent books. The filler can be glued to the clamp and the books put directly under it.

For the head, the gage is set forward and the trimmed tail is placed against the back and side gage. The board filler is placed on top in the same manner as above described and the operation continued. On thin books the board filler may be dispensed with by reversing the backs of the books alternately, so as to distribute the thickness of the back on both sides of the pile.

If there are two splits in the back gage, _i.e._, if it is a three-part back gage, set the center for tr.i.m.m.i.n.g the fore-edge, the left for tr.i.m.m.i.n.g the tail, and the right end for the head. This, however, should be done only when the quant.i.ty to be trimmed justifies it. When the back gage is set, tighten the thumbscrew with the hand. To guard against the marking of the book by the pressure of the clamp, cut a piece of binders' board somewhat larger than the width of the clamp face and glue it on the clamp.

Waste leaves should be placed on the top and bottom of enameled or glazed stock to keep it clean.

To trim quarter-bound cut-flush tablets or pads which are bound two or more on a sheet, as in the case of receipts, trim the fore-edges, cut all the tails alike, then the heads. The knife should cut against the back. In making up books to be bound two or more on, one-fourth of an inch trim must be provided for, to clear the bevel caused by the knife.

This is provided for if books are made up with one-eighth of an inch trim for the head and tail. Thick books can be bound two or more on until the st.i.tching is completed. Then cut apart and proceed with the rest of the binding in the regular way.

Blank books are trimmed so that the standard sizes are reduced one-fourth of an inch for the length and three-sixteenths of an inch for the width. The paper for a medium book is 18 23 inches; when folded, 11-1/2 18 inches. If such standard sizes are adopted the work of forwarding is greatly facilitated, as cases and boards can be made in advance without fear of the books being trimmed too large.

In tr.i.m.m.i.n.g spring-back account-books, sewed straight or on guards, the fore-ends are trimmed, then forwarded until the books are in straps.

Sharp knives are indispensable in tr.i.m.m.i.n.g books which are concave on the fore-edge. Deep rounds should be filled in with waste paper to prevent the top sections and the back from breaking. Board fillers are always laid on top and the book placed so that the knife will cut against the back.

Brochures with extended cover should have the stock first cut to size of cover before printing, and sufficient extra stock allowed for an all-round trim of the inset after, especially at the fore-edge where after folding in sections the inner sheets are apt to bulge forward.

The printer should know how much will be taken off in the after trim to enable him to allow uniform widths of margin. After a job is bound, the cutting machine cannot remedy any defect of edges.

_Paper Cuttings and Waste_

Cuttings and waste may be disposed of by throwing them into a large bag attached to or placed near the machine. When filled, this can be taken away and another subst.i.tuted. Throwing waste on the floor should not be tolerated. It is untidy, costs time and labor to gather up, and is dangerous.

A light box on wheels is also a good plan for caring for waste of this kind. In some places where there is a great deal of tr.i.m.m.i.n.g, a chute in the floor next to the machine provides a convenient method of disposing of waste from a number of machines. This chute leads into a large bin or baling machine below, from which the material is carted away.

The worth of a paper-cutter operator can be measured by an examination of the waste cuttings. A careless operator can waste a large sum of money in a year. Many persons make a good living from the waste paper of large printing and binding plants by buying it at a nominal price and selling it again at a considerable advance.

There is unavoidable waste, of course, but there is often a great deal of unnecessary tr.i.m.m.i.n.g. When the necessary tr.i.m.m.i.n.g runs up into hundreds and thousands of pounds, as it does in all large plants, it is worthy of notice, especially when it is realized that this waste has been paid for at the same rate per pound as the stock that is actually used. Some printers and binders sort and bale their waste and dispose of it so as to make a considerable saving, but few understand how a little care and system can be made to return a good profit.

There is another waste, sometimes far greater in amount, caused by the careless cutting of stock. A thoughtless operator will often try to save ten minutes by hasty calculation and then waste stock through inaccurate cutting that costs several dollars.

In some binderies the operator is instructed to sort his tr.i.m.m.i.n.gs according to the kind of stock; that is, clean white edge tr.i.m.m.i.n.gs kept by themselves are worth more than when mixed with miscellaneous colored tr.i.m.m.i.n.gs. By having two or more bins at hand into which these different kinds can be thrown as they come from the knife the sorting can be done without extra handling.

An intelligent inspection, segregation and saving of the waste cuttings will well repay the effort. The larger pieces of waste can be kept for pads or other use. White stock should be kept separate from colored and where the quant.i.ty will warrant the cost, all waste should be baled in a baling press.

_Depreciation of a Paper-Cutting Machine_

Deterioration takes place in a paper-cutting machine chiefly in the knife, friction clutch, driving-shaft bearings, knife-bar guide ways, and knife pull-down connection. Depreciation in the entire machine occurs rapidly when it is not kept oiled, adjusted, and clean.

Neglected bearings which run dry are ruined in a short time. The times for the daily oilings and weekly cleaning and polishing should be fixed and faithfully attended to.

On modern machines the worn knife and the friction-clutch bearings may be easily replaced or repaired. Knife-bar guide ways and the guide slot for the back gage are made with adjustments for taking up wear, for which the maker will give correct instructions on request. The knife-bar pull-down connections are not so easily corrected for wear, and the simpler and more direct these connections are, and the fewer slots and rolls, pins, etc., the better. The general design of the machine also affects its value, especially if it is not adapted for the addition of improvements or attachments for increasing its production.