CHAPTER III. Cutting, Rounding, Backing. Fig. 35--Rotary guillotine. Fig. 35--Rotary guillotine.

In nearly all cases the book is trimmed after glueing, and it is best to do this before the glue is quite set. Even in extra work books are nowadays trimmed on three sides, that is, before the book is rounded each side is cut one after the other. This method has the advantage that it is quicker, that the top and bottom corners of the round fore-edge cannot break, and that it is easy to treat every side during the process of marbling.

Of course, in the best work the book is first cut at the front, rounded, pressed, and then cut top and bottom.

Under present conditions we might completely abandon the old method of trimming with the plough, for, although this is a most valuable tool, it would not pay to use it now, and the shops where it is still in use are few and far between; besides, our German machines now do the work so thoroughly and accurately that we are able to execute the highest class of work by their aid.

The machines worked by a lever are very suitable for small shops and small books. Rotary action is for heavier work and is more suitable where both heavy and light work have to be done.

The fore-edge is generally trimmed first; the back of the book is carefully adjusted to the "back gauge," the back gauge is so adjusted by moving backwards and forwards that the knife comes exactly upon the point marked beforehand. The first principle to be observed in trimming is that as little as ever possible should be taken off the book. Measuring and marking for trimming are done with the dividers; the latter is called "marking for cutting." When the back gauge has been adjusted so that the points lie directly under the knife, the clamp which holds the book in position is screwed down and the machine set in motion. The book must be cut smooth and quite free from any jaggedness, and if this has not been accomplished the knife must be ground or, at least, well sharpened.

Something must be done in trimming top and bottom to prevent the groove at the back from receiving too much pressure. The simplest means is to glue a thick board on the under side of the clamp. If a piece of stout cloth has been pasted to this board, it will afterwards be easily removed from the clamp if it is lightly glued on at two places only. If cloth is not used, pieces of the board will adhere to the clamp and cause no little inconvenience.

Instead of this, there are metal plates sold which are fastened to the clamp in a simple way, either by screws or springs, and they are just as simply removed.

The bottom edge has to be cut first, as one is thus able to adjust the head—which, of course, must be rectangular—against the back gauge and then to make the bottom edge parallel. After cutting this edge, the book is turned round and the bottom edge adjusted on the back gauge so as to get the top edge ready for cutting. Whilst doing this, care must always be taken that the book is placed under the clamp so that the arrangement made for saving the groove from pressure is effective.

Fig. 37—Top edge arranged for trimming when trimming three edges.

As our machines are made to cut from left to right, the book back must be on the left.

Very often a book contains so many folded plates that it is considerably thinner in some places than at others. These thin places must be properly packed with paper or strips of board, otherwise the knife is sure to tear or jag, no matter how sharp it may be. This packing may be left in the book until the book is quite finished and then taken out.

If any fibrous matter has stuck to the bottom sheets through cutting on a much-used bed, it must be removed with a very sharp knife.

The trimmed volumes are "rounded," i.e., they are rounded and the groove made at the back to which the boards have to be fitted. For this reason the grooves must be made to suit the thickness of the boards to be used.

To round a book, slightly damp its glued back, place it on a firm stone or metal bed, and knock it round with a hammer. Properly speaking the process is as follows: The left hand takes hold of the back of the book lying flat before the worker and works it into a round form, the right hand helping all the time by beating it along the back from one end to the other.

In this way each side is treated alternately until the back is evenly rounded. The rounding of the fore-edge should be equal to one-third of a circle.

Books that have been hammered so much that they fall straight from the centre towards both sides are called "over rounded"; if, on the contrary, the book is round at the sides and almost straight in the middle the book is called "flat rounded." The latter occurs when the thread used in sewing has been too thin or held down too much (see page 37). Great care must be taken to avoid what is called springing a section—this is generally caused by a break in the glued back; but it is almost impossible to round a book perfectly if the sections are very thick or if it contains many pasted-in plates.

There are now very useful machines for rounding books, also hand machines. The work connected with these consists simply in turning the book a few times, pushing the back up to the rollers each time.

When the book is properly rounded, it is "backed," that is, it is so placed between backing boards that they are away from the back just as much as is required for the groove, the width of the latter depending upon the thickness of the boards; a small thin volume gets thin boards and therefore a small groove; a thicker volume requires thick boards, and, of course, a deeper groove. The made groove should be a little deeper than the board set in it. The book and backing boards are placed in a wooden press, screwing up by hand and once more carefully adjusting. To do this, the press is first placed lengthwise on the table so that one end projects a little over the front edge of the table; the evenness of the rounding is then perfected—one hand at the back and the other at the front edge pushing and adjusting. The better and truer the book has been rounded before laying in the boards the less there will be to do when placed in the press. If the rounding is correct, the head and tail must be examined to see that they are exactly rectangular, for the book may have been knocked untrue, and the evenness of the grooves—which are easily disturbed—is also examined.

Backing and rounding is the most important work as far as regards the appearance of the book when finished; it must be done with the greatest exactitude and requires much practice. Although it is hardly perceptible, yet the great difficulty lies in the book itself being so very easily shifted.

When the book is placed in the press without a fault it is screwed up as tightly as possible with the screw key, and through this the grooves already project over the edges of the backing boards; but a sharp groove can only be obtained by the help of the hammer.

The hammer, however, must not be used blindly on the back, but by lightly knocking, blow by blow, the first and last 4-6 sheets must be brought over the edges of the boards. This done, the whole of the back is well pasted, and after remaining thus a short time it is then rubbed with the point of the hammer along the sheets until all superfluous glue is soaked and scraped off. With a handful of paper cuttings the back is rubbed smooth and clean. The use of a toothed cachir iron is strictly forbidden, but the round side of this tool may be used instead of the hammer.

For backing, we have also a useful machine—the backing machine. For small shops it is made for clamping only, and the making of the groove is done with the ordinary hammer. For large shops this machine has a roller going right across the back which forms the groove down each side.

Valuable books are either trimmed at the front and at once backed or they may be backed before trimming. This is generally done with bulky books, as they are liable to throw out a section, and this danger is lessened by backing first. The work of backing remains the same. If the fore-edge has already been trimmed, care must be taken that the grooves do not suffer during trimming after backing. One way of effecting this is to lay the book on a special cutting board with the edge up to the groove, or by making use of the arrangement on the clamp already described, and adjusting the groove of the book to the blocks fixed on the clamp.

Should the fore-edge not have been cut, the book must again be knocked straight after backing; to do this a strong cord is tied round the book about 1-1/2 cm. from the back, the book is then laid upon a firm bed, and the back again knocked straight; this work is called "tying up."

Fig. 42—Backed book arranged for trimming.

It facilitates the work if the book is taken up and lightly held in the left hand whilst the right holds the hammer and knocks the round inwards until the book is once more square.

The squared book is now trimmed, and it is not until the trimming is finished that the cord is loosened.

In pressing, several volumes of the same size can be done in the hand press at one and the same time.

---