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.

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 it’s 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 Fig. 38-Rounding the book one-third of a circle.

< Cutting, Rounding and Backing part 1