Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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rounding and backing machine

A bookbinding machine which performs the two operations of rounding the spine of a text block and forming the shoulders for the boards. The book is placed in the machine fore edge down, and is drawn along until it arrives over a forming bar, where it is gripped between facing rollers revolving in opposite directions while the bar is pushed up against the fore edge. The two sides of the text block are dragged downwards while the middle is being pushed up, forming an arc of approximately one-third of a circle. The text block is gripped between jaws that serve the same function as the backing boards in hand backing, and a rocker above swings in an arc against the spine, finishing off the rounding and forming the shoulders. The rocker is a heavy piece of metal with a concave edge, and is brought down until the concave is in contact with the spine. In library binding, the rounding and backing machine operates in a similar manner, except that each book is inserted by ha nd, fore edge up, and the mechanism must be adjusted to the r,J., thickness of each book. The text block is both rounded and backed by the action of the concave rocker arm. (203 , 320 , 339 )




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