Book screw
Binding screws (less often bookbinding screws or Chicago screws; English screw post ) are a possibility for representative stapling of books, brochures or loose-leaf works , the so-called screw tape . The screws made of metal (nickel-plated or brass-colored) or made of plastic consist in the lower part of an eight to ten millimeter thick washer and a shaft sleeve with a diameter of five millimeters and an M4 internal thread .
The length of the shaft is determined by the number and thickness of the sheets of the bound work, common lengths range from two millimeters for a few sheets - for example in menus or contract documents - to fifteen centimeters for large albums with cardboard-like paper. The shaft is inserted into the standard perforated cover and inside, then the disk-shaped head screw can be screwed in.
The advantage of this stapling process is the detachable connection, which allows pages to be exchanged at a later date; the disadvantage is the laborious manual processing, which is only recommended for small editions.
The screws are also used in leather processing when detachable but fixed connections are required. For example, exchangeable belt buckles can be attached in this way.