A gib is also a kind of angular key, because it is used to prevent the two arms of the strap (Fig. 25) from opening while in use.

The simplest method of making gibs is by cutting out a piece from a bar which is the width and thickness of the gib required. The bar is supported by a screw-prop, while the shape of the piece to be cut out is marked upon both sides of the bar by means of a pencil and straight-edge, and the chisel for cold iron is driven into the middles of the pencil-marks, after which the piece is cut out, while at a yellow heat. It is necessary to cut the piece small enough to allow the gib to be afterwards flattened by the flatter to the required dimensions.

This mode of making gibs is available is cases of emergency or break-down ; but the economical method is by the fuller, and the application of the rule given in page 8. When the length of iron or steel required is ascertained by this means, two dents are put into the edge of the bar while cold; the distance between these two marks is the length of bar required to produce the required length of the opening or gap in the gib. After being marked, it is heated and fullered at the two marks by driving in a fuller, as shown by Fig. 82. The top fuller only is required; after which, reduce the middle portion to the required width and thickness by hammering, and the gap in the gib will then be of proper length.