Pieces of some shapes that cannot be screwed on to the screw chuck can be held on a spur chuck (Fig. 275). This chuck is simply a wooden facing, having two or more short spurs in its face side and secured to an iron face-plate. The piece to be worked is forced on to these spurs, and held against them by the tail-stock, as shown in Fig. 224. While in this position, the edge and nearly all of one side can be finished. The spurs do not usually project more than 1/8 inch, and 1/16 inch is sometimes sufficient. They may be of any desired number, and should be firmly driven into the facing, so that they will not be pressed deeper into the facing, when pieces to be turned are forced against them.

The spurs may be made of wire nails by driving the nails into the facing from the face side, and then cutting them off and filing them sharp. For heavy work the nails may be driven in from the back side, and their heads left to rest against the iron faceplate, so that forcing pieces on to their sharpened ends will not move them.

Fig. 275. Spur Chuck.