Draw-in Collet Chuck

By C. W. Woodson

The effectiveness of the usual small bench lathe may be increased greatly if you will take the trouble to build this neat collet chuck. With it, screw parts, locomotive axles, boat shafting and the like may be built on a production basis, The function of a collet chuck is simple : for turning wire parts, a hollow spindle is provided to hold a length of material, and the chuck vise itself is built into the hollow spindle. The full assembly of the parts required are shown in Fig 1

.

A 7/8" by 4" hand wheel is sweated on a drive fit to the hollow shaft, threaded at the live end is the chuck itself, as shown in Fig. 2.

This view shows the chuck installed. This chuck is threaded 26 threads per inch, 645" root diameter for a length of 5 / 8 " see Fig. 5

A cup is turned out of steel, fig. 4, which in turn is designed to taper seat into the live spindle see Fig. 2.

The dimensions of the chucking collet are shown in Fig. 3.

The wheel on the out end of the spindle is used to hold the spindle while the chuck is drawn up. The collet itself may either be purchased or may be made as shown in Fig. 6 by sawing a piece of steel 1 1/2, from either end at 90 degrees, each cut from the other.

The taper at the head is then cut in. The hole of proper size for the work to be handled is, of course, drilled first, before sawing. The head of the collet is rounded as shown.
The steel should be tool steel or some steel that can be hardened, yet it must not be cased so hard it becomes brittle, for considerable flexibility is desired.

A job like this is admittedly one for the more advanced amateur, but as a tool building project, it will interest many.

(From: "Model Craftsman, the Magazine of Mechanical Hobbies", September 1937, pp. 37.)