Dies

It is used for cutting external threads on round stock. An adjustable round split die has an adjusting screw that can be tightened so that the die is spread slightly. The diameter and fit of the thread can be controlled by adjusting the die. In the plain round split die, a variety of thread fits are not available as these types of dies are not adjustable.

The following are the two main types of dies.

Circular Die: This is generally used for cutting smaller threads and slight adjustment can be affected by the screws in the side of the stock. The die thread is tapered to make an easier start. When fitting the die to the stock, the tapered side must always be away from the shoulder of the stock.

FIGURE

Rectangular Die: It is an adjustable two-piece die, which is used for cutting larger diameter threads. The die has tapered threads to allow an easier start. The engraved numbers on the two halves must be fitted on the same side.

FIGURE

Die nuts are turned using a spanner and are used to clean a damaged thread.

FIGURE

The following is the procedure for cutting external threads.

1. Secure the work in the vice.
2. Taper the rod end slightly to support the start. The external diameter of the round rod must be equal to the crest diameter of the thread to be cut.
3. Place the correct die in the stock and relax the two outer screws.
4. Tighten the centre screw and re-tighten the outer screws.
5. Place the stock and die squarely on the rod and start the cutting process by following the same procedure as for taps.
6. If additional cutting is required, slightly loosen the centre screw of the stock, tighten the two outer screws and re-tighten the centre screw.
7. Repeat the process until the nut is a good fit.
8. Once done, try a new nut on the new thread.