Dies are used for cutting threads on bolts and other similar parts to be placed in holes which have been threaded by taps. The general rules given for the use of taps apply to dies. As the number of threads in a die is much less than on a tap, and because the chips have a much freer exit, it is not as necessary to back up a die as it is a tap.

Solid Dies

Dies for small work are usually made solid, as shown in Fig. 82, and often have a slight adjustment for altering the size. They cannot be sharpened, but have an advantage in readily centering on the work. As the full thread is cut at one passage of the die, it takes considerable power to operate solid dies of large size. For this reason, hand-operated solid dies are seldom used above one-half inch. The holder or die stock shown in Fig. 83 has a guide to hold the work at right angles to the die, but die stocks are often made without this convenience.

Fig. 82. Threading Die.

Fig. 83. Self-Centering Die.

Split Dies

The split form of die, generally known as the jamb-die, Fig. 84, can be easily resharpened, has unlimited adjustment for size, and cuts the thread by easy stages, as it were. It is made in sizes up to 2 inches and is for hand operation only. The holder for this form of die is called a screw plate, Fig. 85. These are not furnished with guides for the work.