Dies

Dies

— dies are called tools for cutting external threads. Another name common in common parlance and professional jargon is "lerka".

In fact, such tools are nuts of a special design, having a set of cutting edges on the inside. Such a nut is put on the rod where the thread is cut and turned — usually with the help of a manual die holder (see the relevant paragraph), although occasionally models for machine use can also be found. For reliable entry of the die onto the workpiece and accurate centering, it is desirable to first chamfer at the end of the product from which threading begins (however, some die holders allow you to do without such a procedure). And when working, it is desirable to alternate turns of the die in the main and in the opposite direction — this ensures the removal of chips from the cut turns.

Note that, unlike taps, dies are originally intended for threading in one pass.