Die holders are tubular parts that attach to the tailstock of a lathe. With the die installed, the holder may remain stationary as the material to be cut on the spindle is advanced into the die, or the material to be cut can remain stationary and the die holder is made to rotate in the tailstock. Using a die, threads can be machined onto a rod-shaped material.
A tailstock die holder is a tube that fits onto a tapered part that attaches it to the tailstock of a lathe. The tailstock is usually held stationary while a rod attached to the rotating spindle is forced through it in order to be threaded. Die holders usually have three screws near the spindle-facing side of the tailstock to position the die, a cylindrical disc containing the cutting tool. Holes cut symmetrically about the central thread cutting tool are for chips of metal or other material. The metal chips that come off the machined part are thrown first into these holes and then back out the hollow of the die holder.
A hex die is one that is shaped like a hexagon, with flat sides that are equal in length. This type of die can be accommodated in regular circular die holders by the die holder’s adjustable screws as long as its radial dimensions are not greater than the inside diameter of the circular die holder. A simple bracketing holder for the hex die takes advantage of the flat sides of the hex die, stabilizing it above and below. In this mode, it cannot be expected to rotate and can only perform its function when spindle-driven material is forced into it.
Acorn die holders have a built-in clutch mechanism that allows the holder to be released without shock. As the cap of an acorn holds up the seed of an oak, so the acorn die holder uses a similar technique for holding the circular die. Rather than using screws to fix either the circular or the hex die, acorn die holders encompass the circular die at its sides, locking onto the thickness of the die to form a tight fit with the rest of the holder, a tapered region, and the tailstock. With the capability of rotation, the advantage with this type of die holder is easy positioning and release.