The die cuts a thread on a preformed cylindrical rod, which creates a male threaded piece which functions like a bolt. The dies shown are
A cylindrical blank, which is usually slightly less than the required diameter, is machined with a taper
(chamfer) at the threaded end. This chamfer allows the die to ease onto
the blank before it cuts a sufficient thread to pull itself along.
The adjusting screws allow the die to be compressed or expanded to
accommodate slight variations in size, due to material, manufacture, or
Each tool is used independently, but are usually sold in paired sets
of both types, one die and three taps. Some sets may provide a lesser
number of taps. The common sets shown are designed for hand operation,
but different types such as helical or spiral may be used in production
tools such as CNC machining tools, which employ die heads to make large volumes of threaded parts.