For the machinist who wishes to created uniform threads, it will be very difficult to do without the use of a diestock. A diestock is a frame which is used to hold the cutting tool, usually hexagonal or round dies. The diestock holds the dies in perfect position which ensures that the threads which are being cut are uniform and cut exactly to specification.
In order to create uniform threads on screws, bolts and pipe, the die is held securely in the diestock. Round dies have razor sharp cutting edges which allow the threads to be cut in the softer metal with little or no pressure applied. The pressure that is applied is uniform which ensures threads of uniform shape and depth. It is the die stock handle that allows the machinist to maintain this pressure as the threads are cut along the length of the item being threaded; screws, bolts or pipes.
There are two basic styles of diestocks; the common type used for cutting threads on screws and bolts has two handles, one on either side of the center cavity which is where the die is secured in place. A less common style but nevertheless often used is a single handle device which is used primarily in the plumbing trade. The double handle diestock is turned continuously through 360 degrees, cutting the thread as it goes. The single handle diestock works on a ratcheting concept where the die is turned by continuously pumping the handle through an arc.
Regardless of the diestock used, the square, hexagonal or round dies are locked into the diestock with set screws that fit perfectly with matching holes in the die; this makes a single functional tool from two components. Although the diestock is common, the dies aren’t, the dies have different thread forms but they all fit in a common handle.
The die is placed on the round bar or pipe which is to be threaded, it is placed perfectly horizontal. The skilled machinist or plumber turns the diestock handles carefully until the die begins to cut the thread. Once the thread is started it is an easy matter to keep turning the diestock to make the thread form as long as specified. During this thread cutting exercise, the die is kept liberally lubricated with cutting oil which keeps the die cool and aids in breaking the chips that are raised by the cutting process.
