Threading Basics
A very common way of threading is used by taps and dies which cuts and makes them. Screw threads are the process of threading. There are many ways to make screw threads. If a thread is rolled for example, it could make micro lathe lead screws or cheap deck screws.
Threads are cut with a tap, die, or lathe. If the thread is rolled, then they are stronger than cut. They have more wear and fatigue resistance, and have up to 20% more tensile strength.
If the thread is cut, it is used when a depth is required, the blank is not very accurate, needing to thread a tapered thread, the material is hard to manage, the quantity is small, or a thread needs to be up to a shoulder is required.
A process called Single Point Threading uses a tool that is single point and produces thread on a cone or cylinder. The work piece will decide the lead of the thread by the rotation, which is very precise, while the tool moves linearly. This process can make female or male threads which means internal or external. In the external cutting, the work piece can be mounted between two centers or a chuck. A chuck is used for internal threading. Chips are removed from the work piece with each swipe of the tool moving across linearly. If right hand or left hand threads are needed, it will move from right to left or left to right. Normally five to seven light cuts are made to create the right depth of the thread.
Most machines used for Single Point Threading are CNC lathes and engine lathes. With CNC, the process is simple and quick because it tracks the spindle and tool position. Software is used with programs telling the machine what to do. Like what length of thread or thread size for example.
Because of low cost of other ways of threading, Single Point Threading is not used most of the time. When there is something unique that needs to be done or the process favors it, then it is used. Most threading all could be done using this process.