TABLE OF CONTENTS Cutting threads on CNC machines can take many forms. The typical methods include tapping, single point threading, even forming (threading die heads are not normally used in CNC work). If the conditions are favorable, one of the best methods of generating a high quality thread is to mill it. Milling threads of many forms has proven to be one of the most effective and most cost-efficient methods of thread machining. Grinding threads is another available method of producing high precision threads, but it is time consuming and very costly. The area of thread milling can be fairly broad, yet the subject itself is not that difficult. First, some background and general considerations.
The key to any type of thread milling is the availability of helical interpolation feature in the control system. This is the absolute must. It is not possible to program a thread milling toolpath without understanding the concept of helical interpolation. Even this knowledge cannot be used, unless the control system supports the helical interpolation feature in the first place. Helical interpolation is often an optional feature on most CNC systems it may have to be purchased and installed on demand. A few controls provide this feature as standard, so it is always worthwhile to find out whether a particular machine (and its control system) supports or does not support this feature.
Note it is actually possible to produce a thread milling cut by simulation. Instead of a smooth, continuous circular and linear motion, a series of...
