Quote Originally Posted by Neale View Post
Still not sure whether a single-point tool could be used for thread milling (although I don't see why not) even if it wouldn't have the "full hole-depth thread in one rotation" capability of the "proper" cutters as used for production.
They're used all the time. No different from any other milling cutter, as it's rare more than one cutting edge is in contact anyway. The main drawback (or could be classed as advantage depending on how you want to look at it), is a lower feed rate as you only have one tooth doing the work. If you have the horsepower available along with the rigidity to handle it, a multi-thread/tooth thread mill is far quicker, as you can do the whole thread height in a single circular pass.
Off course, tapping is usually quickest, but then you're into needing enough torque to handle the tap, having the capability to handle the required synchronisation, and a tap being available in the correct size.