Quote Originally Posted by overkill View Post
The Guhring doco indicates the cold-forming taps are only recommended up to 320 Brinell hardness, so Hardox 450 is too hard for that type of tap. I have a couple of cold-forming taps but due to the extreme torque needed, I don't use them much.
That's how I know it, forming taps are suitable for ductile materials, that said for sure there are specialised forming taps which are good for hard materials...At our work machine shop we have something similar for threading in titanium, but its a machine taps, ie mounted on the milling machine not a hand taps.