Sorry, I have no experience with thread milling yet but am going to have to figure it out for a future project, looking forward to following this post.
I have been doing some reading and web searching in preparation.
And I need to decide on and buy a tool or three.
Have you checked out the thread-milling video on this sight?
http://www.download.sprut.co.uk/Supp...p?showforum=23
You might have to register to the forum to see that particular video
Gerry