Lead in Angle for a Rolled Thread

[rima]

I need to know what the lead in angle would be for a thread before ROLL THREADING in order to produce a 90 degree angle after threading. Before, I was making a CUT THREAD and had a 90 degree angle at the top of the threads. Now I have a 70 degree angle using the same drill prior to roll thread. How do I adjust my tool so that I end up with a thread relief of 90 degrees after roll threading?

[Greg Q]

Hi Rima, and welcome. This site only has a few professional and ex-professional engineers. If you don't get a good answer here, you may wish to post your question on Practical Machinist - Largest Manufacturing Technology Forum on the Web

Good luck with it...

Greg Q

[RayG]

Not sure I understood the question, but here goes...

At a guess, I think you'll have to machine a chamfer that takes away the amount of material that is the difference between 90 degrees and 70 degrees, (lets call it 45 and 35 since we are now talking chamfer) Maybe you could start with a 10 degree lead-in chamfer and see how close that gets you.

There is a bit on roll threading in Machinery's Handbook as well.

Regards
Ray