On Sunday, May 9, 1999 at 12:00:00 AM UTC-7, alain labbe wrote:
Hi, i'm fairly new to metalworking but I'm having a lot of fun. I do have a
small problem thought. I cant seem to find what size a shaft or bar should
be to thread it with a die. For example, i had to make a plug out of brass
(to fix an eccentricly drilled flywheel) out of 3/8 round. I tried to
thread it 3/8-16 and just couldn't get the thread started with a small taper
on the end. Ended up removing an undefined amount of metal, just to get a
long taper before I finaly succeded in starting the thread. I have really
cheap dies which certainly doesnt help but what is the rule. Should a
3/8-16 thread be done on a smaller than 3/8 rod? The one I did turned out
ok for the purpose but I'd like to know what I really should have done.
Thanks
Alain Labbe

use a tap and die chart to help you find the initial inside and outside diameters needed for the tap and die you will be using.