?I'm curious DW, how did you know what size hole he wanted to produce threads in? He may have been wanting to make an internal hole inside a telescope eyepiece mount, or to get higher quality centricity and alignment and fit in a muzzle break. There are special taps for sizes other than 1/4-20 or 1/2-20, but they are more expensive.
By the time you have succeeded, and I have no doubt that you will,
you will have revisited the question of why you didn't use a tap.
