Give me a little time to come up with the origin of this, I use a copy of all this info that an inspector put together, great sheet, I remember him saying it took him quite some time to get all the info because it was not readily available. I could fax you a copy right now if you want. This guy...
Hi Sandy,
I had seen your comment, when you said it looked like a fine thread. And a pitch of .200 to me doesn't look fine.So I was just running some numbers and came up with the 1/4-80, 4 start, which would have a pitch of .05, which to me would be a functional equivalent to a 1/4-20.
Funny...
There is a chart, have one and use it. It is a machine shop practice to chamfer all holes, break all edges, no burrs. 120° is hard to control, gets big in a hurry.
