Joe Miranda
Titanium
- Joined
- Oct 19, 2004
- Location
- Elyria Ohio
I tried this question in the general forum and got no where. Can any of you guys tell me how to mathematically calculate the bginning diameter when programming a pipe thread. My current method is to go over to the tap drawer and pull out whatever size pipe thread I am cutting and measure the tap. Then I program those numbers in and tweak the "x" offset until I get it to gage depth. Not very scientific I admit - but it works. But there must be a formula to calculate this. I have read the Machinery Handbook on this and it is very good about giving the pitch diameter and how to arrive at minimum and maximum thread truncation for NPT's but try as I might I have never been able to knead and massage that formula sufficiently to come up with a number that is any where near what the tap actually measures. So I end up going back and measuring the tap and cutting the threads as such. Your help would be appreciated. Please don't give me the names of books - I am looking for the working formula. If you have worked it and are inclined to pass it on then I would be most appreciative. If you find a formula and have never worked it and don't know how to work it then please refrain from responding - I have already received plenty of those.
Joe
Joe