HELP.....ID calculation for imperial threading

Suzuki4evr

Suzuki4evr

Registered
Registered
Can someone please give me a formula for calculating the ID of any imperial size and TPI. Most of my work is metric and for me imperial is like metric for you folks in the US.........sometimes I don't understand it. Specifically when it comes to core ID. Metric is straight forward to me,so PLEASE HELP:bang head:
 
Do you have a copy of Machinery's Handbook? There are tables for this. Otherwise they can be found online
 
I would go with the rule of thumb for tap drill diameter. Major diameter - 1/ tpi. Example, 1/4 -20, .250 - 1/20 =.250-.050 = 200". This will give you around a 75% thread. It's the same as for metric threads except substitute 1/tpi for pitch.
 
Last edited:
RJSakowski said:
I would go with the rule of thumb for tap drill diameter. Major diameter - 1/ tpi. Example, 1/4 -20, .250 - 1/20 =.250-.050 = 200". This will give you around a 75% thread. It's the same as for metric threads except substitue 1/tpi for pitch.
Click to expand...
Thanks RJ,this I can work with.
 
Ugh, I hate oddball custom threads. That calculator should do everything you need, including creating Go-Nogo gaging by turning male threads with particular over wires measurements.
 
You must log in or register to reply here.
Back
Top