Tap and Die

[albd5a]

With respect to Tap and Die: for External threads is steel, max and min, what diameter to start with, Major Diameter or Pitch Diameter for say, 1”-32 UN ? Thanks.

 

[ChazzC]

Little Machine Shop has a number of online calculators to help with this and other operations:

https://littlemachineshop.com/mobile/menu.php

Unfortunately, while it will provide a detailed spec for 1-32, it doesn’t work for 1” - 32:

However, you can follow the overall guidance of “Major Diameter minus 10% of pitch:”

1.00 - (.1 x 1/32) =0.997”

Don’t forget to chamfer the end.

 

[Lloyd-ss]

Here is one that I like that allows you to get data for any custom thread size that you want. I do a lot of oddball size threads in the ends of tubes, with matching plugs, so it is very handy.

http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

It shows every detail thread dimension including the ones you don't need. And it gives dimensions for different quality classes, also.