3 replies to this topic

[johnv]

What diameter steel rod would I need to cut a 1/4 unf thread on? I can’t make sense of the charts you get from google!

[GraemeC]

Rule of thumb is a fraction (around 5 thou) under the nominal size, so 0.245"

If that's a bit too tight for the die, then reduce it down slightly.

 

You're unlikley to buy steel stock that is correct 'off the shelf' and would need to reduce it down in a lathe

Edited by GraemeC, 20 February 2021 - 04:20 PM.

[nicklouse]

Just buy a longer bolt than you need.

[Spider]

While Graeme's advice is correct, I just about always cut 95% of my OD threads on stock that's on size, so for 1/4", I'll cut that on 0.250" dia stock. Good quality Die Nuts will not only cut the Thread, but also the OD too. You'll find that most Nuts are a few thou over size.

The differences here are not always for technical fit but just as allowances for production and also for plating (if finished that way).