Using a die

I want to thread a rod using a
3/4 - 16 die.
What diameter should the rod be?
I think it's simply 3/4, but I can't
find a (web) reference saying so explicitly.
I've found plenty of tap charts though.
Thanks.
Reply to
stone
Loading thread data ...
Standard 3/4" rod...simply.
Reply to
Tom Gardner
Nominally, 3/4", just as your intuition says. However, if you want it to thread a little more easily, you might shave it down to 0.745" or so. Yes, this is "cheating" but I've done this many times on larger threads if the fit isn't gnat's ass critical. Makes everything go a lot easier.
GWE
Reply to
Grant Erwin
Thanks everyone.
I measured a bolt and it was about .72 -ish beneath the threads.
So that's why I wanted to make sure.
Reply to
stone
A general expression for the size of a rod for threading is: " Major diameter minus (.10825 / # of threads per inch)"
In the case of a 3/4 - 16 it would be: 0.750 - (.10825 / 16) = 0.7432
This would "cut" a class 3A thread, approximately. It might also result in die damage if cutting hard material such as stainless or etc. Check Machinery's Handbook for tables of allowances and max - min major diameters for classes of threads.
Bob Swinney
Reply to
Robert Swinney
Our metalwork teacher told us reassuringly, that a thread form that only had half it's full height still had 70% full strength.
st> Thanks everyone.
Reply to
Jordan
Not sure I'd use that as a guide, as many bolts today have rolled threads. That close to full diameter, though, they are probably cut.
John Martin
Reply to
John Martin
The standard thread strengths are base on 75% full thread. Look in Machinery's Hanbook. ERS
Reply to
Eric R Snow
Well, lets say it *could* yield a class three thread, but that has little to do with the major diameter. Class of fit is controlled by the pitch diameter, which, from class to class, is very close to identical, but not necessarily identical. Each of the classes can share the same major diameter, so you can't discern a class fit by that measurement. As you and I have discussed before, the critical dimensions on screw threads are always the pitch diameters, although all features must be within specs for a proper thread.
Harold
Reply to
Harold and Susan Vordos
Right, Harold. He was asking about threading with a die, so I gave the best advice under the circumstances . . . I think.
Bob Swinney
Reply to
Robert Swinney

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.