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.

Standard 3/4" rod...simply.


"stone" wrote in message
oups.com...
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.

stone wrote:
I want to thread a rod using a
3/4 - 16 die.

What diameter should the rod be?

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

Thanks everyone.

I measured a bolt and it was about .72 -ish
beneath the threads.

So that's why I wanted to make sure.

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

"stone" wrote in message
oups.com...
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.

Our metalwork teacher told us reassuringly, that a thread form that only
had half it's full height still had 70% full strength.

stone wrote:
Thanks everyone.

I measured a bolt and it was about .72 -ish
beneath the threads.

So that's why I wanted to make sure.

stone wrote:
Thanks everyone.

I measured a bolt and it was about .72 -ish
beneath the threads.

So that's why I wanted to make sure.

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

On 10 Oct 2005 16:19:23 -0700, "John Martin"
wrote:


stone wrote:
Thanks everyone.

I measured a bolt and it was about .72 -ish
beneath the threads.

So that's why I wanted to make sure.

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
The standard thread strengths are base on 75% full thread. Look in
Machinery's Hanbook.
ERS

"Robert Swinney" wrote in message
...
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


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

Right, Harold. He was asking about threading with a die, so I gave the best
advice under the circumstances . . . I think.

Bob Swinney
"Harold and Susan Vordos" wrote in message
...

"Robert Swinney" wrote in message
...
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


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