Thread ring gage tight one way, loose flipped.

little.one.der · Oct 3, 2014

I'm cutting a 4.XXX - 4 ACME pin.
I've noticed that when the gage is spun one one way, it has a certain fit.
But if I flip the gage and spin it on, the fit is looser.

Acmes have equal thread angles, so what would cause this?

Could both the part and the gage thread profiles be off angle?

Eric M · Oct 3, 2014

It sounds like your gage has been used primarily from the same side. "Conventional wisdom" says that the ring gage should be started from the side where the writing is; the bad thing about this handed-down knowledge is that it causes the gage to wear unequally. I believe this has happened in your case.

little.one.der · Oct 3, 2014

You think that could happen to a ten year old gage?
It's probably checked ten thousand threads in its life.
Would there be any point to send it out for calibration? It's not a split gage...
Would they just confirm what we think?

Eric M · Oct 3, 2014

Yes, I think that has happened. By "split gage", I'm guessing you're referring to an AGD-style adjustable ring gage. It can't be re-set, so there's no point in sending out for calibration. After 10 years, it's probably time to get a new one.

Gordon B. Clarke · Oct 4, 2014

little.one.der said:
You think that could happen to a ten year old gage?
It's probably checked ten thousand threads in its life.
Would there be any point to send it out for calibration? It's not a split gage...
Would they just confirm what we think?

I'm wondering how many, when sending a thread gauge out for calibration, get more information than just where it is within the pitch diameter tolerance?

This shows typical thread gauge tolerances in relationship to the actual pitch diameter tolerances. See page 2-2.

http://f-m-s.dk/4.02.pdf

I'm also noticing that you wrote "I've noticed that when the gage is spun one one way, it has a certain fit. But if I flip the gage and spin it on, the fit is looser." in your OP. I'm also wondering if you have both a Go and NoGo.

This suggests to me that it is a longish thread so you might just consider using a caliper type.

"Spinning" a thread ring on for example stainless steel will really make it wear fast.

Search

Largest Manufacturing Technology Community on the Web

Search

Thread ring gage tight one way, loose flipped.

little.one.der

Cast Iron

Eric M

Cast Iron

little.one.der

Cast Iron

Eric M

Cast Iron

Gordon B. Clarke

Banned

Similar threads