Can the "no go" on your thread gage go in just a little?

[Dave K]

I've heard many theories on this, and now I've got a situation on my hands that requires me to know the right answer. The thread is an 8-32 class 2 thread. Customer says the threads are "wrong", and the parts are back in my shop. This is in a blind hole. He sent his gage along with the parts, and his gage looks as if it's been through a war zone.

So, I check it with his gage, and the no go goes all the way into the hole. That I know would be bad. But when I check it with my gage that is less than a year old, my no go will enter about 1 turn, then locks up.

Is that thread oversize, or is it ok? It's my customers customer, so I don't get to ask the end user anything, and MY customer admittedly knows nothing about threads. It's his job, we just did the machining on it, and he did the grinding of the O.D. I'm just wondering what the correct rule is on a no go thread gage. I've heard many times you are allowed up to 2 turns on the no go, but to me, that doesn't make sense. It's a no go, there for it should not go at all. What's right?

 

[SeymourDumore]

Would this help: No Go Thread Ring Gages Per ANSI/ASME B1.2-1983




I hate this freakin new junk here where the link cannot be highlighted!!!

 

[metalmaster10]

As posted by Seymour, 3 turns unless noted otherwise. I used to make a bunch of parts that only had 5 threads, so we were allowed only 2 turns MAX.
In your case it sounds like a gage calibration issue.... Someone has a bad gage. That is where I would start.

 

[metalmaster10]

I hate this freakin new junk here where the link cannot be highlighted!!![/QUOTE]

Or the pics can't be scrolled through with the post open, or the posts don't refresh, or the "home" tab logs you out, or the posts show the wrong post time on the home tab....
Any of those things bug you too? Cause they really suck!
Sorry Millacron, I'm sure you didn't do the work, but I really think someone dropped the ball.

 

[Dave K]

Would this help: No Go Thread Ring Gages Per ANSI/ASME B1.2-1983




I hate this freakin new junk here where the link cannot be highlighted!!!

Yes, that did help. I'm looking for answers myself also, and finding that 3 turns is acceptable as a standard. It's not where I would like to run the parts myself, but it appears to be acceptable.

 

[fastone53w]

They can wear and go bad. If his is all beat up and no calibration sticker on it. I would assume his is worn out or damaged. We always used max of 2 and half turns in on no go end, but most of are threading jobs they don't even go a full turn and get tight. Are thread gauges are calibrated once a year and they do wear out.

We have had it the other way around, where go end was damaged and would not go in. We changed drills and taps chased problem around until we tried a back up no/go gauge and it went in perfect. Looked at bad gauge under magnification and first thread was smashed and rolled over.

 

[dstryr]

2 turns. Drop ship him a gage.

 

[Dave K]

2 turns. Drop ship him a gage.

Thanks, this seems to be the consensus.

 

[in2glamisgirl]

Thread plug gauge

On internal threads we allow 3 turns of the no-go (Boeing policy per fed std H28)
Go side must pass with thumb and forefinger.

If the working gauge rejects the part a master gauge is used for referee.
In case you did not know working gauges are made near the limits to allow for longer service life. They will also reject good parts near the tolerance limits.
Master gauges are made on size and should not be used in production due to very limited wear tolerance.

If you have some thread wires check the customers gauge it might be N.F.G.

 

[dstryr]

Thanks, this seems to be the consensus.

In the past I'd go back and forth with the customer. Now a days its cheaper (and easier to deal with) to just send them the parts with a brand new calibrated gage.

I've had customers reject parts by .0001 or .0002. Drop ship them 2 deltronic pins and all of a sudden the parts must have changed overnight because they are no longer rejected.....
HMMMMM

 

[Larry Dickman]

The no go gage may go in up to 3 turns. (that's not my opinion, that's the spec)

Shops with old wore out thread gages are a dime a dozen. Try checking it with thread wires, take a picture of you measuring their fucked up gage, and sent it back with the parts.

 

[in2glamisgirl]

In the past I'd go back and forth with the customer. Now a days its cheaper (and easier to deal with) to just send them the parts with a brand new calibrated gage.

I've had customers reject parts by .0001 or .0002. Drop ship them 2 deltronic pins and all of a sudden the parts must have changed overnight because they are no longer rejected.....
HMMMMM

The untrained Q.A. guys I deal with don't understand gauging allowance with Deltronic pins and would
probably get them stuck in the hole anyway.

 

[dkmc]

2 turns. Drop ship him a gage.

Yes.

1. Drop ship him a gage
2. Send the parts back
3. BILL HIM for the parts+ new gage.

 

[Ox]

Would this help:No Go Thread Ring Gages Per ANSI/ASME B1.2-1983




I hate this freakin new junk here where the link cannot be highlighted!!!

Whad'yah mean you can't highlight it?


-----------------

Think Snow Eh!
Ox

 

[SeymourDumore]

Whad'yah mean you can't highlight it?


-----------------

Think Snow Eh!
Ox

I mean it was s'posed to look like yours above.
Red and bold!

And it ain't got there when I posted the dammned thing.

 

[rnmmhunter]

Pitch mic the thread gauge and see if it is undersize.

 

[Dave K]

Pitch mic the thread gauge and see if it is undersize.

Good idea. I did, and theirs is .0015 under mine. How do you actually wear out the no go? It really should rarely be getting screwed into anything, I would think?

 

[Mark Rand]

Good idea. I did, and theirs is .0015 under mine. How do you actually wear out the no go? It really should rarely be getting screwed into anything, I would think?

If they're using it on every threaded hole of that size they buy in, it could be a lot of wear. Might be nice to politely ask them what their calibration scheme is for their standards.

 

[SeymourDumore]

I can see a Go member wearing out due to too much use, but man, you need to make a whol' lotta f@cked up threads to wear out
a no-go.

 

[Dave K]

I can see a Go member wearing out due to too much use, but man, you need to make a whol' lotta f@cked up threads to wear out
a no-go.

Exactly! That was my point, this isn't he go, it's the no go. And this thing is worn all the way down the full length of the gage. There are parts here where his no go will bury it'self into the part, and my no go will go in 1-2 turns then lock up.

Mark-- I have no access to the end user. This is my customers customer.