Go/No Go Out of Tolerance

CaliperJim

Involved In Discussions
Hi, everyone. A threaded ring gauge was found out of tolerance by an external provider. It was 0.00105 over the max. I'm not sure how to determine if this constitutes a significant out of tolerance condition. It's a Go/No Go gauge; it doesn't provide a measurement. Any assistance is greatly appreciated. Take care.
 

optomist1

A Sea of Statistics
Super Moderator
Hi Caliper Jim, first what are the gages being used to measure in this case go/no go, pls share details drawing or dimensions/features the gages are used on...
 

Enghabashy

Quite Involved in Discussions
the out of max. limit should be relevant also for grade of fitting ; Grade H may different of Grade G,
**the wear is done in Go rather than no go ' because it's mostly used for its all threads rather than No go which 1st or 2nd threads could be used for fitting with workpiece
 

CaliperJim

Involved In Discussions
Hi Caliper Jim, first what are the gages being used to measure in this case go/no go, pls share details drawing or dimensions/features the gages are used on...
2.5-12-UN-3A thread ring gauge.
Part thread detail: 2.5-12UN-2A, major diameter 2.4867 - 2.4981, pitch diameter 2.4378 - 2.4440, minor diameter reference 2.3959.
Calibration data: go pitch diameter test tolerance 2.4455 - 2.44590 with actual of 2.44695, no go pitch diameter test tolerance 2.4413 - 2.4417 with actual of 2.44228.

Thank you
 

DietCokeofEvil

Trusted Information Resource
How did the lab determine how far over it was? There is no reliable way to measure the PD on an adjustable thread ring. There are methods of measurement, but none of them are very accurate.
 

Ron Rompen

Trusted Information Resource
Is this a 'new' gauge that you have just purchased? I am assuming that since you have sent it out for calibration that it isn't.

Assuming that the gauge was in calibration on previous occasions, it is counter-intuitive to me that the GO member would now be oversize......I would accept that it was UNDERsize, as it is subject to wear, but I can't envision (not an expert on thread geometry) a circumstance that would cause the pitch diameter to grow.
Is this the same lab you have used previously? And what instrument(s) are they using to measure an oversize condition of 0.00105"?
 

Miner

Forum Moderator
Leader
Admin
Assuming that the gauge was in calibration on previous occasions, it is counter-intuitive to me that the GO member would now be oversize......I would accept that it was UNDERsize, as it is subject to wear, but I can't envision (not an expert on thread geometry) a circumstance that would cause the pitch diameter to grow.
This is a ring thread gage, not a plug thread gage, so it will grow with wear.
 

gakiss2

Involved In Discussions
Sounds crazy but its happened to me. Calibrator didn't soak temperature of gage before measurement?
 

Ron Rompen

Trusted Information Resource
This is a ring thread gage, not a plug thread gage, so it will grow with wear.
Not sure how I missed that Miner, but yes I agree - a ring thread gage will grow with wear.

My other questions still stand though. Is this a 'new' lab that you are using? And what method are they using to measure the pitch diameter?
 
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