Thread Ring Gage Help

[Mintle]

I need a bit of quality insight to help me with a dilemma I am currently having. We had to purchase some used thread ring gages to get us by while we wait for our new gages to be manufactured. We were provided the results and here is what we have:

No Go: Pitch diameter is .0038" smaller than the allowable minimum (Min: .9355" vs Actual Measure 0.93177"). This would mean that I can potentially "fail" a part that is technically good as I have shrunk my low end tolerance, correct?

Go: Pitch Diameter is 0.0098" smaller than allowable minimum (Min: 0.9433" vs Actual Measure 0.93362"). This would mean that I can potentially fail parts that are also good, correct?

Wrap Up: By using these gages in the interim we will have essentially shrunk our tolerance band significantly, thus holding our parts to a much tighter tolerance than needed. Is this correct?

Here are my thread specs of the part: 1-6 Stub Acme Thread
Major Dia: 1.000-0.9917
Pitch Dia: 0.9420-0.9238
Minor Dia: 0.8800 - 8618

 

[MintJulep]

To be fully robust your assessment should consider the temperature of the gages at the time of your measurements vs. the temperature at the time of use, and the temperature of the parts being measured.

If everything is "about room temperature", then that will change things out in the 6th decimal point - probably negligible.

Other than that, your assessment seems correct.

 

[Tmoose]

Are those used gauges split and have an adjusting screw?

https://cdn.mscdirect.com/global/images/ProductImages/4655378AA-24.jpg

The instructions that come with that style usually say that the brand new gauge must be set initially using a plug gauge.