Minor diameter of threaded ring gage

[Stiofan63]

I received a new gage in and noticed the cert said it had to be adjusted into tolerance. While looking into that I found that they state the PD was increased by 0.00090" while the Minor was decreased by 0.00090" This calibration house previously would not list the tolerance for the minor on the cert and began doing so upon our request as a note saying: "MINOR DIAMETER reported as is. ASME B1.2 tolerance is .0007 in." (tolerance is for this gage, a 1-8 UNC 2A threaded ring gage).

My question is: Is the minor size tolerance critical or required to be accurate? This lab is listed as A2LA accredited and we require that they conform to ISO 17025. These gages are being used on industrial grade fasteners.

<edit> Just found a thread that answered my question. Apparently on nogo ring gages the minor is not testing anything so is not critical.

The thread is listed below but I can not post links yet, it could be a Hormel meat product.

 

[DietCokeofEvil]

OK I have some problems with this.

1. I have been calibrating thread rings for 20+ years and I can count the number of times a P.D. is increased and a minor decreases at the same time on one hand.

2. How can they tell the gage increased 0.0009 on the P.D.? If they are using a setting plug (and if they don't have a 1-8 2A set plug, shame on them.), you can't measure growth or shrinkage at all. Using a setting plug is strictly feel- and is non-quantifiable.

3. The NoGo minor is non-functioning, for the most part. Like any ring, if it gets adjusted too many times, the minor will collapse which could give you a false reject. That being said, I wouldn't be alarmed at 0.0009 undersized on a NoGo, but you may want to run it past engineering just to be sure.