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Clarification of threaded ring gage calibration procedure/requirements

Steve-S63

Starting to get Involved
#1
Here we go again. :deadhorse:

I'm hoping to find some clarification concerning procedures & requirements for threaded ring gage calibration. I've asked some of the labs we do business with to explain their calibration procedures in regards to damage and wear on threaded ring gages. The one that responded mentioned only the IFI method for determining excessive wear of the flanks, consistency of drag on truncated and full threads, and stated nothing concerning damage or tapered wear. I've read IFI-301 2008 (R2013) 15.1, concerning threaded ring gage calibration, and personally feel it's rather incomplete. I'm of the opinion that if the gage is damaged such that it must be opened more to allow the damage to clear the set plug and allow the gage to go onto the set plug then the flanks of the ring gage are no longer in contact with the set plug, only the highest point of damage is. If set to the highest point of damage then the ring is not providing a verification of a series of threads but only a point check of pseudo random points, based on the location of the damage on the ring. This can still provide consistent drag on truncated and full threads if the damage is far enough out on the flank of the ring gage and as such will not be discovered by the method described in IFI-301 15.1. Damage of this nature and tapered wear are, in my limited experience, only detectible in how the drag feels when threading the ring gage on and off the set plug. I was taught that the amount of drag should not increase noticeably after the 1st 1 1/2 to 2 turns onto the set plug and that damage can cause and abrupt increase in drag or a complete stop. Some lesser damage will give a 'dirty' feel as if there is debris involved. I've found nothing in IFI-301 that addresses this and a such seem to have no grounds to stand on when trying to reject damaged and excessively worn threaded ring gages. What are y'alls thoughts on the issue of detecting and verifying damage, taper or wear and IFI-301?

<Edit>
Forgot to ask: Am I off base or on base as to detection of damage and or wear? Am I overcomplicating or oversimplifying?
 
Last edited:

leftoverture

Involved In Discussions
#2
Well, I am no expert in threaded ring gages by any means, but I agree with you that if there is damage such that the ring gage must be opened up to accommodate the high points, that seems unacceptable. Wouldn't you visually inspect for such damage prior to using the set plug and reject the gage if damage is present?
 

Steve-S63

Starting to get Involved
#3
Not all damage is visible. Nor is visually checking each gage viable under the circumstances as they exist here. All I have to perform the visual check with is a plastic x7 eye loupe. This does ok on the larger gages, on the smaller ones it's use is very limited.
 
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