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Plug and Ring Gages

horst007

Plastic
Joined
May 2, 2017
My employer recently purchased a cabinet full of plug and ring gages for various threads at auction. What I am finding is a lot of them simply have a N designation after the thread size. I have found this to point to them being quiet old. What I am curious about is if the are still usable for a UN thread? What I gathered from the ansi standard that I read about is it was updated in 1949 for the standard to be changed from n to un. It has been updated since as well. The only difference I have found is that the pitch diameter was changed ever so slightly at around .0001"-.0002". What I haven't been able to deduce is if the gages are usable or obsolete? :confused:image1 (11).jpg
 
Were any of the plug gages that came with this lot "Set Plugs" for the ring gages? If so, you should be able to have the set plugs evaluated / calibrated, and if they meet the current Unified standard, you should be able to re-identify them appropriately, and use them as standards for your ring gages.
 
Usable? Depends I suppose on what you'd be using them on.

What I would suggest is that the first time you make a thread where you know you can use one (Go + NoGo of each?) then have it/them calibrated. If calibration says it's OK then that'd certainly be cheaper than buying new.

The thread pitch diameter tolerance for the thread ring gage shown (4.250 - 12) is max 4.1939 and min 4.1874 if you have both the Go and NoGo. As both the Go and NoGo gages have tolerances there is IMO no way you can calibrate yourself.
 
you can consider buy again from gaugestools,all thread gauges are brand new, the UN thread gages are produced using latest standard. and their thread gages are cheap, if you buy many items in one time, they also can give you a big discount.
 








 
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