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Thread Gages

G00 Proto

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Feb 18, 2013
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I have a new internal product that has some oddball threads. I plan on cutting thread gages for in process checks. Any problem just making plugs at the bottom of tolerance and top of tolerance using wires? Then using those plugs to build ring gages?

...not exactly aerospace, so I don’t need to pick fly shit out of pepper on these threads. Just gotta make sure the two parts always screw together in production.


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We do it often for one of a kind parts where there is no mating part, or no money for a gage and it's not critical. Repairs where time is critical, you make it work. High Production where you need total interchangeability and meeting tight specs may be a different story.
 
Absolutely nothing wrong with that.

Keep the wired measurements a little on the low side to
account for any form errors. And make your rings out of
something decent if you want to keep them for some time. I've
made one time use gages out of aluminum, but they weren't meant
to last more than a couple of threads.

Also not a bad idea to have a mating part also, as a
"Hey!!! it works" gage.
 
FWIW I taught the 3 wire method for years and never questioned the numbers that are calulated from the standard formula. Turns out "M" generates the pitch diameter for the top limit of a class 3A thread. So if you want some clearance, just reduce "M" by the amount that you want.

M= D +3G-1.5155/N
 
There is nothing wrong with that. Especially if it's something for internal use. But if there is going to be a decent quantity of parts, it may be worth while to get some good gages made. I have had good luck with threadcheck.com. If nothing else they can get you pricing and lead time and you'll know if it's worth it.
 
Works fine, just make sure you have the correct dimensions. The max of a male thread is less than the min of a female thread. I have a thread software that tells all dim's of a thread and the correct size for all gages, including the plug gage for making the ring gage.
 
There is nothing wrong with that. Especially if it's something for internal use. But if there is going to be a decent quantity of parts, it may be worth while to get some good gages made. I have had good luck with threadcheck.com. If nothing else they can get you pricing and lead time and you'll know if it's worth it.

Thanks for the link. Been looking for some ACME plug and ring gauges.
 








 
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