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Uncle Bulgaria · 22nd Mar 2023, 1:07 am

That's a very nice gauge - I have had trouble in the past with unknown nuts as it can be very difficult to identify the threads internally when small without running a die down a suitable piece of bar or finding the right 'known' screw. I think I'll have to look out for one of those...

Looking again at your earlier picture, the markings at the end of the thread do look very like those that occur when a 'quite close' thread is forced to screw up. I think it would be worth trying a 10-32. I've only got some 8-32s or 10-24s here or I'd send you one to test.

I had a long thread-based struggle last month when trying to identify a thread that wasn't quite anything. It measured very close to 5mm major diameter, and while it was just too large to be an Imperial size, the pitch was an extremely close match for 34TPI. That isn't a thread pitch that's used, but is very close to 0.75. The thread turned out to be M5x0.75, which is bizarre.

22nd Mar 2023, 1:07 am	#20
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Re: Top Hat Fixing Washers Name That's a very nice gauge - I have had trouble in the past with unknown nuts as it can be very difficult to identify the threads internally when small without running a die down a suitable piece of bar or finding the right 'known' screw. I think I'll have to look out for one of those... Looking again at your earlier picture, the markings at the end of the thread do look very like those that occur when a 'quite close' thread is forced to screw up. I think it would be worth trying a 10-32. I've only got some 8-32s or 10-24s here or I'd send you one to test. I had a long thread-based struggle last month when trying to identify a thread that wasn't quite anything. It measured very close to 5mm major diameter, and while it was just too large to be an Imperial size, the pitch was an extremely close match for 34TPI. That isn't a thread pitch that's used, but is very close to 0.75. The thread turned out to be M5x0.75, which is bizarre.