I have some buggered threads on some ring mounts. I want to chase through and clean them up with a tap. Called a forum sponsor and they claimed there are many different sizes used for that. They all seem the same to me. Nevertheless, I'd like to order taps for the most common size allen head screw they use. I plan to order some taps to cover any failure so knowing the tap sizes to order will help a lot. Thanks.
Tap size for tiny black screws on Scope rings.
- Thread starter Jim81
- Start date
you can get a basic 5 or so tap set for cheap on ebay that will be fine for small jobs .. make sure it has m3 m4 and m5 and you should be covered ...
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It might help if you specify the ring maker to know if they are SAE or Metric. You might try bringing the screws to a fastener store or buy a thread doctor to ID the threads.
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nice to know exactly what you got, but most cheap aluminum chinese rings you get for 15-20 bucks on amazon will be m4 so its a good bet .. m4 .7 pitch is standard asian ring screw size lol ... if a screw hole is wollard out though doubt chasing will fix it ... you could probably drill it and grind the bottom flat with a dremel and add nuts but hey, is 15 bucks worth all that, naw, maybe the 5 pc tap set w/matching drill bits for 10 bucks on ebay ... that could come in handy for alot of stuff ..
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There’s plenty of drill tap charts available online.
If you measure the OD of the bolt, 95% metric bolts will be slightly undersized like 4.9mm for a 5mm bolt.
You then take the thread pitch gauge and confirm the pitch matches for m5 bolt.
If it doesn’t that u needs to find the pitch for closed sae thread pitch and confirm that.
If u have a tap kit, u can also use the taps for pitch gauges. Laying the tap and the bolt side by see, seeing if the pitch meshes properly
If you measure the OD of the bolt, 95% metric bolts will be slightly undersized like 4.9mm for a 5mm bolt.
You then take the thread pitch gauge and confirm the pitch matches for m5 bolt.
If it doesn’t that u needs to find the pitch for closed sae thread pitch and confirm that.
If u have a tap kit, u can also use the taps for pitch gauges. Laying the tap and the bolt side by see, seeing if the pitch meshes properly
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Or one could cheap out and bump them ALL up a size, generally don't even have to drill it out if it's aluminum, just be careful. Of course the thru holes would have to be drilled larger. OR.....if they are cheap, buy new ones but that's no fun.
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Thanks. I did take your advice and ordered a cheap set of the bay. I think there were f different taps and dies. The quality isn't probably that high but with the little I have to do they will be fine. Thanks again!
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If you have a set of nuts and bolts sorted by thread types, that helps you identify the thread.
You can also buy quick little "thread testers". Things like this: https://www.amazon.ca/Bolt-Thread-Checker-Inch-Metric/dp/B003FJW0GK
That's a bit overkill, but it'll also work. You could probably go to an automotive or fastener shop and get a set for cheaper than the test kit.
I find measuring thread gauge and pitch a little tedious, that's why I rely on the crutches.
You can also buy quick little "thread testers". Things like this: https://www.amazon.ca/Bolt-Thread-Checker-Inch-Metric/dp/B003FJW0GK
That's a bit overkill, but it'll also work. You could probably go to an automotive or fastener shop and get a set for cheaper than the test kit.
I find measuring thread gauge and pitch a little tedious, that's why I rely on the crutches.
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