uuu
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Post by uuu on Jun 7, 2020 15:37:47 GMT
Would anyone have a recommendation for a tapping drill size for a 9/16" x 40tpi thread into cast iron please? Or a calculator program where I can derive the figure?
Wilf
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timb
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Post by timb on Jun 7, 2020 15:42:17 GMT
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Post by springcrocus on Jun 7, 2020 15:47:32 GMT
Wilf, all 40 tpi threads are drilled 1/32" below nominal O/D, therefore 17/32" diameter.
Regards, Steve
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uuu
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Post by uuu on Jun 7, 2020 15:51:47 GMT
Yes, that helps - thank you.
Wilf
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Post by springcrocus on Jun 7, 2020 15:53:29 GMT
Actually, there is a reasonably easy rule-of-thumb that can be applied to ME threads. Just two numbers to remember.
For 32 tpi, drill 40 thou smaller, for 40 tpi drill 32 thou smaller. Useful to remember when the Zeus book is hiding itself.
Regards, Steve
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uuu
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Post by uuu on Jun 7, 2020 16:00:01 GMT
Most threads I can just look up. This one's a bit of an oddball, but I just happened to have taps and dies, so thought I'd use them. I think I screwcut the threads I had first bought them for.
Thanks all
Wilf
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