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5/8x18 tpi tap. Drill size.

Posted: Wed Apr 21, 2021 11:08 pm
by Alpha1
Am I correct in thinking a 14.5mm drill would be OK to use to tap a 5/8x18 tpi thread. And a 15mm drill would work for 5/8x24 tpi thread.

(tpi = teeth per inch)

Re: 5/8x18 tpi tap. Drill size.

Posted: Thu Apr 22, 2021 8:23 am
by Pippin89
Yes 14.5mm is correct for 5/8-18. 5/8-24 should be 14.8mm. 15mm will take you down to about 60% thread which may work for you or may not. Extra fine threads obviously don't take much to lose a lot of thread.

Re: 5/8x18 tpi tap. Drill size.

Posted: Thu Apr 22, 2021 8:43 am
by 1066
I have an easy to use app on my phone that gives all the info for metric and imperial- "machine screw drill-n-tap by JimsJump"