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: Tap Drill Size???

Fullreversal
03-10-2002, 06:41 AM
Ive got some people telling me 27/64's and some others telling me 29/64's for a 1/2" tap drill. What is it? Or are they both right?
Old Scout
03-10-2002, 06:48 AM
NF or NC?


http://www.americanfastener.com/techref/tapdrill.htm

http://www.widell.com/drillsiz.html
AIRZUKI
03-10-2002, 01:15 PM
1/2" UNC ( coarse ) ............ 27/64....... .4219"



1/2" UNF ( fine )................... 29/64 ......... .4531"



these numbers will get you aprox. 75% thread form