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Hole size rule of thumb for taping 1/2" UNF ?
PHULL - 31/7/06 at 08:38 AM

Gday

Could someone help me with what size hole I should drill first and tap a 1/2" UNF thread.

If there is a rule of thumb to what size hole you should drill?

Thanks

MikeRJ - 31/7/06 at 08:47 AM

Get yourself a "Zeus" book, it's cheap an invaluable for this type of information.

For a 1/2" UNF thread, a drill size of 29/64" is required, which is almost exactly 11.5mm.

mitch2b - 31/7/06 at 08:49 AM

this should help

http://www.coastalfasteners.co.nz/tapping_size.htm

Mitch

nick205 - 31/7/06 at 08:50 AM

yup the man from Zeus he say 11.40mm drill size for 1/2" UNF.

Local tool or nut/bolt factors should be able to furnish you with a Zeus data book - a worthy addition to any tool box

PHULL - 31/7/06 at 08:54 AM

Fantastic

thats for your help

Confused but excited. - 31/7/06 at 06:25 PM

quote:
Originally posted by MikeRJ
almost exactly 11.5mm.


Yep, that's close enough.

Peteff - 1/8/06 at 12:12 PM

If your thumb fits in it's too big

rusty nuts - 1/8/06 at 05:12 PM

If you haven't got any information to hand a usefull tip is to find a nut for the thread you need to cut and use the bigest drill bit that will go through nut.