What size tapping drill

[Eric CoxParticipant @ericcox50497]

What is the tapping size for ME thread 1/2" x 32 tpi.

[Eric CoxParticipant @ericcox50497]

[Alain FagetParticipant @alainfaget92863]

Eric

Drill 12mm for this 1/2 32 tpi

Alain

[NJHParticipant @njh]

Harold's Metalwork Data Book and Tubal Cain's Model Engineer's Handbook both show 12mm

N

[Eric CoxParticipant @ericcox50497]

Cheers, I saw it as 12mm in Harold's Metalwork Data Book but thought 12mm was a bit big for a 1/2" thread.

[_Paul_Participant @_paul_]

It might seem big but 32TPI is quite a shallow thread.

Paul

[Robert DoddsParticipant @robertdodds43397]

Eric,

Just be sure your 12mm drill doesn't cut oversize!

Bob D

[Russell EberhardtParticipant @russelleberhardt48058]

Just be sure your 12mm drill doesn't cut oversize!

Start with a small drill and open up in stages to 11 mm before finishing with your 12 mm drill. The hole diameter will be accurate enough then.

Russell.

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