What would be the id of a hole drilled with a 45/64 drill and tapped with a 1/2-14 straight pipe tap? What would be the OD of a 1/2-14 straight pipe tap?

 

Is there any reason why you can't just measure
this?

 

The tap is hard to find, costs around $50 and I would like to understand if it will be the right one so I don't throw away $50.

 

Major Diameter OD (Max/Min) = .823/.813
Minor Diameter ID (Max/Min) = .777/.772

FYI: Recommended Pilot is 47/64"

 

Just go to a machine shop or autorepair shop
and see if they'll let you borrow theirs. They'll
probably charge you nothing, as long as you don't break it.

 

Responding to Jay's Thu, Nov 19, 2:04 pm, query:

If pipe thread is per USA ASA standard, then tap-drill size for a 1/2 inch nominal pipe size, having 14 threads per inch, is:

a) 11/16 inch for tapered thread.

b) 23/32 inch for straight-thread.

Ref is "Standard Handbook for Mechanical Engineers"

Author: Baumeister & Marks.
Publisher: McGraw-Hill.
Library of Congress Catalog Card No. 16-12915.

Regards,
Phil Corso, PE
(Boca Raton, FL)
{Tal-2(AT)webtv.net]

 

Not sure if this is what you want... But according to a table in one reference book I have:

Nominal Pipe Size: 1/2"
Threads per inch: 14
Major Diameter: .8356"
Minor Diameter: .7213
Pitch Diameter: .7784
Tap Drill for Full Thread: 23/32"

Mike Adkins
Electro Mechanical Systems, Inc.