Tap Drill Size Chart

1-27/64 in Drill Size

fractional drill

1-27/64″ 1.4219 in 36.12 mm

A 1-27/64 in drill is the standard tap drill for 1-1/2-12.

What a 1-27/64 in drill taps

Every thread this drill cuts between 50% and 85% of thread, deepest first. Outside that band it is the wrong drill for the job, so nothing below that line is listed.

Threads a 1-27/64 in drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread % thread Chart drill Chart %
1-1/2-12 chart drill 72.1% 1-27/64″ 72.1%
M39 x 4 55.5% 35 mm 77.0%

Other jobs for a 1-27/64 in

Form-tap hole
The published roll-tap hole for 1-1/2-6. A form tap displaces metal instead of cutting it, so it needs this larger hole.

Drills either side

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1-27/64 in drill: common questions

What size is a 1-27/64 in drill?
1.4219 inches, which is 36.12 mm. It is a fractional drill.
What can I tap with a 1-27/64 in drill?
2 threads: 1-1/2-12 at 72.1%, M39 x 4 at 55.5%.
Is a 1-27/64 in drill the standard tap drill for anything?
Yes, for 1-1/2-12 (72.1% thread). That is the size published tap and drill charts give.
What drill is next to a 1-27/64 in?
Down: 36 mm at 1.4173 in. Up: 1-17/32 in at 1.5312 in.