53/64 in Drill Size

fractional drill

53/64″ 0.8281 in 21.03 mm

A 53/64 in drill is the standard tap drill for 7/8-20.

What a 53/64 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 53/64 in drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M24 x 3	76.1%	21 mm	77.0%
7/8-20 chart drill	72.2%	53/64″	72.2%
7/8-14	50.5%	13/16″	67.4%

Other jobs for a 53/64 in

Form-tap hole: The published roll-tap hole for 7/8-9. A form tap displaces metal instead of cutting it, so it needs this larger hole.

Drills either side

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53/64 in drill: common questions

What size is a 53/64 in drill?

0.8281 inches, which is 21.03 mm. It is a fractional drill.

What can I tap with a 53/64 in drill?

3 threads: M24 x 3 at 76.1%, 7/8-20 at 72.2%, 7/8-14 at 50.5%.

Is a 53/64 in drill the standard tap drill for anything?

Yes, for 7/8-20 (72.2% thread). That is the size published tap and drill charts give.

What drill is next to a 53/64 in?

Down: 21 mm at 0.8268 in. Up: 55/64 in at 0.8594 in.