Tap Drill Size Chart

#33 Drill Size

number drill

#33 0.113 in 2.87 mm

A #33 drill is the standard tap drill for #6-40.

What a #33 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 #33 drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread % thread Chart drill Chart %
M3.5 x 0.6 80.8% 2.9 mm 77.0%
#6-40 chart drill 77.0% #33 77.0%
#6-32 61.6% #36 77.6%

Other jobs for a #33

Hard-material tap drill
The size to use in stainless or tool steel for #6-32, where it leaves a shallower thread than the standard drill and cuts tapping torque.
Form-tap hole
The published roll-tap hole for #5-40. A form tap displaces metal instead of cutting it, so it needs this larger hole.

Drills either side

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#33 drill: common questions

What size is a #33 drill?
0.113 inches, which is 2.87 mm. It is a number drill.
What can I tap with a #33 drill?
3 threads: M3.5 x 0.6 at 80.8%, #6-40 at 77.0%, #6-32 at 61.6%.
Is a #33 drill the standard tap drill for anything?
Yes, for #6-40 (77.0% thread). That is the size published tap and drill charts give.
What drill is next to a #33?
Down: 2.85 mm at 0.1122 in. Up: 2.9 mm at 0.1142 in.