27/64 in Drill Size
fractional drill
27/64″ 0.4219 in 10.72 mm
A 27/64 in drill is the standard tap drill for 1/2-13.
What a 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.
| Thread | % thread | Chart drill | Chart % |
|---|---|---|---|
| M12 x 1.25 | 79.1% | 10.8 mm | 73.9% |
| 1/2-13 chart drill | 78.2% | 27/64″ | 78.2% |
| M12 x 1.5 | 65.9% | 10.5 mm | 77.0% |
| M12 x 1.75 | 56.5% | 10.2 mm | 79.2% |
Other jobs for a 27/64 in
- Form-tap hole
- The published roll-tap hole for 7/16-28. A form tap displaces metal instead of cutting it, so it needs this larger hole.
- Clearance hole
- The through hole a bolt passes in, not a tapped hole: loose fit for 3/8-16, loose fit for 3/8-24, loose fit for 3/8-32. See the clearance hole chart.
Drills either side
27/64 in drill: common questions
What size is a 27/64 in drill?
0.4219 inches, which is 10.72 mm. It is a fractional drill.
What can I tap with a 27/64 in drill?
4 threads: M12 x 1.25 at 79.1%, 1/2-13 at 78.2%, M12 x 1.5 at 65.9%, M12 x 1.75 at 56.5%.
Is a 27/64 in drill the standard tap drill for anything?
Yes, for 1/2-13 (78.2% thread). That is the size published tap and drill charts give.
Is a 27/64 in drill used for clearance holes?
Yes: loose fit for 3/8-16, loose fit for 3/8-24, loose fit for 3/8-32. A clearance hole is not tapped; the bolt passes through it.
What drill is next to a 27/64 in?
Down: 10.7 mm at 0.4213 in. Up: 10.8 mm at 0.4252 in.