#0-80 tap drill size
3/64"
- Inches
- 0.0469
- Millimetres
- 1.19
- Thread
- 81%
Drill a 3/64" hole before cutting a #0-80 thread. That is the standard tap drill for about 75% thread.
#0-80 thread and hole sizes
| Thread | #0 diameter, 80 threads per inch, fine (UNF) |
|---|---|
| Major diameter | 0.0600 in 1.52 mm |
| Pitch | 0.0125 in 0.318 mm |
| Tap drill, about 75% thread | 3/64" 0.0469 in |
| Tap drill, about 50% thread | #55 0.0520 in, for stainless and other hard materials |
| Clearance hole, close fit | #52 0.0635 in |
| Clearance hole, free fit | #50 0.0700 in |
| Nearest metric bit | 1.2 mm |
Why 3/64"
A tap cuts threads into the wall of a hole, so the hole has to be smaller than the screw. For a #0-80 thread the hole that leaves exactly 75% thread is 0.0478 in. The closest standard bit is 3/64" at 0.0469 in, which leaves 81%.
More thread than that adds almost no strength and makes the tap much easier to break. In hard or tough material, go one step larger.
Tools for this job
- #0-80 tap
- 3/64" drill bit
- Tap and drill set
- Drill bit size gauge
- Thread pitch gauge
- Cutting oil for tapping
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