#1-64 Tap Drill Size & Thread Specs
Everything for a #1-64 UNC thread on one page: tap drill (#53), clearance holes, wrench and hex key sizes, and the nearest metric thread.
SP-TD-01 · #1-64
#1-64 specs
SizePlate
#1-64 UNC · tap with
#53 drill
.0595″
1.51 mm · 67% thread
- Metric drill
- 1.5 mm · .0591
- Clearance
- #48 / #46
Thread
- Nominal size
- #1 · 1.85 mm
- Major diameter
- .0730″
- Threads per inch
- 64
- Pitch
- .0156″ · 0.397 mm
- Series
- UNC (coarse)
- UNF version
- #1-72
Drilling
- Tap drill (75%)
- #53 · .0595
- Metric substitute
- 1.5 mm · .0591
- Tap drill (≈50%)
- 1/16 · .0625
- Close fit
- #48 · .0760
- Free fit
- #46 · .0810
Nearest metric
- Thread
- M2 × 0.4
- Major diameter
- 2 mm
- Pitch
- 0.4 mm
- Tap drill
- 1.6 mm
- Interchangeable
- No
Not interchangeable means the threads look close but won't run together: forcing one into the other strips both.
Drill size by thread percentage
Larger drill, less thread, easier tapping. 75% is the usual target.
| Drill | Decimal | mm | Thread |
|---|---|---|---|
| 1.5 mm | .0591 | 1.5 | 69% |
| #53 | .0595 | 1.51 | 67% |
| 1/16 | .0625 | 1.59 | 52% |
| 1.6 mm | .0630 | 1.6 | 49% |
| #52 | .0635 | 1.61 | 47% |
Neighboring sizes
Questions
What does #1-64 mean?
A #1 nominal diameter with 64 threads per inch. It’s the coarse (UNC) thread for that size; the fine version is #1-72.
Can I use a 1.5 mm drill instead of #53?
Usually. 1.5 mm is .0591″ against .0595″ for #53, which changes the thread engagement by a few percent at most. The thread-percentage table above shows exactly how much thread each nearby drill leaves.