#1-64 UNC Thread
Recommended tap drill #53
Tap drill Ø 0.0595″ / 1.511 mm
Major Ø 0.0730″ / 1.854 mm
Threads per inch 64
The chart recommendation gives approximately 66.5% thread engagement — the conventional target for average materials. It is not the only valid choice; see the options below.
Specification
| Designation | #1-64 UNC |
|---|---|
| Thread family | Unified National Coarse (UNC) |
| Nominal size | #1 |
| Basic major diameter | 0.0730″ / 1.854 mm |
| Threads per inch / pitch | 64 TPI (0.397 mm pitch) |
| Recommended tap drill | #53 (0.0595″ / 1.511 mm) |
Tap drill options by thread engagement
Any of these standard drills produces a usable engagement for #1-64 UNC; smaller drills give stronger threads but higher tapping torque. Percentages use the conventional approximation (60° thread form).
| Drill | Decimal in | mm | Approx. engagement |
|---|---|---|---|
| 1.5 mm | 0.0591 | 1.5 | 68.7% |
| #53 — chart recommendation | 0.0595 | 1.511 | 66.5% |
Nearest drills to the tap drill in other systems
| Drill | Size | vs #53 | Resulting engagement |
|---|---|---|---|
| 1.5 mm | 0.0591″ / 1.5 mm | −0.011 mm | 68.7% |
| 1/16″ | 0.0625″ / 1.587 mm | +0.076 mm | 51.7% |
Clearance holes
For a bolt or screw of this size to pass through freely. Recommended drills per ASME B18.2.8: close, normal, and loose fits.
Related threads
- #1-72 UNF — same nominal size, 72 TPI (Unified National Fine (UNF)) · compare
- #2-56 UNC — next size up in UNC