UNC · cutting tap · nominal dimensions
#1-64 UNC
tap drill size.
For #1-64 UNC, the reference drill is #53: 0.0595 in (1.511 mm).
The reference value is kept separate from the 70% and 75% calculated targets. Actual fit still depends on thread class, tool, material, runout, and the hole you really make.
Detail A · basic 60° profile
What the percentage describes.
“Theoretical full thread %” is radial thread height from nominal geometry. It is not axial engagement length and not a fit-class acceptance measurement.
Real drill alternatives
Neighboring sizes.
These are diameter neighbors, not silent recommendations. A positive delta makes a larger hole and a lower nominal theoretical percentage; a negative delta does the opposite.
| Bit | System | Diameter | Delta | Calculated full thread |
|---|---|---|---|---|
| 1.5 mm | metric | 0.0591 in / 1.5 mm | -0.0004 in | 68.7% |
| 1/16 | fractional | 1/16 in / 1.587 mm | +0.0030 in | 51.7% |
| 1.6 mm | metric | 0.0630 in / 1.6 mm | +0.0035 in | 49.3% |
| #52 | number | 0.0635 in / 1.613 mm | +0.0040 in | 46.8% |
| 1.4 mm | metric | 0.0551 in / 1.4 mm | -0.0044 in | 88.1% |
| #54 | number | 0.0550 in / 1.397 mm | -0.0045 in | 88.7% |
Why 3D is useful here
A thread is a helix, not a row of triangles.
Load a draggable cutaway to see the continuous internal thread. Exact diameter and profile comparisons remain in the 2D drawing above.
Evidence and limits
Why this row says cross-checked.
Tap-drill row: Rows tagged with this source were matched to a named 65% or 75% cutting-tap column. The discrete drill can calculate to a slightly different percentage from nominal dimensions.
60° geometry: Public primary reference for Unified and metric 60-degree thread geometry. The percentage-thread equation is a theoretical basic-profile calculation, not a fit or torque guarantee.
Open National Institute of Standards and Technology geometry source
The repository also records 11 source records and a dataset version on every page.