Metric coarse · cutting tap · nominal dimensions
M10 × 1.5
tap drill size.
For M10 × 1.5, the reference drill is 8.5 mm: 0.3346 in (8.500 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 |
|---|---|---|---|---|
| Q | letter | 0.3320 in / 8.433 mm | -0.0026 in | 80.4% |
| 8.4 mm | metric | 0.3307 in / 8.4 mm | -0.0039 in | 82.1% |
| 8.6 mm | metric | 0.3386 in / 8.6 mm | +0.0039 in | 71.8% |
| R | letter | 0.3390 in / 8.611 mm | +0.0044 in | 71.3% |
| 21/64 | fractional | 21/64 in / 8.334 mm | -0.0065 in | 85.5% |
| 8.3 mm | metric | 0.3268 in / 8.3 mm | -0.0079 in | 87.2% |
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.