Metric coarse · cutting tap · nominal dimensions
M6 × 1
tap drill size.
For M6 × 1, the reference drill is 5 mm: 0.1969 in (5.000 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 |
|---|---|---|---|---|
| #9 | number | 0.1960 in / 4.978 mm | -0.0009 in | 78.6% |
| #8 | number | 0.1990 in / 5.055 mm | +0.0021 in | 72.8% |
| #10 | number | 0.1935 in / 4.915 mm | -0.0034 in | 83.5% |
| 4.9 mm | metric | 0.1929 in / 4.9 mm | -0.0039 in | 84.7% |
| 5.1 mm | metric | 0.2008 in / 5.1 mm | +0.0039 in | 69.3% |
| #7 | number | 0.2010 in / 5.105 mm | +0.0041 in | 68.9% |
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.