Drill Point Depth
Drill-tip allowance and the depth needed to reach a full-diameter hole.
Example
You enter
- Drill diameter (in) 0.5
- Point angle (deg) 118
- Desired full-diameter depth (in, optional) 1
You get
- Point length (tip allowance) 0.1502
- Drill-to (tip) depth 1.1502
Details, formula, and sources
Drill-tip allowance (point length) = (diameter / 2) / tan(point angle / 2) and the tip depth to reach a desired full-diameter depth, for 118 / 135 degree and custom drill points (first-principles drill-point geometry).
point length = (diameter / 2) / tan(point angle / 2); tip (drill-to) depth = full-diameter depth + point length; a 118-degree point is about 0.3 * diameter.
Drill-point geometry; the 118 / 135-degree drill-point relation as in Machinery's Handbook (Industrial Press), by name; first-principles trigonometry.
Pure geometry, public; web thinning, drift, and the machine depth stop govern the actual hole.
Estimate. AHJ and licensed professional govern.
Field names used by the API: diameter_in, point_angle_deg, full_depth_in, point_length_in, drill_to_depth_in
- Ideal conical point treats the point as an ideal cone; ignores web thinning and split-point geometrydrill-point geometry