KEVOS® MAKEOS · Manufacturing
Countersink Depth and Breakthrough
How deep is this countersink, and will it reach the opposite face?
Resolve axial cone depth from pilot diameter, mouth diameter and included angle, then compare it with material thickness.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Pilot-hole diameter | mm | Finished cylindrical pilot-hole diameter. |
| Countersink mouth diameter | mm | Required diameter at the entry face; at least the pilot diameter. |
| Included cone angle | ° | Full included cone angle, verified from the tool and drawing. |
| Material thickness | mm | Axial thickness from the entry face to the opposite face. |
Method and formulas
- h = (mouth − pilot)/[2 tan(included angle/2)]. Remaining thickness = thickness − h.
- Mouth diameter at just-through depth = pilot + 2 × thickness × tan(angle/2).
- Example: 6 mm pilot, 12 mm mouth and 90° included angle gives 3 mm depth, leaving 2 mm in 5 mm material.
Limitations
- Ideal coaxial cone and cylindrical pilot; burrs, runout and tolerances are excluded.
- Zero or negative remaining thickness is reported as breakthrough. Positive remaining material is not proof of adequate strength.
- This is geometry, not a fastener-seat standard or a counterbore calculator.
- Default values are worked examples, not recommended settings or material properties.
Typical uses
- countersink geometry
- remaining wall
- breakthrough
Who it is for
- Machinists
- Design engineers
What you get
- Axial depth
- Remaining axial thickness
- Mouth diameter at just-through depth
Interpreting the result
- Confirm the drawing uses the included angle.
- Verify a trial part and assess the minimum-thickness tolerance condition.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 852–853. Topic reference; implementation and examples are original, and no source tables are reproduced.
- Method: right-triangle geometry of the cone half-angle.
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