KEVOS® MAKEOS · Manufacturing

Turning Cusp Height

What ideal peak-to-valley cusp follows from feed and nose radius?

Compare exact circular-nose turning cusp geometry with the small-feed approximation.

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How this tool works

Inputs, units and where to find them

InputUnitTypical source
Axial feed per revolutionmm/revActual straight-turning axial feed per revolution, not feed per minute.
Circular nose radiusmmCircular nose radius from the insert geometry, not a wiper effective width.

Method and formulas

  1. Exact h = r − √(r² − f²/4). The equivalent f²/[4(r + √(r² − f²/4))] retains precision at small feed.
  2. Approximate h = f²/(8r). Multiply millimetres by 1000 for micrometres.
  3. Example: f = 0.2 mm/rev and r = 0.8 mm gives exact cusp 6.274607 µm; the approximation gives 6.25 µm.

Limitations

  • Peak-to-valley geometry is not measured Ra or Rz; no surface-parameter conversion is made.
  • Wiper geometry, chatter, wear, built-up edge and material recovery can dominate finish.
  • Feed must be below the nose diameter; this bound does not establish a suitable cutting setting.
  • Default values are worked examples, not recommended settings or material properties.

Typical uses

  • turning finish geometry
  • nose radius
  • peak-to-valley cusp

Who it is for

  • Machinists
  • Process engineers

What you get

  • Exact ideal cusp in micrometres
  • Small-feed approximation
  • Approximation difference

Interpreting the result

  • Compare geometric trends, then measure the specified surface parameter.
  • Check tool data and stability before changing feed or nose radius.

References

  • Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 733–742. Topic reference; implementation and examples are original, and no source tables are reproduced.
  • Method: circular-segment geometry. Handbook pages explain surface-texture terminology, not guaranteed finish.

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Open the Turning Cusp Height calculator