Ra and Rz from geometry
Calculate theoretical Ra_geo, Rz_geo, profile mean line and scallop height for the entered stepover.
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Scallop height, Ra and Rz calculator
See the ball-end surface cross-section, calculate theoretical Ra and Rz, or choose stepover for a target geometric Ra.
NCTune CNC Toolbox
Choose a machining stepover for the target surface
The calculator analyses an ideal periodic profile between neighbouring ball-end paths and presents it as a clear cross-section.
Stepover for target Ra
Enter the expected Ra_geo and the calculator numerically finds the corresponding cutter-path spacing.
Clear limitations
The model is not a measurement and excludes slope, feed-per-tooth marks, runout, vibration and profile filtering.
FAQ
Frequently asked questions
Does a smaller stepover always reduce scallop height?
Yes, in this geometric model reducing stepover reduces the theoretical cusp height.
Will calculated Ra and Rz match a measurement?
Not always. These are ideal geometric values. A measured result also depends on the process, tool, measurement direction and profilometer filtering.
Does the calculator include surface slope?
No. It models a ball end mill on a flat surface; slope changes the effective geometry.
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