Scallop Height Calculator
Estimates geometric scallop height left between adjacent passes of a round profile. A visible substitution makes it easier to catch a misplaced unit before scallop height reaches later work.
Enter the program and setup values
Scallop height
Stepover on the same basis as tool radius
CNC geometry, program data, tool-life records, and costing inputs should refer to the same operation and revision. Here, the recorded tool radius determines how that guidance is applied.
Record when and where tool radius, stepover were measured. Reusing scallop height after a setup change without that context can be more misleading than a visibly approximate estimate.
Stepover and the limits of the simple model
Establish which scallop height is required before entering tool radius, stepover. The printed equation then provides a check on whether the calculation is being run in the intended direction.
Use the printed in as a dimensional target. Work backward through the equation to identify a missing conversion or a field entered on the wrong basis. The worked condition ties this guidance to tool radius rather than to an unlabeled assumption.
Scallop height: moving from baseline to a second case
Compare scallop height with the posted program revision and the control settings on the actual machine. Simulation time and commanded motion may not include every controller delay or operator action.
Preserve the entered tool radius and stepover in the program and setup sheet. If either changes, rerun the relationship and identify the revised program revision, machine, tool, and setup rather than editing a rounded result.
One independent check on the formula
The equation uses tool radius, stepover to report scallop height in in. The stepover must not exceed twice the radius, and deflection, runout, tilt, and surface curvature can change measured texture.
A 0.25-inch radius and 0.1-inch stepover create a theoretical scallop of about 0.00505 inch.
Scallop height: assumptions to review before release
The stepover must not exceed twice the radius, and deflection, runout, tilt, and surface curvature can change measured texture.
Controller motion, acceleration, tool wear, probing, setup practice, and machine limits can shift a CNC result away from the ideal relation. In this setup, stepover is part of the same documented condition.
Stepover: credible high and low conditions
Treat the worked value as a baseline, then alter one of tool radius, stepover while leaving the other entries fixed. Predict the direction and approximate size of the change before reading the new scallop height. This separates a real relationship in the formula from a typing error or an unnoticed unit conversion.
Use historical or drawing limits to bracket scallop height. A sensitivity range grounded in the actual process is more informative than a best-case combination that cannot be produced.
Name the operating state behind each scallop height. This prevents a catalog maximum, a shop average, and a drawing nominal from being mistaken for one simultaneous condition.
Scallop height: the role of tool radius
Compare scallop height with the posted program revision and the control settings on the actual machine. Simulation time and commanded motion may not include every controller delay or operator action.
Preserve the entered tool radius and stepover in the program and setup sheet. If either changes, rerun the relationship and identify the revised program revision, machine, tool, and setup rather than editing a rounded result.
Tool Radius belongs beside the answer
Store scallop height with its input values, units, date, product or operation, and the equation version. Do not let extra displayed digits imply measurement accuracy the source data did not have.
Separate computational guard digits from usable precision. For scallop height, final rounding should reflect the least certain field and the resolution of the next operation.
The same setup record can also support milling step over, ball nose cusp height, drilling peck count and ball nose effective diameter.
Interpreting scallop height in practice
How much precision is useful for scallop height?
Keep guard digits while checking or reusing the result, then round to the resolution supported by tool radius and the next decision.
How should two scallop height cases be compared?
Change one uncertain input at a time, label each condition, and compare the resulting scallop height values before building a combined best- or worst-case scenario.
Is scallop height a measured value?
Scallop height is calculated from the labeled entries, including tool radius and stepover. Actual performance may differ because the equation does not represent every loss, tolerance, or source of variation.
What can cause a surprising scallop height answer?
First check the unit basis and whether tool radius and stepover belong to the same condition. Then verify any zero divisor, percentage conversion, or empirical constant.