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Runout: the hidden feed killer
How tool runout overloads one flute, and the tolerances saw and end mill makers publish.
With runout, one flute sits farther out than the others and takes a bigger chip. Harvey Performance explains that runout raises cutting forces because the flutes engage unevenly. Some flutes wear faster, and miniature tools break [1].
Published targets
| Item | Target | Source |
|---|---|---|
| Slitting saw arbor / holder | ≤ 0.0002" | [2] |
| Saw seating | < 0.0001" | [2] |
| Saw side runout | < 0.0005" | [2] |
| Tooth-to-tooth (saws over 0.020") | ~0.0001" | [2] |
Reducing it
Harvey recommends shrink-fit or press-fit holders for small tools, plus maximum shank contact and minimum stickout [1]. Check runout with an indicator before the first cut.
Open the slitting saw calculator
Tooling for this job
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