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Spindle Speed Variation SSV

M38 / M39 Spindle Speed Variation On/Off

Spindle Speed Variation (SSV) allows the operator to specify a range within which the spindle speed continuously varies. This is helpful in suppressing tool chatter, which can lead to an undesirable part finish and/or damage to the cutting tool. The control varies the spindle speed based on Settings Mach parameter 1941 and 1942. For example, in order to vary spindle speed +/- 50 RPM from its current commanded speed with a duty cycle of 3 seconds, set Setting 1941 to 50 and Setting 1942 to 30. Using these settings, the following program varies the spindle speed between 950 and 1050 RPM after the M38 command.

M38 - Turn On SSV (Spindle Speed Variation)

Vary the spindle speed to help with chatter issues while cutting


  • P (optional) RPM to very the speed by
  • E (optional) Time interval that the speed is varied by
M39 - Turn Off SSV (Spindle Speed Variation)

Turn off the spindle speed variation

Spindle Speed Variation is only available on Modbus controlled VFDs at this time