Speed is fluctuating during operation

It is normal for spindle speeds to fluctuate occasionally during the course of a job due to variations in the cutting mechanics. However, excessive fluctuations may point to an issue with the spindle.

Note the change in pitch of the fluctuations:

• “Peaking”: the spindle speed briefly INCREASES to a higher speed, before quickly returning back to nominal speed.

• “Dipping”: the spindle speed briefly DECREASES to a lower speed, before quickly returning back to nominal speed.

Causes for excessive “Peaking”

• Check the PCB in the spindle is correctly constrained (check this article)

Causes for excessive “Dipping”

• Check spindle clamp has not been over-tightened

• Check spindle data connection

• Check the condition of the spindle brushes. Check that the brushes are still over 9.5 mm long (illustrated here).

• Evaluate the job parameters (see “Evaluate the job parameters” in this article)