Your machine's been trying to tell you something for weeks — you just haven't been listening.
A new rattle, a grinding note, a rhythmic knock. None of it's random. Here's what each sound actually means.
Grinding or Rumbling from the Spindle
Low grinding or rumbling that changes pitch with spindle speed? That's spindle bearing wear, almost always.
Stop the machine now. Keep running it and a straightforward bearing swap turns into a full spindle rebuild — and a much bigger bill.
Rhythmic Knocking During Axis Movement
• Knock at regular intervals during travel — usually a damaged section of ball screw
• Clunk when the axis changes direction — backlash or looseness in the drive train
Neither needs an instant stop, but don't ignore them. They only get worse.
Squealing or High-Pitched Noise
• From the spindle — dry or poorly lubricated bearing. Check your lube schedule
• During aluminium cutting — tool's rubbing, not cutting. Check tool condition and parameters
• From the cabinet — could be a cooling fan bearing on its way out
Rattling
Usually the least urgent — loose covers, swarf in the chip conveyor, loose fixturing. If it's coming from inside the cabinet though, get it checked.
Heard something you can't place? Describe it to us — we're good at diagnosing machines over the phone.
Call CNC G on 0121 272 5242 or email service@cncguru.co.uk.
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