Jammed spindle collet nut

CNC Machines
4

Usual preface, I’m with PreciseBits so while I try to only post general information take everything I say with the understanding that I have a bias.

As Will said most likely the collet wasn’t snapped into the nut. If it was you need to check the eccentric extractor ring in the nut. They very rarely will fail.

To get the collet and bit out. Move the spindle where you can put something soft under the bit and lower it to less than an inch of clearance. The old rubber mouse pads work great for this. Then take a slotted screwdriver and insert it into the groove in the collet as deep as you can go. Tap the back of the screwdriver with a mallet / hammer while walking the screwdriver around the groove in the collet. It should eventually drop out.

After you get it out check the spindle and collet for grooves or damage. If you aren’t sure on something post a picture and I can at least give my opinion. You can see the damage that can be caused by not snapping the collet in here (Link).

In terms of too much torque, the spec for an ER11 with a standard nut is:

    6ft-lb or 8Nm for 1-2.9mm diameter bore

    18ft-lb or 24Nm for 3-7mm diameter bore

Those are MAX torque and exceeding those can damage the spindle, collet, and nut. Or at the very least increase runout.

Hope that’s useful. Let me know if there’s something I can help with.

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