Colombo Collets Breaking

[magnum]

I have not broken a collet on my Bridgeport in 19 years - this week I broke 2 1/4" collets in the Colombo - why? Anyone else have this problem? Am I over tightening? Been cleaning between changes with a toothbrush and air. Also getting a grinding noise intermittently in the 15000 rpm area. Is this normal? Only had a few weeks on this machine.
TIA

[Brady Watson]

Barry,
Make sure that the spring collet is correctly seated in the collet nut. You have to press down and turn 90° for it to be properly snapped in and seated. Then thread the nut/collet assembly onto the spindle...then insert your tool and tighten. The spring collet should appear to be even with the bottom ring of the nut.

You should not be getting a grinding noise at any RPM...However you may be hearing vibration coming from the cooling fan or other metal parts near the spindle causing resonance & vibration.

-Brady

[magnum]

This is not how I have been doing it. Will try to put the collet in first and then put the nut on. The nut never seems to go on easily - hard to keep all parts together and get the thread going - thought the Italians were crazy here....

[Brady Watson]

Barry,
If you snap the collet into the nut, it should not be difficult to screw on to the spindle correctly. Hold the shaft with one hand and spin the nut on.

-Brady