I’ve just recently started getting a rather odd effect. My spindle seems to be either going harmonic, or going out of balance, I’m not quite sure which. It runs quite smoothly with no bit in it, but putting a bit in it seems to sometimes cause very odd vibrations, and sometimes not. I’ve tried bits ranging from a 1.5" long 1/4" diameter V-bit, to a 3" long four-flute quarter-inch endmill, and it seems to be VERY random. I’ve checked all of my V-wheels, the tightness of my spindle in the carriage, the tightness of every screw on the darn thing… I can find no reason at all that this should be building up such a vicious vibration just spinning free in air! To the extent that I have to immediately shut the spindle down, because the bit is visibly vibrating at the tip through perhaps .020 of oscillation! The noise is horrible, and the vibration is worse.
I know the bits are good, because they’re largely the same bits I’ve been using since I got the unit. I have been able to continue running by installing and re-installing the bit until the vibration is minimal, but it’s still there… Something isn’t quite right here. I’m not terribly worried because I’ve got the mount for my DeWalt showing up next week some time, but I’d like to be able to keep it running until it shows up, and I’m starting to be afraid for the longevity of my Z-axis with that kind of vibration building up.
What else should I check here? I’m somewhat at a loss!