6 CAUSES OF YOUR SPINDLE VIBRATIONS
What is imbalance: An unequal distribution of mass in a rotating body cause the imbalance.
A bearing without lubrication tends to wear out quickly and will vibrate before failing.
If the spindle and motor and not couple and align together correctly it will cause vibration.
If the taper of your spindle doesn’t have the right % of contact surface, this will create vibration and premature wear of your bearings and also your tooling.
Gears & Belts
Gears and belts of a CNC machine always tend to produce vibrations, mainly because of their mesh or teeth. Items that tend to cause excessive vibration in the gears are misalignment of the motors and spindle. Make sure that the fit of gears or tension of your belts is correct.
If your tool-holders are not properly balance it will also affect the lifetime of your bearings in your spindle. Make sure that your tool-holders are well balance and that they are replaced when surface contact in the taper is no longer in specs.