Crazy question, do the collet adapters wear out? I am getting a weird vibration.
You don’t mention what type of machine that you are running, or what type of spindle. If you are running a Dewalt 611 router, you may get a vibration if your 1/8" to 1/4" adapter is loose, or if the collet nut is worn or loose.
If you are running a DC spindle on an older machine which uses the ER-11 collets, you will get vibration if the collet is not snapped into the spring retainer inside the collet nut. Remove the collet nut from the spindle or router, and check that the face of the collet where the cutting bit inserts from the front, is flush with the front edge of the collet nut.
Other things that can cause vibration are improper speeds and feeds when cutting materials. Cutting too much in one pass, or spindle/router speeds too slow will also cause chatter and/or vibration.
The collet and nut on the Dewalt 611 are integral to each other, and are made as a set.
Thanks for the info. I replaced the collet and everything seems to be working much better.