Series 1 Spindle Vibration / Chatter

[kewl_cat]

I have a Series 1 w/Erickson 30 quick change doing fairly light work cutting aluminum. Fast or slow RPM or feeds the result and sound is the same. 3/4 or 1" end mills seem to make no difference. I have tried a new quick change end mill holder, different end mills, up/down milling. Climb milling does produce a little better finish but not like I am used to. I even had one of my machinist friends help me and he said he thought there was a mechanical problem and not a feed/speed problem. It does make slightly better cuts at very slow RPM under 1000. But still fairly nasty looking cutting for a mill. I took the spindle out and it did not see anything apparent. I did tighten it 1 click on the nut with no change. I did notice it had Fafnir M206KDD and M207KDD bearings. I was going to just change them from a local bearing supply house but my machinist friend told me they are specially cut to put preload on them?? Any ideas or suggestions??

[machintek]

NC CAMS has posted a lot of data on these spindle bearings. Search the posts.

George