Originally Posted by
andrew2085
I actually was able to get the runout down to about 0.0001" measured at the end mill shank. I covered the collet's taper in blue sharpie marker, then tightened it with an end mill in. I put a dial indicator on the shank and rotated the spindle by hand. I marked the side of the collet where the highest positive runout was. When I took the collet, out I could see the high spots where the collet contacts the spindle taper. I just lightly filed the high spots opposite where my max runout mark was. After that I smoothed the file marks with some sandpaper to bring the original finish back. Just doing that brought the runout from 0.0007" to what looks like about 0.0001".
The real test would be to have something perfectly straight stick out 4 or so inches and measure runout at the end. I only know that the shank is centered on the axis of rotation at the end of the collet. Its not necessarily perfectly parallel to it. That would also be a lot harder to fix. I think I can live with it.