On Saturday, February 14, 2015 at 6:23:49 PM UTC-6, Electric Comet wrote:

But after some routing and closer inspection I found that the bit just
isn't stiff enough at top speed to remain straight.
Two things occurred to me.

But even so a router bit needs to remain straight and stiff
and this doesn't at ~23,000/rpm


At the point the shaft is no longer straight, i.e., where it meets the bit aspect, there is a slight curved "lip". If you sink your shaft all the way down to the collet, the collet will/may catch on that lip, rather than fully grasping onto the straight part of the shaft. If this happens, the results will/could be a misaligned bit and, hence, vibration. When this happens, your bit could possibly become loose from the collet's grasp, sending your bit flying.

Try not to sink your bit's shaft all the way down to the collet, hence avoiding the collet grabbing onto that lip.

Sonny