The edge-forming router bit you're chucking keeps sliding all the way down in the collet, but it needs to be higher. With both hands occupied with collet wrenches, you can't hold the bit in position.

Slide a rubber O-ring onto the router-bit shank, as shown above, before you insert it into the collet. (You'll find 14 " and 12 " inside-diameter O-rings in the plumbing aisle.) Position the bit at the height you want, and slide the O-ring down to the collet face. Now, you can tighten the collet nut while the O-ring holds the bit in place for you.
—William Sand, Morristown, Minn.