1/4 inch bits in collet insert

[jackellis]

I needed to cut some 1/4" thru slots in a piece of 3/4" oak using my Hitachi M12V. To do this, I have to use the collet insert that comes with the router. Much to my surprise, the bit repeatedly tried to climb out of the collet insert and no amount of tightening would stop it. Switching from the Woodcraft bit I was using to a new MLCS 1/4" bit seemed to solve the problem but I'm not sure whether this is a temporary fix or a permanent one.

Has anyone else run across this before? Are the Woodcraft bits just not that good?

[RodKirby]

Sounds like the collet slots aren't lined up.

Assuming the insert has only one slot, make sure that slot is aligned with a slot in the router collet. This should allow you to tighten as you would normally.

I'm also assuming both the router collet and insert, and the bit shank are perfectly clean!

[jackellis]

Slots?? I guess I'd better take a look tomorrow when the light's better.

The insert seemed to be clean but I didn't think to check whether the insert had also climbed out.

I'll be ordering some 1/2" bits from MLCS in the next few days but unfortunately their slot cutters still require a 1/4" collet.

[Holbren]

Is the bit bottomed out in the collet? Maybe heat expansion is causing it to move.

What kind of bit are you looking for in 1/2" shank? Post link if you can.