Router bit won't stay put

[KLF]

Having trouble with a router bit, thought I'd ask here for advice.

Using a Sears multi-piece bit (bit on an arbor with a BB pilot) in my old Sears router, 3/8" round-over bit. Made a test pass to check setup, noticed it seemed to be moving, so I cranked down really tight on the chuck. Ran it down the board, which it ruined. Stupid bit walked about 1/4" out of the chuck! Ruined a perfectly good piece of clear 1x6 pine.

What is weird is I had just used the rabbeting bit on the same arbor a few minutes earlier, it was no problem. Weird.

I may just get a new arbor and toss this one.

Any ideas?

[LarryG]

How far did you insert the bit into the collet? The correct procedure is to push it all the way in, then pull it back out about 1/8" before tightening the collet. This keeps the collet from clamping down on the rounded fillet where the shank joins the cutter head; the fillet is larger than the shank itself, making it virtually certain the bit will work loose.

(I don't know what your experience level is, so forgive me if I'm telling you something you already know.)

[Uncle Cracker]

It might be time to disassemble and clean your chuck and collet. These can get clogged with shavings, resin build-up or other debris, making the even and positive compression on the bit difficult. If your collet is double-ended, turn it around. As with most problems, you won't have it, and then suddenly, you will. Hope that's all it is.

[cabinetman]

Make sure the collet nut will screw past the point of where it grabs the shank. The threads on the nut or the router may be damaged, i.e., threading short. With the bit out, see if the nut threads all the way. When inserting the bit, you don't want to seat the shank of the bit all the way into the collet having the shank bottoming out. Tightening when that occurs may lead to the bit loosening up. And as UC stated, maybe there is debris or resins enabling the shank to slide.

[KLF]

Yes, I always leave a little "stickout" on the bit, not burying it all the way into the chuck. Sometimes make removing easier too.

I'll try these suggestions, see if that helps. Off to Lowes to buy another piece of pine...

[dlminehart]

I've heard of folks inserting an appropriately-sized rubber O-ring in the collet so the bit doesn't go in quite so far, but can be reinserted to the same depth later.

[cwsmith]

You didn't mention how old your Sears' router was or tell us the configuration of its collet.

I too have an old router which I had never used, but I had loaned it to my father. When I got it back a year or so later, I noticed a couple of the bits were burned and he told me that the thing simply wouldn't hold the bits tightly.

On examination, the collet is very small, probably no more than 5/16's in length and it has a single split. Compared to the more modern routers that I've seen, that particular collett (on my old router) seems to be a very poor design and with any wear at all, I would consider it unsafe. (Too bad though, because the router itself has some nice attributes. I wish I could find a better collett though.)

Likewise, I think these multi-piece router bits leave and awful lot to be desired. Consider that if the bit has started to climb out of the router's collett, at what point does it become a projectile. No thanks... I think I'd opt for a different bit and maybe even consider a better router.

CWS