When router-cutting dovetails in my drawer project the dovetail bit slips in the collet, no matter how much I try to tighten it, resulting in a gradually deeper cut. This means I have to loosen, re-seat the bit, and tighten the collet at each corner and, believe me, this is a monumental hassle. Has anyone else had this problem and have you found a solution ? I have replaced the collet and the same problem occurs with both collets. This also happens with two different dovetail bits. I have tightened it as much as I can tighten it with hand wrenches. I have also blown the dust out of the receiver in the router.
Yonak, wow. I feel your pain. Hard to believe that really tightening down on the collet does not lock the the bit in place. But that is your experience. So, have you tried cleaning out the collet with a brass collet cleaning brush? I have found these brushes useful and have several sizes; well actually only a 1/4-inch and a 1/2-inch size. Google them. Jim
John, the first bit was well-used, for sure, and fairly dull but, the second one was a brand new Amana bit. Both are 1/4" shaft.
I must also say that there seemed to be more vibration than I expected and than I had experienced on previous drawers. I adjusted the depth using oak, though the drawers are cherry. Oak is pretty hard. Maybe that caused the vibration, although it vibrated with the cherry too.
Maybe my router is the issue. I'll try a different router.
Try bits with a 1/2" shank.....there's a lot more metal there for the collet to grip.
Try roughing the router bit shank with some 60 grit sand paper......just enough to make the shank have some scratches and give the collet more to grab onto.
Make sure that you are not bottoming out the bit when you place the bit in the collet. Raise the bit about 1/8" from the bottom of the collet before tightening.
Just study the collet to see how it works. As you tighten the collet, you are screwing the top part of the collet.....the part that squeezes the router bit shank.....towards the bottom of the collet. If your router bit is already bottomed out then there is nowhere for the top of the collet to go.....things are fighting each other and the collet cannot be tighten adequately.
I agree. I was going to recommend the same thing because it sounded like he was inserting the bit all the way in. I learned long ago to always leave a bit just shy of the bottom. This also aids in getting one loose when changing.
Clean the collet and the bit. I use lacquer thinner in case there is any oil or lacquer on the shaft and in the collet. I have used brass brushes in the collet, but did not know wones made specifically for collets were available. I used ones form a gun cleaning kit. Probably the same thing that found a new market.
Don't bottom the bit. More important that it seems. You buy O rings of rubber balls that will slip in and stay in to help you resist the temptation.
I have scuffed the shaft on bits, but I used really fine sandpaper and made very slight rings around the shaft. Not sure this is a good idea because it may reduce the contact area, but try it as a last resort. Don't reduce the diameter of the shank.
If you can, use two wrenches, one on the shaft and one one
the collet. Allows you to make a fist around the two wrenches and really cinch down on the bit. I am a little leary of the shaft lock, afraid I will strip it.
What are the chances the vibration are coming from failing bearings? Does the router vibrate with every bit or just this one? How old and well used is the router? Does the bit vibrate in other routers? Some bearings are relatively easy to replace. Pay a little extra and get really good ones.
Thanks for your answer, Barry. Please expand a bit on the use of O-rings. You put them in the collet for the end of the bit shaft to rest on ? How about, say, an inner tube or a felt pad cut out with a hole punch ?
If you've been bottoming out the bit and then trying to tighten the collet, that's almost certainly the problem and you don't need to rough up the shanks of your bits......
What brand of router? I had a Sears router that the bits would pull out of the collet during a heavy cut. I fixed the problem with a Porter Cable and a Bosch router. Not slippage since the "repair".
The Idea is to put something a little cushy into the collet that will have enough friction to stay put, and not take up too much room. So find an O ring that will just slip into the opening and use that, or cut a little circle of rubber, or a slice of pencil eraser, or whatever. Not sure about the felt, but maybe.
The idea is the collet does tow things, it squeezes to a smaller diameter and at the same time retracts the bit into the shaft. So that little air space or compressible material is important.
While thinking about this is occurred to me you could fix this problem with a credit card. Just take your credit card down to the local Wood Craft or other tool emporium and buy a new router.
(My problem with that approach is I would keep both routers and forget which one had the problem and screw up my next project.)
The technique that I've read about is not to put anything into the bottom of the spindle cavity, but to use a tiny o-ring on the shaft of the router but to hold it up in the collet.
Others have mentioned the bit bottoming out. Yes, you never want that to happen. Another thing to watch for is that there is often a little shoulder at the top of the shank, just below the cutter portion of the bit. That's where the paint ends and you can see the cleanly machined steel of the shank. You want to be sure the collet is gripping the sides of the shank and not this shoulder. Otherwise, there's just a tiny amount of grip and the bit can slip to freedom. Then your careful adjustment will be for naught.
Crapsman router with bits that slipped cured me of the disease of buying their power tools.
Had this issue just once with my PC 690 router. In the end I decided that I was at fault (inadequate tightening of the collet) because I have not had any subsequent issues.
I drop a 'space ball' raised panel spacer into the collet and seat the bit against it. It's soft and 'squishy' enough to allow the bit to shift when the collet tightens.
Been using this method for years, with no failures that I can recall.
It's a Porter Cable 90690 90th Anniversary router, it's somewhat vintage but was "only used three times" by a sweet old man who needed the shelf space in his garage. ..But I'll tell you, it comes in a beautiful metal case. I guess I'll retire it, in box, to my shelf . . .
Mark the outside of the collet with a black Sharpie taking care to cover all the surfaces. Next install a bit and torque the collet as usual. Remove and "read" the pattern on the collet to see if it is seating evenly on the spindle. Try the same procedure with the spindle. Could be a bad collet.
Have you measured the shank of the router bit that slips with a micrometer?
