Replies

1. 
   bilyo | Mar 08, 2023 09:30pm | #1

   I can only think of two possibilities. If your collet is made so that a long shaft can bottom out, don't allow it to happen. When you drrop the bit into the collet and it hits bottom, pull it out about 1/8" before tightening it. I can't explain why, but hitting bottom can keep the collet from properly tightening. Also, notice that the shaft of the bit has a small rounded area or shoulder where the shaft meets the cutter head. Don't let the bit drop in all the way so that the outer edge of the collet is in contact with that area. Again, pull the bit out about 1/8" before tightening. If the collet tries to tighten down on that shoulder area, it won't tighten properly.

1. 
   Pali | Mar 08, 2023 10:22pm | #2

   Thanks. I starting to think it's the bit, not the Bosch router or collet, because the same bit also slipped when I just tested it on my small Dewalt DWP611 router. The bit is new and measures and looks fine, but maybe not. Maybe I have to make room for random mystery.

2. 
   pantalones868 | Mar 08, 2023 10:59pm | #3

   Try cleaning the shaft with some lacquer thinner . A little blue thread locker can stop the slip as well. Black or red is too much but the blue works well.

3. 
   stevieray | Mar 09, 2023 03:09am | #4

   I had the same problem, with the same size bit. A solid carbide 1/4 bit. I was cutting panel grooves in frame pieces, and the bit actually rose up and penetrated the upper surface. Thankfully my fingers weren't there at the time but it got me worried. Using 1/4 collet on Porter Cable router mounted in my table. And, yes, I know about the not bottoming out business. Like the original poster, I tried all the usual solutions. Other bits, by the way, behave fine. Just the one 1/4. So like the OP, I think I got a bad bit.

4. 
   kudzupatch | Mar 09, 2023 10:28am | #5

   Sounds like it is time to try a new collet. That one may be worn or damaged. Especially if one has slipped in there, that is a good sign it is time to replace it.

5. 
   Pali | Mar 09, 2023 12:51pm | #6

   Thanks everyone. When I get home this evening I'm starting with blue thread locker and then, if necessary, will order a new collet, even though the three other bits I've tried work fine and don't slip. Unlike last night, I did get the slipping bit to work in my other router so I'm back to thinking collet.

6. 
   ebourg | Mar 09, 2023 07:11pm | #7

   Agree with Bilyo above. Don't let the shaft bottom out in the collet before tightening it up. When you tighten it pulls the collet up deeper into the router in order to collapse the collet and grip the shaft. pulling the shaft up by 1/8 or so before tightening will resolve this issue as well as the chance that the collet it trying to grip on the radius where the shaft meets the cutter head.