keeping bit from rising

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Forum topic by tommyd posted 08-06-2010 04:41 AM 1584 views 0 times favorited 4 replies Add to Favorites Watch
View tommyd's profile


77 posts in 3161 days

08-06-2010 04:41 AM

I need some advice on how to keep my router bit from rising when I am cutting. I am trying to cut a dove tail down the middle of a board and than down the sides of another so I can join 2 long pieces together. On the board that i,m cutting down the middle I have cut most of the wood out on the saw so there is room for the chips. I am using a 1/2 shaft in my router in a table. when making the cuts the bit seems to rise up about 1/16” how or what do I use to keep bit from rising?

-- Life is too short for negative drama & petty things. So laugh insanely, love truly and forgive quickly!

4 replies so far

View Mark Shymanski's profile

Mark Shymanski

5621 posts in 3742 days

#1 posted 08-06-2010 04:57 AM

When you put your bit in the collet is it bottomed out or is there a wee bit of space between the bit and the bottom of the collet. My understanding is that if you bottom out the bit the collet cannot effectively squeeze the shaft and thus will actually be loose especially under load. I think it was here where I learned that you must leave a bit of a gap for the collet to tighten correctly. I believe one of my Lee Valley bits actually comes with instructions for adding an O-ring to the bit shaft to guide you from inserting the bit in too deep.

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View BertFlores58's profile


1698 posts in 2951 days

#2 posted 08-06-2010 11:18 AM

Two things to do and check:
1. Check all the slots of the collet or 1/2 drive screw itself if free from any obstruction to be squezzed. Some occasion, i pass a hacksaw blade to be sure if its free. Even you tight hard the nuts, the collets does not squeze and hold the bits firmly because of the obstruction.
2. Check the diameter of the bits. 1/4” collet cannot be used with 6.0 mm bits. It will be loose 0.3 mm because 1/4”=6.325mm. If the router bit has already deter or been worn-out so it should be replace. It work sometime to rough the bit shank by chiselling it and make it coarse.

On general check, take a new bit and use it.. If it is the same, then the collet or the drive shaft is blocked to hold the bit… then do no. 1 above. If it holds steady with the new bit, then the subject bit that was rising is already worn out then do no. 2.

Hope this will help.

By the way, there is no effect whether collet will be reversed. It works on both ways upside down or up. Please note. there is a spring on the bottom part of the drive shaft to help easier way for taking out the bits.

-- Bert

View Gene Howe's profile

Gene Howe

10548 posts in 3457 days

#3 posted 08-06-2010 02:27 PM

I wish I could help. I have the same problem…..with one bit, only! I miced it and it’s right on.
Very frustrating.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View Gregn's profile


1642 posts in 3012 days

#4 posted 08-06-2010 04:41 PM

I confer with Mark and Bert on their advice. If you are still having problems get different collet. I went through this and got a different collet and had no problems. The old one looked perfectly fine but found out it was a tad bigger than the new one.

-- I don't make mistakes, I have great learning lessons, Greg

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