# cutting bit movement



## Cabbie41 (Nov 28, 2010)

Guys--
I'm stumped! I set up my Skill plunge router to do some rabbeting on MDF and poplar. The poplar was done with a top-mounted bearing bit, while the MDF used both a spiral down-bit as well as a straight flute 3/8" bit.
The collet was disassembled, cleaned thoroughly, and the tightening was "vigorous". Set the plunge depth to about 1/4" and began the cut. Within the first foot or so of cut the depth had changed to over 1/2", ruining my piece. I've now scrapped three workpieces with the same issue!!
What's happening? The only way I can get this to work is if I limit the cut depth to about 1/16", which is ridiculous and time-consuming.
Any ideas as to what's causing t he problem and how to fix it? The router is old (15-20 years) but not used very much.
Any help would be appreciated!
Thanks


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## vindaloo (May 30, 2009)

Is the plunge lock not working or is it the bit coming out of the collet?

What's the size of the bit shank and the router collet?

I bought some cheap bits and they turned out to be 12mm and not 1/2", which meant they were loose even with the collet tightened as much as was possible.


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## Shop guy (Nov 22, 2012)

My guess is the bit is bottoming out in the collet. Try taking it out. Reinstall it the pulled it out about an 1/8" and try it again on a piece of scrap.


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## Stick486 (Jan 4, 2013)

use another/different bit on scrap and see it behaves the same way...


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## Quillman (Aug 16, 2010)

Spirals, like drills, screw themselves into the work.
As such, the cutter is being pulled from the collet.
Especially one as old as yours.
New router or new collet now.


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## RÖENTGEEP (Feb 18, 2014)

vindaloo said:


> Is the plunge lock not working or is it the bit coming out of the collet?
> 
> What's the size of the bit shank and the router collet?
> 
> I bought some cheap bits and they turned out to be 12mm and not 1/2", which meant they were loose even with the collet tightened as much as was possible.


Same questions and comments here.


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## Cabbie41 (Nov 28, 2010)

Plunge lock is still solid. I tried lifting the bit shank out of the collet by "1/8" or so", but it's a bit of a guess as you're working blind. In any case it didn't work. The bit shanks appear OK, and they're from a set of Craftsman carbide bits and are supposed to be high quality, but I'll measure them anyway just to be sure. I can't afford a new router just now, so a fix is needed.
Thanks for any advice.
Jim


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## Stick486 (Jan 4, 2013)

new collet...
I trust there is no lubricant on the bit or collet...


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## Cherryville Chuck (Sep 28, 2010)

Cabbie41 said:


> Plunge lock is still solid. I tried lifting the bit shank out of the collet by "1/8" or so", but it's a bit of a guess as you're working blind. In any case it didn't work. The bit shanks appear OK, and they're from a set of Craftsman carbide bits and are supposed to be high quality, but I'll measure them anyway just to be sure. I can't afford a new router just now, so a fix is needed.
> Thanks for any advice.
> Jim


Some people use a rubber grommet or an o ring in the botton of the recess to prevent bottoming out. Another way to do it is to take the collet out of the router and stick the bit in it all the way and then mark the shank of the bit. Then you can see how much needs to go in. As long as you are using 100% of the collet there is no advantage to having more shank in the collet.


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## Cabbie41 (Nov 28, 2010)

Just ordered a new collet from ereplacementparts.com ($16.95+ shpg)--I hope that does it. In the interim I'm going to try using a bronze gun bore cleaning brush witih some naptha or acetone to get it good and clean.
I'll let you all know how things turn out.
Thanks for your help!
Jim


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## Cabbie41 (Nov 28, 2010)

Quick update:
New collet did the trick--works great. Haven't tried the "bore-brush & naptha-cleaned" old collet yet--having too much fun using the new one!


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## JOAT (Apr 9, 2010)

Shop guy said:


> My guess is the bit is bottoming out in the collet. Try taking it out. Reinstall it the pulled it out about an 1/8" and try it again on a piece of scrap.


Yep, that was the solution to my problem, so that would have been my answer too. But then I read Pat's post, so I'll go with him. :laugh2:


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## BrianS (Nov 7, 2004)

Cabbie41 said:


> Quick update:
> New collet did the trick--works great. Haven't tried the "bore-brush & naptha-cleaned" old collet yet--having too much fun using the new one!


Jim, thanks for letting us know what the final solution was. Always nice to keep that in the back of the mind for the next person with a similar problem.


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## ranman (Oct 27, 2017)

Stick486 said:


> new collet...
> I trust there is no lubricant on the bit or collet...


Great info............ that esplains My 9 year old Dremel tool bits slidin out every time I use it.


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## DesertRatTom (Jul 3, 2012)

I recall reading that the Bosch Colt went through collets fairly fast, so I just bought an extra 2, stored in the router's case so I can find it. Don't want to stop mid project to order and wait for a new collet.


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## Mycrossover (Dec 29, 2017)

ranman said:


> Great info............ that esplains My 9 year old Dremel tool bits slidin out every time I use it.


Collets don't last forever. In your case it will just be a trip to the local big box store and low cost.

Sent from my SM-G900V using Tapatalk


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