# Broken router bit



## stripit (Oct 21, 2012)

Hi. I'm trying to cut a circular frame using rocker elipse circle jig. I watched the video, set everything up and started. I thought I was going the right way, clockwise, It looked like that in the video. The bit came loose twice, then it broke.
I'm using an up cut spiral bit 1/4", cutting 1/8" at a time. Am I going the wrong way, is that why the bit came loose and broke????

I did one already out of pine and had no problem, this one is ash.

Thank you any suggestions you may have.


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## BobAnderton (Oct 5, 2010)

The bit came loose twice? That sounds like the problem. Once it came loose the 3rd time no telling how deep a bite it took. Is the problem that your 1/4" collet needs replacement? I take it you're forming the groove with the bit, so clockwise vs counterclockwise shouldn't matter.


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## Rayne (Mar 9, 2014)

I'm thinking 1/8" in Ash is probably too much to take out at once. You'll need ot take about 1/16" at a time for that one. My guess on coming loose is the bit is heating up too much and came loose. Bits will definitely break if taking too much out at a time.


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## stripit (Oct 21, 2012)

I took the collect out and cleaned. I have another collect to try, but have buy a new bit first.


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## MrUnix (May 18, 2012)

+1 to what Bob said - sounds like your collet needs some attention… either cleaning/roughing up or replacement. Under no circumstances should a bit come loose. As for direction, it doesn't matter when you are doing a plunge cut (as opposed to an edge cut). But just an FYI, the video I watched from Rockler shows them going counter-clockwise, not clockwise 

Cheers,
Brad


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## bondogaposis (Dec 18, 2011)

An upcut spiral bit will try pull itself down into the wood if it isn't tight in the collet. You likely ruined your collet or maybe it was worn to begin with. Try it with a straight bit.


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## BurlyBob (Mar 13, 2012)

Joel, If you've got access to someone with a sand blaster Get them to shoot the shaft of your router bit. It doesn't to be heavy just enough to abrade the surface of the shaft so the collet can get a grip on the bit. I had a router bit traveling out of the collet as I was making a dovetail. No matter how hard I tried to tighten that collet the bit would travel out. That little bit of abrasion made all the difference.


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## Lazyman (Aug 8, 2014)

Is it possible that your bit is actually a 6mm bit instead of a 1/4"? They make upcut bits for CNC machines in metric sizes and it may be close enough in size that perhaps your 1/4" collet can hold it, just not tight enough?


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## HerringImpaired (Mar 13, 2019)

Was the bit bottomed out in the collet? Best practice is to bottom the bit out, and then pull upward about a 1/16" to 1/8" or so, and then tighten the collet. 
(Nice shoulder decoration! I have an African Grey on my shoulder as I type this)


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## CaptainKlutz (Apr 23, 2014)

Hmm, when the bit became loose the 1st time, did you check if it was bent? 
Bent bits will vibrate themselves out of a good tight collet. 
1/4" bits bend really easily if you push them too fast in hardwood.

I always try a different bit before blaming the collet.

Best Luck.


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## stripit (Oct 21, 2012)

Thanks to everyone who took the time to right. I tried all your suggestions, change to a sright bit with a 1/2" shank, which meant a new collect, even sand it a little. The bit still came loose. I think I have found the problem, I needed the smallest circle I could get.with this jig which is 9 1/4". To get this you have to leave off the base plate, and just use the small dove tail piece (about 1 1/4" long) and this does not give a enough support for the jig. the jig tends to tip just a little, and I think that is putting stress on the bit. So I guess I'll go to plan B for Christmas.

The bird is a sun Conure and rules the roost around here.
Thanks again.


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## geraldvg (Jul 5, 2013)

I would have put my money on the bit being "bottomed out" in the collet. If the bit shaft is bottomed out, the collet cannot grip adequately. My solution to the issue is to cut and slip on each bit's shaft really short sections of Tygon (clear plastic) tubing to effectively make an "O-ring" that prevents the bit from sinking too deeply in the collet while you are trying the get the nut tightened.


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## Tony_S (Dec 16, 2009)

Don't convince yourself that the jig is the problem. It isn't. 
It doesn't matter what happens as far as tipping, jamming, kick back etc. or the type of bit. The router bit should NEVER come loose.
I understand that you put on a new collet and router bit….but there's something wrong with either the collets, the chuck, the bits, or you're not tightening the bit properly.
Once in a rare while, I've come across bits that have a slightly undersized shaft, but it usually isn't anything that an extra crank on the collet won't solve.
Does the router vibrate? Maybe the bearings are shot and the vibration is causing the collet to loosen?


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## DrTebi (Jun 16, 2009)

I am with Tony_S on this one. I have cut dozens of large circles for speakers, and never had a bit come loose.

Maybe tell us how exactly you are tightening your router bit, or show us some pictures of the setup. There just might be something else that causes the problem.


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