# problem with bit grabbing/chattering



## bigmuddyriver (May 29, 2011)

I am attempting to route some 1/4" mortises into a 1 3/4" square leg. I am using a Bosch 1617EVS with the plunge attachment and the Bosch RA1054 fence and a brand new spiral upcut 1/4" bit.

When I make the plunge at each end of the mortise (1" deep) the bit seems to want to grab or chatter a little. Kind of a scary sound. Also when I do the clean-out between each end, which I do in small increments.
What am I doing wrong? My thoughts is that there could be some rocking of the router since it is only sitting on 1 3/4" stock. I'm not noticing any rock but I imagine that a very minute rocking could cause this. Could my speed be wrong? I'm not sure of the rpm but the speed wheel is sitting between 5 and 6.

I can double up on the legs to give the router a wider base. The reason that I haven't done that is because I'm doing this on a piece of practice stock and don't have any matching material without doing another glueup.

I have a hollow chisel mortiser but wanted to use the router method because I get less than great results using the 1/4" hollow chisel bit with cleanout and burning. Ideas on solving that problem would be much appreciated also.

I can also switch to the router table, marking the fence and lowering the stock down over the bit.

I just wanted to try this method because you guys make it look so easy. :wink:

Tom


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## Stick486 (Jan 4, 2013)

Are you saying you are making a 1'' deep cut in one pass???


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## Quillman (Aug 16, 2010)

Control issue. Edge guide, if not one on both sides, will pull from the edge and chatter (the cutter) like hell.
Router must also be flat on the work; you have to make support for it.
1.75" is not enough surface for the near 7" casting. 
And rout the whole thing end to end, do not dig 1" deep holes on the ends.


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## bigmuddyriver (May 29, 2011)

Stick
No, I'm not trying to cut full depth in one pass. The videos and online classes that I've watched suggest that you plunge to full depth at each end of the mortise then hog out the rest in shallow passes which is what I'm attempting to do.


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## bigmuddyriver (May 29, 2011)

Quillman said:


> Control issue. Edge guide, if not one on both sides, will pull from the edge and chatter (the cutter) like hell.
> Router must also be flat on the work; you have to make support for it.
> 1.75" is not enough surface for the near 7" casting.
> And rout the whole thing end to end, do not dig 1" deep holes on the ends.


Ok sounds like a shop made guide with guides on each side of the stock may be what I need. I do experience the most difficulty when plunging the holes at each end so I will try routing it end to end.

My practice stock is pine but the actual stock is QSWO. I'm wondering if the oak may be easier because of it's tighter grain. Or maybe worse??


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## bigmuddyriver (May 29, 2011)

*Think I have this resolved*



Quillman said:


> Control issue. Edge guide, if not one on both sides, will pull from the edge and chatter (the cutter) like hell.
> Router must also be flat on the work; you have to make support for it.
> 1.75" is not enough surface for the near 7" casting.
> And rout the whole thing end to end, do not dig 1" deep holes on the ends.


I followed your suggestions along with making my own jig with edge guides on each side and it made a big difference.

Still getting a little chatter at the end of the mortise but at least its not pulling the bit off track. Thinking the problem may be chips getting lodged in at the end so will hook up dust collection to see if that helps.

Thanks

Tom


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## Nickp (Dec 4, 2012)

Could it be that when the bit exits the wood and into the hole the bit is trying to grab the wood it is exiting...?

You could try just making the start hole and travel to the end using a stop rather than a start and finish hole...?


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