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Can runout or deflection cause a router to kickback?

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RichardDepetris:
I am asking my question here instead of the woodworking forum because my question is really a general machining question. I haven't had a satisfactory answer from my woodworking forums, nor any searches.

I am pattern routing a plane tote on my router table and I have been experiencing a kickback the moment the cutting edge of the bit touches the work piece.  It happens on both a 2 flute, top and bottom bearing flush trim bit and a top bearing flush trim spiral bit. I am trimming away less than 1/8" of red oak end grain.  I am also routing from right to left.  Oddly, I was able to round over the piece with a 1/2" roundover bit with no kickback. I did get lots of burning and tear out. 

After trying several suggestions, I decided to inspect the router.  It's Porter Cable 690 and it is very old and it is the first time I am using this particular router.  I checked it with my indicator without the bit and I got .005" runout at the shaft and nearly 0 inside the collet.  With my thumb, I pressed with firm pressure against the shaft and got over .010"  runout depending on how hard I pressed it.  During use, there is a lot of vibration, very loud and makes rattling clanking sound as it spins down. I assumed it was because routers are supposed to be noisy.

Can such a deflection on the shaft cause a kickback?  If so, why?  Moreover, why did the roundover bit not kickback, albeit the finish wasn't very good? 


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John Rudd:
I'd say your cutter is blunt....and needs sharpening, if its not a new one..or judging by the description further on your router has worn bearings

RichardDepetris:

--- Quote from: John Rudd on February 04, 2017, 02:11:58 PM ---I'd say your cutter is blunt....and needs sharpening, if its not a new one..or judging by the description further on your router has worn bearings

--- End quote ---

Thanks! Would the observed deflection worsen or effect the TIR even with light pressure as the bit spins at 25,000?  My guess is that the centrifugal force and heat may play a part. 


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Biggles:
I agree with John its more than likely the bearings and made worse by using a blunt bit. :coffee:

chipenter:
How firm is the mounting to the table a little bit of rock will grab and kick , my table is a dual saw and router and the plate has to be set level and tightend down well .

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