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  1. #1
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    damaged router bit?

    When I took the router bit out of the collet I observed grooves around the top of the shank. Obviously the bit slipped.

    This happened when I tried out a router table for the first time, and I must have fed the wood too fast, since the bit heated up so much that the nut below the collet now has a bluish tinge, instead of the black it used to have. (Maybe I just didn't notice the purplish color on the top before?)

    Maybe I just didn't tighten the bit enough. I cleaned all the burnt crud off the bit and tested it, and it seems to cut fine. But these grooves around the bit are bad, right?

    I'll try to smooth out the bit with emery cloth, as my router book suggests.

  2. #2
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    RE: damaged router bit?

    Oooo, not a good feeling. See how well they clean up with emery, and try it again, and if they come back... it may be time to get rid of that bit.

    It could possibly be caused by an undersized shank, too. That happens once in a while, but it's rare these days.

    Or... your collet could have some crud down inside it, preventing a good "seal" against the shank.

    -- Tim --

    Belief that anarchy leads to chaos
    implies that the believer would be chaotic
    without supervision.


  3. #3
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    RE: damaged router bit?

    Didn't think about the crud option. There is tons of MDF dust under the base plate, dust that became exposed when I took off the plate to attach the router to the table. If that dust got down in the collet, that would explain why the bit slipped, because I usually tighten them pretty well, and my test cut was going well with no burn, and then all of a sudden, massive burn.

  4. #4
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    RE: damaged router bit?

    Are you raising the shank of the bit from the bottom of the collet before you tighten it?

    Sawdust Making 101
    http://sawdustmaking.com
    Frank C

    Sawdust Making 101
    http://sawdustmaking.com

  5. #5
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    RE: damaged router bit?

    Generally, yes.

    But I had to use just a bit of clearance to bore the hole into the router table. I installed the bit so it hit the bottom of the collet and moved it up about 1/16 of an inch. The router wouldn't fit underneath the table because the table had no hole in it. So I pushed the bit back in, closer than I normally do, but enough (so I thought) to not have it bottom out. I screwed the router to the table, turned on the motor, and pushed the 3/4'' bit through the MDF to make a hole. This operations created a lot of burning because, not having a plunge router, I had to turn the knob to make the router go deeper. I know, it seems like a stupid way to make a hole in hind sight, but I was just following the instructions in the book.

    But for the operation that caused all the burning, I had plenty of clearance between the bit and the collet, as much as 1/8 of an inch. Of course, the previous operation could have caused the shank damage.

    This bit damage really bothers me. I like to buy good tools, but I can't do that if I keep comprising bits. I don't think my experience yesterday provided me with a good introduction to the router table and did not inspire confidence. For my practice run, I tried to route a 3/4'' wide dado 3/8'' thick in MDF. I didn't realize I had set the depth so deep. I wonder if the metal got so hot that this caused the slipping, or if crud got in the collet, or if I just didn't tighten the collet enough. Of course, I want to avoid this mistake again.

  6. #6
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    RE: damaged router bit?

    Blow out the collet with compressed air...the higher pressure the better.

    It's been my experience that when a bit shaft slips in the collet, the bit will attempt to come out, ruining the cut. I had that happen a time or two with a Craftsman router I had.

    I dunno. Something about your description doesn't jive in my mind. I'm not totally convinced that the bit actually slipped inside the collet. It could just be that you were taking too big a bite in that MDF.

    Cody
    Tyler, TX


    He is no fool who gives up what he cannot keep for that which he cannot lose.



  7. #7
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    RE: damaged router bit?

    For the record, the bit was a 3/4 '' straight bit with a 1/2 '' shank. The router is a Milwaukee body grip.

    I sanded the shank with 100 grit sandpaper. The person at the box store told me this sandpaper would serve in the place of emery cloth, since the sandpaper had a flexible backing. I sanded out the rings, and finished with 220 grit sandpaper, but now the shaft has very tiny sanding marks, instead of being smooth like a new bit. I assume that you don't want the ring marks because the collet can't grip it. On the other hand, if you have to smooth away too much metal, the collet might get too narrow and not be able to grip it anyway.

    I am in the middle of painting several cabinets, and not wanting to produce any dust, won't get a chance to test the bit for several days. I'm going to make sure I really tighten my bits. My book on routers says that tight enough means holding both wrenches with one hand and squeezing the wrenches closed. My router really requires that I position the wrenches on opposite sides of the bit, and I just make sure that the collet is snug; I don't put a lot of muscle into tightening, afraid I will over tighten.

    Obviously I'll have to make sure no dust resides inside the collet before I stick in a bit. Go light no my cuts, especially when using MDF, and see how my bits fare...

  8. #8
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    RE: damaged router bit?

    The person at the box store needs to be hose-whipped. The advice to use sandpaper instead of emery is REALLY BAD advice.

    Ah, you've maybe not wrecked your bit... but don't do that again. Really, use emery and nothing but emery.

    The reason... the little abrasive crystals in ordinary sandpaper (garnet, especially, but also alumin(i)um oxide and silicon carbide) are sharp-pointed crystals that make little fine scratch marks, eroding the surface you're sanding like cutting corrugates in a field. By comparison, emery is little roundy-shaped abrasives that flatten scratches & polish the surface. Emery yields a far better machine surface than sandpaper, and much lower cost of metal.

    Give your bit a try & see what happens. It may be OK this time... but if you have any more troubles with it, ya'd probably best s-can it & get another.

    -- Tim --

    Belief that anarchy leads to chaos
    implies that the believer would be chaotic
    without supervision.


  9. #9
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    RE: damaged router bit?

    >The person at the box store needs to be hose-whipped. The
    >advice to use sandpaper instead of emery is REALLY BAD
    >advice.

    Ugh! I thought something didn't seem right. Stupid, stupid box stores. My local hardware store is staffed by idiots who don't know anything, and the big box store--well.

    Now I know at least.

  10. #10
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    RE: damaged router bit?

    Yeah, that's the way it is all most of those stores, from mom & pop to the big boxes... with the big boxes being the worst offenders. I sure wish there was something to do about it...

    -- Tim --

    Belief that anarchy leads to chaos
    implies that the believer would be chaotic
    without supervision.


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