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Thread: Bit slipping out of collet

  1. #1
    Join Date
    Mar 2011
    Location
    SC
    Posts
    36

    Default Bit slipping out of collet

    Twice recently I've had a 1/4" upcut bit slip down in the collet of my porter cable router while making a profile pass. The material is hardwood and I'm cutting .030" off in one pass at a depth of .735". Speed is 50 ipm. I decided to throw away the collet and have ordered some of the ER collets from PreciseBits.com. Now to my question: Will the new ER collets hold the upcut bit tight enough to keep this from happening, or should I also switch to downcut bits. I prefer upcut because I use carbide end mills that are reasonably priced compared to the downcut router bits.

    Thanks,

    Charlie

  2. #2
    Join Date
    Mar 2004
    Location
    Delray Beach, FL
    Posts
    3,708

    Default

    Your problem should be over with the new collet.

  3. #3
    Join Date
    Nov 2009
    Posts
    727

    Default

    You made the right decision to throw away the collet.

    If you still have a problem the bit is too small.
    Michael Schwartz - Waitsfield VT
    Shopbot prs standard 48x96. Aspire. SB Link.

  4. #4
    Join Date
    Jun 2009
    Location
    Thermwood Corporation, Dale IN
    Posts
    61

    Default

    There are two types of collets. If you look closely at them, some are split or have multiple splits from one end only, while others are split from both sides alternately. When the collor nut is tightened, the one split from both ends will compress evenly along the length of the bit. Whereas, the one that is split only from one end has a tendency to crimp the bit at one end or simply, it does not clamp evenly along the length of the bit.

    Also, I agree with the other comments. Once you slip a bit in a collet, get rid of the collet plus your bit is probably suspect also.

    Dennis

  5. #5
    Join Date
    Mar 2004
    Location
    Lenox High School, Lenox MA
    Posts
    916

    Default

    Have you tried doing a thorough cleaning of the collet? I had the same problem, bit slippage. I used a credit card to get into all of the openings and clean out the debris. It worked quite well. You may need a magnifying glass to do a good inspection.

    Phil

  6. #6
    Join Date
    Mar 2011
    Location
    SC
    Posts
    36

    Default

    Thanks for all the comments and advice. The new collets are arriving today and I will definitely take more care in keeping them, and the spindle bore, clean.

  7. #7
    Join Date
    Nov 2009
    Posts
    727

    Default

    When in doubt throw them out.

    I have seen some scarry situations resulting from the use of a bad collet.

    Keeping spares around is advisable as you won't be tempted to one that is questionable.
    Michael Schwartz - Waitsfield VT
    Shopbot prs standard 48x96. Aspire. SB Link.

  8. #8
    Join Date
    Feb 2008
    Location
    Miller Marine Products, Ridgefield Washington
    Posts
    877

    Default

    Here is a little collet 101 Never bottom out the bit in the collet always leave a little room. It is possible to not get the bit tighted properly because as the collet closes it draws the bit up if it can't move up it will not tighten properly. I have watched several people do this in the past.

    Mike
    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

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