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Bridgeport rattle in head when taking heavy cuts

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  • Bridgeport rattle in head when taking heavy cuts

    I have a Bridgeport step pulley machine, noticed that I get a rattle in the top of the head when taking heavy cuts, is this normal? If not what is the problem/fix

    Thanks

    Mike
    Mike Hunter

    www.mikehunterrestorations.com

  • #2
    It is an inherent characteristic of spline spindles.
    They tend to chatter, even to some extent when
    brand new and unworn.
    The problem is exacerbated by the fact that the
    cast aluminum top belt housing acts like a
    resonator, and the resultant harmonics make the
    chatter into a repeating cause and effect loop.
    The Bridgeport M-head is very bad for exhibiting
    this scenario of chatter propagation.
    Some (not all) milling machine designers recognize
    this, and have engineered a solution in different
    ways. Tree milling machines use a preloaded ball
    spline shaft for their spindle. Gorton chose to use
    a spline backlash eliminator mechanism. Deckel
    employs sliding broad face gears. And having the
    incidence of interface bathed in oil always helps.
    Shot answer is, no, it is probably not something
    that you are doing wrong. This is why Sir John
    hates Bridgeports.

    --Doozer
    Last edited by Doozer; 01-18-2016, 09:11 AM.
    DZER

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    • #3
      Dooser

      Thanks

      Mike
      Mike Hunter

      www.mikehunterrestorations.com

      Comment


      • #4
        It could also be some lash in the castellated coupler that disengages when you flip the lever for low speed or back gear. But that has some adjustment to it.

        JL...............

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        • #5
          The old timers solution to the noise is to fasten a cork with a heavy wire/rod clamp and place the cork against the spindle nose as a drag.
          The "snubber" does not make a lot of heat and just prevents the snap back in the spline. You use the indicator clamp to the right of the head casting for mounting the snubber .
          Rich

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          • #6
            Originally posted by Doozer View Post
            It is an inherent characteristic of spline spindles.
            They tend to chatter, even to some extent when
            brand new and unworn.
            .................................................. .................................................. .................................................. .....................

            --Doozer

            Exactly. I picked up a Bridgeport M-head to put on an horizontal mill. The head chattered badly. Replacing an internally splined coupler sleeve solved the problem. This was a few years back when B'port had the part in stock for 80 bucks.

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            • #7
              Yep.. many sources of noise in BP'S - the spline coupler, the spline itself, the dog clutch (high/low). You can go broke eliminating the source, especially if it's the spindle spline. To prove that, see if it does it the same with the quill extended (i.e., find a less worn spot). For the dog clutch (part is the spline coupler) - try it engaged or not. The engagement is tapered/straight when new; I seen them worn almost round. And... if you a have a vari-speed, a worn belt or sheave sleeves/shaft.
              Last edited by lakeside53; 01-18-2016, 12:18 PM.

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              • #8
                Or you could get more teeth into the cut by using a higher flute count. Two-flutes are the worst. Or use a higher helix angle.

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