Jacobs keyless chuck loosens when starting the mill.

Discussion in 'HMEM Forum Support & Suggestions' started by Frank Bauer, Aug 12, 2018.

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  1. Aug 12, 2018 #1

    Frank Bauer

    Frank Bauer

    Frank Bauer

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    I have recently been having a problem with my Jacobs JKP-130-J6 keyless chuck loosening when I start my Bridgeport. It has thrown the drills when I see they have come loose and turn off the mill. Has anyone else experienced this issue? Can the issue be resolved by disassembly and cleaning of the chuck? Any suggestions??
     
  2. Aug 13, 2018 #2

    Brian Rupnow

    Brian Rupnow

    Brian Rupnow

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    Frank--How old is the chuck, and how much work has it seen? I don't think you can fix that. Try a total degreasing of the chuck. If that doesn't fix it, then junk it and buy another. There are enough things in our shops that will hurt us without trying to save $100 on a worn out chuck.
     
  3. Aug 13, 2018 #3

    Frank Bauer

    Frank Bauer

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    Thanks, Brian. The chuck is about 15 years old but has not seen what I would call "heavy" use. However, it has been a key piece of equipment in the building of my 1.6" Mikado live steam locomotive. I'm planning on giving Jacobs a call tomorrow and hearing what they have to say as well.
     
  4. Aug 13, 2018 #4

    MachineTom

    MachineTom

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    Some years ago I installed new jaws in an Albretch keyless chuck. On their website the direction state Do NOT Lube the jaw carrier. Well I did anyway, quickly found out why. Turn the machine off from high speed and the chuck opens an spits out the drill bit.
    Sometimes the direction really are correct.
     
  5. Aug 13, 2018 #5

    rklopp

    rklopp

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    The symptoms sound strange. My keyless chucks would tend to self-tighten from their own inertia during startup acceleration. That is because right-hand rotation tightens the chuck and right-hand rotation is what one normally gets when turning on a mill. The only time I have had issues with inertial loosening is with lightly-chucked flimsy plastic parts in a scroll chuck and lightly-chucked flimsy plastic parts in a collet with a large handwheel collet closer. In both cases, the direction of acceleration is opposite the direction of tightening of the scroll or handwheel.
     

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