Cutter/collet stuck in spindle
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  1. #1
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    A year ago I purchased a used Bridgeport 2J at auction. I'm finally hooking it up. It came with a cutter and collet installed in the spindle. I can't seem to remove them. I've hit the drawbar with a hammer a few times, but they are still stuck. Any suggestions?

    Many thanks,
    Ken

  2. #2
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    I hear that's what happens when the collet locating pin breaks.

    I would not try to knock it out with the draw bar ..might damage the threads.
    I would find a bar of similar size to the size of the collet end ..and bang away on this .
    one huge tap being better than several.

    might be an idea to make a bar in with the end that fits into the collet .but don't screw into the threads...........but has a shoulder on it as well.

    all the best........mark


    all the best.....mark

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    OK assuming that I can get it out using the method you suggest what then is the condition of my machine. Can I still use it, or do I need to repair it? Any idea how involved this type of repair is?

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    From what I've read here
    The collet is softer than the bore of the spindle
    The grub screw/set pin ..will have become squashed and in-bedded into the collet ..
    there will be little damage to the spindle bore ..with any luck .
    hope it all turns out OK for you ..

    what you have to remember when smacking it ...is that you are smacking the balls into the spindle races.


    so if you have to work hard at this ...new spindle bearings should be ordered
    all the best.mark

  5. #5
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    More than likely there will be little damage and you will be able to use it. You may need to stone the inside of the spindle if there are any high spots. If there is considerable damage you will have to get it reground and that needs to be done by someone who knows what they are doing. You will remove the spindle (with bearings) and send/take it to them and they will regrind it in the bearings, that way the spindle stays accurate.
    Best bet is to wait and see what the damage is, it might even just be seized with being in so long, its amazing how they can gum up after not being removed for a while.
    Hood

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    If it is the collet locating pin, you do not need to replace it. This usually happens when the R8 taper is overloaded and spins. The pin (actually a set screw) is not adequate to prevent this. It is faster to change collets without the locating pin and causes no harm.

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    Thanks everyone for your help.

    > It is faster to change collets without the
    > locating pin and causes no harm.

    Then what was the purpose of providing the locator pin in the first place?

  8. #8
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  9. #9
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    If at all possible you want to avoid axial stress on the spindle which might unseat the bearings.

    Take a block of steel and bore a hole just big enough to fit over the cutter and clear the collet. Bring the table up and lower the quill until the spindle nose is supported on the block on the table. Then hammer away.

    Another possibility would be to remove the spindle from the head and work on it separately. Much more convenient. You might be able to use a hydraulic press rather than beating on it.

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    Then what was the purpose of providing the locator pin in the first place?
    "Locator pin" is a nis-nomer. It's actually a drive pin. Since the R-8 taper is symmetrical about the axis of rotation, no "location" is possible. The pin will apply torque to the collet to drive it if it's not fully seated in the spindle.

    I believe the original intent was to just snug up the collet, then rely on the pin to provide driving torque. If the cutter jammed or was overloaded, the drive pin would shear and protect the machine from damage. But that's not the way most folks use the machine, and most drive pins are long gone.

  11. #11
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    I thought the pin was to stop the collet from turning whilst tightening the drawbar but more than likely I am wrong.
    Hood

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    I thought the pin was to stop the collet from turning whilst tightening the drawbar...
    It's identified in the parts list as "collet aligning screw", so perhaps that's its only intended function. I was taught that it was a drive pin. But since its function is not described in the literature, we're left to conjecture

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    I thought that all the drive was provided by the taper (ie morse int 5c 4c jacobs ect ect .)so
    why not just have straight shafts ?.

  14. #14
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    I thought that all the drive was provided by the taper (ie morse int 5c 4c jacobs ect ect .)so
    why not just have straight shafts ?.
    Taper would be needed to close the collet but it also provides the drive, I certainly wouldnt like to rely on that small pin as a drive. Then again when I think about the pin that holds the drive gear in my Student lathe ...... [img]smile.gif[/img]
    Dont suppose we will know for sure what the pins for, but my way of thinking is, the sooner the pin is taken out the better, but thats just my opinion.

  15. #15
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    Think the pin is there for short arses with short arms who cant reach and hold the collet and the drawbar at the same time...remember, when the bridgeport was thought up, people were smaller.

    A six foot bloke, would have been a giant in 1947 [img]smile.gif[/img]

    all the best..mark

  16. #16
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    Had that happen once on a #9BS, being a conservative sort.... Put a collet block on the table, placed a carbide drill in it and started drilling the collet out. At some point changed to a shank mounted boring head in the collet block. Eventually the pieces fell out.

    Lesson on the #9BS btw is keep them lubed... dry self holding tapers damn near weld themselves in.

    Cyclotronguy


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