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Thread: wobbly Mini chuck problem

  1. #1
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    wobbly Mini chuck problem

    I have two chucks, both from PSI. One is the big Barracuda 4, the other is the GMC3 Mini.
    I have had the Mini for a long time and it served me well with my old lathe, the Grizzly G1067Z. It ran true and smooth.
    Then I bought my new, fancy-dancy, Grizzly G0632 EVS lathe. On the new lathe, the big ‘cudda 4 runs just fine, true and smooth. But, the Mini is wobbly awful. Problem may be that it seats thread to thread.
    I went to a friends shop, an accomplished turner, and let him try it on his Powermatic. On that it seats on the shoulders of chuck and spindle and runs true.
    However, he showed me that his own chucks (which are Rolex class expensive) do not run true on his Oneway (yes, he has both). So, to correct that, he made wood washers for the chucks to seat against. Using those, his chucks run true on the Oneway also.
    So, I come home and made a washer out of Osage Orange. Tried the Mini and still was in the Wonderful World of Wobble. Not sure what the problem is. I’m quite certain I made the ends flat and as parallel with each other as possible. I’ll try some more flattening today on the belt sander. But, would appreciate any input on this.
    Attached Thumbnails Attached Thumbnails chuck 1.jpg   OO washer.jpg   chuck with washer.jpg  

  2. #2
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    Not sure what the problem could be Frank...hope you can figure it out of maybe someone here can. Doesn't look like you had to add an adapter to work on your new lathe...but sometimes those cause problems I've heard. Have you tried calling PSI?
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  3. #3
    I noticed a split in the ring you turned. when you tighten down the chuck does the split open up any? Have you tried indexing the spacerby putting a reference mark on it and then trying it at 90 degree intervals to see if it gets better or worse.

  4. #4
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    Quote Originally Posted by Alan Bienlein View Post
    I noticed a split in the ring you turned. when you tighten down the chuck does the split open up any? Have you tried indexing the spacerby putting a reference mark on it and then trying it at 90 degree intervals to see if it gets better or worse.
    The 'split' is pretty sturdy. I turned the washer on my big chuck with an inside grip and stressed it quite hard to test. It didn't open up at all. The pith was way off to the side and that is part of it. Strange.
    I'll try the indexing thing after I attempt to flattend the sides some more.

  5. #5
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    Have you tried taking a dial indicator on a magnetic base to it? Check for runout on rotation and against the face too. Also try it with your Barracuda as a reference. Might as well check your spindle runout while you're at it as well.

    My cheapo Grizzly set has saved my bacon when sorting out problems on my woodworking machinery. http://grizzly.com/products/Magnetic...-Special/G9849

    Have you tried the wobbly chuck again on your old lathe just to double check? Maybe try spinning it up with no jaws installed, just to check it out.
    Last edited by Dan Gonzales; 04-17-2009 at 04:11 PM.
    Dan Gonzales
    Whittier, CA, USA
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  6. #6
    Frank I just saw in the second picture of the wooden ring a difference in the color of the end grain which indicates to me that the two sides are not parallel.

    It's on the side with the split.

  7. #7
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    Frank, are these standard thread dimensions any help in sorting out the chuck register, you certainly don't want to rely on the thread form for alignment.

    If the attached is not big enough to read clearly then a larger pixel version is here.
    http://quest42.co.uk/woodwork/bin/AxminsterThreads.jpg
    Attached Thumbnails Attached Thumbnails AxminsterThreads.jpg  
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  8. #8
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    Quote Originally Posted by Dan Gonzales View Post
    Have you tried taking a dial indicator on a magnetic base to it? Check for runout on rotation and against the face too. Also try it with your Barracuda as a reference. Might as well check your spindle runout while you're at it as well.

    My cheapo Grizzly set has saved my bacon when sorting out problems on my woodworking machinery. http://grizzly.com/products/Magnetic...-Special/G9849

    Have you tried the wobbly chuck again on your old lathe just to double check? Maybe try spinning it up with no jaws installed, just to check it out.
    Old lathe gone. But it does run true on the Powermatic.

  9. #9
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    Quote Originally Posted by Alan Bienlein View Post
    Frank I just saw in the second picture of the wooden ring a difference in the color of the end grain which indicates to me that the two sides are not parallel.

    It's on the side with the split.
    Good catch, I'll skew or sand it flat and see what happens.

  10. #10
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    Quote Originally Posted by Chas Jones View Post
    Frank, are these standard thread dimensions any help in sorting out the chuck register, you certainly don't want to rely on the thread form for alignment.

    If the attached is not big enough to read clearly then a larger pixel version is here.
    http://quest42.co.uk/woodwork/bin/AxminsterThreads.jpg

    Thanks, they are the same as the General. 1 1/4"X8tpi.

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