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Thread: Problem using a chuck

  1. #1
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    Problem using a chuck

    Hi,

    I purchased a Oneway Talon Chuck. I turned a square 2 x 2 x 14 piece of hardwood into a cylinder. The cylinder diameter was the maximum possible with the piece of wood.

    Problem: After one, sometimes two, passes the wood would be loose in the chuck. I would tighten the heck out of it, repeat the action, and get the same loose wood result.

    I had previously turned a similar piece from the same piece of wood and had no problems. However, I was using a center drive with teeth instead of a chuck.

    I could not feel any flex in the wood in either case. Of course being a newbe to turning there could have been flex I would not know it.

    Where did I go wrong?

    Thanks for your response in advance and

    Enjoy,

    Jim
    First of all you have to be smarter than the machine.
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  2. #2
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    Hi Jim,

    I'm wondering if you are gripping the corners of the 2 x 2 stock with the chuck jaws? If so, the resistance that builds up as you turn can move the wood in the chuck to where the corners fall between the jaw plates and the wood comes loose. If this is the case, try holding the wood in the chuck with the corners between the jaw plates and that will give you two points of contact in each jaw and the corners held tightly between the jaws.

    It's 6.24am here and my brain is still asleep so I am probably way off the mark.

    Brendan

  3. #3
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    How are you gripping the square stock, Jim? The four corners of the square should be sticking out through the gaps between the four jaws, sort of like this:

    Click image for larger version. 

Name:	Chuck Square Grip.jpg 
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    Another approach would be to start out turning the piece between centers (with the spur drive) long enough to form a round tenon on the end of the piece of wood. Then you can grip it in the conventional way, like this:

    Click image for larger version. 

Name:	Chuck Tenon Grip.jpg 
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    When gripping a round tenon, it's important to not have the end of the tenon touching the bottom of the chuck. The piece should be resting on the shoulder of the tenon, as shown in the picture above.

    Let us know if any of this doesn't make sense.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

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  4. #4
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    Jim, are you sure your Tailstock is in alignment with the chuck spindle.

    Tailstock mis-alignment has little or no effect on between centres turning unless excessive, but if out when the stock is held in the chuck jaws, causes the wood to flex as it rotates, this then has a tendency to crush and bruise the wood slackening the grip in the jaws.
    Chas. just a traveller on the road of time.

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  5. #5
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    Hi Brendan,

    The jaws were on the flat parts and did not close enough to touch---there was at least an eighth of an inch space between the jaws.

    Thanks for the reply and Enjoy
    Jim
    First of all you have to be smarter than the machine.
    VOTING MEMBER

  6. #6
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    Hi Vaughn,

    The corners were sticking out between the jaws.
    I used the chuck instead of a spur just to do something with a chuck I had never used.
    I will go check. The wood may be touching the chuck body.

    Thanks.

    Enjoy,

    Jim
    First of all you have to be smarter than the machine.
    VOTING MEMBER

  7. #7
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    Hi Chas,

    The tailstock center and the drive center pin align within a tiny fraction of a millimeter. They were so close that I did not try to align them. The tailstock was well seated each time I retightened the chuck.

    Thanks and enjoy,

    Jim
    Last edited by Jim C Bradley; 10-29-2009 at 02:11 AM. Reason: Left a letter off of a word
    First of all you have to be smarter than the machine.
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  8. #8
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    Quote Originally Posted by Jim C Bradley View Post
    ...I will go check. The wood may be touching the chuck body...
    If you're chucking a piece of square stock, I believe it is advisable to have the piece "bottom out" on the chuck body. It's only when you're using a round tenon that you should rely on the shoulder of the tenon and keep the stock off the body of the chuck.

    Another thought...is the piece truly square, or is it slightly rectangular?

    I hope you can get it figured out.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  9. #9
    Join Date
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    Let's troubleshoot with another piece of wood, if we may... chuck up another blank (it can be really pretty short - maybe 2" or 3" long), and tighten the chuck just as you did this time.

    Release the chuck, take the wood out, and examine the jaw marks on the workpiece. Look really closely, even take a photo if you need to - we want to memorize what the jaw marks look like.

    Now chuck it back up again, tighten as before, and rough-turn it to a cylinder. When it's round, check it for looseness. If it's loose in the chuck, tighten it down again, then unchuck it for another examination.

    Compare the jaw marks now with the jaw marks from the first tightening. If they're really similar - not vastly different - then the chuck is somehow loosening on you (oil in the scroll? Something binding in the chuck?).

    If the second-time jaw marks are much deeper than the first-time jaw marks, then the wood is compressing under the pressure of the jaws and the stress of rough-turning. I suspect this is the case... especially if you're not using a live center to support the tailstock end.

    -- Tim --
    -- Tim --

  10. #10
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    Thanks Tim,
    I will try the short piece as you suggest.
    I did have tailstock support on the piece I was turning.

    Aside: Your avitar shows Gumby. Clocke was a patient of mine when I was in practice in Ontario, CA. He lived 7 miles away in Claremont, CA. I saw his original film he made to demo the Gumby concept. It was sheets, rods, spirals, etc. that changed in with the musical background. I don't know what they call it. However, there is a type of music that is VERY stimulating to a human and this is what Clocke used.

    He showed the film to a group. After the short presentation everyone was really high...you would have thought they were on drugs.

    Enjoy,

    Jim
    Last edited by Jim C Bradley; 10-30-2009 at 04:35 AM. Reason: Typo
    First of all you have to be smarter than the machine.
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