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Thread: Questions on Chucks

  1. #1
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    Questions on Chucks

    Hi All

    There are several articles, posts etc on the various chuck designs for holding objects such as bowls.
    I wanted to ask advice on the merits of these various means having read a number of differing posts.

    I just completed my own making of a Longworth chuck. Given the wing nuts that go on the rear I had to make up a spacer to push the mounting nut forward to clear the motor on my cheapo lathe with Reeve drive and motor proud of the spindle. Although its complete I am not so sure about the safety of these chucks. I have 5 "holding points".

    Then there are cole jaws with essentially similar mounting to the Longworth if one considers the rubber buttons being pressed against the side of the bowl.

    Then there is the doughnut chuck with two plates one being a ring.

    Can an enlightened turner shed some light on the merits of these chucks and when to use them and what to expect to achieve with them.

    I have made mine, battled with getting it to rotate without a wobble after truing up each step of the way. Its good but still wobbles a little.
    I want to use it to turn out the base of a pretty flat bowl and insert a disc of different wood which i have turned. Want to create a step in the cut out but the "wobble" now seems a little too much for my liking.

    I will get to take some pictures and post. But I have now considered that maybe making a cole jaw chuck using my real chuck jaws and only introducing the variable of mounting the plates on the front of the jaws as a better proposition to the Longworth. But what about the other doughnut version.

    Making these devices is one thing, using them another thing altogether.

    Please throw you 5 cents in the ring.
    cheers

  2. #2
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    Rob,
    I just made my Longworth the other day too... ran into the same problem of needing to move the chuck forward to clear the motor. The plans call for a spacer on the back to accept the face plate... I went one step further and added a second spacer that was sized to fit in my Barracuda chuck... this way I don't tie up a face plate and by placing it carefully in the chuck, I get a fairly true spin and the wing nuts are far enough away from the motor to not hit it.
    Chuck
    Tellico Plains, TN
    https://www.etsy.com/shop/TellicoTurnings
    My parents taught me to respect my elders, but it's getting harder and harder to find any.
    If you go looking for trouble, it will usually find you.

  3. #3
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    Rob, I've not used Cole jaws yet, but in my experience with Longworth and donut chucks, it's real difficult to reverse a bowl and get it to spin perfectly true. In most cases you can get it pretty darned close, but I don't think I've ever gotten it to be "machine shop" exact. I've just gotten things lined up as good as I can, did whatever cutting was necessary (with the the tailstock also holding the piece as much as possible) then evened out any discrepancies with sandpaper.
    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

  4. #4
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    Rob when I use a longworth chuck or donut chuck I leave the bowl in the chuck. I remove the chuck with the bowl still chucked and put it on a adaptor in the tailstock. Mount in the donut chuck and remove chuck off the bowl. Walla bowl is centered and runs true.
    Bernie W.

    Retirement: Thats when you return from work one day
    and say, Hi, Honey, Im home forever.

    To succeed in life, you need three things: a wishbone, a backbone and a funnybone.

  5. #5
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    Bernie, great tip thanks!
    -Ned

  6. #6
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    Thanks guys for all the feedback. You comfirm my thoughts. Thanks Bernie for the really practical tip. I will try that next time as i have already removed this bowl.

    Just on the side i had a pm from a member that reminded me of past experience which i had buried so deep in my memory.

    I had a stint involving vibration monitoring on turbo machinery such as turbines in power stations. Our "spinny" lathes a mini replica of this type of device in that there is a shaft (spindle) being driven and running in bearings to which we attach essentiall an overhang weight.

    When we true up a piece of wood on a "good" machine we essentially somewhat balance the object since part of the wobble we remove is not merely the out of true wood but additional weight that is causing the object being turned to wobble somewhat.

    Next time i am in the shop, I am going to examine the "wobble" inherent in my lathe.

    I know we all love to make tools etc and I am inherently frugal on some things for reasons i do not know and then spend like crazy on others for similar reason.

    But one things for sure with tools, you get what you pay for most times.

    At a recent WW show I got to look at some of the "more decent lathes" still in the mid range. Boy when i got home and examined some of the similar aspects of my POJ (new acronym Piece of JUNK) i realized why it was the price it was. Hey but its given me a lot of fun ,,,,,,,but also needless frustration at such a potentially dangerous machine.

    Well overall i thouroughly enjoyed making my Longworth Chuck and thats whats important to me. Still i would like to turn something nice so I will give Bernies idea a try.
    cheers

  7. #7
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    Quote Originally Posted by Bernie Weishapl View Post
    Rob when I use a longworth chuck or donut chuck I leave the bowl in the chuck. I remove the chuck with the bowl still chucked and put it on a adaptor in the tailstock. Mount in the donut chuck and remove chuck off the bowl. Walla bowl is centered and runs true.
    I do the same thing, especially when using the vacuum chuck, but I've learned that the bearings in my tailstock live center (where I attach the scroll chuck) have a very slight amount of play in them, so the weight of a bowl and chuck hanging off the live center can cause it to droop a miniscule bit...enough to make things off center if I don't lift the bowl slightly when I attach the chuck.

    Also, with a donut chuck, if the rim of the bowl isn't perfectly flat and perpendicular to the scroll chuck, the bowl will be a bit off-center when it's put in the donut.
    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

  8. #8
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    Quote Originally Posted by Bernie Weishapl View Post
    Rob when I use a longworth chuck or donut chuck I leave the bowl in the chuck. I remove the chuck with the bowl still chucked and put it on a adaptor in the tailstock. Mount in the donut chuck and remove chuck off the bowl. Walla bowl is centered and runs true.
    Bernie,
    Do you have a picture of your adapter??

    I do something similar.. when I'm ready to mount a bowl in the longworth, I find the center of the bottom of the bowl, set the point of the live center against that, then move the bowl into the longworth. I can then move the holders up to the bowl and tighten... usually get a pretty well center bowl.
    Chuck
    Tellico Plains, TN
    https://www.etsy.com/shop/TellicoTurnings
    My parents taught me to respect my elders, but it's getting harder and harder to find any.
    If you go looking for trouble, it will usually find you.

  9. #9
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    There is something in this conversation re Bernies concept that has me puzzeled. When you guys slide your tailstock toward your spindle with the lever loose (naturally ) how much side to side play do you have.?
    cheers

  10. #10
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    Quote Originally Posted by Rob Keeble View Post
    There is something in this conversation re Bernies concept that has me puzzeled. When you guys slide your tailstock toward your spindle with the lever loose (naturally ) how much side to side play do you have.?
    On my Jet, I don't notice any side to side play..the tail stock sits flat on the ways so there's little room for play..
    Chuck
    Tellico Plains, TN
    https://www.etsy.com/shop/TellicoTurnings
    My parents taught me to respect my elders, but it's getting harder and harder to find any.
    If you go looking for trouble, it will usually find you.

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