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Thread: help with chuck questions

  1. #1
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    help with chuck questions

    Can someone please explain to me the limits or restrictions a 50mm chuck will allow me?
    Im a bit confused with all the chuck sizes available since I thought the jaws open and close to various sizes.

  2. #2
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    The chart below shows the minimum / maximum travel of Nova chuck jaws.
    Min. / Max travel of Nova chuck jaws

    But the best holding power is when the diameter of the recess / tenon is close to the circle of the jaws closed.

    As shown in the picture: when the tenon is a lot larger than the diameter of the jaws, only the 2 corners of each jaw bite into the tenon. These concentrated force would crush the tenon. The holding power would be smaller than when the whole arc of each jaw is making full contact.



    For the same reason, when the recess is too big, only the apex of each jaw is making contact.
    Gordon

  3. #3
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    so according to that chart, the contracting size for square stock is between 1.22 and 2.04, so is my thinking incorrect?, the optimum hold will be at somewhere right in the middle of those two numbers?

  4. #4
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    There are 3 pairs of numbers there.
    Expansion mode: The chuck jaws are expanded into the recess.
    The min. is 2.008" but the max has 3 figures, ranging from 2.402 to 3.228. It is because the 3 models of chucks has different range of movement.

    Contraction mode:
    1) square stock: 1.220" to 1.614" wide square stock.
    2) round tenon (spigot): 1.654 to 2.047~2.874 (depending on chuck model)

    In use, the ideal recess size is slightly larger than 2.402 (that is when the jaws are almost fully closed).
    In tenon, slightly larger than 1.654.

    Of course, wood would shrink, if you double turn, you will have to allow extra for truing up the tenon when it shrinks and deforms after drying.

    In woodturning, you don't need jaws to cover the whole range of sizes. You can always use glue block and jam chuck to augment what your don't have.
    Gordon

  5. #5
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    Im going to get a 50 mm chuck.
    Im very new to this spinning stuff.
    Cant I just take an old 1.5 inch diameter closet pole and cut down 1 inch pieces to use as glue blocks for anything small I spin? I used birch and had a hell of a time cutting it off. when I used a 2x4 for a block, the cutting tool went thru it like butter and cut it off in a perfect straight line.
    Im thinking a turning book might be a big help to me.

  6. #6
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    The 50mm is a good size that covers a lot of things. I use my 50mm jaws for probably about 85% of the stuff I do. Keep in mind you can always get other jaw sets for your chuck later.

    The 1 1/2" diameter closet pole will be a bit too small to fit in the 50mm jaws. 1 3/4" would fit. A piece of 1 1/2" x 1 1/2" square stock will fit, though.

    I think once you get the hang of sharpening your turning tools, you'll find the birch also cuts like butter.
    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

  7. #7
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    I went with Tecknatool super nova 2. I hope I made a good choice.
    since my lathe knowledge is zero at this point, Im hoping a chuck like the nova will help me(as in facilitate the procedure) turn knobs for alot of the flatwork I do.IM currently just about finished with the lingerie cabinet, and would love to turn 2 door knobs, and 3 drawer pull knobs.simple simon stuff, but Id still like to do it myself.

  8. #8
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    That's a super chuck, Allen. It's at the upper end size-wise of what you can run on a Jet Mini, but it's also a chuck that'll move up to a bigger lathe easily when you decide you want to turn bigger things than the mini can handle.

    I have two chucks for my Powermatic...the Nova G3 and the Supernova 2. The Supernova is my big one.
    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
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    woodcraft had them at 35 or 39 dollars off with free shipping.

  10. #10
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    allen, i've had one of the first nova chucks, and one of the first supernova chucks, and i like the super better. the t-bar tightener is a lot better than the 2 bar system on the first one.
    benedictione omnes bene

    www.burroviejowoodworking.com

    check out my etsy store, buroviejowoodworking

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