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Thread: Stretch Wrap Chuck

  1. #1
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    Stretch Wrap Chuck

    A few days ago in Tom's Donut Chuck thread, I mentioned using a roughed-out bowl as a friction chuck. Since I had a bowl bottom to finish, I took a camera along for the ride.

    Here's the basic idea...the shallow bowl that's mounted in the chuck is a roughout that I don't plan to finish. It's got some hairline cracks that I don't think are worth the effort to fix. The bigger bowl on the right is the one I need to finish the bottom on:



    I put a sheet of rubber shelf liner/router pad in between the two, and used the tailstock to hold the bowl in place:



    At that point, I'd typically turn the tenon down to a nub, do any finish turning to the bottom of the piece, then turn the nub down to a cone and remove it, doing any final sanding of the foot off the lathe. I've used this method for a lot of bowls, and have been happy with the results. You can use a similar method for finishing the bottoms of hollow forms. To do that, the "chuck" bowl needs to be bigger than the hollow form, so the vessel fits inside of the bowl.

    But with this particular pair of bowls, I didn't really like the way the big bowl fit over the smaller bowl. So I went back to the scrap bowl pile and picked out another, larger bowl to use as the friction chuck. If you look closely at the photo, you can see I've re-trued the rim of the "chuck" bowl:



    Here again, I used some beat-up rubber shelf liner as an interface pad:



    And used the divot in the tenon from when the piece was first roughed out to center the bowl on the friction chuck:



    Giving me this:



    And from another angle. I should point out that the blue line near the bottom of the bowl shows me where the inside bottom is. Before reversing the bowl, I use the laser pointer on my hollowing rig to accurately determine the bottom thickness, so I know how much I can (or should) remove from the bottom as I finish it:



    Then I do any final shaping of the bottom 1/4 of the bowl, as well as start whittling away at the tenon on the bottom:



    Once the tenon was down to about 3/4" in diameter, I decided to take out a little extra insurance in the form of plastic stretch wrap. I wrapped it tightly around the joint between the two bowls, making sure to wrap in the same direction as the lathe rotation. (I don't want the lathe's spinning to unwrap the plastic.):



    Here's another view. You can see that I've done some initial sanding of the concave foot area (by hand, with the lathe running):



    The I go about turning the nub down to a cone. Here's a spinning shot:



    And another photo showing how I hold the detail gouge to get a shearing cut on the cone. I'll point the gouge the other direction to make similar shearing cuts on the foot itself. It was a bit exciting taking this shot one-handed, while holding the gouge in place right next to the spinning wood:



    And, the "free at last" shot. Notice that the bowl is still turning but the cone is not.



    Here, I've stopped the lathe and moved the tailstock back a bit. You can see that the cone stays stuck to the live center:



    At this point, any of the work I've done on the bottom of this bowl could have been done without the stretch wrap. As I mentioned earlier, it was there just for insurance. But since it was there, and since it was holding the piece securely, I decided to do a little bit more tooling on the foot after moving the tailstock out of the way. Here's the finished bottom after the extra tooling and final sanding:



    Although I didn't get any decent photos of it, the inside of the finished bowl did show some marks (they looked almost oily) from the rubber pad. Those marks sanded away easily with 400 grit sandpaper after I took the bowl off the lathe. The stretch wrap, however, leaves no trace on the finish-sanded raw wood.

    This isn't the only way to finish off the bottom of a bowl or hollow form, and it's not even one that I use very often (I usually skip the stretch wrap part), but it's one of many ways that works well.

    Questions and comments are welcome and appreciated.
    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

  2. #2
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    Pretty cool Vaughn. Posts like this are really tempting me to try my hand at spinning.
    Faith, Hope & Charity

  3. #3
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    You should give it a try, Bob. It's not addictive at all. Trust me.

    From one of my t-shirts...

    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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    This is a great example of using cling wrap to help solve turning problems.

    Here are a few other ideas for using cling wrap:

    When vacuum chucking a piece with voids or worm holes wrap the piece in cling wrap to help attain vacuum.

    When hollowing banksia pods use cling wrap on the exterior to help maintain integrity of the piece.

    When jam chucking a box body that refuses to stay on the waste block use several wraps of cling wrap just as Vaughn shows on his bowl to secure the box body to the chuck.

    When turning the inside of a bowl or hollowform with numerous voids and bark inclusions wrap the exterior with multiple layers of cling wrap to hold it all together. Sometimes by doing so you can finish an "impossible" piece of wood.
    I may be getting a little older physically but mentally I'm still tarp as a shack.

  5. #5
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    All good points, and ideas guys!

    I've also wrapped a HF that I was roughing out green that I had to leave over night and not finish with the wrap, I use the flat twine stuff sold at the home centers. It is a very versatile product!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  6. #6
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    Thanks for the how to pics Vaughn. Speaking for myself i find seeing how a pro like you accomplishes various operations moves me way up on the learning curve.

    Now seperately "THAT" bowl is looking awesome. Why? Well what struck me was depth/length/height call it what you like, but the proportions of the bowl look fantastic.
    So often we see shallow bowls, if not then hollow forms, but this apparent high wall and width of bowl .... well it just does it for me well done how about some VM good photos of the finished bowl and some actual dimensions. V nice.

    sent from my Atrix
    cheers

  7. #7
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    Quote Originally Posted by Rob Keeble View Post
    ...well done how about some VM good photos of the finished bowl and some actual dimensions. V nice.
    Thanks for the kind words, Rob. The pics will be coming soon. I'm waiting for the BLO to cure before it gets lacquer.
    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 Stuart Ablett View Post
    ...I've also wrapped a HF that I was roughing out green that I had to leave over night and not finish with the wrap, I use the flat twine stuff sold at the home centers. It is a very versatile product!
    I wrapped a wet hollow form that had only been shaped on the outside...no hollowing yet. Very pretty flame box elder, but it was real punky in spots, so I soaked it in Minwax Wood Hardener and wrapped it up tight and left it in a corner of the shop. A month or so later I opened it up and it had an amazing colony of black and white mold all over it. We're talking science project/Haz-Mat material. Some of the punky spots had turned to pudding. It was gross. And to add insult to injury, it had cracked, too.
    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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    This will sound trite...but that is a great looking bottom...the bowl that is Seen the same oily look from the padding and it does sand right off. I've had great luck wrapping up wet blanks in plastic since I have no sealer. No cracks in months...just mold.
    Your Respiratory Therapist wears Combat boots

  10. #10
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    very good tutorial and nice idea.............I will remember that
    First you have to learn the rules - Beginner
    Then you have to learn advanced rules - Professional
    Then you disregard the rules - This takes you to the master level................

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