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Thread: reversing a bowl

  1. #1
    Join Date
    Jan 2015
    Location
    greensboro nc
    Posts
    198

    reversing a bowl

    can anyone help me out on this,,when I reverse a bowl to clean up the bottom using a chuck I always end up marring the inside which I have just finished,,i have used different kinds of materal to put on the chuck jaws to help but I still get bad results on the inside,,and reguardless of how you do it,,you have to have it tight or else it will go flying,,if anyone cold help I would really appreciate it,,i have thought about making some kind of soft jaws for the chuck but I don't really know what material I should use,,thank you

  2. I would recommend NOT using your 4 jaw chuck as a jam chuck! At least make one out of some wood, and use a couple of paper towels to cushion the inside mating surfaces. I use a Holdfast vacuum chuck head a lot of the time, which has a rubber seal on it, but still use a mouse pad for cushion to protect the mating surfaces.
    Last edited by Roger Chandler; 09-07-2019 at 1:26 PM.
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  3. #3
    I agree with Roger. Best to turn yourself a piece special for this purpose...something that will conform to the bottom of the bowl. And yep....mouse pads make great cushions.
    But keep in mind that any slippage will cause a bit of extra smoothing that will be visible
    ~john
    "There's nothing wrong with Quiet" ` Jeremiah Johnson

  4. #4
    Join Date
    Sep 2018
    Location
    Maryland
    Posts
    46
    In my opinion this is one of the harder parts of turning for the beginner (I have been turning for about a year and a half). I am eager to try a vacuum chuck but it is a relatively expensive solution and would require buying a more powerful compressor than the little one I have. Or a separate vacuum pump.

    I have one of Ron Browns combination donut/longworth chucks and it works well. But I find this is best when I am finishing the piece off of the lathe. If I want to use a friction polish I tend to use a mortise on the bottom of the bowl or remove the tenon with the piece off of the lathe because I find that reverse chucking usually damages a friction polish and I cant get it pristine again.

  5. #5
    I always turn a tenon on the bottom of my bowls and use that to grip with the chuck when I reverse the bowl to turn the inside. When the inside is done I put on as many coats of WOP as I need then I put the bowl on my jumbo jaws and turn off the tenon to get a smooth slightly concave bottom... http://www.leevalley.com/en/Wood/pag...330,69091&ap=1

  6. #6
    Join Date
    Apr 2018
    Location
    Cambridge Vermont
    Posts
    438
    What brand chuck do you have? Like Barry I use a set of cole jaws for my Vicmarc. One of the reasons I went with the Vicmarc is their "grippers" are square shape. Two sides have a concave curve to them while the other two are convex. Most of the other brands they are round. It just seams like more surface area to grip the bowl the better it would be to keep it from spinning. I would guess that the Vicmarc ones could be used with any brand of jaws but they are pretty expensive. I think Nova also has a square style.

  7. #7
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    8,324
    Quote Originally Posted by jeff oldham View Post
    can anyone help me out on this,,when I reverse a bowl to clean up the bottom using a chuck I always end up marring the inside which I have just finished,,i have used different kinds of materal to put on the chuck jaws to help but I still get bad results on the inside,,and reguardless of how you do it,,you have to have it tight or else it will go flying,,if anyone cold help I would really appreciate it,,i have thought about making some kind of soft jaws for the chuck but I don't really know what material I should use,,thank you
    I've used all sorts of way. My favorite is to turn a recess in the bottom, decorate around it and turn and finish the outside, then reverse and hold by the recess to turn and finish the top. All done, go to next project. Some old school turners are offended by this but that's their problem.

    penta_maple_ellis_c_IMG_5435.jpg bottom_PC012804_e.jpg bottom_cherry_IMG_7424.jpg BOC_D_demo_IMG_6702.jpg

    No jam chuck, cole jaws, donut chuck, or vacuum system needed.

    JKJ

  8. #8
    Interesting, John. Sounds great. Do you have to clean up any indentations left behind by the chuck jaws after turning around?
    ~john
    "There's nothing wrong with Quiet" ` Jeremiah Johnson

  9. #9
    Join Date
    Jan 2013
    Location
    sykesville, maryland
    Posts
    304
    I also do as John does. I'm still a beginner, but I find the mortise-first approach to be the best for me. Then you don't have to reverse it to remove the tenon. I use dovetail jaw sets. No marks yet.

  10. #10
    Join Date
    Jan 2009
    Location
    Harrisburg, NC
    Posts
    798
    I use a friction drive held in my chuck. I have about six to fit different size jaws and different diameters of the base. I try to have the drive "about" the same size as the base will be so that the wood will be supported directly under the cut. I find 3/4" ply works well and won't warp over time. I round the edges about a 1/4" and run thin CA glue where the chuck meets to give them longer life.
    To your question I have tried several things. Leather was the worst. Good is throw rug underlayment pad to keep a rug from slipping on hardwood floors. Cheap for a big piece at Kmart or about the same thing at a woodworking shop called a router pad but 1/4 the size and 3X the $$$ since it is now specialized.
    The best, and what I now use are the thin rubber jar openers from the kitchen. Thin so you do not have to apply a lot of pressure and gives a really good friction with the bumpy side towards the bowl. I used temp glue to hold mine on the ply so they are always ready to go. Three for $1 at the dollar tree but probably 2$ (?) each at a grocery store.
    Last edited by Michael Mills; 09-07-2019 at 9:04 PM.
    "I became insane, with long intervals of horrible sanity." - Edgar Allan Poe

  11. #11
    Join Date
    Dec 2014
    Location
    Cuero, Texas--Not too far from the third coast.
    Posts
    55
    I don't use a friction chuck. I'll use either a Longworth or my Vicmarc Cole jaws. To keep supported, I bought a Tailstock Steady that was developed by a friend--he markets them-- keeps the bowl in place and allows access with tools to clean up the bottom.
    Using Texas woods--especially Mesquite, the "Queen" of woods.

  12. #12
    Join Date
    Sep 2015
    Location
    San Diego, Ca
    Posts
    1,227
    I'm very frugal, but one of the best investments that I made was buying a vacuum pump from frugalvacuumpump dot com. I made a couple of vacuum chucks that connect up with it. It is SUCH A JOY to work with.

    It doesn't leave marks. It is great for cleaning up the bottom.

  13. #13
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    8,324
    Quote Originally Posted by John Hart View Post
    Interesting, John. Sounds great. Do you have to clean up any indentations left behind by the chuck jaws after turning around?
    No, I make the recess to just clear the closed jaws so there are no corner indentations. I also dovetail a bit so any minor marks are hidden. When gripping maple and other light-colored woods I wrap a but of scotch tape around the jaws to prevent any dark staining. I've probably done 100 of these so far and teach it at demos.

    I generally turn a little raised or depression inside the jaw seat for looks. The recess can be shallow, 1/8" or less - leaves a nice shadow-box effect for a place to sign the work. Non-turners love the surprise and detail when they turn the piece over. While some turners have said "you can't do that!", probably because they were taught that way, some of the most vocal have slowly started using this method. It solves a number of problems!

    bottom_goncolo.jpg bottom_IMG_4687.jpg

    bottom_IMG_4749.jpg

    bottom_maple_IMG_7444.jpg bottom_olive_IMG_7435.jpg

    BOC_A_comp.jpg

    penta_platter_cedar_IMG_7434.jpg

    I've used in on pieces from 6" to 20" in diameter. Never had one come off the lathe, even with a 1/16" recess. I do tighten the chuck gently and carefully, multiple times in each chuck socket. None of the cranking hard on one socket then spinning - I'm convinced the other method holds much better. (BTW, always dry wood for me.)

    JKJ

  14. #14
    A jamb chuck will protect the inside. However, if you are too aggressive with it, it can spin out which can burnish the inside. To prevent this, I use kt tape or sometimes even just a used 5 sanding disc, upside down so the soft side is against the bowl and the grit side is against the jamb. That provides enough friction. This also allows you to tighten the tail stock a little less. Really wrenching it down can cause your tenon to split when it gets Thomas you turn it off.

  15. #15
    Thanks John....I'm gonna give it a try the next time I do a bowl. Looks and sounds perfect.
    ~john
    "There's nothing wrong with Quiet" ` Jeremiah Johnson

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