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Thread: Finishing Bowl Bottoms

  1. #16
    Join Date
    Feb 2008
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    Quote Originally Posted by Mark Greenbaum View Post
    John, it was a real pleasure to meet you last weekend at TAW Symposium. How do you make the bottom on that last photo with the eccentric rings?
    I enjoyed meeting you too! (And a number of other people.) I had a great time. I decided not to win the Powermatic lathe to give you a chance.

    The multi-axis platter base idea is from my good friend Frank Penta:
    http://www.frankpenta.com/index.php/...out.pdf/detail
    He uses a wormwood screw to hold the platter off-axis in three places to turn detail in the bottom. I decided to make that one a little different with a common flat bottom on each recessed turned ring - a little challenging but not too bad. I was surprised at how little wood was needed to to hold the big platter to turn the front. Sapele.

    Oh BTW, I meant to post another photo of a recess I left in the bottom of some other platters. These platters are also sapele, 14" and 18+":

    platters_two.jpg platters_two_bottom_IMG_4753.jpg

    JKJ

  2. #17
    John -where did you hold the wood on this? On the inside of the large circle (expansion jaws)?
    Thanks,
    Tom

  3. #18
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    Quote Originally Posted by Thomas Wilson80 View Post
    John -where did you hold the wood on this? On the inside of the large circle (expansion jaws)? Thanks, Tom
    The chuck jaws are expanded in dovetailed recess at the smaller circle.
    I think adding detail distracts the eye from the recess and it's far easier than reversing again to cut away the recess (and I'm lazy).

    The recess is 3" diameter on this one and about 4-1/2" on the larger platter.

    platters_two_bottom_arrow.jpg

    JKJ

  4. #19
    Join Date
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    Quote Originally Posted by Thomas Wilson80 View Post
    Interesting idea Leo - I would have thought that those wood braces would either scratch or indent the bowl, but from the finished pictures that is clearly not the case. Might have to try that!
    Thom I never had a problem with scratching the pieces, but if you don’t trust it you can easily glue some soft material on these frogs or just add some paper tape, that would already make it less likely to scratch the finished wood.
    Have fun and take care

  5. #20
    Quote Originally Posted by Thomas Canfield View Post
    A loose fitting jam chuck/piece of scrap wood shaped to fit a ring of contact at about 1/3 or more of diameter of piece and a piece of rubber shelf liner, leather, or other soft pad will drive the piece with pressure of the live center in tailstock. You can then turn and finish the majority of the bottom leaving a small nub (diameter determined by quality of wood) that should be cut off with flush cut saw with protective material against bottom or chisel. Breaking off the nub can result in tearing out the bottom. Also care should be given to the pressure on the tailstock with a thin bottom.

    This is the method I use as well. I do sometimes use a vacuum chuck but thin bottoms and open grain wood will suction air right through the bottom.


    That is the reason to always leave a center point in the bottom to align for remounting. This jam method works for all sizes and even natural edge pieces. A modification of method with longer jam piece can be used on hollow forms when support of top.

    This jam method works vacuum will not work due to worm holes, bark will not fit cole jaws, out of round will not fit a donut chuck, ..............
    I use the jam and nub method mostly as well. Sometimes a vacuum chuck if the bottom isn't too thin.
    Pete


    * It's better to be a lion for a day than a sheep for life - Sister Elizabeth Kenny *
    I think this equates nicely to wood turning as well . . . . .

  6. #21
    Leo, any chance you might show describe how you made the extensions for your Oneway Mega Jaws?
    Pete


    * It's better to be a lion for a day than a sheep for life - Sister Elizabeth Kenny *
    I think this equates nicely to wood turning as well . . . . .

  7. #22
    Join Date
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    Quote Originally Posted by Peter Blair View Post
    Leo, any chance you might show describe how you made the extensions for your Oneway Mega Jaws?
    Peter I read your ??? but forgot about it, so I’m sorry for the delay.

    I have 2 sets, but this one was closest and I just placed one of the pieces on the jumbo jaw plate, you can see that I only have holes drilled for anything larger than the regular jaws can hold, the the other set I made first from MDF has more holes farther out and I actually tapped thread in the MDF to hold the buttons, works fine and with longer bolts I can have nuts on the back side.

    You can see that I used the long slot in the jaws to bolt the extension to it,rather than go trough the treaded holes, this works just fine for me on the Oneway Mega Jumbo Jaws.

    Mega Jumbo jaw extension.jpg front side extensions.jpg

    Maybe I should explain how I made it, cut a large circle of ¾” plywood on the bandsaw, laid the chuck with the jumbo jaws mounted and slightly open to mark the slot openings on the plywood and lines to saw the circle of plywood in 4 quarters.

    Marked/numbered the pieces so they sit the same when mounted, drilled the holes for the bolds to go through the slots, outer holes bigger and deep enough for the bold heads to sit flush or slightly lower.

    Mounted the pieces after they where sawn and trued the perimeter and scribed lines to drill the holes for the buttons and at the same distance apart.

    Any other ?? just ask
    Last edited by Leo Van Der Loo; 02-07-2018 at 11:43 AM.
    Have fun and take care

  8. #23
    Thanks Leo
    Pete


    * It's better to be a lion for a day than a sheep for life - Sister Elizabeth Kenny *
    I think this equates nicely to wood turning as well . . . . .

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