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Thread: Turning off the Tenon

  1. #1
    Join Date
    Oct 2006
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    Tokyo Japan
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    15,582

    Turning off the Tenon

    Well there seemed to be some interest in turning off the tenon on the bottom of a bowl, I was doing one tonight, so I took some pics.

    Attachment 7571
    here is my smaller Donut chuck

    Attachment 7575
    I have a variety of rings for it, as well as an uncut blank or two.

    Attachment 7570
    Here is a small Cherry bowl I was just about finished, I only needed to turn off the tenon on the bottom.

    Attachment 7572
    I put the bowl in the chuck, but I was not happy with the size of the hole, it was a little small, it would not allow me access to the tenon and the sanding later, so I needed to make another ring with a bit larger hole in it.

    Attachment 7573
    I have some blanks for just this purpose, when I made the donut chuck, I cut 4 or 5 flat rounds for it, and as I need, I make new rings. All of the blanks were drilled and indexed together, so making a new ring is easy, just line up the mark, and bolt the ring to the face of the chuck, then cut a new hole in the new blank.

    Attachment 7580
    Here I have cut a new hole, I left the ring with the smaller hole in place, as I did not want to damage the foam on the flat of the chuck.

    Attachment 7574
    I then put a round over on the inside of the ring, by hand with a sharp knife, and attach some weather stripping stuff to the ring to protect the bowl.

    Attachment 7576
    Here I've centered the bowl in the new ring, using the tail stock. You can see that this ring will allow me greater access to the bottom of the bowl

    Attachment 7577
    I then turn off the tenon..........

    Attachment 7578
    ...and sand it, as well as put a coat of sanding sealer on it......

    Cont............
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  2. #2
    Join Date
    Oct 2006
    Location
    Tokyo Japan
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    .............

    Attachment 7581

    here is the bowl ready for some hand sanding, then a coat or two of spray on lacquer, some buffing and some wax.....

    Attachment 7582
    The bottom of the bowl

    Attachment 7583
    here is my other donut chuck, a little bit bigger for bigger bowls, and the plywood is thicker too.

    Works well.

    The other way, maybe simpler way is to just use your normal 4 jaw chuck as a jam chuck

    Attachment 7584
    I have a piece of foam all cut and ready to do this.

    Attachment 7586
    here you can see the foam padding on the inside of the bowl, protecting it from the 4 jaw chuck

    Attachment 7585
    Here the jam chuck is ready to use, but, on this bowl, I left the center nub, on the tenon, way to small, and the nub would most likely break off, causing bad words to be said.

    This method works well too, you usually have to do a bit more hand sanding but that is no big deal.

    Hope this helps.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  3. #3
    Being a Clutz....I prefer the donut method but on some spindle work I will turn away the tenon with either a parting tool or my skew with the lathe speed turned down; supporting the turned object with one hand and the tool doing the parting with the other hand. Note ...I generally hold my breath while I do this.....

  4. #4
    Join Date
    Oct 2006
    Location
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    Ken on spindle work, with a live center, not a cupped center, I'll do that too, no problem, little trick, just as it gets close, give your tail stock half a crank, and often when the last little nub is cut, the cut off piece pauses for a second, then keeps on spinning, just from the friction.

    A little nerve wracking at first, but I find it works well.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  5. #5
    Join Date
    Feb 2007
    Location
    St. Joseph, MO
    Posts
    52

    Exclamation

    Stuart,

    Maybe I'm one of those lop-sided people. I built a donut set-up because I'd seen one posted somewhere. But, I have a great deal of difficulty getting the piece centered perfectly.

    How to you assure that you are 'right-on'?

  6. #6
    Join Date
    Oct 2006
    Location
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    Sandy, you NEVER get it perfect, you get it real close, make the chuck fairly loose, so it is applying just a bit of pressure on the bowl, move the tail stock up, and put the live center tip into the hole on the nub, while doing this, slowly rotate the chuck and bowl by hand, when it looks fairly goo, tighten up each bolt a bit at a time.

    once I get it fairly tight, I turn the lathe on at maybe 500 rpm (while standing out of the line of fire, just in case ) and take a look, if it is really wonky, have another go.

    The thing is to not do a lot of cutting on the area that is NOT the tenon, if that makes sense, and the cutting that you do, is very light, then you use the #80 grit gouge to blend the two areas

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  7. #7
    Join Date
    Feb 2007
    Location
    St. Joseph, MO
    Posts
    52
    And don't we all LOVE that 80 grit gouge.

    Reminds me of a golfing incident when I was in a sandtrap and resorted to a 'hand wedge' to get out.

    Thanks - my patience doesn't usually allow for a lot of tweaking and twiddling. I have to start relaxing more and 'git rid of my "Git 'r done" attitude'.

  8. #8
    Join Date
    Apr 2007
    Location
    Decatur, Illinois
    Posts
    177
    new guy to turning so ignore stupid statements...

    i saw this article in april 2007 popular woodworking on a longworth chuck. it looked like it would answer my question of how to hold a bowl to finish off the base or foot. so i built one following that article.

    Attachment 8074

    Attachment 8075

    this is a small chuck so only room for four buttons. a larger chuck would take six buttons. the mounting is hickory with threads so it mounts directly to the headstock.

    one of the things that seems at odds with this design is that the buttons must be slightly loose to tighten the chuck on the workpiece by rotating the two plates. then you tighten the buttons with the wing nuts. if the buttons are not uniformly loose when you rotate the two parts of the chuck it seems they would pull the piece off center when tightening the wing nuts.

    anyone have experience with such a device???
    Last edited by Clark O'Neill; 04-02-2008 at 12:27 AM.
    99% of lawyers give the rest a bad name...Steven Wright.

  9. #9
    Join Date
    Oct 2006
    Location
    Tokyo Japan
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    15,582
    Greetings Clark, welcome to the family!

    The Longworth chucks have been around for a while and generally get great marks!

    I've not made one............. yet, but I will, at some point

    Your little one looks good, nice and smooth, how does it work?

    I've seen even larger ones with only 4 buttons, but usually they have 8. I understand that they are really only for finishing the bottom, no heavy cuts of any sort, as they are only holding by them little rubber buttons.

    To center a piece on the Longworth chuck, it would be best to bring the tailstock up and use that to center it, then rotate the two plates of the Longworth chuck to tighten it up. If you don't have that little nubbin on the foot of the bowl to center with the tailstock, then I guess you will have to root around a bit to get the best center you can find.

    Again, Welcome, and thanks for posting with pics!!

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  10. #10
    Join Date
    Oct 2006
    Location
    ABQ NM
    Posts
    29,079
    Clark, I've got a Longworth chuck. Gimme a bit of time to take a few snapshots, and I'll start a thread about it. I've found it to be useful, but a bit limited. Like Stu said, light cuts only, and in my limited experience there is still some tweaking and compromise to be done as far as getting the piece exactly centered. (Much like the donut. The 80 grit gouge saves the day.) I use the live center to get it as close to centered as I can, and try to get the foot as finished as feasible before removing the tailstock, which is left on the last little 1/4" or so diameter nubbin. The longer I can keep the tailstock in place, the lower the odds of me launching the piece. (The only time I've been hit by a flying bowl was using the Longworth chuck, so I'm a but leery.)

    Oh, and welcome aboard. Glad to see we finally got you in...always nice to add a turner to the Family.
    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

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