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Thread: off set tenons

  1. #1
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    off set tenons

    Building a billiard chair, which is my first chair of any kind.
    20190210_133642.jpg
    And the upper and lower back rails are curved - going to re-saw and glue them up on a pattern, no problem there - but the tenons are off set.
    2019-02-10_20h17_10.jpg
    How do you guys and gals cut these? By hand? Make a jig for the TS? I have a nice cast iron tenon jig so I suppose I could McGyver something and use that. Just curious if there is a tried and true method. Or at least your favorite method.
    TIA
    Bill
    I'm not old. I've just been young for a very, very long time.

  2. #2
    Bill, i would lay them out carefully, cut them by hand leaving them a little thick, then chisel or plane them to fit.
    Stevo

  3. #3
    I'm not seeing how you cut that tenon out of that lamination. I would use a loose tenon to avoid the cross grain situation I'm seeing.

  4. #4
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    Tenons should be in alignment with the grain, the mortise should be made an angle to accommodate those tenons.
    Bumbling forward into the unknown.

  5. #5
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    I have been making some chairs for myself with a similar back rail. The curve seemed pretty slight so I just cut it out of a piece of 8/4, cut the tenons and shaped the curve after. I can see if laminated the tenon should follow the grain.

    59D67E90-8B8C-44F7-8CE8-8CBE92D31387.jpg

  6. #6
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    Joe, I cut them the same way from solid stock when the stock thickness allows for enough cross-section since it does follow the grain even though there is a curve to the part. In Bill's case it sounds like he plans to laminate them, so he's be making short grain tenons if they were cut into that shape.

    These are the bridle joint version of that same scenario:



    Bumbling forward into the unknown.

  7. #7
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    Cut them out of solid stock. As already said, cutting them out of a laminated curve creates short grain tenons.

    Offset tenons are used all the time with chair making. You set them out and cut them while the stock is still square, then cut the curve. A good tenonning machine does this. Doing them other ways may require extra set ups. Cheers

  8. #8
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    When you laminate them, fixture it such that the ends bend back straight at the end (at least to some amount).

    Then run through the bandsaw to cut the first cheek on the convex side (the tips will be guided off the bandsaw fence at each end). This gives a flat surface to register against as you then cut the next cheek on the inside/concave side.

    Then yes often I end up cleaning them up with a shoulder plane.

    At least that is how I have done it.

  9. #9
    Quote Originally Posted by Brian Holcombe View Post
    ...


    That's a great looking piece!
    "Anything seems possible when you don't know what you're doing."

  10. #10
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    Quote Originally Posted by andy bessette View Post
    That's a great looking piece!
    Thank you!
    Bumbling forward into the unknown.

  11. #11
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    thanks for the comments folks. I think I'll get some 8/4 stock and cut the tenons and then cut the shape. Seems like the most straight forward process.
    Bill
    I'm not old. I've just been young for a very, very long time.

  12. #12
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    All of the other advice given here should be considered seriously, but I'll just say that I made tenons on a steam-bent rail just like Bill wants to make on his laminated rail, using jigs and my router table:
    Tenon Routing Jig.jpgCutting Back Rail Tenons.jpg
    Yes, there is some short grain. It may fail one day. So far the chair is still rock solid after four years.
    Chuck Taylor

  13. #13
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    Bill, based on the dimensions given in your drawing, if you're going to saw it out of one piece, you'll need a piece of wood at least 2-3/8 in. thick. See this. I don't think 8/4 will cut it.
    Last edited by Dave Richards; 02-11-2019 at 10:01 AM.

  14. #14
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    Quote Originally Posted by Bill Carey View Post
    Building a billiard chair, which is my first chair of any kind.
    20190210_133642.jpg
    And the upper and lower back rails are curved - going to re-saw and glue them up on a pattern, no problem there - but the tenons are off set.
    2019-02-10_20h17_10.jpg
    How do you guys and gals cut these? By hand? Make a jig for the TS? I have a nice cast iron tenon jig so I suppose I could McGyver something and use that. Just curious if there is a tried and true method. Or at least your favorite method.
    TIA
    Those are easily made with a shaper, I just put a tenon cutter on the spindle and it cuts both cheeks simultaneously.

    You could make a jig for your table saw to cut those as well, or you could cut them with a hand saw....Rod.

  15. #15
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    Quote Originally Posted by Bill Carey View Post
    thanks for the comments folks. I think I'll get some 8/4 stock and cut the tenons and then cut the shape. Seems like the most straight forward process.
    I have done a set of chairs this way and they were completely acceptable. Note that when you cut an arch you are cutting across the grain at an angle, so the grain pattern will look different than it does if a flat sawn board (or flat sawn then bent...)

    The back of the attached chair is close to your dimensions. These were laminated and bent then tenons cut. Sure the grain is at a angle, but not by that much and there little chance it will break (imo).

    I will look for a pic of the ones I did from thicker stock. With thick stock you have to cut a nice arc, then smooth it (I used a scraper followed by sanding). (and with bending you need a nice arc on the fixture but sometimes this is easier if built up from multiple layers)

    Both worked equally well imo.
    Attached Images Attached Images
    Last edited by Carl Beckett; 02-11-2019 at 4:46 PM.

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