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Thread: Problem with steam bending jointed panel

  1. #1

    Question Problem with steam bending jointed panel

    I matched and jointed two 1/8" thick 8" wide panels for a
    speaker. One of the panels needs to be bent because the
    speaker curves toward the back. The wood is figured Oregon Big
    Leaf Maple and I judged that I need steam to bend it so
    I fixed a panel jig to bend it and all that went well. The problem
    is that the bent panel has a crook and doesn't line up with
    the other panel. The 2 options I can think of are
    1) joint that panel again, which is a hassle because the panel
    is bent and the match would be off a bit.
    2) kerf bending the panels instead of steam bending, but I worry
    the panel will split because it is already 1/8 inch thin.

    Any other options?.

  2. #2
    Join Date
    Mar 2003
    Location
    San Francisco, CA
    Posts
    10,301
    One fix is to glue curved ribs to the panel to force it into the correct shape. You can hide the ribs inside the box, or apply them outside and call them decoration.

  3. #3
    I would be tempted to buy some maple veneer, some figured for the show areas and plane for the core and insides. I'd laminate them on a form under vacuum or because they are not wide with bungees or surgical rubber tubing.

  4. #4
    I think need to explain more Here it is dry clamped. The curved panel is
    on left:
    DSC02383.jpg

    Here it is at the top. The right panel is true but the
    left panel is flush at the top and bottom only:
    panel end.jpg
    But as you see below not in the middle: The crook is on the left panel.
    Panel crook1.jpg
    Here is my bending jig:
    Panel bend jig2.jpg

  5. #5
    Join Date
    Aug 2013
    Location
    Providence, RI
    Posts
    517
    Is the curved panel laying flat on the substrate from side to side when it is clamped? If it is standing proud in places, this could cause the sort of gapping you observe. You can use wedges underneath the band to focus clamping force on problem areas.

    Tape across the joint (with reinforced packing tape or the like) to pull it tight before you clamp.
    -- Jim

    Use the right tool for the job.

  6. #6
    what about a ribbed sled for the table saw? With the proper blade tilt you could control the cut more than jointing.

  7. #7
    It is flat on the substrate. Basically what happened with the bending is that
    it stretched out the middle to the side, sort of like when you roll out dough and
    roll out more in the middle

  8. #8
    Quote Originally Posted by Bradley Gray View Post
    what about a ribbed sled for the table saw? With the proper blade tilt you could control the cut more than jointing.
    That is a great suggestion. Much easier to control the cut. That's what I will do unless I find a way to avoid the crook while bending. I was wondering about
    blocks on either side of the jig the width of the panel to keep the shape. Isn';t that the role of the blocks on a steel belt when you bend curves for chair backs,
    etc.?

  9. #9
    The end blocks on a steel backing strap are to keep the wood being bent in compression. Your situation is different because you are bending across the grain. Bending is not an exact process (for me anyway). I think you will need to trim after bending.

  10. #10
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    I would try to hand plane the high spots on the edges in order to get a better fit. From the pictures this would seem the best solution. Just mark the high spots, trim them carefully with a shatp handplane taking thin shavings, repeat as needed.

  11. #11
    I think I have my answer. Bending is not an exact process, and I need to do the final
    jointing with a plane or tablesaw after bending. Thanks everyone!!

  12. #12
    Join Date
    Apr 2017
    Location
    Michigan
    Posts
    2,754
    Steam it again. It will flatten out in the steam box. Adjust your form to add the extra bend where you need it.

  13. #13
    The bend is fine. The problem is that there is a crook in what started out as a perfect joint. So
    whereas before the two panels where perfectly flush, now the bent panel is not flush anymore
    but curves away in the middle.

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