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  1. #1
    smieglitz's Avatar
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    another bellows construction dilemma

    I'm at the stage of assembling a square bellows and have a dilemma. I can't figure out a good way to glue the bellows together without envisioning a horrendous sticky mess.

    I have the stiffeners cut and ready to glue in place, have both spray adhesives and contact cements which should work, and I've even constructed a form from foamcore to help shape the bellows. The patterns have all been marked on the inside layer of the outer material (rubberized nylon darkroom cloth from Porter's) and I have cut the inner material (a a tightly woven, matte-black, pseudo-suede polyester) to a size and shape that matches the outer material. The stiffeners are alternating pairs of trapezoids and rectangles dimensioned to leave a 1/8" gap between them. The trapezoidal stiffeners will extend into the corner folds. ( I derived this pattern after tearing apart an old B&J bellows and looking at a Korona bellows that is falling apart.)

    The inside of the bellows will be 9 1/4" and the outside dimension 11 1/4" with 1" wide webs (is that the proper term?).

    I realize with a conical bellows you can just construct the thing inside-out and then push the small end through the large to invert it, but I can't see doing this with a square bellows without messing up the stiffeners.

    I'm thinking what I need to do is reverse the process from what I've read (View Camera article, Bardell's web page, a downloaded Deardorff pdf file, Hasluck's book). In other words, glue the stiffeners to the liner first, wrap the liner around the form and glue the liner seam. Then, glue the outer material and wrap it around the liner/stiffener layer and glue the outer seam.

    Am I overcomplicating this? The other option I envision is to simply lay the whole thing out and glue the layers together so it becomes one piece. Then I'd wrap it around the form and glue a single seam together. While this might be the easiest procedure, I'm concerned that this would double the thickness of the seamed area and cause problems. At the seam, there would be two thicknesses of liner, stiffeners, and the outer material. While I have planned for a 1" wide diagonal seam to minimize the seam thickness, I'm concerned this might cause some other unknown problem. I'm considering cutting the stiffeners on the seam layer and shortening them by 1" (the width of the seam) where the liner and outer material will overlap in order to reduce the overall seam thickness. While this might introduce a weaker spot, the thickness of the seam might compensate.

    Any thoughts or suggestions on all this? Any help appreciated. My brain hurts.

    Thanks,

    Joe

  2. #2

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    Hi Joe,
    have you been to http://www.srv.net/~vail/ and looked at how he layed out his bellows? How I made my bellows was to glue the stiffeners to the outer layer, when it came to the panel where the seam is I only glued half the stiffener down thenI glued the inner layer on top starting fromthe same side that had only half the stiffener glued leaving the opposing half of the panel unglued. Then when I formed the bellows into shape I glued the unstuck half of stiffeners to the inner layer(after carefully marking where each point must reach) then finally glued the outer layer. I used a half inch seam for the inner liner and then an offset seam that ran 1"from the center seam at the front to 2" at the rear.
    I think commercial bellows makers wrap the inner layer around a form glue on the stiffeners and the glue on the outer layer, this way you could have seams on opposing panels . Hope this helps

  3. #3

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    Hi Joe(again),
    I just realised you are making a square bellows and understand your concerns regarding the overlap. As long as your materials are pretty thin and ofset I don't think you will have any problems, you could make up a test piece from any offcuts to see how bulky it gets. Accuracy in strip placement is probably of more importance,both in keeping them parallel and spacing.
    good luck



 

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