Fast unique assembly method !

Discussion in 'Wooden Boat Building and Restoration' started by redreuben, Mar 8, 2011.

  1. redreuben
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    redreuben redreuben

    Found this on a Yahoo forum for K designs, clever and fast assembly method for ply boats, this will probably be copied. Check it out !
     
  2. redreuben
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    redreuben redreuben

  3. redreuben
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    redreuben redreuben

    Question. Do you think the keyhole or jigsaw method of joining panels (photo 2 ) is as good as a scarf or adequate for the task ?
     
  4. rwatson
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    rwatson Senior Member

    yes, I think it would work fine. The keyhole technique adds a lot of strength to the panel, especially of the curves are really deep.

    I just built a test kayak out of 4mm mdf to check the panel cutting, and I glued the slightly curved joining ends with epoxy.
    Mdf is really rubbish material, but it showed no sign of delaminating or breaking while flinging the panels around the shop.

    That design looks really good, and as long as the outside is covered in glass and epoxy, the end grain poking through should be fine, probably even better than just gluing the inside frames as is normally done.
     

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  5. PAR
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    PAR Yacht Designer/Builder

    Am I the only one that sees the obvious issues with this method?
     
  6. redreuben
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    redreuben redreuben

    Well enlighten us ! Is it the end grain exposed on the hull exterior or the keyhole joins ? I posted this for discussion and enlightenment not snide comment !
     
  7. Squidly-Diddly
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    Squidly-Diddly Senior Member

    very similar to concrete form wedgies and ties.

    http://www.wallties.com/laydown_forms.htm

    genius.


    PAR, you understand this is just to hold the panels in place with the glue cures or while other fasteners can be installed, then you cut the tabs flush and do a little sanding.

    I believe the advantage of the wedgies and tabs is ease of adjustment when fitting the panels. Same idea as the temp wires in "stitch and glue" but different in that it all sets up as a solid mass of glued wood and it then cut flush.

    Looks like you could just grab and wiggle them loose or shove snug, or bump or tap around a little with the heel of you hand.
     
  8. rwatson
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    rwatson Senior Member

    I suspect that the wedges would be very firm, based on similar exercises in small woodworking projects, especially if they are glued there.
    In the 'old days', they used to build whole boats, and buildings like this, and wrap the 'sticking out bits' in rope or wet leather to hold them tight for the life of the structure.
    In this application, they are using the wood as its own fastening and after having spent a couple of days drilling holes for plastic ties and pulling them tight, it appeals to me. Of course, this would require proper tabbing on the inside as well - assuming they could reach all the inside of the hull.
     
  9. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I'd span the keyholed joints on the inside with a piece of the plywood

    all slathered with glue about 6" wide, just to make my self feel better.

    Sand the exposed end grain to a little under the surface of the hull and fair with that epoxy filler.

    One thing to keep in might when running wood in different directions is wood shrinks parallel with the grain.

    Well Know Example: the joists on a house floor will shrink/expand "height-wise", so any short blocks with grain running perpendicular should be cut 1" short and positioned 1/2" from both top and bottom of joist so it wont poke through if joist shrinks.

    Hopefully the wood on this sort of plywood boat will never get wet once finished and sealed.
     
  10. Squidly-Diddly
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    Squidly-Diddly Senior Member

    certain aspects of this harken to traditional Japanese

    carpentry where tensile strength of wood is used instead of metal fasteners.
     
  11. rwatson
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    rwatson Senior Member

    Hmm, I wonder if the encapsulation is going to be as thorough as a traditional hull that has no 'ribs' or other structure in it when the inside glass layer is applied .. ?

    Nope - another look ,and we have the rot setting in right up in the bow where there is no epoxy, and no way of putting any in with the floor in place.- also ,no way to tab the bow former to the hull material.

    Sure, the water will drain to the stern, but bare wood in the bow is a reall no no - especially with no ventilation up there.

    So, because the tab system relies on an internal skeleton beofre you can coat the inside of the hull, its a real worry.
     
    Last edited: Mar 9, 2011
  12. TeddyDiver
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    TeddyDiver Gollywobbler

    No you aren't..
     
  13. basil
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    basil Senior Member

    A possible solution to the issue of the ply rotting might be to epoxy coat the entire kit ply before assembly. I think the concept is fantastic, however the price of the kit seems a bit expensive.

    Tony
     
  14. redreuben
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    redreuben redreuben

    I asked the manufacturer if he glassed the back of the keyhole joins,
    "Hi,

    I think you're kit joining method is very clever, regarding the joining of the sheets, do you fibreglass behind the keyhole joins after assembly ?"

    And the answer...
    "hi
    yes i do if i use epoxy , if i use plexus i dont.
    regards
    claude"
    Which just begs more questions ! Plexus extraordinary !
     

  15. daiquiri
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    daiquiri Engineering and Design

    You need a very high cutting precision to match the slots in the sheets to the tabs protruding from the frames, don't you? Or you'll end up with a wavy stressed surfaces everywhere.
    Not for a backyard builder who wants to start from the scratch, imho, but could be a fast and innovative method for ready-to-glue kits.
     
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