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[bolger] Re: Michalak butt joints

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  • bianco@asi.it
    bianc-@asi.it wrote: Leander, there s a lot of info around on plywood backed butt joints, but not always coherent. I have two books treating the matter rather
    Message 1 of 5 , Sep 3, 1999
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      bianc-@... wrote:

      Leander,
      there's a lot of info around on plywood backed butt joints, but not
      always coherent. I have two books treating the matter rather
      extensively, i.e. "BOATBUILDING WITH PLYWOOD" by Glen L. Witt and "A
      MANUAL OF MODERN SMALL PLYWOOD BOAT CONSTRUCTION TECHNIQUES" by Paul
      Fisher.
      Witt gives the following guidelines:
      1)use screws (nails only on the smallest boats) on 2" centers,
      staggered;
      2)the width of the backing plate should be 15 times the thickness of
      the plywood.
      He says that this butt joint is as strong as a scarfed joint.
      Fisher gives indications on how to avoid the flat bump: use a 4"-5"
      wide back plate for 1/4" ply, 6" for 3/8", 8" for 1/2".
      Dave Carnell is a strong advocate of FG splices and details the matter
      in his web page http://home.att.net/~DaveCarnell/.
      I'll use FG splices for my Micro. Best, Pippo


      original article:http://www.egroups.com/group/bolger/?start=212
      > I was looking at Jim Michalak's site and his essay on plywood butt
      > joints. Thinking about using his joint in the sides of the folding
      > schooner. The plans call for an 8" plywood butt plate glued and
      > fastened with clinch nails.
    • David Beede
      I just built featherwind using Dave Carnell s glass tape only butt joints and found it pretty straight forward. I tested all the trimmed strips for strength
      Message 2 of 5 , Sep 3, 1999
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        I just built featherwind using Dave Carnell's glass tape only butt
        joints and found it pretty straight forward. I tested all the trimmed
        strips for strength and none broke the joint - rather the ply to either
        side.
        David

        harding2@... wrote:

        >
        > I was looking at Jim Michalak's site and his essay on plywood butt
        joints. Thinking about using his joint in the sides of the folding
        schooner. The plans call for an 8" plywood butt plate glued and
        fastened with clinch nails. I did the clinch nails on the Gypsy and
        they never did finish out neatly. Wondering about using screws, epoxy
        and a 1/8 for backing as per Jim's essay. Would it be too stiff? We
        made tape joints for the six hour canoe we built. They have worked
        well but it was finicky and as Jim says it is hard to get everything
        perfectly flat and smoothed out. Taping the outside face of the side
        panels after they are in place looks a lot easier to me. What do you
        think?
        Leander

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      • jmbell@mindspring.com
        jmbel-@mindspring.com wrote: My windsprint has the 4 wide plywood butt blocks hel in place by epoxy only and a strip of 6 oz FG tape on the outside. Works
        Message 3 of 5 , Sep 3, 1999
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          jmbel-@... wrote:

          My windsprint has the 4" wide plywood butt blocks hel in place by epoxy
          only and a strip of 6 oz FG tape on the outside. Works well. I tried to
          clinch the nails as specified by Payson but like you I found it was a
          mess. So, I pulled them.

          My other boat has a piece of lumberyard 1x4 as butt blocks. They are
          glued with epoxy and secured with brass screws. This was what was
          recommeded by Michalak in the plans. It didn't tape anything in the
          butt, but the outside of this boat is glassed. Again, no problems. It
          does make more of a flat spot on the topsides than a thinner butt block
          might.

          JB


          original article:http://www.egroups.com/group/bolger/?start=212
          > I was looking at Jim Michalak's site and his essay on plywood butt
          > joints. Thinking about using his joint in the sides of the folding
          > schooner. The plans call for an 8" plywood butt plate glued and
          > fastened with clinch nails. I did the clinch nails on the Gypsy and
          > they never did finish out neatly. Wondering about using screws, epoxy
          > and a 1/8 for backing as per Jim's essay. Would it be too stiff? We
          > made tape joints for the six hour canoe we built. They have worked
          > well but it was finicky and as Jim says it is hard to get everything
          > perfectly flat and smoothed out. Taping the outside face of the side
          > panels after they are in place looks a lot easier to me. What do you
          > think?
          > Leander
          >
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