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Re: MDO Plywood

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  • Roger Peterson
    ... Vince, Did you epoxy/glass the outside of the hull? Did the MDO soak up a lot of epoxy, more than the raw plywood? Roger
    Message 1 of 3 , Dec 28, 2000
      --- In bolger@egroups.com, Vince and Mary Ann Chew
      Vince,
      Did you epoxy/glass the outside of the hull? Did the MDO soak up a lot of epoxy, more than the raw plywood?

      Roger


      <vachew@f...> wrote:
      > I am using 1/2" MDO to build Dakota. I have 50 sheets in the hull so far
      > and every seam was tape butt spliced first. See the pics in the Dakota
      > folder at the "Files" link.
      >
      > Epoxy sticks extremely well to MDO. I am using Raka Epoxy which is low
      > viscosity to begin with, and I store it in an old fridge with a light
      > bulb keeping it above 70 degrees F. It saturates the paper and well
      > into the wood.
      >
      > However, when taping a butt splice, you dish out the wood equal to the
      > thickness of the layers of tape you will use. So you are glueing to wood
      > not paper. Pre-coat the wood with epoxy. Don't forget to butter the ends
      > with thickened epoxy as well. For my splices, I used three layers of 9
      > oz. bias tape. I split my 6" tapes with a roller cutter. I cut three
      > 48" lengths then ripped two into 2" and 4" strips and one into 3" and
      > 3". This is enough for both sides of one joint. I dished the the end of
      > each sheet exactly 1/2 the width of the widest tape. Since my widest
      > tape was 4", I dished the plywood back 2" on the end of each sheet. I
      > have tried several methods for dishing the wood including a power plane
      > and a router. What I like best is a 4" angle grinder with a coarse #36
      > flap disk.
      >
      > I work an a table of sawhorses and planks 40' long. I tape both sides at
      > once. Instead of using weights, I made up pairs of clamping boards --
      > each from two layers of 1/2" MDO cut 9" X 52" with the outer ply grain
      > running lengthwise. When I glued the boards together, I rested the ends
      > on sawhorses and set enough weight in the middle so they set up with
      > about a 1-1/2" bow. In use, I clamp the ends together against the
      > curvature. This spreads the pressure evenly across the splice in both
      > the top and bottom. Of course, I have to place the plastic, peel-ply and
      > the saturated tapes on the lower clamping board and then position it
      > under the splice. On top I place the tapes in the splice, then the
      > peel-ply, plastic and set the second board on top. I lay my tapes with
      > the narrowest innermost, but I am not sure it makes any difference. I
      > clamp the ends and let it set.
      >
      > For the bottom of my boat with three layers, I used one-sided MDO for
      > economy since any voids on the backside would be automatically filled
      > with thickened epoxy when I laminated the layers together. For the
      > topside panels I got two-sided MDO since both sides will show. I paid
      > about $38 and $42 respectively.
      >
      > Vince Chew
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