Re: MDO Plywood
- --- In firstname.lastname@example.org, Vince and Mary Ann Chew
Did you epoxy/glass the outside of the hull? Did the MDO soak up a lot of epoxy, more than the raw plywood?
> 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