I circled back to what should have been my first step .. what are the relative densities of materials?:
200 kg/m3 for NL-20
http://www.corecomposites.com/products/ ... ecork.html
2 lb/yd = 0.99 kg/m (I hope I used the correct conversion)
My 50" x 20" x 3/4" cork board ended up weighing 10lbs 7oz compared to my 48X18x1 1/4 paulownia board that came in at 7lb 6oz. Not exactly an apples to apples comparison but I think the point is the same. I might do the actual comparison math later but it seems heavy. Cork starts out lighter than Paulownia but absorbs a lot more resin. As executed, there was no compelling buoyancy benefit to the cork compared to wood.. That was part of my motivation.
A lot of the core cork builds I see in retrospect use templates more like foam body boards but thinner than my build.
In principal I can get some weight out by fairing the cork to seal it against unwanted infusion of resign but that might also make the bond weaker. I could also use unidirectional flax instead of woven flax fabric. The woven flax even with a vacuum took on a lot of resin. The unidirectional that I will use in future projects lays flat and absorbs less to get the same results. I can lay perpendicular layers if I need strength in both directions.
I was able to mold the cork core to get a bit more rocker than I have in my solid wood boards and I also got the right amount of flex compared to my more ridged wood board. With wood you either need to waste a lot of material or do so some splicing to get my target rocker.
- Big Wave Charger
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the corecork is a fantastic material. It disperses the energy of the blows avoiding damage to the board but maintains flexibility. if you put EPS boards with fiberglass and corecork they are important
weight. That is your big problem. It absorbs the same amount of resin as its density. a Cork of 250 giving it epoxy can be put in more than 400. a barbarity. That happened to me 3 years ago when doing an EPS board. poor choice of materials
I'm thinking of 2 thin 2mm birch veneers one on each side. in the middle xps. there will be a delamination problem but since it does not absorb water, it is not necessary to throw a perfect seal
I do not know how to make rounded rails very quickly. with just this recipe the rails come out square
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