Monday, January 23, 2012

Graphics and substitute reinforcement

Philip the kite surfboard maker gave me a tip on doing encapsulated graphics. Print them on tissue paper using an inkjet printer. To make sure the tissue paper feeds through the printer without getting crumpled you can spray an A4 sheet of standard paper with a very light coat of spray on adhesive such as kwik grip in an aerosol can( that you can buy from Bunnings hardware) and press the tissue paper onto it. Worked like a charm.

I guess you need to make it very light so that you can peel it off again and so that you don't make it water proof. You can encapsulate the tissue paper between layers of glass or just press it into the top before you bag it. Apparent both work well and for the top surface, at least, the extra scratch resistance of encapsulating it is probably not an issue.

I was going you 2x200gm layers of eglass on this board but in persuit of the goal of reducing the number of steps I 'lashed' out and bought some 450gm 0/90 stiched e-glass. This should be stronger than the 2 layers of woven e-glass because stiched material is basically 2 layers of unidirecetion glass with a small about of bonding agent and then layers stitched together. This removers the crimp that reduced the strength and effective elastic modulus of the reinforcement.

453 gm stitched e-glass
It comes in 1270mm widths at FGI and this turns out to make it more economical than buying the 200gm woven fabric because its wide enough to use for at least 2 boards if not 3 whereas the widths the 200gm came in meant that it was enough for one board width and a lot of wastage.

However, this is likely to make the board stiffer than BoardOff would estimate because the 50% reduction in the theoretical elastic modulus of e-glass used to model the woven fabric will probably underestimate it for this fabric. This means a stiffer board.

I was eyeing off the triaxial glass but the lightest weight is 750gm/sqm which would translate into about 1.4 kg compared to around 800gms. Given its a light wind board the extra strength and weight might be overkill.

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