Hi all, being a bit lazyon the searching so i thought i'd ask here. Does anyone know if Fiberglass and Resin sales in Welshpool has surfboard core foam (is it polyurethane??) or other cores? I actually tried to call them but they are closed today...

Cheers for that Decrep! What are the surfboard blanks like? Are they rectangular blocks of a certain thickness or they already have some kind of shape to them?

Mark _australia said...

>>>the cheapest by faaaaar is Herex from the mob on Port Kembla Dr in Bibra Lake but I can't remember their name. Anyone?

Summit?

Hi Decrepit

Do you know the difference in weight between closed cell polyurethane and polystyrene per 100ltrs volume.

Also is the closed cell stronger to begin with as in:

1. are the properties much better with closed cell for avoiding depresson, and/or memory to return to original shape, and
2. Is closed cell stronger from shearing/breaking.

Just interested in what is going into boards these days and whether we would be better off sacrificing some weight for the greater strength and longivity. I know there is a lot more to it with the laminate (ie divinycell/EPS and the layups (carbon/E-glass) etc) as well as the stringers and box/hardpoint protection.

the blanks are in a shape that provides the greatest variety of shapes without excess waste and , as mentioned before, they get softer the further you cut into them.

Usually the blank manufacturer will get the shapers from his biggest customers to shape a plug, and make the blank mold from that. That way they get what they want and cant whinge that it isnt right! The blanks can be tweaked easily by pulling the stringer up when gluing it in.

polystyrene blanks are hotwired to rough shape for a custom board.

TonyC said...

Hi Decrepit

Do you know the difference in weight between closed cell polyurethane and polystyrene per 100ltrs volume.

polyurethane as in surfboard blanks varies a bit, there used to be 2 or 3 grades, normal, light and superlight, I'm only guessing but I think the "normal" was around 40kg/m3, (think that's 4kg/100ltrs) being heavier near the crust and lighter in the middle. For a surfboard 1 layer of 6oz cloth gave reasonable strength, for a sailboard, 2 layers of 6oz on the bottom and most of the top, with a 3rd layer of 6oz around the feet area.

Mark Stone of Stone Surf Boards, is using a very light polyurethane foam in his boards, with sandwich construction.

Polystryrene used in board construction varies from 1.3kg/100ltrs to 2.4kg/100ltrs

Also is the closed cell stronger to begin with as in:

1. are the properties much better with closed cell for avoiding depresson, and/or memory to return to original shape, and
2. Is closed cell stronger from shearing/breaking.

for the same weight foam I'm not sure, Mark would be the person to ask, I'm sure he's done all sorts of tests.

But keep in mind when specifying "closed cell" thats not a very specific definition, There's also a closed cell version of polystyrene. Bluejuice has made several boards from it, and I've made a couple, trouble is now they don't make it light enough to build a reasonable weight board from.

Thanks for the advice! I'd still prefer a square bloc tho ... I'd love to try the sandwich vaccum bagging too but that'll have to come later. Will let u know how it goes!!

Try the insulation places - I used to use extruded polystyrene for composite glider wing cores, and could get a 2400x600x40 sheet of the stuff for $32(nzd).

One of the trade names is 'Styrodur'. It all seems to be made in Saudi-Arabia.