:: View topic - flat layup - material and cassette sizes

hey

im shaping some new moulds next months and thinking about to switch from prebent, 99% fitting-in-the-mould cassettes, to flat cassettes. till now im using stainless steel and aluminium cassettes, alu 2mm, steel 1mm. all pre-bent fitting the moulds almost exactly.

i do full-length woodcores (3mm tip/tail thickness) with 12mm abs spacers in tip/tail area, laying up in prebent cassettes is a nightmare as you could imagine.

what cassette material and thickness do you recommend for laying up flat?

i heard from ski grace that they re using 3/16 aluminium, trusting my conversion table this is something like 4,6mm...they have ribmoulds so i guess the thickness is required to prevent from waves in the bases. pretty thick piece of metal anyway. i doubt if the bladders of my press would push that sandwich proberly in tip/tail sections, or upgrading my press with some pneumatic rams is necessary!?

i still dont know what my next moulds would look like, massive mdf or ribs, one requirement, the moulds must be adjustable, ribs of course need thicker cassettes...

what is a good material thickness for massive moulds and what is minimum thickness for rib moulds?

I use 1.2mm for the bottom sheet and .8mm for the top.

I think I would prefer a tad thicker on the bottom sheet.

I use 1.6mm on bottom. 1mm on top. Aluminium.

Full MDF molds. The bottom sheet doesn't return to completely flat after pressing, but the top sheet does.

18ga all around in al. Returns to flat. Almost.

16ga top and bottom, returns to about 20% of what you bent it, still fine for laying up flat. I think if you want it to come back fully you want spring steel = $$$$$

2mm thick aluminum sheets...return to almost flat.

Prob depends a little on the temper of the aluminium and also the radius it is being bent in to as well.