Yeah I know that this has been adressed before but I’m damned if I can find it now. I’m planning a cheap polystyrene blank project cos someone’s kindly donated some epoxy for almost no money. With polystyrene what density am I looking for? and is the type used for building insulation any use? I have found a yard locally who sell 8’ x 4’ sheets of 1 inch, or 2 inch thick but it’s like expanded stuff I think. Is this going to be a waste of time, money and epoxy?
I was planning to laminate 2 x 1’ sheets over curve to form the rocker then cut, add stringer and shape. Anyone got any thoughts on doing it like this? If I do procede, how many layers of cloth will need to go on to make it strong enough (I’m planning a 8 ft mal type thing for the missus who weighs about 10 stone and is only likely to surf 2’ beach break).
Any advice would be well received.
Thanks awfully
Terribly English Jase (MMM)
Prioritise your karma dude!
I used Sheltersheath Insulation from Home Depot for my blank. I bought 2 sheets and cut them in half so that I had 4 pieces 6’2 long and 24 inches wide. They were $7 per sheet. I’m not sure on the density but I used 3 layers of it to form my blank and it shaped nicely. Here is the thread with pictures showing the foam and how it was shaped. There are a lot of pictures so give it time to load up. Not sure if it helps but maybe it will?
http://www.swaylocks.com/forum/gforum.cgi?post=275731;#275731
Your in the UK and that is sorta in the EU right ?? Well the industry standards in europe for styrofoam have been standardized under some Brussels mandated standard.
It boils down to a combination of characteristics in the foam. What you need is dense styrofoam. This is typically with a density of about 30kg/m2, under the current EU standards this is equivalent to “EPS 200” standard. Check with your local foam manufacturer, they should understand this definition, don’t use what is in the DIY stores as this is most likely EPS 60 foam and is far to light.
Some links about the the standards:
http://www.eumeps.org/about3.htm
http://www.eumeps.org/literat/pdfs/White%20Book_public_2004-04.pdf
Now there, I answered you on stuff I figure you wouldn’t find in the archives, as for the rest of your questions, you really really will find it in the archives, just search for terms EPS EPOXY and you will find a bunch, there is an EPS construction Primer which is a must read.
Some Wickes stores do 3 inch thick sheets of EPS. You should be able to cut a bit of a rocker into it, and then bend the remaining few inches in when you glue up to your stringer. I found that easier than glueing sheets together to make a rocker, and easier shaping too without a glue line to shape through.
I think the stuff they sell is EPS70, so that’s pretty light, possibly under 1lb density? 3 layers of 6oz on top and 2 layers of 6oz underneath seem to make a reasonably strong board, dunno if you’d have to make it stronger for a mal, I’ve only done shortboards.
Nice one, well useful! I may use a heavier weight cloth and go with 3 layers top and 2 bottom. I’ll let you know how it goes as it progresses.