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Bending foam sheets into shape

Old 07-28-2011, 01:04 AM
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earthsciteach
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Default Bending foam sheets into shape

This is off topic as far as its not directed towards RC airplanes, but I have no doubt this is the best place to ask this question!

Is it possible to shape 3/4" Polystyrene foam (sheething insulation) into a gentle curve? I want to build skim boards for my kids and me. They are really simple, just foam core covered with layers of fiberglass cloth and epoxy or other foam safe resin. But they can cost upwards of $300 for a "good" model! I need to add rocker to the foam blank. I can do that by slicing the blank in half and gluing a shaped wooden stringer in the middle, but I'd rather use heat, weights, or whatever to give the sheet of foam the front to back contour that I desire.

Is anyone familiar with techniques for doing this?
Thanks!
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Old 07-28-2011, 01:30 AM
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gramps2361
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Do you have a Ocean State Job Lot in your state you can buy them cheaper than what it will cost you to make one, and less work.
We have one that is made of light plywood and I just give it a coat of marine varnish every year and my son used to have a ball with it Thing is 8 years old and still going strong. To bad you don't live close I would give it to you he doesn't use it any more.
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Old 07-28-2011, 01:39 AM
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earthsciteach
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I want to build it out of foam because those boards can skim into the waves and be surfed back into shore due to their buoyancy. They are really mini surf boards.

Thanks for the offer! That is very kind of you!
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Old 07-28-2011, 02:58 AM
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Just figure out what the front has to be turned up say a 1 1/2 inches and the back has to be turned up some. Take a block of wood what you need for the front and one for the back. Place some wgt. in the middle to hold down the foam in the middle then start with some fiberglass and epoxy and lay that down to hold the shape. Once it sets then you can have at it with the glassing of the rest of it.

Bub Steve would be a good one to help you out with this one he builds boats and does a lot of fiberglassing if I am correct.
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Old 07-28-2011, 04:51 AM
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Larry3215
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You can shape the foam in a few ways.

For what you want, probably the easiest is to put the foam sheet on top of some thick carpet or layers of blankets. Not tooo thick. Maybe 1" or so.

Then get something like a basket ball and roll it around on the side you want to dish. You will have to play with how hard to roll and how large an area. Start lite and small and keep rolling as needed. best to go a litle at a time to keep from breaking the foam.

You can also heat the foam and form it but it takes boiling water. large pieces could be risky to do that way.
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Old 07-28-2011, 09:04 AM
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get some 3/4" wood planks about 3" wide, pine will be fine, put them on the front tip of the foam on both sides, 2 or 3 inches of the wood onto the foam, and put the foam and wood in a vice, dont tighten to tight, get 2 hair driers and heat both sides of the foam, while pulling the top on the foam to put pressure for the desired bend, dont heat the foam to much, keep working the hair driers back and forth where you want the foam to bend at, while adding pressure, you will need a helper, or you can use a bungy cord to add the pressure with, hope that helps, Chellie

ps, practice on a scrap piece of foam,
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Old 07-28-2011, 02:49 PM
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You guys are awesome! Thanks!
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Old 07-28-2011, 08:05 PM
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Bub Steve
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I was doing a little research before I Posted and came up on this site,,
I aways vac bag my foam projects but you don't have to,, the shape should be researched (v-tail or pin tail,etc,,) in the 50's as a kid we used 1/2"plywood for skimming at got fairly good at it (lived on the beach),,
use a good bi axle cloth on you foam blank to start with then go to 12Oz or what you got,,you should be able to make it in one piece but a stiffener down the middle would make it quite ridged ,,best of luck,bubsteve
http://borachi.tripod.com/borachiskimboards/id11.html
and this ones for foam,,,
[media]http://www.youtube.com/watch?v=1Z4x67dhw-s&feature=related[/media]
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Old 07-28-2011, 08:42 PM
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Thanks, Steve! That is a very helpful site. For entertainment purposes, I've attached a picture of myself from earlier today trying to skim on a boogie board. There was no surf, so what else was I to do? It didn't end well.
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