General home insulation foam.... Just go to the hardware store and see what they have. Should be like 4' x 8' x 2" or so for $8. Don't buy the low density (styrofoam like) foam. Get the real stuff. Mine's pink, I've heard others using blue with success... Maybe take a small chunk home with you (hehe) to see if it'll work with your resin, and not melt on you.
You can use the pink or blue insulstion sheets you can get at Menards or Home Depot, BUT you have to either:
1)use the more expensive Epoxy Resin, the Polyester Resin will eat the unprotected insulation
2) cover the insulation with some sort of protection, to use Polyester Resin(I just made a custom Subwoofer enclosure for a friend, and before fiberglassing, I covered the whole thing in masking tape, then sprayed on cooking pam)
If you want to make it a composite of foam and fiberglass then you will have to use option #1 or use Urethane sheets(I think it's harder to get, but it cuts and forms easier and you can use the Polyester Resin)
If it's something small I've hear you can use those little "potting foam bricks" that you stick fake flowers in
[This message has been edited by ds21 (edited 05-25-2003).]
Make your shape in foam then cover it with plaster, that will keep the glass from eating the foam. You can sand it smooth and wax it before you make the mold.
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05:00 PM
ltlfrari Member
Posts: 5356 From: Wake Forest,NC,USA Registered: Jan 2002
To make a composite(foam/figerglass sandwich), that stuff would be great, but just to make a shape to make a mold from it's too much $$$.
I'm going to be experimenting with a totaly new way of working, I've yet to see anyone else here try, should be a lot easier and quicker, I'll let you know if it works!
[This message has been edited by ds21 (edited 05-25-2003).]
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07:50 PM
Nashco Member
Posts: 4144 From: Portland, OR Registered: Dec 2000
Like ryan.hess said, you can use the blue or pink 4x8 sheets with decent success. You can hot glue sections into layers so you could actually make a cube out of it and carve it up if you wanted. BEWARE, some resins will eat the foam...test some of it out first. If the resin eats the foam before setting, you can paint the foam with latex paint and still use resin on it. I used this method and the expanding foam that comes in a can; you can fill a really big area, carve the excess, then paint it with the latex. The canned foam is a few bucks and you can get a cheap can of "that's not the color I wanted" paint at the big hardware stores for a couple bucks usually (mine was pink...blech!). The big 4x8 sheets of foam are less than ten bucks and are much denser, cut pretty good with a hot wire too.
If you give more detail about what you're trying to accomplish, we may be able to help more.
Bryce 88 GT
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11:20 PM
Howard_Sacks Member
Posts: 1871 From: Cherry Hill, NJ Registered: Apr 2001
Don't bother with the expensive aircraft spruce stuff unless you're going to be doing moldless construction or have money burning a hole in your pocket.
If you're going to be doing layup with a poly based resin(or doing touch up work with bondo), make sure you coat the foam with something so it doesn't get "eaten" by the catalyst.
I use a paint called "Alkyd" to make a barrier between the foam and the body filler, prep, then paint with an epoxy based paint, clear it and sand to a high gloss.
I don't have any pictures on the web of working with the foam raw(weird huh?), but :
This was for the first seat prototype. I kinda model'd what I wanted in clay. Had someone solid model it on the computer. Imported it into mastercam. Rough cnc'd 10 or so pieces of foam. Glued them together.
and here we go:
In need of much work:
what it should look like when you're done:
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11:25 PM
Howard_Sacks Member
Posts: 1871 From: Cherry Hill, NJ Registered: Apr 2001
Just had another thought, although this isn't what you're asking, I've been having a lot of success working with two part expanding foam. I just make a rough shape of what I want with cardbard or aluminum sheet , then fill with two part foam.
I call the stuff buck in a pinch.
Just bought five gallons of the stuff from US composites.
The problem isn't shaping it, it's shaping it too much! Sandpaper works good. You can cut it with an electric carving knife. If you're making rough cuts, score through it with a utility knife and break it off.
If you use Urethane foam, do NOT try to hotwire it or melt it, it releases a poisonous gas that can cause nerve damage and possibly death.
Last a foam is a polyester plyurethane type foam with very small, closed cells. It's great for shaping and sanding.
Divinycell foam is good to as it can be bent and formed with a heat gun. Heat it to 200 degrees F and you can vacuum form it if you want to make a nice, smooth curve.
A PVC type foam can be used with polyester resins, if you use a urethane type foam you need to stick with epoxies.
Aircraft spruce is one source. I prefer Wicks Aircraft. Much better service IMHO, and I've dealt with both for 20 years. http://www.wicksaircraft.com
John Stricker
quote
Originally posted by the need for speed:
also what are u using to cut and shape the foum with?thx guys
