Concave - How?

[hugoc]

Hello,

I'm going to be building a foam core laminated board using a rocker table and cure it in a vacuum.

Do you just sand the core to achieve the desired concave or modify the rocker table to also apply the concave by putting a convex shape on the table?

Thanks guys.

[munteruk]

Your foam laminate will take whatever shape you put in the rocker table. For this reason you really need to pull the concave into the surface of the table. I've done this on my last two boards by jamming a space inbetween the underside of the table surface and the table's frame so that it pushes up in the middle. Its not particularly scientific but you can control the amount of concave reasonably well.

I'm trying to work out a way of putting double concave into the boards with a rocker table - not so easy!!!

[hugoc]

Your foam laminate will take whatever shape you put in the rocker table. For this reason you really need to pull the concave into the surface of the table. I've done this on my last two boards by jamming a space inbetween the underside of the table surface and the table's frame so that it pushes up in the middle. Its not particularly scientific but you can control the amount of concave reasonably well.

I'm trying to work out a way of putting double concave into the boards with a rocker table - not so easy!!!

Thanks Munteruk. I read that a steel pipe or even PVC pipe will work well under the table.

[Toesidereefer]

Get a planer and start making dust. I love carving out the foam and sanding it. Let your mind be creative. Don't be afraid to use power tools on the foam it is more foregiving than you think.

[blowhard]

I run the planer down the middle of the bottom until I get as much of a groove as I want and then ease it to the sides until I get within 2 in. of edge,(like Jimmy lewis') and then I leave a flat section ,after removing planer marks with a D/A sander and 24-40 grit ,
I'm done with the mold
after design it is the most rewarding part kinda like rough framing a house, done in a hurry
I use a 20 oz. triax and it covers most imperfections ,sand 220 and then a 4 oz. to cover the triax, a coat of waxed resin and then 220 on the D/A
then PPG polyester filler sanding coat ,wetsand with 400 ,put on sealer and paint