Foam board for CF laminate?

[mark5pa]

I have found a number of company's that sell 1/4" closed cell foam for carbon fiber sandwich, but none that will ship more than a 4' X 4'.
Is it available at auto parts supply, or home improvement stores, that I can get a 4' X 8' sheet?
I am going to do my knee boards & starboard cockpit side.

Thanks

[Mike45]

Mark,
Not sure if this will help or not but here is something I use. The blue roll up foam you can buy in any store that sells camping supllies. It is 1/4" thick and does not retain any water. Although it only comes in sheets that are around 2'x6' but the company that makes these may be worth contacting if you need a 4x8 piece.

[mark5pa]

Never thought about that stuff. I use it for a knee pad in the boat, and on the floor for kneeling in the shop.
I am going to laminate the foam with CF and press between 2 flat pieces of slate with weight on top.

[BillCNC]

Are you using Styrofoam or Polyurethane foam?

[mark5pa]

Are you using Styrofoam or Polyurethane foam?

I think stryo foam will melt with West epoxy, so it should be closed cell poly.

The lumber yard sells closed cell insulation foam. Wonder if that would work? Not to concerned with the knee boards, but the cockpit side I want the right stuff (5# min)

[BillCNC]

Styrofoam WILL NOT melt from "Epoxy", however, Polyester and Vinylester WILL melt Styrofoam. It's the Ester that does the nasty work.

Styrofoam is pretty weak as a filler, but Urethane foam is much stronger and stiffer than Styrofoam but it weighs a little more.

Now I have not used the panels your talking about for a boat, ... but I have had years of experience in laying up composite sandwiches and just about everyone with a Styrofoam core has failed under light loads or they dent just by touching them when they are built that thin. Your CF would have to be laid thicker and more resin to do the job, ... then again, now your at the weight of doing the job with urethane, which is both cheaper than the resin or CF. The thicker your sandwich, the stronger when it comes to Styrofoam which might make your part to thick if you use Styrofoam.

Maybe urethane would be better?

Bill

[FJOHNSON]

Foam

Most people in our region used a-550 or I used M80. Noah's boating supply is where to get it.

[crfabbro2F]

I have found a number of company's that sell 1/4" closed cell foam for carbon fiber sandwich, but none that will ship more than a 4' X 4'.
Is it available at auto parts supply, or home improvement stores, that I can get a 4' X 8' sheet?
I am going to do my knee boards & starboard cockpit side.

Thanks

The core does not have to be used in one continuous piece. Buy the smaller pieces and butt joint them to get the length. When I core the sides of a 36' boat the Divinycell sheets are that size! This will have zero bearing on strength. Also, if you are not going to vacuum bag it I would suggest 3/8-1/2" core ( assuming that this is for the cockpit sides).

[mark5pa]

Thanks guys.
Fran- When I was eyeballing you cockpit side at Crystal Lake, you said "if you had to do it over again", then someone offered me a beer, and I didn't hear the rest of the story. Would you change the foam, or not use the hybrid cloth?

Chris- I would love to vacuum bag, but for the few pieces I am doing, doesn't seam worth the expense. If I can find someone local to loan me a pump, I may give it a try.

I will be using CF & Kevlar on the outside. Do you lay them up together, or do the Kevlar first, then after it cures, do the CF?

[crfabbro2F]

Both at the same time. I would carefully flip the panel over as soon as its hard enough to do so and lay-up the other side. Don't let one side fully cure before doing the other, it warp on you.

[FJOHNSON]

Hybrid

I would not have used only 1 layer of the hybrid.

[mark5pa]

Thanks for all the info. Ordering everything tomorrow. Start laying up after the holidays.

[crfabbro2F]

Good luck!