Thread: carbon fiber sub box

getting the CF to lay right is a *****.

You need the self leveling resin, and if you don't work it in the right temperatures, you will run into problems with it self leveling too much and you will end up with pitting.



For more pics:
http://www.mj-garage.com/cpg/thumbnails.php?album=25

First attempt ever with CF, in near freezing temperatures and about 30 hours of wet sanding on the sub enclosure alone to try and get rid of some of the wave in the resin.

If you have any questions, feel free to ask.

well, i wont be going for as flashy a setup as that one! the CF i have is not available to the public, and comes pre-treated and pre-soaked with resin. all i gotta do it heat it to 250* for 120min for it to cure. unless its done under pressure, it doesn't have the glazed-over look that you have, which i am trying to figure out how to accomplish in an oven at home rather than the industrial machines at work. i can always sand and buff it though, and/or paint over it if something goes wrong.

im gonna be making mostly flat surfaces, so itll take some extra layers, but look like something clean enough to be factory (the goal=simple and clean). my oven is not that huge tho, so i will have to do it in a bunch of pieces and bridge them with fiberglass behind the scenes.

im using insulation foam boards as a basic mold for the glass, and when its built up, i will do some cf for looks and minimal extra strength. pitting should not be a problem for me on flat surfaces, i hope

on a side note: i've got to hand it to mp3car.com for how big its gotten. when i used to frequent here a couple years ago, it took a day to get a response a lot of the time! long live carputers and at-home fabrication!!!

Originally Posted by stkdidy ntshidy

i am trying to figure out how to accomplish in an oven at home

ummmm, that's one of the biggest no nos of all fabricating time. There are so many chemicals in that stuff that it's unreal. If you ever plan on using that oven at home again, or if you plan on being around for any time during or after that process, it's not a very good idea.

Originally Posted by Red GTi VR6

ummmm, that's one of the biggest no nos of all fabricating time. There are so many chemicals in that stuff that it's unreal. If you ever plan on using that oven at home again, or if you plan on being around for any time during or after that process, it's not a very good idea.

its an oven in our run-down cottage that is gettin trashed when we rennovate. no food that i can remember has been cooked in it, and i wont be around it except to put it in and take it out. btw, there are no odors of any kind before during or after curing.

plus, recommend me something that can heat to 250* in a controlled environment that is laying around a typical house...lol! i appreciate the concern however

edit: what are focal berilium's? I haven't heard of them, yet i run focal's

Originally Posted by Damon

The stuff you have access to is known as preimpregnated (prepreg) mat. Heat activated resin. (Actually, it is most likely frozen, as the resin will begin to flow at room temps on most prepregs, the reaction is just real slow at freezing temps.) My point being that just tossing it in an oven will most likely not be good enough. Vacuum bagging in the oven would be ideal. When the resin starts to flow, you run the risk of it pooling at the low spots (can't beat gravity...) and generally looking bad.

I did, at one point, have the hairbrained plans for an at-home autoclave (the industrial unit you speak of...), but never got around to building one. Maybe now is the time...

Another tip: If you are just doing flat panels, get yourself a piece of 1/4" glass and put about 10 coats of wax on. Lay your panels up on that. When you pull the panel, it should be "smooth as glass"

i appreciate the input!

i scrapped the idea of doing a fiberglass buildup after realizing in a sample piece that i would never get a flat surface out of it. instead i picked up a bunch of 1/4in 2' x 4' pieces of plywood from home depot, and am building the box out of reinforced pieces of that. i have most of the main panels cut and shaped, and carbon fiber-ed the side panel. it turned out alright, with a couple tangential issues:

*the board warped 1/4 of an inch (16in long, so it not a problem, just an imperfection).
*the finish came out great, but not glossy smooth. i waxed up the bottom of a big flat aluminum tray (to simulate aluminum autoclave) and put it on top of the fiber, with a heavy cooking stone on top of that to weight it down. the tops of the bumps for each weave are shiny, but they whole thing has a sort of texture to it. is there any type of gel-coat resin or finish i can put on to give it a "deep, smooth" finish on top?
*when sanding down the edge of the panel, i got stuck pretty hard by a fiber, and it hurt...lol

im going to liquid-nails the panels together (from the inside of course), as they are pieces of wood being bonded anyway. then im going to fiberglass the inside of the box for rigidity, cohesion, and to make it air tight. that 12x16 side piece is freaking strong though!

note: ill try the glass on top instead of the tray. cooking was done for 120min at 275*F.

you can get a flat surface from it.

You don't lay glass on the top, you use duraglass on the bottom for structural support, bondo the top to get the smooth surface, then lay your carbon fiber over that.