Fiberglassing Question

[knochgoon24]

I'm getting a FMIC, so I'll now have that space open in the wheel well for some sort of a cold air intake. I plan on making a duct from where the opening is in the bumper up through where the stock SMIC pipe was (I'll enlarge that hole a bit). I'm going to sculpt a mold out of foam, then fiberglass it. Then use a bit of carbon fiber, on the parts that are visible when installed, to add some looks.

Now my question is, how many layers of fiberglass do I need? I'm trying to figure out how much to buy. I need it to be strong enough to take a hit from a small rock, but I don't want overkill. I've never fiberglassed before, so this is all new for me.

 

[livedsm4g63]

i would say to do 2 coats, but they are pretty much done at the same time. so i think it is going to be, more of your call, then anything else due to how much material you lay down with the resin.

be ready for the horrible smell as well. haha

 

[knochgoon24]

Started looking for fiberglass cloth and found this. Fiberglass Cloth Tape 6oz x 2" wide ( 50 yards ) - eBay (item 300148227548 end time Jun-30-08 15:20:58 PDT) <-$28 shipped to my house.

Few questions for someone who knows a little more about this than me...
1. Is this a good price? Where should I look to buy it if I don't get it online?
2. Should I use a wider tape? I figured this would be a good width for keeping curves neat.
3. I've seen 6oz and 17oz. Is the one stronger? Or will I be fine with 6oz?

I figure if I go with the 2" wide stuff. I can overlap it 1" and just spiral right up my mold, so I get 2 layers at a time. Then, the second time I wrapped, I'd wrap it in the opposite direction so the cloth crosses the other last layer, so the seams don't line up. To do the carbon fiber, I'd lay it down first so that it is on the inside of the ducting near where it will open at the bumper. And put it on last on the top, where it will stick out into the engine bay a bit.

^^ Does that sound like the right way to go at it?

Just checking before I buy $50 in fiberglass, carbon fiber, and epoxy.

 

[OddNotion]

My favorite epoxy was once available at Home Depot, made by Bondo. It could probably be found at a boat supply store, or online it could be ordered from a myriad of suppliers. I even saw a coloring agent that can be added to it. It's a two part epoxy, 1:1 mixing ratio, it has little smell, and about a 30 minute working time.

Because fiberglass has a weave, you shouldn't need to spiral it around to achieve an alternating pattern, although it's thinking along the right lines. You will build a lot of weight that way but it will be mostly epoxy, and that's not good. You will find that when laying up the fiberglass, if you use spirals, it will be hard to squeegee the excess epoxy resin out because the spirals will catch and move around.
Read these:
http://www.dsmtuners.com/forums/articles-parts-fabrication/257621-making-composite-intake-tube.html
http://www.dsmtuners.com/forums/articles-intake-exhaust/195667-diy-ram-air-duct-cold-air-intake.html

 

[knochgoon24]

I plan on doing something like the second, but making it completely fiberglass. I just figured that buying the fiberglass in tape form and spiraling it on would be the easiest way to get a complete and even cover. I think I need to read up on fiberglassing a bit more because I didn't know that you needed to wrap when you let it cure.

 

[OddNotion]

Well, you don't necessarily have to wrap it. That's just one way of achieving the goal of removing excess resin. One of the simplest and best ways is to remove the resin is with a simple plastic scraper/squeegee type thing. The scraper I speak of is sometimes used to mix body filler- it's flexible, yet kind of stiff. An example of it working well would be fiberglassing a wooden model boat. You drape one large sheet of fiberglass on the bottom of the boat, pour on a bunch of liquid resin, and spread it out with the scraper. You work from the center out, spreading and adding resin as needed. There is a point where the glass cloth is fully wetted, but only just enough. The scraper seems to do a good job of both forcing the resin into the fabric and removing the excess with a wiping action. This is why you would want to cover the object you are glassing with as few individual sheets of fiberglass as possible. In the boat example, the glass cloth is pliable enough that 1 sheet bends and forms enough to continuously cover the hull. For a structural object like an intake, you would want a couple of layers of a nice medium weave.

 

[roadrunner2176]

It doesn't soundlike your going to be needing all that much fiberglass, just go to your local auto parts store and buy a small package of it for 5 or 6 dollars. Package size will run from 8-10 square feet. I would use fiberglass mat for the first 2 layers, followed by three layers of fiberglass mesh. Matting is stronger, but not as smooth, while mesh is smooth and used for finish applications. I would do 5 layers, because the top 1-2 layers will be sanded off in preparation for the carbon fiber sheets. Last thing you would want is a rough looking final product.

As for applying the fiberglass, make your mold, wrap it in foil, cut all your sheets to size and than mix your resin. Properly mix your resin to the material your using. Too mush resin, gets firm and will crack easier, too little resin, wont hold. Coat your foil with a light coat or resin, lay a sheet of fiberglass, coat that sheet with a light layer of resin, apply another sheet and so on. If the process is done correctly, there should be no need for a squeegee, as there should be no runoff. For a better final appearance, you can cover the mold in plastic, and roll out the air bubbles, or put it in a bag and use a shop vac or an air compressor vacuume setup -- highly recommended if applying carbon fiber. If the fiberglass is done correctly, it will be strong, light, and flexible if needed to be.