Alrighty basicly i want the light weight fiberglass without forking over the high dollar for the fiberglass body panels that are out there. I do comp mud racing and i want to lighten up the truck even further on the front end and doors, and i'm thinking of playing with fiberglass to do this.

Now i have the time and a little spare cash to get started as i talked to a few people and i can get the matt/resien fairly cheap. Anyway what i like to do is start out small on something to get the process down so i don't waste time/money on bigger stuff.

So essentially i want to end up with fiberglass door skins/front fenders/ and hood, and here is where i need help. As i've never really worked with fiberglass for body work and if someone could point in the direction for the working with the stuff (i have a general idea but thats it) and any tips or hints would be useful too.

Next is the design side. How would you guys and gals go about making a fiber glass panel? Ideally i know making a mold would be best but what would you make it out of? or would you cut the majority of the metal out of the panels leaving just enough for the shape and some structure then do it the same way you build fiberglass speaker boxes with using a fabic of sorts then laying the matt and resign on top of that, so lets hear you ideas on the best method for doing this which will be the lightest and strongest.


Thanks for any help .

 

Fix the part you are going to duplicate, even if you have to bondo it up and prime and sand it. The better the part you make your mold from, the better the part you will produce. Most people make a female mold to produce the part from by laying up many layers of fiberglass and reinforcing it on the outside. Often you will have problems with complex parts removing it from the mold if you don't make a split mold you screw together with parting flanges. I dont think a fender or door skin will be a problem with a one piece mold.. You could also make your mold out of plaster of paris, if only doing limited parts. It will be cheaper to make a mold out of. You need to wax your part with a mold release before making your mold, and also wax the mold before laying up your mat and resin inside of it. I use paste floor wax for the small parts I've done, but they make other products to use for mold release also. I'd use around 3/4 or 1 1/2 oz matt for the first layer for sure. You want something that will form into bodylines and corners realitively easily. Work the resin into the matt and try to elimate airbubbles with a paint brush. Or you could use a fiberglass roller to work out airbubbles, but I haven't been using one. Lay up enough layers to get sufficient thickness and strength to the part. If you use too much resin or mix it too hot, or heat it up to much trying to speed the cure, it will make for a more brittle part. Don't forget to add any metal reinforcement needed when laying up (for example hoods always have a metal plate where the hinges bolt to it, or if you have to add any threaded fasteners. If you are making a completely new part, then you will have to build a plug to make a mold from, however you choose to build it. Another option could be to just make a male part with no mold, by waxing the piece first, laying a layer or two of matt and resin on the outside, reinforcing and removing, and then grinding the inside and laying more layers up inside. It will be larger by the thickness of the glass you layed on the outside and require a lot more filler work and priming to prep for paint. I think for the door skin, the way I would do it is make the skin out of fiberglass, remove the metal skin from the door by drilling out the spotwelds, and grind where the skin meets the flanges and glue it on with panel adhesive. Grind inside flange and neatly lay a few layers of glass on the inside to make the lip, and finish it off inside by grinding the glass and using some bodyfiller to make it look like the flanged door skin edges on the factory door, Or you could take a strip, place it inside the door over the inner flange. V out where it and the outer door skin you made meet for strength, and grind and glass it shut and finish it off by doing some filler, blocksanding and primer work.
Here is a link, showing a little of them making a mold to reproduce a part, and making it out of plaster. I don't think you'd necessarily need to reinforce the mold with steel, just making a skin or fender, if you have enough thicness and are carefull. Possibly some plywood reinforcements to keep the mold from shifting or getting out of whack or breaking may be a good idea.
http://www.grandsportcorvette.com/gs/body.htm

 

Wicked that helped me out alot. I think what i'll do is first cover the fender or hood with tthe mold release, the lay a thin layer of glass over the outside of then part, then remove the steel and layer the glass up on the inside after doing a clean up. I think for some strenghtening on the part i cut some thin pieces of wood and lay then in the direction need then glass over it, shouldn't take much i think. As i said before this is for a comp mud truck so it doesn't have to be perfect.

Now i was thinking and i had a couple questions, you brought up the weight of the matt, now what type of matt, (and whats the difference?) would you use to make the strongest, but more importantly, toughest part, as this will take a beating.

Next is what type of strength will this part be quilivant to, like wcan you lean a bunch of weight on it, will it take a hammer blow, so really can i expect it to be similar to factory body panels made from glass' in strength, and also will the weight be compareable?

Lastly, how thick will this end up being, around 1/8-3/16?

thanks again.

 

Try googling for info. on kayak and canoe molding; those guys are worried about strength and lightness, so it should be pretty relevant.

 

Personally I think I would just use 1 1/2 oz mat for it all, several layers till it looks like you have fairly good thickness. Use a smaller piece first layer in areas that may be harder to work and form the mat to. 1 1/2 oz should be fairly easy to saturate and form into the mold and about 5-6 layers I think you will start getting pretty good thickness. Then a little sanding and priming of the part after Like angus said, google that or boat building as there is a lot of information to be found in a search. Fiberglass will crack if it gets a good whack. I would think you could build a part just as good as one you bought, Many are probably built the same way, hand laying up mat in a mold. Granted the bigger places might bag it and vacuum to remove airbubbles. The strength will depend on how good you do your layup, saturated and without air bubbles, with the right amount of hardener to resin, and not too resin rich. Now I imagine there are other materials that are stronger then mat such as kevlar or carbon fibre. Also I believe by orienting the fibers in different directions in your layers will increase strength. There is also sandwitch construction with a core between layers of fiberglass such as urethane foam or honeycomb. I am no expert, but do fix a lot of fiberglass on semis at work, and did a quite a bit of reading. I was thinking about making a 34 ford body at one time, and went as far as making a good part of the body out of plywood and foam, but I abandoned it. The parts I've made so far have been small. But it is kinda fun to do and don't think it will overly difficult if you think things out. Do some searching and reading, there really is quite a bit of information on the net if you do some searching. I think fiberglast has some information as well, and how to estimate how much mat based on square feet you are doing and the weight of the mat (more weight means more resin to saturate) and resin you may need. If you are just going to do the male method, you could try neatly using saranwrap over the piece, You basically want something the fiberglass won't stick to and the piece, brush on some mixed resin, lay pieces of matt over the surface, and saturate them with resin and work out airbubbles with the brush and repeat process for other layers.

 

yep i did a bit of searching. Seems like the canoe guys like the woven stuff, and it seems a bit stronger, but yeah they made mention to fiber direction, and the fact to keep air bubbles out of it. I was thinking of using some foam or something for a core but i want this to be light. I think i got the jist of it, i'll probably make a number of small (like 6"x6") test squares to get the hang of it and to see about what will stick to what, and also with fiber direction and such.

I appreciate the help.