There isn't really a place for this, but I know there are alot of intelligent, motorhead, do-it-yourselfer fabricators in here.This should be a fun, positive brainstorming project for you people!

Here is the deal. A friend and myself have just built a basic kart with a 66" wheelbase, 3" ground clearance, 12" tires (slicks), and a 12h.p. Briggs (we also have a YZ 125) incase the level of burnout we achieve is not satisfactory[img]i/expressions/face-icon-small-happy.gif[/img])

Anyhow, the stage we are at now is building a fiberglass body. It is either going to be an early '90s Chevy Astro Van body, or a more comical UPS truck. These were are two options because we wanted to be totally enclosed in this death-trap and not have our heads or upper-bodies sticking out like most scale go-karts. The finished body will be very roughly 80-90 inches in legth, 40" wide, and under 40" tall. Here's where I need your help. We are thinking of glueing together a foam board reinforced model to achieve all of the proper curves contours and body lines. Then building a box that is slightly larger than the model. We would then fill the bottom of the box with Pour-in Polyurethane Expansion Foam up to about the 2 foot mark then place the model in the box upside down into the foam. Then proceed to fill the empty areas around the body. A release agent is also used. This produces a very dense, smooth surface, negative foam mold. Next would be more release agent, and "alot" of fiberglass matting and resin.

My question is, does anybody have any experienct with larger castings like this or know of anybody who has done this type of work.

Brainstorm and talk back at me. Much appreciated guys!

 

I used to get a catalog from a company I think was named Fiberlay. They have everything you could want for something like this. I will try to do a search and see if i can find it again.
d

 

Here's the link...http://www.fiberlay.com/
hope this helps
dave

 

I'll check it out. Anyone else, different ideas.

 

see if there are any boat manufactures around where you live and see if you can get a tour... maybe somebody there will help you out and make the body on the side. The process you described is basically how a boat hull is made.

What about carbon fiber??

 

I did some fiberglassing for a while, And then worked at a plant that built fiberglass campers. I will talk to some of my old co-workers and see what they say. I didnt do alot of glassing, but here is what I remember.

Basically, to get a smooth texture you require a mold. Be very carefull as to what you decided to use for a mold. Activated glass resin will eat through most substances (polyurathane??). The chemical that is used to activate the resin is called ORGANIC PEROXIDE and will do a real good number on almost everything. Most molds are made of a special type of fiberglass which uses a different kind of resin. I have never built a mold, But have seen it done. It is NOT an easy task. I have seen medium sized RV molds that cost well over $1 million. But anyways, Once the mold is created (it has to be perfectly smooth) a wax type compound is used to stop the fiberglass and resin from sticking to the mold. I would say it is an unwise choice to use this method for your purposes. A cheap-mold could produce a rough draft and smoothed out afterwards. Highly labour intensive though.

Well, anyways, thats most of what I remember about molds. The other method I have used for glassing is to hand-layup sheets of glass (most molds use a chopper gun to spray chopped up fiberglass) But this requires a frame and usually leaves a bumpy texture. Like I said I will throw this one at my glasser buddies and see what they come up with. It would be benificial to know what kind of materials and\or budget you are working with too.

 

If you are going to do the UPS truck body, wouldnt it be easier to just use sheet metal or aluminum? After all, a UPS truck is square with almost no compound curves.

 

You are all being very helpfull. I appreciate the input. I have a friend who is a mechanical drafter and we guessed that a high volume professional mold would cost about $100,000. Since we only need one I am thinking that we can build ours for under $200-$300. We did consider the sheet metal method if we did a UPS truck. I am anxious to here back from you with their tips.

 

If it were me, I would do the UPS truck thing. Maybe you could make it look like that flamed one one the NASCAR/UPS commercial. To keep the weight down you could build a "frame" for the body out of small square steel tubing, then pop rivit the aluminum sheet metal to it. Then make it flip up like a funny car body does! schweet!