Body building polycarboate vacuum forming
 

My 1/5 scale needs a cool body and was wondering if there is a thread or a different forum on how to make your own body ?
All I know is I need to sculpt a mold and then vacuum form it

Want a body like a GTP, Ferrari Enzo, LOLA . Something Low and race'ee

Youtube has some do it yourself videos using your oven and a vacuum cleaner. The guy was making Helli canopy's.

I've seen some homemade ones on the web. Mostly they look like a big air-hockey table, just a tray/box with a bunch of holes in the surface, and then a frame around the edge to hold the edge of your work material. Many use shop-vacs or the like to create a vacuum. Bigger the surface, bigger vacuum source needed. Of course it's not just the amount of vacuum pressure, it's the speed too. Pump A might be able to create more negative pressure than pump B, but if it can't do it fast enough it's no good.

The other part is what you use to heat up the polycarb sheets to get them soft. One guy doing small scale stuff used a radiant-type pizza cooker! But for your scale you'd need bigger. Some use really hot lights, or other types of radiant heat coils. Building a good heating system could be more work and more expensive than building the actual vacuum tray depending on how you go about it.

Being able to have the heater and former in one unit (heating setup over the vacuum tray) would be a big plus on the bigger scale stuff. You don't want to be trying to heat up the sheet at one "station" then moving it over to and clamping it down at another "station" if you can avoid it.

Thank you, it all makes sense.

Any ideas what material I should use to carve the mold ?

Clay is expensive.

Searching all over the web and only getting "how to vacuum forming" results
I need to know what material for the mold

Try some playdough or better yet, see if can buy pottery clay from your arts and crafts store.

I had an idea for a simple/cheapish vacumm former. I would have a table/surface, with a frame that the lexan could be clamped to. Now you need a 10gal air tank, larger diameter (say 2") pipe with a 1/4 turn ball valve. Hook up a vacumm pump (I have an auto ac unit that will get down to 26' mercury) to the tank with the vlave shut and vacumm it down. Then when you have your mold and leaxan ready, just open the valve and the vacumm in the tank will suck the lexan into the mold. Not quick to repeat, but effective!

here you go: http://cgi.ebay.com/Automated-Vacuum...item3ca8c9b15b

Maybe a wire skeleton and then clay?

mold making: http://www.youtube.com/watch?v=jh7-bel2VsE

I think paralysed's link with the solid MDF is about right and probably the cheapest way to do it, I wanted to make a scale Bowler Wildcat body for my buggy, found a RC body maker willing to do short runs and made a wooden body from 3/8" mdf but when I took it to him he said it wasn't sturdy enough, he explained that he pulls over 6psi vacuum which over my roughly 2 square feet of body is the equivalent of parking a small car on top of it and my mould would crumble into fragments instantly, I suggested I could fill the inside with plaster of paris to make it solid and he was still dubious about it being tough enough for lexan although it may be enough for an ABS body which doesn't need as much vacuum, unfortunately making it from solid is a lot more work to add to the work I had already done making the hollow body and I am lazy so the project fell by the wayside and I ended up buying a WRC focus body for it.

pricey sucker
" MDF" Meduim Densisty Fiber board . I could screw together some 2x2's and then layer some MDF to get a similar shape then cover in Clay and sculpt the clay down
I see these videos all over but no body answers what material they use

Thanks guys, appreciate your input and ideas.

Yea it's not looking good to make a body of Polycarb, price wise that is.
Just aim for clear PVC or clear milar or acetate sheet I found info on an rc airplane site think it was rc-groups http://www.rcgroups.com/forums/showthread.php?t=621858

I was going to go to Home depot today and pick up a chunk of pine but I may just get some Blue foam or some regular white polysteren packaging foam and carve a rough cut then cover in Pottery clay and get it perfect.

Next big obstacle is making a heating element for a 35" long body :surprised:

Most of the 1/4 scale guys make a buck out of foam, either sheets layered up or a couple big chunks. Once they carve it to the general shape, its covered in bondo. This alows for sharper lines and to add detail as well as smooth the foam. The buck is then painted for a smooth, non porous surface and used to make a mold for the final body which is usually fiberglass. But they aren't exactly concerned with weight most of the time either in 1/4 scale machines.

It may sound bizarre, but what about concrete? I'd think that it could be used to fill the buck and be plenty strong to withstand the pressure of vacuum forming lexan. I think concrete with a layer of clay on it would be less likely to crack than solid clay. I'm just talking out loud here btw, throwing out ideas

I found some great info on rcgroups, a guy used PEPG .040 plastic for his airplane canopy and it turned out perfect

So once I get my free foam and some clay I can start shaping the body:smile:

The bondo idea is cool.
this whole material build i do worry about chemical reaction

If you have a bodie you like, or you want to shape a little bit, fill it out with plaster, gypsum or stuff like that, buy sandpaper and start grinding:mdr:

don´t forget a mask:rules:

I used to build formula style bodies at uni and the process goes like this.

1. Get blocks of polystyrene foam, get the denser stuff as it holds a smoother shape when sanded.
2. Make accurate sections at intervals from think plywood or mdf. This gives you a guide to shape the foam. The more accurate and numerous the plywood sections the better, but remember wood takes longer to sand than foam.
2. With a hotwire cutter get the foam blocks into the appropriate size. Then in an alternating fashion glue the foam and wood section using a water based adhesive, such as "liquid nails water base".
3. Begin shaping by sanding the foam areas. Remember to go slow here as it is easier to take material off than put it on. Long light strokes over big areas will get a smoother curve than short strokes. It is also very easy to over sand in the foam areas since the wood is much more difficult to sand.
4. Cover in a thin layer of epoxy or fiberglass-epoxy composite
5. Use a light automotive filler and cover the whole mold and fill in any big holes.
6. Sand the filler layer smooth with 2000grit as your final sandpaper. This is the longest step and the most important, go slow as any mistakes here will great affect the end finish.
7. Paint over it with acrylic paint.
8. Give it another sand with the finest grit you can get your hands on.
9. Apply mold release agent if necessary or gelcoat(a semi-deformable layer that provides a protective layer to the mold to give it re-usability.
10. Ready to make your final product

Very time consuming process, but it's always better to go slow and get it right during the sanding steps than fixing errors after you waste time and money making faulty prototypes. Bog and bondo does dissolve polystyrene, hence a thin layer of epoxy or fiberglass is applied to protect the foam and the mold from impacts. I have heard of people using covering films used in R/C aerofoil construction substituting the epoxy layer.

Due to the complex nature of the Lola bodies you should divide into sections, which can then be glued together later, this way also allows you make mistakes without jeopardizing the entire mold.