How to make a protoype shell?

[Northy]

English?

G

[DCM]

Dude, I thought I explained this before.

Use some plywood and cut and glue sandwhichws of it together to get the rough shape, then you use body filler to build up the areas prior to sanding. Sand one side to your liking, then use a profile board so when you sand the other side, you can make them near identical. Once done, blow ALL the dust out, ensure your window/cooling vent lines are defined and then get it vacformed, use a thinner sheet at first, it will mould easier (less heat).

You can't use Clay, as to use it to pull a mould, you have to fire it first, and it will shrink....

[pro4nut]

Originally Posted by Northy

English?

G

The web link bit?, make mould out of would, cut the flat bit out of a 2 litre coke bottle get it warm, lay it over give it a blast with a heat gun to aid the plastic 'drooping' over the mould.

If you make a wood mould you can actually drill out the centre and make lots of holes around the bottomand a couple hidden in the window and vent indents, then attach a hoover attachment. Do the same thing with the coke bottle just this time you have a basic vacformer. Mr Northy send me a pm if you want any info.

[pro4nut]

Originally Posted by DCM

Dude, I thought I explained this before.

Use some plywood and cut and glue sandwhichws of it together to get the rough shape, then you use body filler to build up the areas prior to sanding. Sand one side to your liking, then use a profile board so when you sand the other side, you can make them near identical. Once done, blow ALL the dust out, ensure your window/cooling vent lines are defined and then get it vacformed, use a thinner sheet at first, it will mould easier (less heat).

You can't use Clay, as to use it to pull a mould, you have to fire it first, and it will shrink....

Try the jellutong instead of ply, believe me a much easier material to work. Has almost no grain and needs very little filler.

[mad max]

I found this

http://66.249.93.104/translate_c?hl=...language_tools

Is that a good method?

Nice to see the stuff coming 'round *gg*
The thing is - the coke bottle acts like a heat shrink. You won't be able to make any vents or other small concave details with this method.
Polycarbonate sheet will just soften when exposed to heat, then you can vacuform it almost any shape you like. But it will also pick up any surface defects of your mould. The bottle material just tightens around it. For the piranha I could use a simple balsa wood mould without any filling or hardening the surface..easiest way, but limited in detail..

[pro4nut]

For anyone that has been looking for jellutong try searching for jelutong instead. Spelling is not a skill i have.

It is actually nearly as soft as balsa but be sanded and detailed across the grain and with the grain

[terry.sc]

My area of expertise this, been a professional modelmaker for years. As you can probably guess from what follows I am looking at producing shells myself.

Pro body makers carve the body design in clay,(which is easy to work with by hand) or modelling board (easier to machine). When the pattern is finished a mould is made from the pattern in silicone, then the mould is made in tooling resin, which can withstand the temperatures of the vacformer. Total cost of the materials for this is in the region of £300 per pattern. For a production run tooling resin (at £50 per kilo!) is the only option that will last.

Bodies are vac formed in polycarbonate, if anyone wants any 1mm polycarbonate let me know, I usually sell it in A4 size pieces but can supply bigger sheets. Vacforming polycarbonate at home isn't practical, apart from needing to build a vacformer you need to dry out the polycarbonate before you can mould it.

Oasis foam will just melt if you try vacforming over it. Epoxy resin will also attack it.

The best material for making a pattern from is modelling board. Softer boards are easier to carve but harder ones last longer. They have no grain, so gives a great surface finish. Vacforming over it will distort the pattern over time, but perfect for prototyping. I get mine from here http://ccgi.johnburn.co.uk/products.php?broId=17

An alternative is jelutong timber. Easy to carve and relatively stable with no knots and a very close grain. It still has a grain so the surface finish will always have a texture when formed over, unless you use a filler over the top of it. Very soft wood, easy to dent accidentally. Also distorts with repeated use as a former. I get mine from Arnold Laver at Mosbrough http://www.timberworld.co.uk/sheffield.asp
Also available in small quantities from EMA
http://www.ema-models.co.uk/shop/cat...e-LF.html#LF11

Once you have made your pattern you will need to do some work before it can be vacformed. It will need drilling with a 1mm drill in all the low points to get air out of between the pattern and the plastic as it is moulded. Look at any bodyshell and you should be able to find small dots in the body, this is where it has been drilled to vent it. It will then need fitting to a mounting board, the design of this depends on that machine it is vacformed on and you will need to discuss this with whoever does your vacforming.

BTW Attached are photos of a recent project of mine, shows what can be done with jeltong, filler and urethane resin.

[Rattlesnaker]

terry.sc, What type of plastic do you recommend for "home" use? I've tried PET-G, it forms ok, but seems kind of brittle, then again I've just started to trying vac forming.

[terry.sc]

Polycarbonate can be used, just expect it to have small bubbles all over it. PET-G moulds very nicely with low power vacuum systems and is wehat I would recommend, but as you have found out nothing is as tough as polycarbonate. PET-G is also slightly hygroscopic but nowhere like as bad as polycarbonate or acrylic.

The lower temperature that PET-G softens at also helps for home use.

[LEGEND]

I have just realised, I would probably be able to do most of them steps at my school. The art department may let me use the clay if i make the model as my project or something. Or, the design technology department will let me use the wood anyway. They will probably let me use the vacformer is i have a good reason.

[BenG]

Tried the coke bottle method, but it just shriveled lol.


Going to lower the heat on my heat gun, maybe using a deflector.

[Nick Goodall]

I saw the team Aero mould for their new body (lee was running it at Kiddy) and it was CNC machined alloy - looked absolute quality with really clear defined edges etc. Seemed a fairly good way to do it, but i'm sure it's not cheap?

[Body Paint]

I remember seeing a touring car shell mould at the Schumacher factory about 15 years ago. From memory they had machined it out of a solid block of Aluminium with there new spark eroder..

It looked awesome all polished up ready for vacforming.

[super__dan]

deleted!!

[b4rs]

me too legend, im gonna make like 30 b4 rear wings on the vac former out of thin acrylic. then sell em on for a small profit, say £5 or somat.

[BenG]

I wouldn't make acrylic wings, its ve y brittle.


Have a look on eBay for lexan, buy it in bulk, and have fun making a profit

[b4rs]

i did wonder about it being a little brittle, lol. good advice, thnks

[LEGEND]

At the moment I am making a mould for a B4 rear wing out of MDF. The school uses loads of this types of stuff to make moulds for diffent projects. I dont think they use acrylic though. all I know is that it is see-through, thin and is able to be used on a vac former

[b4rs]

most probably acrylic then

[LEGEND]

You are probably right, but as far as i can remember it never was that brittle it was probably just as strong as the one you can buy now. Apart from the Jconcepts one's they are thicker and stronger i think.