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View Full Version : How to make a protoype shell?


BenG
10-04-2007, 08:48 AM
Ok.

I have on the quiet finally finished my *first* prototype B4 conversion. I still have many mods to make, however, I want to make a shell for it now, as everyone else does, like out of coke bottles?

Please help.

Also, can you tell me the best materials to use to make a mould?

I was thinking car body filler.

Thanks,

Ben

BenG
10-04-2007, 08:53 AM
I found this

http://66.249.93.104/translate_c?hl=en&ie=UTF-8&oe=UTF-8&langpair=de%7Cen&u=http://www.offroad-cult.org/Special/Formteile/Formteile%2520selbstgemacht.htm&prev=/language_tools

Is that a good method?

Could I make a shell out of body filler, and mould it like that?

Lee
10-04-2007, 10:27 AM
I think pro`s use some sort of clay, you will find the body filla will "go off" too quick and become unworkable

BenG
10-04-2007, 11:12 AM
I think pro`s use some sort of clay, you will find the body filla will "go off" too quick and become unworkable

I will try clay, I did make a B4 mould a while ago, its hard, but easier to re-shape as you say ;)

Thanks for the tip.

elvo
10-04-2007, 11:43 AM
PICS! PICSSssss!!

BenG
10-04-2007, 11:49 AM
PICS! PICSSssss!!

Will post pics as soon as I create a working prototype. (Out of the delrin I got today) ;)

Northy
10-04-2007, 11:50 AM
I found this

http://66.249.93.104/translate_c?hl=en&ie=UTF-8&oe=UTF-8&langpair=de%7Cen&u=http://www.offroad-cult.org/Special/Formteile/Formteile%2520selbstgemacht.htm&prev=/language_tools

Is that a good method?

Could I make a shell out of body filler, and mould it like that?


Is there an english translation?

G

dave g
10-04-2007, 11:50 AM
oasis block is very easy to work with and can be shaped easily just by rubbing firmly with the fingers,make sure you get the denser stuff tho,i used to make all my diarama's out of it because its sooo easy to work with and texture.
you can then coat it in pva glue to harden it when shaped.

the other alternative..balsa?
again coated in pva glue when finished.

philly
10-04-2007, 12:15 PM
[quote=www.tyrc.co.uk;32509]Ok.

I have on the quiet finally finished my prototype B4 conversion. I still have many mods to make,

Not wanting to be discouraging, but 'finished prototype' with 'many more mods to do' :wtf:

I'm looking forward to seeing the end results though.;)

BenG
10-04-2007, 12:25 PM
sorry that should read my *first* prototype hehe

BenG
10-04-2007, 12:28 PM
Is Oasis block the stuff they use for floral arrangements?

Is PVA glue heat resistant? If I gently mould a shell to fit, it may take a bit, so will the PVA hold-up?

Definitely looks cheaper than using other stuff.

I wonder if I could make moulds from it?

jim76
10-04-2007, 12:28 PM
Ok.

I have on the quiet finally finished my *first* prototype B4 conversion.


Will post pics as soon as I create a working prototype. (Out of the delrin I got today) ;)


:confused: :eh?: :wtf: :confused: :eh?: :wtf: ?!?

tc2k
10-04-2007, 12:43 PM
Would the oasis block be suitable for creating a mould for making a carbon layup chassis like the piranha?

pro4nut
10-04-2007, 12:46 PM
i would recommend jellutong, it is what i used to make the shell mould for the car i built for my A level.

Once you have formed the shape coat it with P38 and when it has hardened rub it down with 1200 grit.

Oasis could not be put in a former.........

PVA glue will lose adhesion and become sticky under heat, it also isn't water proof.

Can i recommend a trip to the library or a visit to an adult learning centre.
Might also be worth getting a few GCSE Design and Technology text books all this was covered in the national curiculum when i was going through teacher training.

pro4nut
10-04-2007, 12:48 PM
Here is a web link with info on Jellutong,

http://www.monarotimber.com.au/sp_jellutong.htm

BenG
10-04-2007, 12:53 PM
Thanks for the info

tc2k
10-04-2007, 12:54 PM
pro4nut, you seem to know alot.
If you look at the piranha p2 chassis, it has been moulded around some sort of base. Would the oasis block be a good material to use for a mould for a carbon layup chassis or is it too easy to dent?

BenG
10-04-2007, 12:54 PM
:confused: :eh?: :wtf: :confused: :eh?: :wtf: ?!?

I have made a prototype from acrylic type material, so I wouldn't use it unless I was crazy. However it has allowed me to see the proposed layout e.t.c

BenG
10-04-2007, 12:59 PM
pro4nut, you seem to know alot.
If you look at the piranha p2 chassis, it has been moulded around some sort of base. Would the oasis block be a good material to use for a mould for a carbon layup chassis or is it too easy to dent?

My grandma has the stuff knocking about, if I remember its very easy to dent simply by poking it. Perhaps, if you put a Tarpaulin sheet over the oasis and hold it tight it may be solid enough to hold the carbon lay-up.


.

pro4nut
10-04-2007, 01:06 PM
I haven't used carbon fibre so i would not like to make an incorrect statement. I have worked with fibre glass and the resins used generate a lot of heat. An option could be to use blue or pink polystyrene foam to make a male mould, which in turn you use to create a female mould. This can be done by putting the male mould in the bottom of a box, pouring plaster or a cold cure resin of some sort. Then to remove your origanol polystyrene mould just disolve it out with a solvent. This mould can then be used to create a more durable working mould. This lets you work with a material that is easy to form and then create a copy in a harder more durable material.

Northy
10-04-2007, 05:21 PM
English?

G

DCM
10-04-2007, 05:40 PM
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
10-04-2007, 06:12 PM
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':confused: 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
10-04-2007, 06:14 PM
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
10-04-2007, 06:43 PM
I found this

http://66.249.93.104/translate_c?hl=...language_tools (http://66.249.93.104/translate_c?hl=en&ie=UTF-8&oe=UTF-8&langpair=de%7Cen&u=http://www.offroad-cult.org/Special/Formteile/Formteile%2520selbstgemacht.htm&prev=/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..:rolleyes:

pro4nut
10-04-2007, 07:03 PM
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
11-04-2007, 12:41 AM
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/catpages/page-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.:cool:

Rattlesnaker
22-04-2007, 04:20 AM
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
23-04-2007, 11:27 PM
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
24-04-2007, 07:21 AM
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
17-05-2007, 02:00 PM
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
17-05-2007, 03:11 PM
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
24-05-2007, 06:52 PM
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
26-05-2007, 04:04 PM
deleted!!

b4rs
27-05-2007, 11:48 AM
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
28-05-2007, 06:15 AM
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
28-05-2007, 01:53 PM
i did wonder about it being a little brittle, lol. good advice, thnks

LEGEND
28-05-2007, 02:46 PM
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
28-05-2007, 02:58 PM
most probably acrylic then

LEGEND
28-05-2007, 03:05 PM
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.:)

LiamD
28-05-2007, 03:24 PM
What's wrong with the wings that come with the bodyshells? :o

LEGEND
28-05-2007, 03:34 PM
Nothing is wrong whith the wings that come with bodyshell, if you can stay on all four wheels most of the time.I have found that after a while of abuse the standard ones start to crack along the edges which makes them look a bit scruffy.:)

LiamD
28-05-2007, 05:20 PM
You can buy new ones... not as if they're expensive. :o

I really don't get it, Pro Line and JConcepts probably spent a lot of time and money getting their wings right, they didn't just throw any old mould together and hope for the best.