matt.c
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 posted on 2/11/11 at 08:42 PM |
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Vacuum Forming RC bodies
Been playing about a bit with Radio control stuff.
Been building a 1/10 scale nitro euro Racing truck. It has taken me a while to find a racing truck body shell as these are like rocking horse sh*t to
get hold of now. They look like this:
Now i have one on the way to me its made me think about trying to copy it and make some more. The bodies come in 3 parts and in clear plastic.
How would i be able to make copy's? What about vacume forming? I dont know much about this and was hoping some one on here could give me some
idea's how to do it the locost way 
Many thanks for your time
Matt
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emsfactory
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| posted on 2/11/11 at 08:48 PM |
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I have a pretty big vac former. 66cm square. If that helps.
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tegwin
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| posted on 2/11/11 at 08:50 PM |
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Make some wooden plugs that fit inside the plastic parts you have...
Then take the plugs to someone with a vacuum former and get them to suck them off for you :-)
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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StevieB
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| posted on 2/11/11 at 08:54 PM |
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Fill the original with plaster of paris to get a buck from it (make sure it will pull out first though!)
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matt.c
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| posted on 2/11/11 at 08:54 PM |
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Have had a look at youtube and found out how to make the vacuum former but how would i be able to copy the inside of the original body? Making it out
of wood would be really tricky.
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dhutch
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| posted on 2/11/11 at 09:03 PM |
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quote:
Originally posted by StevieB
Fill the original with plaster of paris to get a buck from it (make sure it will pull out first though!)
Yeah, shouldnt be to hard are they will have been vac formed origanally.
- Mixed up the plaster of paris, coat the parts to about 0.5-1inch thick, then add a load of polystrine packing to the mix and use that to fill the
rest. Saves plaster and makes it more manage in weight.
Then speak to the guy with the vac former! RC bodys are formed in polycarbonate.
Daniel
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locoboy
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| posted on 2/11/11 at 09:20 PM |
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I made some spares for my Shumacher Cat many years ago using the plaster of Paris method and our schools vac former, dead easy.
ATB
Locoboy
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lewis
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| posted on 2/11/11 at 09:31 PM |
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As above but could you use a heat gun? Locost and all that.
I am a driving god!..........sort of
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plentywahalla
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| posted on 2/11/11 at 09:37 PM |
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quote:
Originally posted by dhutch
quote:
Originally posted by StevieB
Fill the original with plaster of paris to get a buck from it (make sure it will pull out first though!)
Yeah, shouldnt be to hard are they will have been vac formed origanally.
- Mixed up the plaster of paris, coat the parts to about 0.5-1inch thick, then add a load of polystrine packing to the mix and use that to fill the
rest. Saves plaster and makes it more manage in weight.
Then speak to the guy with the vac former! RC bodys are formed in polycarbonate.
Daniel
I can see a few problems with that. I used to make vac forming tools. You are looking at about a ton per sq ft of pressure so 1/2 inch of POP is going
to be a bit too weak. I would at least reinforce it with hessian scrim and back it up with Leca (lightweight expanded clay aggregate) instead of
polystyrene.
Another problem to bear in mind is that POP expands when it cures so it is going to be difficult to demould without generous draft angles which if you
are casting from a moulding is not going to be easy to guarantee. We used to use lard as a release agent for plaster casting!
If you want a tool which will last for volume production, cast it in Araldite iron filled epoxy resin with Leca as a void filler.
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locoboy
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| posted on 2/11/11 at 09:54 PM |
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Daniel
If you want a tool which will last for volume production, cast it in Araldite iron filled epoxy resin with Leca as a void filler.
That's a lot of 15mm tubes of araldite!!!
ATB
Locoboy
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CNHSS1
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| posted on 2/11/11 at 10:17 PM |
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having spent 19 years in the RC industry, up until last few years, ive had lots to do with rc bodyshells.
some issues to think about. The bodies are made from polycarbonate (trade names lexan to the Yanks or Macrolon to us in blighty). in its thicker form,
its bullet proof and what the police make their riot shields from. Unlike most vac formable plastics, lexan doesnt propagate splits, is incredibly
tough and being clear, can be painted on the inside which stops the paint being damaged when crashed!
The main issues for the DIY vac former is that polycarbonate is very heat specific. if you start with a 1mm sheet, heat it uniformly (vac formers have
a range of heating elements), then suck down over your buck, as soon as the highest point of the buck hits the heated sheet, it starts to cool. This
then means that this section will 'pull' less than the other areas. The effect means that you end with a thick roof, reasonable thickness
window areas and very thin sides to the bodyshell. Trick is to heat the sheet differently across the sheet. hotter in the centre, cooler at the sides,
this allows a more uniform pull thickness.
ideally the heating elements need to be independantly controlled.
second tip, is to have the buck made from metal which is pre heated. Obviously the production tooling will be CNC'd from an alloy, but you could
use liquid metal to pour into a mould as a cheaper method. If you wanted to be cleverer still, you could put heating elements into the alloy buck to
heat the roof sections to aid an even pull.
Next is the material. Production bodyshells will be from glazing quality (100% opticlaly perfect) sheet, which isnt cheap. Polycarbonate sheets, like
many plastics 'sweat'. They trap moisture which when heated causes issues, steam pockets etc etc.
Back to the heat issues, lexan has a very small operating window between forming properly and burning or at least covering the surface in pin holes.
Production methods would be to gently kiln dry the huge sheets of lexan and have dehumidifier in the drying room.
The best competition bodyshells are made with computer controlled vac machines, which often have footplates that lift the buck up towards the sheet at
the same time as the sheet is vac'd down. Names to look out for are Proline, Protoform and Yokomo. The best detailed bodyshells are
unquestionably Tamiya, but they often employ multiple methods, 2/3/4 part metal bucks and some maybe blown rather than sucked onto the bucks. Detail
is mega though, although at the expense of strength and material thickness.
Basically, if you want to copy a bodyshell in lexan, dont bother. The ball ache involved is huge, material costs for the tiny quantities the DIYer
will buy are high and chances of success tiny. You could use polystyrene or acrylic sheet, much easier to work with, cheap too, but a fraction of the
strength and abrasion/split resistance.
By all means have a go, i have, but dont bother if you think itll be a cheap or quick alternative to ordering an off the shelf body kit.
Oh, and i built and airbrushed the first Yokomo trucks in the UK when i was with the european distributor for a trade show
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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plentywahalla
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| posted on 2/11/11 at 10:19 PM |
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quote:
Originally posted by locoboy
Daniel
If you want a tool which will last for volume production, cast it in Araldite iron filled epoxy resin with Leca as a void filler.
That's a lot of 15mm tubes of araldite!!!
We used to buy it in 25 kg drums from Ciba Geigy in Duxford.... A bit cheaper and quicker than pushing a trolley load through the checkout at B&Q
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plentywahalla
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| posted on 2/11/11 at 10:36 PM |
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I agree with all that CNHSS1 says, but a few points to add.
Iron filled epoxy tooling gives the same benefits as metal tooling at a fraction of the cost. And you can cast it from a moulding.
If you don't have profile heating You can reduce problems of 'freezing' off the sheet by pre heating the tool and blowing a bubble
in the sheet as the tool comes up into the sheet clamp.
High impact ABS sheet would be the best low cost alternative to polycarbonate, not acrylic or styrene.
Don't be put off. It is do-able.
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matt.c
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| posted on 2/11/11 at 11:04 PM |
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quote:
Originally posted by CNHSS1
By all means have a go, i have, but dont bother if you think itll be a cheap or quick alternative to ordering an off the shelf body kit.
Oh, and i built and airbrushed the first Yokomo trucks in the UK when i was with the european distributor for a trade show
The only reasion for trying to copy it is that you cant buy them anymore.  I wouldnt bother if you could buy them.
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matt.c
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| posted on 2/11/11 at 11:45 PM |
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im pretty nervous about filling my new shell with plaster.
It took me so long to get it and i know i prob wont be able to get another. I dont want to mess up the only body i have.
What could i cover the inside of the orignal body with to protect it just incase the moulds dont work?
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CNHSS1
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| posted on 3/11/11 at 10:01 PM |
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quote:
Originally posted by matt.c
quote:
Originally posted by CNHSS1
By all means have a go, i have, but dont bother if you think itll be a cheap or quick alternative to ordering an off the shelf body kit.
Oh, and i built and airbrushed the first Yokomo trucks in the UK when i was with the european distributor for a trade show
The only reasion for trying to copy it is that you cant buy them anymore. I wouldnt bother if you could buy them.
ring CML Distribution, the Yokomo distributor, and ask for Wes Myles. Tell him Craig Hughes suggest you call him and ask him if he can check which
store but the last ones or bought the truck shells in quantity. The were never the biggest seller compared to car bodies, so quite likely theres one
in stock at a shop still.
Modelsport in Otley would be a good shout to try (ask for Jules or Paul), as would Apex Models, DMS Racing in Watford (Darren), Marionville Models
Edinburgh (Scott).
If no joy in the UK, ask Wes or Mark Varley at CML, to check who they shipped them to in Europe, may find one in a german, french, maltese, Irish or
Italian shop/distributor
as for coating the inside, its unlikley the plaster will stick properly, but likley to scrath the surface a bit. I seem to remember theres a plastic
kit modelling masking material called something like Liquid Mask, that paints on, dries, and can then be peeled off like Evostik off your fingers!
never tried it for your purpose (as a barrier to the plaster from the lexan) but might be worth a try on a scrap of lexan to see if it comes off OK.
Also worth waxing the shell inside with GRP release wax as a precaution, maybe PVA relaase agent too?
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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BenB
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| posted on 3/11/11 at 10:46 PM |
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I've just built a vacuum former for making a RC canopy for my 1kw+ 40" flying wing Simples. But I'm using HIPs not lexan. POP may
compress but standard plaster sure doesn't. I've made some nice bucks out of standard brown.... doesn't stick either.
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matt.c
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| posted on 3/11/11 at 11:13 PM |
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quote:
Originally posted by BenB
I've just built a vacuum former for making a RC canopy for my 1kw+ 40" flying wing Simples. But I'm using HIPs not lexan. POP may
compress but standard plaster sure doesn't. I've made some nice bucks out of standard brown.... doesn't stick either.
Sorry to sound stupid but what is "HIP" and "POP" and "standard brown"
Have you got any pics of your vacuum former?
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Angel Acevedo
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| posted on 4/11/11 at 11:08 PM |
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Would making an external Mould not work?
Then you could use it to make Fiberglass copies.... Or an Internal Buck.
Then you would use the buck to vacuum form the copies...
Too much work... I think.
Beware of what you wish.. for it may come true....
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stevebubs
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| posted on 5/11/11 at 12:22 AM |
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quote:
Originally posted by matt.c
im pretty nervous about filling my new shell with plaster.
It took me so long to get it and i know i prob wont be able to get another. I dont want to mess up the only body i have.
What could i cover the inside of the orignal body with to protect it just incase the moulds dont work?
For Plaster of Paris? If it sticks, just wash it out...
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BenB
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| posted on 10/11/11 at 09:55 AM |
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quote:
Originally posted by matt.c
quote:
Originally posted by BenB
I've just built a vacuum former for making a RC canopy for my 1kw+ 40" flying wing Simples. But I'm using HIPs not lexan. POP may
compress but standard plaster sure doesn't. I've made some nice bucks out of standard brown.... doesn't stick either.
Sorry to sound stupid but what is "HIP" and "POP" and "standard brown"
Have you got any pics of your vacuum former?
Oops, sorry for the time lag 
HIP is high impact polystyrene. POP is plaster of paris. Standard brown is just wall plaster...
I'll get me camera!
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