swanny
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| posted on 25/3/15 at 03:28 PM |
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custom RC cars
Hello all,
i have an idea for creating new bodies for RC cars using laser scanning and 3d printing.
i know its possible but the issue would be cost. not looking to scan full size, rather accurate models, and do slight tweaks to ensure they fit
standard RC chassis for other enthusiasts. Not looking to make any money and would be happy to hand over to a proper manufacturer
just wondered if anyone was involved in this as a job/hobby to have a discussion with about it?
regards
paul
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coozer
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| posted on 25/3/15 at 03:32 PM |
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I'm building a 6x6 truck, not to any scale but as big as the axles and wheels allow.
Need a body, like a Man Kat or Tata trials truck... Was going to have ago at building the cab based on a picture I took of a full size military man
using the wheel and tyre diameter to get the appropriate body size.
1972 V8 Jago
1980 Z750
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olimarler
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| posted on 25/3/15 at 04:50 PM |
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I use to race buggies few years back!
Go to a forum called oople they will give you the best info on bodies and what material they use to make them
Oli
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dhutch
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| posted on 25/3/15 at 05:45 PM |
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The bodies are polycarbonate vac-formings.
I expect modern cnc machines and or fdm machines or the like could be used, but I slightly wonder if your going in a rather niche market. When I was a
kid (10-15 or so) I used to race electrics at the local club weekly buggies in summer, touring cars in winter, then moved to nitro trucks just for
hobbie use, before ended up with a 1/8th scale buggy once at uni, now it gets a flurry of use 3-4 times maybe every other year.
The buggies all have there own shell, which mates with the under tray to a close fit all round. So forget that segment.
The TC's and trucks will take basically anything, and some of the touring car and mardave v12 people used to put a lot of care into the
bodysheles, but at the same time, you could get most things you wanted off the shelf, the internet must have made that even more the case, and while
money wasnt tight and the paint was half the cost, I dont think many would spend time times the price to get a E36 compact rather than an E46 saloon.
Maybe I am wrong and I dont want to put a huge damper on it, but I think its going to be a bit of fun on the side sort of venture not a money making
one.
Daniel
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CNHSS1
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| posted on 25/3/15 at 08:19 PM |
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I was in the rc industry for 18years, spending two stints, approx 9 yrs total, working for one of the largest high end importers and exporters of rc
car stuff to europe, US and Japan.
I have experience of commisioning new rc bodies to be made as well as dealing with many of the large manufacturers of aftermarket bodyshells.
I think your idea has legs, so these are points to consider not reasons not to persue it :-)
To vac form bodies in ABS a la mardave is a piece of cake, most schools have vac formers capable. I made one years ago from leccy fire heating
elements and a big vacuum cleaner. ABS is poor for detail though, and heavy in rc terms. Polycarbonate (also known by US brand name lexan) is 100
times better, but about the same amount more difficult to vac form. Polycarb has a very narrow window of operating temp. Its tough to
'pull' if too cool, and blisters if even a few degrees too hot. You will need a variable heat heating element platten too, or even if the
correct temp, as the buck is pulled into contact with yhe lexan, it will start to cool and you then end up with a thick roof and progressively thinner
sides, so much so that the areas at the bottom of the doors become paper thin
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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CNHSS1
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| posted on 25/3/15 at 08:27 PM |
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The idea is to have the centre of sheet of polycarb slightly hotter and the lower edges (front and rear valances, sills etc) slightly cooler, so you
get and even thickness pull irrsspective which part of the finished body you check. This means an expensive vac form machine or build your own.
Polycarb also sweats when stored in sheets, bit like a ream of damp photocopier paper, so the sheets should be parted and left to warm a little before
use, or the damp can boil and create steam spots
Copyright was getting a big issue when i left the industry (about 9 yrs ago), the likes of ferrari, BMW and others actively sued if the rights werent
paid. Many of the race body manufacturers got around it buy making a body that was based on a car, lets say 3 series BTCC car, but with their own
stylized aero kit so it was an original (ish...) design. When marketing them it would be a model 'B' shell...
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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CNHSS1
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| posted on 25/3/15 at 08:36 PM |
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The other issue to consider is to make the shape 'releasable'. With vac forming, the bottom of the shell has to be wider than the top with
no undercuts, or all you end up with is a lexan wrapped buck! Its a bit like the release shape with a grp layup, so yhe shape needs thought.
Ways around it and to get more realsitic detail, is mutipart metal molds. The buck shape is created in mdf and filler, then a really thick body pulled
from abs or lexan. When pulled its stregthened ( grp over the outside etc) and then inverted and epoxy metal poured in. When cured the old body mould
is removed and discarded. Then metal buck can be chopped into at least 3 sections witha bandsaw. With this method undercuts are possible so realistic
bumper detail front and rear is possible. When the 3 piece buck is then vac formed, the lexan wraps around the buck. When cold, the buck is trapped so
The centre section is withdrawn and yhen the front and rear sections can be wriggled free. Proper faff, but doable.
The other advantage of a metal buck is that it can be preheated so the coolibg effect of the sheet hitting the buck is reduced so it aids a more even
pull thickness all over.
Cleverest body tools are
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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CNHSS1
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| posted on 25/3/15 at 08:45 PM |
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Cleverest body bucks are metal and seperately heated.
Another tip is rather than the sheet material being suspended just above the buck and heated and relying ourely on suction to pull the body, the bucks
are actuall lifted through the sheet at the same time. An adjustable height buck platten, a metal buck and variable heating of the sheet material all
help make accurate production methods.
Lastly, best most detailed bodies these days, are actually blow moulded. The sheet is blown from below and into the negative buck. This is multi piece
mould so again undercuts are now issue. Tamiya have been the leaders in the detail for years and pioneered blow moulding over vac forming in rc
bodies.
One final point before you nod off from boredom, is that perfect scale models dont look 'right' to the eye, so the vast majority of bucks
are made to look right rather than be accurate. Its to do with the brains idea of the perspective. We look at real cars from eye level so a 6ft person
would only be 8-10 inches above the roofline wheres a model you almost solely look at in near plan view. Accurate models look wrong, whereas ones
tweaked to account for perspective look much more realistic to the eye
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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CNHSS1
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| posted on 25/3/15 at 08:48 PM |
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3d printing will be great to make the initial buck but being heat moldable itself cant be used a mould buck. The abs material used for printing
wouldnt stand up to one crash impact let alone the abuse rc bodies get, so other than for park'n'pose rc models its no go imho.
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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Irony
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| posted on 25/3/15 at 09:40 PM |
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You might have better luck with 3d printed scaletrix cars. I once built a 36m track within a scaled down city for VW. Vw wanted scaletrix mk 1 golf
gti and mk 6 gti card. The mark 6 was new at the time and bespoke made bodyshells were 10k!!!!!
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swanny
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| posted on 25/3/15 at 09:59 PM |
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Fascinating stuff. Never knew that stuff about perspective either. My plan wasn't to make any money at this.
I like brisca f1 stock cars, and there are a number of body available for these (kamtec etc) but they are all for indoor/smooth Tarmac tracks.
I wanted a toy (not a race car to compete with ) that would run on any surface as the real things do.
So the currently available ones won't work for what I want. To me a good base would be the sand rail buggys as proportionately these look as
close to the real thing (relative width of wheelbase versus length ) and this would avoid having to make customer chassis.
There has also been a surge in interest on old cars from the 60's 70's 80's . Thre are a couple of people making highly detailed
hand build static models of these cars (I have a couple) so I think I have something I could scan rather an try to create he cad file from scratch.
I have talked to kamtec and they have offered to send a pic comparing existing bodies with a sand rail they have so I can start to compare.
Cheers for the responses
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