jkyle69
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 posted on 31/10/05 at 09:33 PM |
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Making a 1:1 model
Does anybody have any experience of making a 1:1 scale model? I currently have a highly detailed 1:1 scale model in 3D Studio Max and I am looking to
have this produced in 1:1 scale. Any help ideas appreciated.......
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flak monkey
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| posted on 31/10/05 at 09:34 PM |
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Why not just build one 
In which case a lot of people can help you here
Sera
http://www.motosera.com
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jkyle69
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| posted on 31/10/05 at 09:38 PM |
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eh....
It is a mid engined sports car and I will be trying to produce a carbon fibre or fibreglass monocoque. I dont think I would be
'tha't' confident doing that myself in case it turned out to be a big disaster.......especially if I was in it at the
time.....
[Edited on 31/10/05 by jkyle69]
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flak monkey
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| posted on 31/10/05 at 09:47 PM |
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My uni project this year is on a composite monocoque. Its tricky stuff and you need to do some research into it as its properties are very depndant on
how you construct the structure and eactly what materials you use.
There are a few people on here with a lot of knowledge in composite structures, though they may not be willing to share info that freely.
Making a model will not help you much to be honest. If its a new design you will have to do the reading. Which means getting hold of lots of advanced
materials books. Then doing the math and mocking up some parts of the design to see how they react.
Modelling before doing any analysis is pointless in my opinion.
David
Sera
http://www.motosera.com
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jkyle69
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| posted on 31/10/05 at 09:50 PM |
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Modelling...
You think it is worth doing a 1/4 scale model? I am not an engineer so will likely get someone else to do that bit I think. I t seems that people seem
to think I need to produce a 1/4 scale model and then a 1:1 scale model but if I have all of the 3D models do I actually need to do this?
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flak monkey
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| posted on 31/10/05 at 09:56 PM |
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The model does nothing other than tell you that it will in theory fit together. It doenst mean its suitable for its job.
Not being rude, but if you have no knowledge of composite materials, stay well away from composite monocoques etc. Failure die to poor design can be
catastrophic to say the least. And due to the failure mode of most composites (ie brittle) design of the structure to suit the material is very
important.
Polymer sandwich foams are relatively forgiving, however to get the best properties from the you need specialist equipment such as vacuum bags or auto
claves. Same goes for pre-preg CF.
Composites are complex as they are not a isotropic material. They behave very differently to metals.
David
Sera
http://www.motosera.com
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jkyle69
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| posted on 31/10/05 at 10:00 PM |
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I was not going to any of the design and production of any monocoque myself; I am definately leaving that one to someone else. I was wondering whether
I have to produce a 1:1 scale model of the car or is that really just a touchy feely thing for designers? The 3D models I have are all 1:1 scale and
of a very very high quality so can a chassis designer use these rather than having a scale model (I should imagine so). I am thinking about using a
spaceframe/monocoque system as is used in TVR production but interested in other possibilities - I have been recommended using a carbon fibre
monocoque central section with front and rear spaceframes but I am not sure what would be the best route (I dont want to go down one avenue to only
back up and begin again).
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flak monkey
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| posted on 31/10/05 at 10:06 PM |
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The mixed steel and CF chassis is a good idea, and I am sure one of the sports car manufacturers use it to good effect, though i cannot remember which
one.
A competant engineer who is skilled in composite structures will be able to work from the CAD model you have and decide whether it will work and
probably suggest changes to the design if some areas will not work.
Your best bet is getting in contact with a skilled person and seeing wha they suggest.
Oh and I hope you have money to burn, as any CF structure will cost you, especially if it has to be developed and tested before a final hing can be
made.
Very expensive and time consuming.
May I ask what your reasons for wanting to use composites are?
They do offer seriously light weight ans very high stiffness if used correctly. But the costs are staggering.
David
Sera
http://www.motosera.com
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jkyle69
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| posted on 31/10/05 at 10:11 PM |
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The CF was just a recommendation from a car builder but I would prefer to use fibre glass and a spaceframe as basically it is loads cheaper (including
if mistakes are made) and weight is not really a huge consideration. Could I use a ladder type spaceframe chassis and a grp monocoque?
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flak monkey
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| posted on 31/10/05 at 10:13 PM |
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If you are not bothered about weight why not just make a steel spaceframe and grp bodywork.
There are several people on this site doing just that.
Take a look in the mid engined section. Specifically at Alan B's project!
David
Sera
http://www.motosera.com
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jkyle69
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| posted on 31/10/05 at 10:20 PM |
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ok thanks for the help
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Volvorsport
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| posted on 31/10/05 at 10:36 PM |
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im building a steel/composite tub (well actually i have) , and worked for darrian cars making monocoques from grp/kevlar carbon etc .
what do you have in mind ?
u2u me if you like
www.dbsmotorsport.co.uk
getting dirty under a bus
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jkyle69
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| posted on 31/10/05 at 11:31 PM |
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Have sent you a u2u message 
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liam.mccaffrey
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| posted on 31/10/05 at 11:48 PM |
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off topic a bit
i printed out full size floor plans and profiles of my space frame, just for fun
Build Blog
Build Photo Album
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jkyle69
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| posted on 1/11/05 at 12:03 AM |
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You must have a fair bit of space knocking about 
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sgraber
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| posted on 1/11/05 at 03:30 AM |
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I built my bodywork (correction - still building...) after designing it in 3ds max and then exporting sections of the body shell shape at 6"
intervals as dxf files. Then those outlines were opened in autocad and printed full scale on a plotter. Those plots were then taped onto plywood (or
particle board) and cut with a jigsaw. I call those the ribs. A central spine was created down the centerline of the car made out of a stout beam and
all of the ribs were attached to the center spine at the original 6" interval. Then I glued foam between each set of ribs and cut it to shape
with a hotwire. All of this was covered with plaster and sanded to shape. The plaster is coated with a hi-fill epoxy primer and currently being sanded
to 1200grit. A mold will be pulled from this effort and the original plug will be destroyed.
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I will NEVER do this again! 
Before I ever try to build a car body in this fashion again I would rather have all of my fingernails pulled from my hands with a pliers.
Instead I would first build a large gantry style cnc router. Export my model to G-code and let the machine carve the perfect shape out of a block of
foam.
But if you have 50,000 to burn, let someone else build your model for you.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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andygtt
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| posted on 1/11/05 at 09:18 AM |
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When I did some research into the feasability of producing an all carbon fibre car, I discovered that insurance companies frown upon composite chasis
as a small prang meant a complete new chasis.
It turned out that this was why most cars claiming to be carbon tub etc were actually only partial with removable crush zones front and rear.
I know insurance may be furthest from your mind at design stage, but If you want it to be a road car I'd recomend you check.
Andy
please redefine your limits.
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