RazMan
|
| posted on 7/11/07 at 12:43 PM |
|
|
Model Making
I've been asked to look at producing a 1/5th scale model of a new car for a radio controlled enthusiast.
Thinking about it, the processes involved would be identical to making a full sized bodyshell except that it will fit on a workbench with ease.
Has anyone got experience in making a model like this? Also has anyone got any info on 3D scanning this sort of thing? I'm thinking that if the
design is successful, a full sized version could be built from the CAD data.
Any pointers guys? 
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
|
|
I love speed :-P
|
| posted on 7/11/07 at 12:49 PM |
|
|
Do want it 2 move? If so, really I would use a 23 cc 2 stroke engine as they start and run so much better than nitro. If you search for FG they do
both on road and off road 1/6 cars and trucks which you could use the running gear out of?
Phil
Don't Steal
The Government doesn’t like the competition
|
|
|
Hammerhead
|
| posted on 7/11/07 at 12:52 PM |
|
|
I have made models like this in MDF laminated to take moulds. I have also made models in blue foam, which is a lot easier to shape.
You could have it cnc routed from foam if you produce the model in 3d studio max or some other program. I think it is easier to model it in cad rather
than digitise it after you make the physical model.
However, someone on here has digitised lola t70 bodywork. Not sure if it was Dick Bear or CanAmSa. But there is a detailed blog on the method.
ETA: If you want to make it a something that can be cheaply produced for RC guys then i'd suggest designing the car to be vacuum formed.
Also I think that scaling a RC body for a real car would be difficult as the proportions in RC are exaggerated, but you never know, it might just
work!
Keep us posted.
PS. Ditch the Witch
D
[Edited on 7/11/07 by Hammerhead]
|
|
|
RazMan
|
| posted on 7/11/07 at 01:08 PM |
|
|
quote:
Originally posted by I love speed :-P
Do want it 2 move? If so, really I would use a 23 cc 2 stroke engine as they start and run so much better than nitro. If you search for FG they do
both on road and off road 1/6 cars and trucks which you could use the running gear out of?
Phil
I'm not going to get involved in the chassis or engine - I will leave that up to the experts 
I just need to sort out the body shell. One option is to take a scan of an existing design and then 3D scan it to get a basis for a new design
(don't want to re-invent the wheel) and then get to work with a CAD prog like Inventor or 3DS etc. When the design is finalised I would like to
hand it over to a CNC machinist to create the buck - but I havent a clue where to start looking for this type of engineering company.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
RazMan
|
| posted on 7/11/07 at 01:14 PM |
|
|
quote:
Originally posted by
PS. Ditch the Witch
D
The witch is now ditched
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
Johnmor
|
| posted on 7/11/07 at 01:43 PM |
|
|
This may provide a basic chassis and RC gear
This is on Ebay at the mo, may provide engine , even basic chassis etc
Item number 300167177860, If link doesn't work.
http://cgi.ebay.co.uk/HUGE-1-5-scale-Kyosho-Lancia-petrol-rc-car-Futaba-
|
|
|
Delinquent
|
| posted on 7/11/07 at 02:22 PM |
|
|
I've made these before using the simple rib approach, but you are right there is no reason at all you can't have it CNC machined from CAD
- just look up CNC in your local area on yell or touch and give em a call. It's not exactly cheap even for small things mind, for full size
it's horrifically expensive!
If you can wait about 12 months I should have my 20ft CNC mill ready :p
|
|
|
ettore bugatti
|
| posted on 7/11/07 at 03:10 PM |
|
|
Vacuumforming is used a lot in RC. But you still need a mould.
|
|
|
RazMan
|
| posted on 7/11/07 at 05:38 PM |
|
|
quote:
Originally posted by Delinquent
I've made these before using the simple rib approach, but you are right there is no reason at all you can't have it CNC machined from CAD
- just look up CNC in your local area on yell or touch and give em a call. It's not exactly cheap even for small things mind, for full size
it's horrifically expensive!
If you can wait about 12 months I should have my 20ft CNC mill ready :p
LOL It will probably take me a year to get to a stage where I am ready to get the full sized version made - I might give you a call
Actually I was thinking about the rib approach like a few people on here have used to good effect on full sized cars. I would like to take the CAD
data and slice it up into ribs at convenient intervals and then get them cnc routed, mount them on a frame and 'fill in' the gaps, making
the plug - a sort of 2D approach which should be easier and cheaper.
I'll have a look in Yell and see what turns up.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
Fred W B
|
| posted on 7/11/07 at 06:09 PM |
|
|
Oo oo oo... Check this out
This pic is the results of a test run on the CNC controlled 3D router my friend Andrew (guy who drew my body) made himself. This was cut from a block
of foam, with a toolpath derived from the model we drew way back. The surface is actually smoother than it looks in the pic, the flash picks up the
texture in the foam.
I think its pretty damn impressive for a home made machine. It has an X, Y and Z travel of 1600, 700 and 150 mm respectively
Raz, if I was asked to do what you are planning, first prize is to get the shell drawn completly in CAD if you can, and then CNC cut in one piece in
foam. Nowadays, on full size work they cut the foam a few mill undersize, then apply the surfacing filler and recut the plug final size, so then just
have to wax and take moulds
If the CNC you have access to is a router with limited Z height I woul sugest rather than cut thin ribs and fill between than manually, have foam
sections cut in say 30 mm slices, glue then together and then blend the countours together with plaster filler.
Cheers
Fred W B
 
model cut
[Edited on 7/11/07 by Fred W B]
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
|
|
|
RazMan
|
| posted on 7/11/07 at 06:29 PM |
|
|
That is a thing of BEAUTY Fred 
Now THAT is what I would like to end up with - a 3D shape that I can take a mould from. However I am reliably informed that a CNC sculpture like that
would cost an arm and two legs to get machined.
I have followed your design & buck production process with great interest and presumeably you decided to go with the 'rib' method to
keep costs realistic.
Can I ask what program you used to extract the routing data?
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
RazMan
|
| posted on 7/11/07 at 07:48 PM |
|
|
quote:
Originally posted by Fred W B
I woul sugest rather than cut thin ribs and fill between than manually, have foam sections cut in say 30 mm slices, glue then together and then blend
the countours together with plaster filler.
That makes a lot of sense Fred - it would certainly make the shaping process a lot easier as there would be only foam to shape and no wood. A skim of
filler over the surface would hold it all together and allow a super smooth finish to take moulds from. I doubt that the buck would survive the
extraction very well, but then it is normally regarded as expendable anyway.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
|
|
|
Fred W B
|
| posted on 8/11/07 at 08:15 AM |
|
|
Hi Raz
WRT motivation for rib method, see some discussion in THIS THREAD
I asked Andrew to answer your question re “what program you used to extract the routing data”. His reply is below.
He suggests you have a look on "www.cnczone.com" - site for amature cnc machinists like us and some do small jobs, mabe you will find
someone in the UK? - look at the "Request for quote" page
Cheers
Fred W B
________________________________________
I draw 3d parts in Inventor or AutoCAD
3d models are converted to .stl format for the cam package (Visual Mill 5) to accept. Visual mill will accept 2d .dxf files as well.
Visual Mill takes the drawing or model and the milling tool dimensions that I specify to generate a path that the tool must follow to achieve the
desired shape. This Path is described in G-Code, basically a text file.
The router controller can interpret this G-code and move the X,Yand Z axes accordingly.
Hope this helps.
Andrew
[Edited on 8/11/07 by Fred W B]
[Edited on 8/11/07 by Fred W B]
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
|
|
|
