View Full Version : Seek CAD model for any yamaha motocross frame

24 September 2010, 2325
I just downloaded GrayTech Software's free (really - no strings attached!) CAD software, CAD X11 .
Now, would any of you CAD-savvy guys point me where I can get (or provide me) a model (".plt") of a motocross frame to use as starting point? It can be any modern yamaha, suzuki motocross byke.
What I want is to visualize how an elongated swing arm, supported by a shorter shock would translate in a custom-like frame for the electric conversion I intend to make. The safety issues (stress points, reinforcements, etc.) have been studied, do not worry!

I am not in America, where a custom chopper frame can be used without the authorities taking your ride away from you. Israel does not make it easy on this kind of stuff, hence my desire to use a "brand" frame as donor (don't get me wrong, I love my country very, very much:p)

Drawing a full frame is simply impossible for a newcomer to CAD... let alone one that is dimensionally true to the original - no way :( :confused::confused:
Please help me out!

25 September 2010, 0840
I'll keep my eye out and see if I can get you something.


25 September 2010, 0901
I'm not familiar with .plt as a 3D model format. I think AutoCAD used to use the .plt extension for raw 2D plotter data.
Does CAD X11 support import of any other 3D formats?
You might also look at Blender - it's more illustration/rendering than CAD/CAM oriented, but it's open-source and free and supports a lot of common 3D file formats, so it might open up options in converting a model you find in one format, into something CAD X11 can read.

25 September 2010, 0957
Not familiar with .plt or CAD X11 either, I use Alibre Expert.

To get going with a specific frame, what I do is import a side image of the bike as a backdrop, and in 2D, draw a line between two known points, usually the front / back wheel nuts. Then use the 'dimension' tool to measure how long the line that I've drawn is.
Say for example that the line is 98mm. Next I look up what the actual wheelbase length is, say 1469mm (Kawa KX250F).
Divide the real by the measured .. 1469/98 .. 14.99 .. then 'scale' the image up by this amount.

You now have an actual size image of the bike. Next zoom in and around the image, tracing (drawing) lines as you go.
Delete the image and save the sketch. If you set a few datums, you can then 'assemble' other views e.g. back / front etc. and end up with a 3D wireframe representation.

Don't know if any of the above is doable in CAD X11, but pretty sure there is a free Alibre version that will do what you want if not.

Hope this helped, Rob

25 September 2010, 1004
Thank you guys! I have googled "convert jpg to .plt" and got tons of results; have downloaded at least two programs which claim to deliver .plt, but don't! Maybe 'cause it is the "trial version", I don't know.
Magicsmoke, your suggestion seems good, I will try it. That is exactly what I use to do in corel draw, when I draw plans for airmodels. I will give it a try. At this moment, I really do not need 3D, 2D would do fine...
Again, you are all very supportive, todaraba! :)

25 September 2010, 1206
Dang, am I frustrated! Why oh why isn't this CAD thing as simple as paint brush? :p

25 September 2010, 2348
Uh-oh... after reading Carl Vogel's advice on frame basics and the effects of modifications on his book "Build Your Own Electric Motorcycle" I realized my smart idea to have a custom-looking byke from a motocross rolling chassi is not so smart after all.
The implications to rake and trial are self-evident in the stunning picture attached (painstakingly worked out in Paint Brush "Pro") :p . The two "floor lines" on the front wheel say it all.

29 September 2010, 0535
I just got Google Sketchup 3-D CAD software legally free from google's website, and even a model of a motocross byke. There are many tutorials in the net (youtube and google itself). I am struggling to figure out how to modify the model to suit my needs. It's fun!

29 September 2010, 0936
This is what I got so far frame-wise. The drawing is incomplete, but shows the basis of my idea. What do you guys think of it?