Page 289 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

266 Making Things Move

Digital Translation
If you created a part using a solid modeling program (like Alibre Design), you can skip
right to tool-path generation. If you used a mesh modeler (like Rhino), you may need
to check or clean up your design first before sending a file to a fabrication machine.
You can also create 3D objects to make with 2D methods by slicing or unfolding the
model. Here are the digital translation possibilities:

• Cleanup MeshLab (an open source program for processing 3D meshes) and
Blender allow you to clean up 3D files generated in mesh modeling programs.
Sometimes models generated by these programs can be nonmanifold. This
means that a fabrication machine might not know which surface is the inside
and which is the outside, or be otherwise confused.
• Unfolding If you’ve designed a 3D part that you want to make out of 2D
material or fabric, a few programs can figure out the unfolding or slicing for
you. If you used Google SketchUp, you can download an Unfoldtool plug-in
for free from http://sketchuptips.blogspot.com/2007/08/plugin-unfoldrb.html.
Pepakura Designer is a low-cost program that breaks down 3D models into 2D
panels that can be folded from paper to create the 3D object. Lamina Design
and Rhino offer more unfolding options and flexibility (for a slightly higher
price).
• Tool-path generation Tool-path generation programs can take 3D models
and break them down into tool paths and layers that machines like laser
cutters and 3D printers understand. Some options are ReplicatorG, Skeinforge,
Pleasant3D, and SketchUp SliceModeler.

Fabrication

There are two ways to make something: do it yourself or get someone (or something)
to do it for you. The problem with doing it yourself is that it can take a long time. To
determine the actual amount of time it will take to make something, consider the rule
of pi: multiply how long you think it will take by pi (3.14). This rule of pi is surprisingly
accurate. So in the spirit of getting things done, whenever possible, get someone or
something to make it for you.