Page 282 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

Chapter 9 Making Things and Getting Things Made 259

2D Design
2D design is the digital version of sketching on paper. You’re already familiar with
one 2D program if you made your own gears in Chapter 7. In Project 7-1, we used
Inkscape, an open source vector-drawing program similar to Adobe Illustrator. These
programs can create lines that computers are able to read, which is how a laser cutter
knew how to cut the gear shapes we made.

A more sophisticated tool that’s still simple and affordable is QCAD (www.qcad.org).
QCAD is designed to create parts and 2D plans, while Inkscape and Illustrator are
primarily drawing programs.

The next step up is to use full-blown CAD packages like AutoCAD for part design, but
this is overkill (and over budget!) for a lot of beginners. See Table 9-1 for a comparison
of 2D and 3D modeling programs.

3D Design
Most 3D parts start life as 2D sketches that are pushed, pulled, or otherwise formed
into 3D models on your computer screen. Some programs use a kind of wire mesh
frame to create objects, others use solid shapes, and a few use more of a direct
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mathematical language. Solid modeling programs talk to fabrication machines the
best, but designers with any computer science or programming experience might
prefer the math-based ones.
Table 9-1 lists the computer programs available for 2D and 3D modeling. In order to
navigate the large number of options, look for the asterisks (*), which indicate
favorites, the notes that include ease of use, and the x’s that indicate on which
platforms the software will run.

NOTE You can use Boot Camp, Parallels, or VMware Fusion to run
Windows-only programs on a Mac.

An exciting feature of some of the 3D modeling programs listed in Table 9-1 is that
you can create assembly files that include multiple parts, and relate the parts to each
other just as they do in real life. This allows you to move parts around on the screen to
mimic their real functions, and make sure the pieces don’t jam into each other when
they move, so there’s plenty of space for the range of motion you want.