Page 185 - Robot Builder's Bonanza

154 DRAFTING BOTS WITH COMPUTER- AIDED DESIGN

Using Transfer Paper and Scribes
Sometimes you can’t (or don’t want to) physically stick the paper to the material. You can use
transfer paper instead. It works just like old- fashioned carbon paper, but it isn’t as messy.
Trace the design on the paper using a ballpoint pen. The tracing will appear through the
transfer paper. Unwanted transfer lines can be removed with a soft pencil eraser. Find transfer
paper at art supply stores.
For materials with a rough or irregular surface, the pattern can be transferred using a
scribe. A machinist’s scribe is the appropriate tool for the job, but these can be expensive.
Most any sharp metal implement, such as a scratch awl or nail (with its tip sharpened) will
work with plastics, aluminum, and other soft metals.

CREATING LAYOUTS WITH COMPUTER GRAPHICS PROGRAMS

Whatever you can do with a paper layout by hand, you can do better with a computer graph-
ics program. You can create and store your layouts for future use, share them with others,
and, given the right kind of program, make tweaks and changes for quick updates.
There are two general types of graphics programs: bitmap and vector. The difference is
how the program stores the shapes you draw.

• Bitmap graphics is composed of a series of dots, like the dots in a newspaper picture.
Windows Paint is a good example of a bitmap graphics program. Pick a drawing tool, and
it creates a swath of dots in some distinct shape, size, and color.
• Vector graphics is composed of lines and other shapes. You make drawings by combining
different shapes— squares, rectangles, lines, and so on— together. See Figure 15-2 for an
example.

Changes are harder with bitmap graphics, because once the bits for a shape are laid down
on the digital canvas, the shape itself can no longer be edited. On the other hand, with a vec-
tor graphics program you can directly change any of the shapes, even delete them. Changes
are much easier.
Vector Graphics Best Choice
Of the two, vector graphics programs are by far the most useful in drafting your robots. You
can use the program to create the overall design— basically a drawn picture of how your robot
will look when finished. Or you can use the program to create drill and cutout templates— the
same idea but better execution to layouts drawn by hand.

Circles &
ovals
Lines
Squares & Figure 15-2 Prepare a
rectangles
construction template using simple
shapes by combining circles, squares,
rectangles, and lines.

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