Page 189 - Hacking Roomba

170 Part II — Fun Things to Do

Adding a Paintbrush to Roomba

The term paintbrush is being used lightly here. Because Roomba has no way to control the
amount or color of pigment or even lift the brush, a real paintbrush would be difficult to use.
And since paint takes time to dry, there’s the possibility of Roomba tracking across wet paint.
This might be neat artistically, but it makes for a messy robot.
Thus the paintbrushes used must be things that produce a mark when moved along a surface
with little pressure and make a mark that dries quickly. Marker pens and chalk both meet these
criteria. Normal pens or pencils could also be used, but the lines they create are thin and hard
to see compared to the markers. A large mark makes a bold statement and also makes it easy to
see what Roomba is doing.

Brush Types
The main type of brush used is a marker pen, the wider the better. Sharpie makes some huge
markers, but the indelible ink used in them smells pretty toxic and permanently stains materials
you may not want stained. Crayola makes some non-toxic, more water-soluble markers that
produce reasonably thick lines and are easy to clean up in case of accidents. Also, the Marks-A-
Lot and Sharpie markers are harder to use because they both have chisel tips. The conical tips
of the Crayola markers make a more consistent line. Try out the chisel tips to see if you like the
variation effect it produces as the robot spins.
Markers assume you have something to mark on. If you don’t have big sheets of paper, there’s
still the option of using chalk on your driveway. The brightly colored sidewalk chalk available at
most craft stores has the added benefit of being easily swept away with a push broom, making
erasing quick and easy. The chalk has the downside of being less precise and you must constantly
reposition the chalk as it is consumed. Plus, you can’t easily save your masterpiece when done.

Attaching the Brush

The Roomba’s smooth plastic surface doesn’t lend itself to attachment devices that must touch
the ground. One option is to take Roomba apart and find the appropriate places to drill holes
for markers. This would enable you to create a very stable holder for the marker but would def-
initely void the warranty.
Whatever attachment method you use, it must press down a little on the marker so it makes
a decent line. There’s room for experimentation here. The following sections detail the three
non-destructive techniques for attaching markers used in this chapter.

Duct Tape
Rumor has it the world is held together by duct tape. The embedded cloth fibers and strong
adhesive of duct tape provide a decent anchoring for markers and enable you to position a
marker virtually anywhere on Roomba. Duct tape only works on non-porous materials, how-
ever, so it will not hold chalk in place.