Fig. A: Scribbler software converts images, such as
webcam portraits, into dense networks of straight lines,
blurring the line between representation and abstraction.
Fig. B: Plotter axle and carriage: 1. Pen attached to
stylus bearing with zip tie; 2. Stylus bearing on carriage
rod; 3. Carriage motor and belt; 4. Main belt, bearing, and
track; 5. Main belt pulley and axle. Fig. C: Full system,
with webcam and software on laptop.
For the motors themselves, I just used generic y-axis. The entire carriage slides left and right on
Chinese models. top of the main track, which supports it. After a
The Scribbler Bot software (see sidebar next bit of experimentation, I realized that I needed
page) is written in Macromedia Director. Conve- some additional clearance between the carriage
niently, Director also has an ActiveX control that and the baseboard. So, I raised the main track off
handles parallel port I/O. Embedding this control of the board by adding some nylon washers onto
into the Scribbler project software lets it control the bolts underneath the aluminum brackets.
the A200 board directly, through Director, rather The carriage has two structural pieces: the frame
than having to go through the A200’s own separate and the track. The frame is a length of 1" square
controller application. aluminum tubing, which bears the weight and
carries the motor, pulley, and track assembly. The
track is a smooth ¼" aluminum rod running par-
allel to the carriage frame that the stylus bearing
slides along.
To get the carriage frame to slide along the main
tracks, I attached two ½" internal-diameter linear
bearings, which I bought from Skycraft Parts and
Surplus (
skycraftsurplus.com). These fit around
each rod like cuffs, and they slid up and down
the tracks perfectly, but mounting them to the
square-shaped box tubing was a bit of a challenge.
I eventually cut the ends of each tube down 1" on
3 sides and glued the bearings into the cutouts
with JB Weld epoxy. I had to make sure that the
bearings on each side were perfectly parallel,
Building the Structure
The roughly 42"× 40" drawing area of the Scribbler
Bot is framed by the main tracks, which define
the plotter’s x-axis. The tracks consist of two
smooth metal rods that run along the top and
bottom edges. These are held in place at both
ends by brackets that run down each side, bolted
to the flat wooden base. The track rods are just
lengths of ½" rigid steel electric conduit tubing.
The brackets are L-shaped aluminum bars, which
I drilled at both ends so I could slide the tracks
through them.
The carriage track, which carries the plotter’s
stylus, is oriented up-and-down to control the
