ust like the inevitable new entry in the
perennial horror movie franchise of the day,
another October means another punkin
chunkin robot. For all of those worrying that
yet another air cannon article would be as
tired as finding yet another Jigsaw apprentice
by the time we got to Saw 3D, fear not! We’re
completely mixing up the franchise like they did in
the Michael Myers’ free (and highly underrated)
Halloween III: Season of the Witch. Instead of
sinister Halloween masks, the fresh centerpiece of this
project is something that we have been seeking for a long
time: a simple and effective solution for linear motion.
This month, it was a real treat to work with the
mightyZAP linear servo motors from IR Robot. The
mightyZAPs are a line of linear servo motors that come in a
variety of different strengths, ranging from 6N to a
whopping 100N — all in a tiny servo motor package.
What mechanisms could the linear servos make as
simple and efficient as Jason Voorhees mowing down the
unfortunate visitors to Camp Crystal Lake? Would our
pneumatics-free punkin chunker be a trick or a treat? There
was only one way to find out.
The Hills Have Lines
The mightyZAPs solve a problem that is as ubiquitous
as the well-worn horror movie tropes of the final girl or the
unkillable villain: linear motion. There are so many
mechanisms that are most efficiently and easily achieved
with linear motion: lifters, pushers, pullers, stabbers, etc.
Any of these mechanisms can, of course, be achieved using
a run-of-the-mill rotary motor, but that usually requires
more complicated designs (like four bar linkages, cams,
Archimedes screws, racks and pinions, or many others) that
don’t efficiently translate the rotation into linear
displacement. The most straightforward way to solve a lot
of these problems seems obvious — a linear actuator!
However, that’s easier said than done — or rather, found.
Linear actuators are everywhere, but they don’t often
come in a package that can be easily implemented on a
small robotics project. A classic example of a powerful
linear actuator is a pneumatic piston, but that requires an
entire pressurized air system that for many projects would
seem as unnecessarily complicated as a Jigsaw trap.
Linear actuators also come in the electric motor
variety, but in our experience, the small ones have usually
been too pint-sized and strength-limited to be terribly
useful (like the disappointing monsters in Don’t Be Afraid
of the Dark), and the ones that are decently strong are
often quite bulky. It would be great to have a linear
actuator that was comparably sized to a standard servo
motor, but with enough power to create strong and
That’s where the mightyZAPs from IR Robot come in.
As their name suggests, mightyZAPs are indeed a mighty
unit in a tiny package — much like Chucky from Child’s
Play. The mightyZAPs are comparably sized to standard
servos ( 57. 5 mm long, 29. 9 mm tall, and 15 mm wide),
and they come in strengths ranging from 6N to 100N.
The naming convention on the mightyZAPs bestows a
plethora of information about the device.
by Bryce Woolley and Evan Woolley
Punkin Chunker V:
Season of the
THE MIGHTYZAP LINEAR SERVOS FROM IR ROBOT.
48 SERVO 10.2017