length, and adding a nut or two can allow
for some adjustment of the overall reach of
the actuator. We prefer this end-effector to
a servo horn as strongly as we prefer the
original classic to the shoddy remake (we’re
looking at you, Poltergeist).
So, what about mounting the servo
itself? At first glance, the body of the
mightyZAP appears to be so sleek and
smooth that it is as totally devoid of
mounting points as Hellraiser’s Pinhead is of
pity. However, the mightyZAP does indeed
have a mounting point — at the rear of the
The servo comes with a few plastic
mounting pieces. The base piece has a
beveled plus shape pattern that allows it to
firmly snap onto the servo. A screw keeps
everything tightly held together. The base
piece sports a through hole not unlike the
one on the end-effector, and that’s all you
need to firmly attach the servo to something. The plus
shaped beveling means that you can orient the through
hole in whatever direction is most convenient for your
In addition to the base piece, the mightyZAP comes
with another bracket that picks up the through hole to
make a dandy little hinge. The bracket comes with its
own holes for mounting it to your project. All of your
mounting and designing can be done without having to
bust out the calipers to measure the servo dimensions.
The IR Robot website even has detailed technical
drawings with all of the key dimensions of the
Raising the Dead Weight
For our first mechanism using the mightyZAPs, we
opted to try out a type that we’ve often built in the past,
but always with rotary motors — a classic as iconic as
Night of the Living Dead: the lifting arm. We’ve outfitted
Ptorobot with a highly mechanically advantageous lifting
arm equipped with a pulley system, and we’ve
experimented with various four-bar lifter designs with the
MINDS-i Rover and other platforms.
However, all of those lifters have taken some careful
design work. The most straightforward way to make a lifter
seems to be a linear actuator. So, would it be any good, or
would it run out of steam like Survival of the Dead?
We quickly fashioned a simple lifter with VEX parts,
opting for the upper hinged upward lifter. We attached the
40N servo with its rear mounting point to the VEX frame,
and used a screw through the through hole on the end-effector to attach it to the underside of the lifter. We
hooked up the wires and were ready for the first test.
Tilting the joystick caused the lifter to move up and
down with the smooth grace of Regan MacNeil’s spinning
head in The Exorcist. The default zero position for the
mightyZAP is in the middle of the stroke, but can be
adjusted in the Servo Manager.
Even so, we were impressed by the reach of the lifter.
Would we also be impressed with its strength? Lifting
seems like a simple enough task, until you take on a lot of
weight. Gravity doesn’t like to be cheated.
We wanted something heavy and seasonally
appropriate to test the lifter on, and a few hefty Stephen
King tomes fit the bill nicely. The lifter had no problem
with The Bazaar of Bad Dreams, so we moved on to the
SERVO 10.2017 51
READY FOR ACTION!