74 SERVO 06.2015
resistors as possible. The closest you’ll get with two readily
available resistors is to use two 2. 2 kΩ resistors. One end of
the voltage divider goes to power, one to ground, and the
middle of the divider goes to the signal pad. The Futaba
servo had just that kind of voltage divider in place, but we
were forced to dispose of it as mercilessly as Boba Fett
dispatches his bounty. We soldered the PWM cable leads
into its place, and that gave us three continuous rotation
servos to choose from.
The Force is Too Strong
with This One
With the servos and Force arm ready, we needed a
robot to test them with. Fortunately, ServoCity had us
covered in that respect too — we would make a testing
robot out of Actobotics pieces.
One of our least favorite parts about working with
servos over the last few years has been the challenge with
interfacing them with structural units. Servo horns are often
made of thin plastic and dotted with oddly patterned holes.
Drilling mounting holes on structural parts for use with
servos can be a tedious process because even after
meticulously measuring the placement with calipers,
marking the location with a center punch, and carefully
positioning your drill, if the bit walks even a little smidge
your tiny mounting hole meant to accommodate a tiny
screw will be as effective as C-3PO is at being rude.
Actobotics solves that problem by providing structural
parts with a unique overlapping hole pattern designed to
align perfectly with servo horns. In addition to the structural
bits (made from aluminum and heavy on the cool factor),
Actobotics also boasts gears, motor mounts, bearings, and
everything else you might need to build an awesome robot.
Some of the Actobotics parts that caught our eyes
were the gripper kits. A robot with two claws would be a
perfect way to test the Force servo arm — one claw would
be equipped with a normal servo, while the other would
use the Force arm. We anticipated that the normal servo
would be capable of gripping durable objects effectively,
but when tasked with picking up something fragile it would
IN THE FORCE.