e have a deep and abiding love for SERVO
Magazine, but the same cannot be said for
servos themselves. It’s like the current popular
fascination with Vikings — on the surface, their
exploratory and seafaring ways have an
adventurous glamor to them, but on closer inspection
their violence is a bit off-putting. We find that servos
similarly disappoint under scrutiny.
While we appreciate the ability to incorporate simple
position control into robotics projects, we aren’t huge fans
of the fiddly fragile nature of many servos. Our displeasure
is particularly acute when it comes to the inability of
servos to handle a large amount of force. We like to build
fighting robots and giant cannons and other things where
large forces are the name of the game.
Fortunately, the folks at ServoCity have a solution:
ServoBlocks. ServoBlocks are essentially a load isolating
exoskeleton for your servo that significantly enhances the
ability of the servo to withstand large forces.
A simple aluminum frame that gives your servo
superhuman strength sounds almost too good to be true.
Could the ServoBlocks really be so simple and effective?
Could a ServoBlock turn a humble servo into a warrior that
even Vikings would be proud of?
There was only one way to find out.
Pain is Weakness Leaving the
Most RC servos were originally meant for use in RC
airplanes, where simple and affordable position control is
needed to control things like the ailerons, elevators, and
the rudder on the tiny aircraft. An RC aircraft elevator is
extremely lightweight, and even with all the wind
resistance encountered in a gravity defying aerial
maneuver, the forces involved in actuating an elevator are
not that extreme. So, even though the PWM control on
servos made them a natural fit for robotics applications,
unmodified servos were not originally intended to handle
the forces encountered in a lot of robotics projects such as
heavy weights at the end of a long lever arm, or even the
forces on a drive wheel.
Standard servos are not designed to handle
significant lateral loads. A servo horn is usually
fastened to the spline by a solitary screw, and the
horns themselves are often made from thin plastic.
A heavy load at the end of a lever arm, for example,
could easily deform the plastic horn or rip it off the
If the solitary screw in the spline is unusually
robust, then a heavy load might instead deform the
servo’s plastic case or rip the top of the casing off.
If a standard servo was a Viking, it would be Ivar
We’ve often found ourselves working on
by Bryce Woolley and Evan Woolley
New Kids on the
AN HSR-2645CRH SERVO FROM HITEC.
54 SERVO 01.2018
THE DISASSEMBLED HUB SHAFT SERVOBLOCK.