accommodate the motor by placing washers between the
Mounting R/C Servos
The world is quite a different place when working with
R/C servos. By their nature, servos have mounting flanges.
What’s more, servo sizes and mounting configurations are
fairly standardized giving you the option of using premade
mounting solutions if you don’t want to “roll your own.”
Whatever the method, servos should be securely
mounted to the robot so the motors don’t fall off while the
thing is in motion. Over the years, I’ve found hard
mounting — using fasteners like screws and nuts — to be
the best overall solution. This greatly reduces the frustration
level of building and using your robot.
All servos have mounting holes in their cases. It’s simply
a matter of finding or drilling matching holes in the body of
your robot, or using brackets with properly spaced holes in
You have two kinds of screws to choose from:
• Self-tapping metal or wood screws don’t need a nut
on the other end to hold things in place. Drill a small
pilot hole to start, then insert the screw. The threads
of the screw dig into the material and hold it in
• Machine screws and nuts are ideal if you need to
disassemble your creation and rebuild it, or use parts
for something else.
With the popularity of servos for robotics applications,
there’s no shortage of pre-made mounts for all types and
sizes of servos. These are available from online sources such
as Actobotics, Pololu, Budget Robotics, and RobotShop. See
the Sources box for website details. Figure 5 shows just
one offering for mounting servos. This one is an aluminum
bracket, providing multiple ways to attach the bracket to
the body of your robot.
You can also construct your own servo mounting
brackets using 1/8” thick aluminum or plastic. A template is
shown in Figure 6. Note that the template is not to scale,
so don’t trace it to make your mount. Use the dimensions
to fashion your mount to the proper size.
The first step in constructing your own servo mounting
brackets is to cut and drill the aluminum or plastic. Use a
small hobby file to smooth off the edges and corners. Use
4-40 screws and nuts or #4 self-tapping screws to attach
the servo mount to wood, plastic, or other materials.
Mounting Wheels to
Often, it’s the most obvious things we take for granted
— like the wheels we use to build rolling robots. In the
world of amateur robotics, you can now find motors that
match the wheels made for them. These are the easiest to
use when building a bot, but there are many other options.
With some effort, you can adapt a wheel to most any kind
of motor, using either a direct connection or by using a
When I first started in robotics, I used to spend an
inordinate amount of time combing through various surplus
catalogs looking for motors and wheels that could go
together. It wasn’t always easy to find matches. Today,
there are numerous specialty online robotics retailers that
offer low cost DC motors and wheels that are designed to
complement one another.
While matching motors and wheels are handy,
selection isn’t always extensive. You may want a smaller or
larger wheel than what’s offered, or you may not like the
width of the rubber treads on the wheel. That’s when you
need to come up with your own motor-to-wheel solution.
If your wheel already has a hub with a setscrew, you’re
in business ... assuming the wheel hub is the right size for
40 SERVO 04.2014
Figure 5. All-aluminum bracket for mounting a servo to a robot
base. Available for standard and quarter-scale motors.
Figure 6. Make your own radio control servo mounts following