and two of them even burned up. The moral of that story is
this: Do not buy your servos on eBay unless you like to
make your life difficult. It turns out that there are a lot of
imitation servos being sold there that are junk.
A better option is to use Hitec servos. They work the
opposite from Tower Pro servos, so the software has to be
changed to match them. The MG995/996s can be replaced
with Hitec HS-625 or HS-645 servos; the MG958 servos can
be replaced with Hitec HS-940 versions.
So, what exactly are these servo building blocks? They
are metal brackets that allow you to connect servos
together to make different robots. They usually include the
• Servo Mounting Bracket — Designed to hold servos
• Short U Bracket — Fits over servo
• Long U Bracket — Fits over servo
• Angled U Bracket — For shoulders
• Straight Bracket
• Angled “L” Bracket
• Waist Bracket — 3. 5 inches long
• Feet — 2. 5 by 5.0 inches
You will also need some hardware such as servo horns,
bearings, and screws.
The typical robot chest is made out of several small
pieces. There are two angle brackets and a short U bracket,
as well as the waist bracket and two servo mounting
brackets. If you make a solid chest out of some three inch
by one inch aluminum “C” channel, it will look a lot better.
Besides looking better, a homemade chest gives you a place
to mount an Arduino or Raspberry Pi controller.
Figure 2 shows the mechanical drawing for the
improved chest design.
Besides making a better chest, you might want to add
a better looking “head” to your robot. I made a head out
of a 3. 3 inch clear plastic Christmas tree ornament. First, I
cut two slots: one on either side of the hole used to hang
By Bob Davis
SERVO 04.2016 27
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Figure 1. Typical robot chest.
Figure 3. Making a robot head.
Figure 2. Improved robot chest design.