number four bolts and nuts, and a roll of self adhesive
Velcro™. These parts cost around $45. (I bought extra.)
A Box of Happiness
I put all of the parts into a box and hauled them to my
second job. I began the project in their shop late at night
after work. I needed to cut open the top of the Heineken
can, and knew that the can had been pressurized. So, I
took a hammer and center-punched a small hole in the top.
I was gifted with a whoosh of gas and the unpleasant smell
of very old beer residue (eew).
I wanted to leave about 3/4” in the top of the can’s
metal, so I could mount the domed head. I used a piece of
stiff solid core wire, a sheet rock screw, and a Sharpie™
pen. I put the sheet rock screw in the center hole where
the can’s dispenser valve used to be, and made a loop in
the wire to hold the Sharpie. I then used the wire/guide
(pulled tight) to trace out a circle on the top of the can.
Using a Dremel rotary tool and a cut-off wheel, I cut out
the circle, removed it, and the exhausted internal gas
cartridge. I gave the can a thorough bath inside and out in
hot soapy water to remove the smelly old beer residue. I
then proceeded to totally disassemble EVA, so I could get
her two Vantec RET 411 motor speed controllers, battery
packs, and power switches, and lay them out on the table.
There were several test fittings done to see how to get
all of the parts inside of the can, while pondering how to
wire Beer2D2 and make it easy to do maintenance and
battery charging. In the initial design, I placed the speed
controllers and the battery packs in the very bottom of the
can to keep the robot’s center of gravity low so it would be
semi stable. I placed the entire speaker system on top, and
it all fit. Time being
a factor, I figured
that was good
enough for now. I
had to build the
This part of the build
I actually did over a
couple of nights.
drivetrain uses four
Futaba S3004 servos
hacked for full
rotation, with all of
They are mounted
with 4-40 machine
screws to a piece of
that was notched
using a Dremel to fit
the motor’s case. Each set of motors is wired in parallel and
connects to one of the Vantec RET 411 speed controllers.
The motors are fed 9. 6 VDC from a 2,000 mAh NiCad
battery pack. Actually, 9. 6 VDC is a good over-voltage level
for stock hobby servos with nylon gears. If you use a higher
voltage, you should use servos with metal gears.
It was a bit tricky fitting the motors and 3” Dave Brown
Lite Flite wheels inside of the butter dishes/motor housings.
All of the holes I drilled were 1/8” and the drill bit liked to
grab the plastic as it went through. As usual, I ended up
bleeding a bit from the cuts acquired from reaching into a
For the front wheel housing, I made a bracket with
some 1-1/4” angle aluminum and a long through to act as
the axle, to support another non-driven 3” Lite Flite wheel.
Eventually, I would regret this.
After I had assembled the housings and tested the
SERVO 08.2015 47
Beer2D2 and my handy Dremel. Beer2D2’s feeding time.
Beer2D2’s motor frame.