jigsaw. At first, the going was very slow, and we
thought either the aluminum was tougher than
we thought, or jigsawing was tougher than we
remembered. It felt like we were torturing
Dustin Hoffman in Marathon Man.
The real culprit was a jigsaw blade on its
last legs, which gave out halfway through the
bottom jaw. With the new blade, the rest of the
dental work went swimmingly. We sharpened
the teeth with a pneumatic angle grinder,
installed the jaws with some 1/4-20 screws, and
prepared for the final assembly.
Everything went together nicely except for
mounting the gearboxes. We couldn’t fit
anything into the bottom mounting holes —
both the screw head and the nut couldn’t fit
either inside the tube or outside on the bracket
because of the foot on the angle bracket. Surely
there were elegant solutions that we didn’t have
the patience or finesse to implement (we’ve all been
there). Perhaps a quick trip to Hank’s Hardware for
some socket head 6-32 screws would have solved our
problem. Or, perhaps a different bracket design could
have worked with the fasteners we had on hand.
We had already cut these brackets and gotten at
least two screws to fit on each one, and we wanted to
get to crushing things and making a mess (we’ve all
been there, too). So, we tightened down the Nylocs by
an extra quarter rotation (or whatever we could muster
without stripping the screws), mounted the gearboxes,
and plowed full steam ahead with our crusher robot
just like Spielberg after going millions of dollars over-budget on the production of Jaws.
Another One Bites the Can
After wiring up the bot, we were eager to see how
the gearbox would work. We were concerned that the
7:1 ratio might slow down the device to a glacial pace,
but our first test dispelled those fears. The jaws opened
and closed at an appropriate bitey speed, and we were
ready to give the robot something to eat.
Our first test was with an empty half can of Diet Coke,
and it was about as satisfying as that beverage. The thin
aluminum can yielded to the jaws with no resistance at all,
like the soft flesh of an unsuspecting sea creature yielding
to the jaws of a Great White.
Next, we tried a full half can of Diet Coke. The jaws
descended and pierced the can as if it were the soft fleshy
vegetable of our tests with the ServoBlock and battle axe. A
caramel colored gout of soda spewed from the can, making
a sugary puddle in the driveway that we would surely need
to hose down if we didn’t want ants (because that’s how
you get ants!).
For the final test, we went with a full size can of Dr.
Pepper. The sweet beverage was no match for the gearbox
driven jaws. Appropriately red-colored liquid sprayed
everywhere like a kill in an ‘80s horror flick. The down force
of the jaws forced the inadequately supported gearboxes
upwards, but even such skyward travel was not enough to
save the sacrificial soda.
Overall, we were very pleased with the servo gearboxes
from ServoCity. They were easy to assemble, and with a
more clever mounting solution they would have even more
efficiently transferred a staggering amount of torque from a
When it comes to comparing the torque of a standard
servo equipped with a gearbox versus a super expensive
but unadorned high-end servo, we would have to say that
the gearbox crushes the competition. SV
SERVO 03.2018 59
GUZZLING SODA JUST LIKE US.
A SPOUT OF DR. PEPPER.