PARTS IS PARTS:
Prototype Testing: FingerTech Robotics Mini-Spark
● by Mike Jeffries
In the 150 g weight class, there are only a few options for drive
systems. Finger Tech Robotics is
looking to add some diversity to
the market with their new Mini-Spark gearboxes.
The Mini-Sparks will come in a
range of ratios ( 10, 20, 30, 50,
150, 210, and 298:1), but for this
test I opted for the 20:1 ratio as
that would result in very good
speed with a two cell LiPo and
the 1.4” wheels I was intending
to use.
Externally, the Mini-Spark
resembles many of the competitor
motors. However, there are a few
characteristics that separate it
from the other motors in the
same weight range.
First, there are several gear
ratios to choose from that result in
usable rpm ranges. Second, the
hardened gears mean the gearbox
will likely survive more abuse
which can be the difference in a
match.
Third, the motor is slightly
heavier and noticeably more
powerful than the motors used on
similar gearboxes.
The small size and common
mount points make them a
potential swap for existing
gearboxes. For this test, however,
I built a new robot that was
designed to stress the gearboxes.
With highly visible wheels and
a horizontal spinning weapon, the
gearboxes are exposed to shock
loads not only from other robots,
but from its own weapon
throwing the whole robot around
the arena.
The first round of testing was
purely functional, and consisted of
basic driving maneuvers in an
FIGURE 1. 20:1 Mini-Spark shown with a
Finger Tech tinyESC.
open area to verify that there
were no defects in the gearboxes.
After that, the next round of
testing was aggressive
maneuvering which consisted of
quick direction changes, slamming
the robot into the wall, and
bouncing the wheels off of the
FIGURE 2. Two Mini-Sparks mounted in the chassis of the bot
that is being used for testing.
SERVO 02.2013 41
