The second revision of T6.
The inner workings of the third
revision of T6.
lower profile and for better
protection. The overall height of
the robot shrunk to 1.875”.
Lynxmotion 595 rpm gearmotors
were used to make for a faster
robot. The wheels were staggered
in a skid-steer fashion to lessen the
counter-rotation of the chassis
under spin-up. A much larger
brushless outrunner was used to
power the ring. I fabricated a new
self-tensioning system for the
outrunner. The more power that is
sent to the weapon motor, the
harder the friction drive pushes into
the ring.A more effective tooth
design was also employed.
A flexing baseplate resulted in
the bearings coming out of the
groove in the ring under impact,
and the drive motors jammed up,
resulting in a 0-2 showing at KBXI.
Blunt tool
steel teeth as
used on the
second and
third revisions
of T6.
24 SERVO 04.2009
Self-tensioning friction drive used in the
second revision of T6.
Maybe it’s time to give up on this
design ...
Revision 3, the latest revision:
I don’t know what keeps
drawing me back to this design.
Perhaps it’s the challenge.
While taking a break from my
other robots, I decided to see if it
would be possible to fit four drive
motors and wheels inside of T6’s
ring. It looked like it would fit ...
barely! The catch was that I’d have
to use 1-3/8” diameter 0.4” wide
Banebot wheels. That meant that
the ring and weapon teeth would
have to be cut down to 1-1/8”
tall in order for the wheels to
extend out of the top and bottom
of the ring.
Finding a weapon motor to fit
in such a cramped space would be
tough! Luckily
Hobbycity.com has a
huge selection of brushless motors,
and I found a 37 mm OD outrunner
that would fit. Since T6’s layout was
going to be a mirror image side-to-side, there would be room for two
weapon motors!
Excited with my findings, I
quickly worked towards getting the
robot built as quickly as possible.
Fitting the larger 1,350 mAh 30C
Lipoly battery and the wiring for
two brushless speed controllers into
the super low profile robot was
proving to be another big challenge.
Shiny finishes make good looking bots.
Keeping the wiring from contacting
the inside of the ring was also a
problem. I fabricated inner walls out
of more aluminum to keep the
wiring and components away from
the moving parts.
It was soon obvious that I had
run out of room for the 2X5 motor
controller. Fortunately, I had a pair
of Fingertech Tiny ESCs laying
around from another robot. But
would they be up to the task of running all four Banebot 24:1, 16 mm
gearmotors? Yup! In a weaponed
robot, they worked just fine.
The self-tensioning rocker arm
design from revision 2 was used
again, but had to be dramatically
reduced in size to fit in the very
cramped quarters.
Completed the night before a
SCRC Demo event, I was anxious to
try out the new version of T6! To
my surprise, it worked great!
Spin-up was almost instant, and the
weapon was very effective for
smashing up the chassis’ of old
mantisweight ( 6 lb) robots! T6 was
even able to remove an internal
combustion engine from its 1/8”
garolite base plate! Halfway through
the demo, a brushless motor came
apart ejecting motor parts throughout the arena, but T6 kept working!
Having two weapon motors was not
such a silly idea after all!
The latest revision has not yet
seen a true combat event, but
another rebuild with a host of
improvements is due to happen in
the near future. A new heavier ring
with angled sides milled from a
billet of Fortal aluminum, a carbon
fiber base plate for weight
savings and strength, and four
weapon teeth are on the list of
improvements.
Taking the road less travelled,
while being more of a challenge, has
turned out to be quite rewarding.
Employing a proven design may be
easier to be successful with, but the
challenge of making an unproven
design work well can be much more
rewarding. Well, at least for me
it is! SV
