the drive system, it was discovered
that there was no way to install the
keystock with the stock shafts because
the keyway did not extend the full
length of the shaft.
The eventual solution was to
extend the keyway in the shaft to
allow the keystock to be suspended in
the drive sprocket during insertion. To
make the modification, the initial
cutting was done on a small
manual mill with the final
cutting and shaping done
using a rotary tool, as the
final portion of the shaft
was too hard for the mill
tooling that I had available.
With the modifications
complete, the drive shafts
were able to be inserted and
the drive train assembly was
soon completed. The shafts
are located with a
combination of aluminum
shaft collars and UHMW
tube stock cut to length
and used as spacers.
One major difficulty with driving
this style of robot is that forward and
reverse are constantly switching.
Which side of the robot is forward is
dependent on which direction you’re
travelling and how aggressively you
accelerated to move in that direction.
The solution to this problem was to
paint the top and bottom armor
panels with a
such that no matter
the orientation, there
would be an easy to
spot indicator of
which direction was
The final step for
the base platform
was wiring. As with
the rest of the robot,
the wiring was kept
as simple as possible.
The electrical components consist of a
six-cell 2,650 mAh LiPo battery, a
Team Whyachi MS-05 power switch,
three Holmes Hobbies BR-XL speed
controllers, and a Hobbyking R610
receiver. Two of the three BR-XL speed
controllers are used to operate the
drive system. The third BR-XL speed
controller has a small plug attached to
the motor side that allows powered
weapon systems to be
quickly connected to the
When stripped down
to the base platform,
Spanky weighs 22 lbs 0.2
oz, which leaves just under
8 lbs for any weapon
The design and
construction of the
chainsaw, circular saw, axe,
and hammer attachments
for Spanky will be covered
in Part 2. SV
30 SERVO 04.2014
FIGURE 5. Drive system prior to the installation of the drive side shafts.
FIGURE 6. Fully assembled drive system with wheels and optional axle wedges.
FIGURE 4. This is the weapon mounting bracket part way through the welding process.
FIGURE 8. The electrical system of Spanky with the motor side of the third BR-XL disconnected.
FIGURE 7. The zigzag pattern identifies the relative front of the robot.