R/C Tank Combat

Tank #T001

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The upper hull remains completly unchanged during the retrofit process. The sealed rotate arm allows the turret to be easily removed and allows the turret to rotate fully without worrying about the wires that go right through the center of rotation. The round wear pattern is from the bearings on the bottom of the turret that ride on the deck.

The drive axles are supported by two interior bulkheads bolted to the hull that hold the axle bearings. The exterior bearings are mounted inside a solid disk attached to the outside of the hull with smaller bolts. The M01 scooter motors make for a very compact arrangement, with only short #40 chain loops driving the axles. I rotated the faceplate of one of the motors to get a symmetric mounting position. The motors are mounted to 1/2" thick pieces of HDPE, which are then bolted to the hull.
 

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The back of the lower hull serves as the tensioning system for the rear axle and holds the main battery and electronics battery switches. The raised metal strip keeps the top hull in place, while allowing it to pivot when the front is raised. Simple but effective.

The inside of the back section shows the steel brackets for reinforcement and the simple tensioning blocks. The 5/8" rear axle slides nicely through the 3/4" square steel tubing, which is drawn backwards by turning the 3/8" bolts from the outside of the hull. This allows the tracks tension to be quickly adjusted in the field as needed.
 

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August 2008: After the new M01 motors snapped the old 1/2" drive axle in half during the last battle, it was time to install a new set of 5/8" drive axles. A wheel hub consisting of a 2" fender washer and a 5/8" shaft collar was welded to the shaft, with three bolts to hold the drive wheel in place. The drive wheel will be sealed using epoxy and then rubber strips glued and nailed around the outside to drive the tracks. On the motor side, a 3/16" keyway was cut into the shaft to mount a 15-tooth #35 chain sprocket.

The M01 motors come with an 11-tooth #42 chain sprocket. Unfortunately, it's not easy to find #42 sprockets for the drive axle and #41 chain didn't work well on the #42 sprocket. So, with a little machining, a more standard 11-tooth #35 sprocket was mounted on the motor. The sprocket started as an unfinished 3/8" bore sprocket, was milled down to reduce it's thickness, then re-bored to 11mm and finally a 4mm keyway was cut using a keyway broach, a homemade 11mm bushing and an arbor press. Entire process takes about 15 minutes with the right tools (after spending a few weeks researching parts and processes for cutting keyways in sprockets).
 

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