March
Picking a speed controller
We considered using a Vantec speed controller, but worried that the peak amperage was too high for the RDFR23, which was the only real option for our price range. Instead, we decided to go with a pair of Innovation Victor 833s running at 24 volts, since they could handle higher peak amps. We picked up a Omark radio mixer at the recommendation of TeamDelta to allow single stick control of both speed controllers.
Gear Box Built
In order to use the windshield wiper motors
effectively, we had to design and build a
gear reduction assembly. The 16 pitch aluminum
gears used were purchased from Berg. They
were chosen so that we would get approximately
a 6:1 reduction. The box to hold the gears
was machined out of aluminum. This allows
the lifting arm to move through a 90 degree
arc in approximately 1.5 seconds.
Frame building begins
We picked up the steel tubing locally at
a steel fabrication shop. After cutting the
tubing to size, two wheel housings were welded
together. We did not initially weld the two
wheel housings together, so that we could
double check our CAD model and ensure that
everything would indeed fit. Once we were
convinced everything would fit, we installed
the cross braces.
The wheels came with internal roller bearings, so we opted to use these bearings so that we didn't have to build a hub and pillow block assembly. Instead, we attached brackets to the frame, and ran the original 1/2" bolt through the brackets.
Drive Train Assembly
Simple motor mounts were designed and then
fabricated from 6061-T6 aluminum. Sprockets
were attached to the wheels with four socket
head cap screws tapped directly into the
wheels plastic core. This was done due to
not needing a hub assembly, as described
above.
To attach a sprocket to each motor, we used .060 wall 1/2" diameter steel tubing and drilled and tapped the tube for a 3/8"-24 bolt. This was the thread on the output shaft of the drill motor to attach the drill chuck. The original reverse thread locking screw was re-used. The 1/2" bore sprocket could now be mounted to this adapter.
Build Progress: February March April May