Shane's R2 Build Log
Legs: Wiring the Legs
I have to admit that I agonized over leg wiring way more than I probably needed to. I stared at wire gauge charts, calculated wire resistance, and did all the math in an effort to come up with optimal wire gauge to run through the legs.
In the end, I (unscientifically) chose 12 AWG wire just because that's what the foot drive motors were already wired for. I probably could have gone with 11 AWG. Anything 10 AWG or thicker is kind of a PITA to work with and I really didn't want to, or feel I needed to, go that thick.
My plan for wiring was that it would come out of foot, into the battery boxes, back out of the battery boxes, into the side of the ankle, run up the length of the legs, and then enter the frame through the shoulder flange. That's probably hard to visualize. But the gist of it is that I needed to drill a big hole in my ankle and another big hole in my legs within the perimeter of the shoulder flange.
For the ankle, I drilled a hole horizontally centered, 1" from the bottom large enough to accommodate a 7/16" rubber grommet. The grommet is needed to keep the insulation on the wiring from getting cut and exposed by the sharp aluminum. What I hadn't expected was that the thickness of the aluminum would be too much for any rubber grommet that I had on hand. So it ended up looking a little janky. But it still worked. I can carefully slide two 12 AWG wires in and out of the hole just fine. The battery boxes will cover this, so I don't have to worry about the ugliness being exposed.
I had originally planned to put another rubber grommet into the legs, but the legs are pretty thick too. So I opted for another solution - flex tubing. The flex tubing would protect the wiring from the sharp aluminum edges as it passed out the legs and into the frame.
I drilled another hole in between the hole used to mount the shoulder hub and one used to mount the shoulder flange. I basically used a stepper bit until I found a size that worked for the tubing.
I then fished about 7' of red and black 12 AWG wire through the leg, through the tubing, and out the leg. I duct taped the tubing down to the inside of the leg to keep it from sliding around.
I routed it around inside the frame and basically left it hanging until I figured out what I wanted to about the electronics.