Sunday, September 6, 2009

He's Moving!!

The foot drive system all went in as planned. Originally, I had decided to put the wheels in the front of the brackets and the motors in the back. My thinking was that I wanted to get the wheels as close as I could to being directly under the point of the leg, and I was trying to maneuver around stuff inside the foot shells like the nuts and backside of the knurled hose fittings. So I cut some big holes in my beautiful, flawless foot shells and battery boxes last night. I put the bracket in there without the motor and tried to project as well as I could where the motor needed to go. I sketched the hole on the inside of the foot shell, then I rough cut it out with a 2.5" hole saw. Then with some hacking and grinding to adjust the hole, the brackets with wheels and motors fit right down inside.

But once I got them all together I flipped it over to see how it all looked. I was recalling that Dan Baker had had trouble with his R2 doing wheelies when it took off because he had just one wheel on each leg. He added a little caster wheel in back to act like a wheelie bar to solve the problem. I was wondering if I was going to have to do the same thing. Sure enough, when I got him turned over, having the wheels in the front of the battery boxes puts them really close to the front wheel in the middle foot shell. That is, his wheel base was quite short. You don't think this when you look at pictures, but his weight is pretty high, and if the wheels are close, he's tippy.

So I looked at it and thought about it a bit. I could add a caster, but there wasn't much room in there for anything else. Then I thought, the brackets, the spacing, the mounting holes and everything are symmetrical, so why not just turn the brackets around by switching the right to left and left to right, and putting the wheels in the back of the outer foot shells to increase the wheel base and eliminate the wheelies. That would require cutting two more holes in the foot shells for the motors in the back instead of the front, but I'm getting pretty good at that now. The only issue was making sure that the cuts into the battery boxes were far enough back that they didn't cut into the recessed section in front where the harnesses sit. I did some measuring and it looked like I could get behind the battery harnesses, so I cut the new holes. That made the battery boxes look like hell on the inside, but it's all hidden by being tucked up against the foot shell.

And this tricked worked perfectly. The foot motor brackets fit right in reversed, and when I flipped him over to check the tipping problem he was very stable. So I didn't have to add casters.

Once those were in, I hooked them up to some power wires that I had run down through the legs yesterday. I couldn't resist, so I put a battery to the leads just to see him move. This video is a bit Blair Witch Project-y because my 7 year old was running the camera, but I'll be damned, he moves:

video

1 comment:

Victor Franco said...

Sounds like the laugh of glee when R2 makes his first moves to me. :-) Congrats on this big milestone!

-Victor