January 4, 2008 - Best Foot Forward

Work progresses on the foot shells. Because it's so cold here, I ended up working in the home office this afternoon. The smell of curing model cement is much more pronounced in a closed-in space, so if this entry rambles, please understand!

The picture above shows one of the outer feet in its completed state. Of note are the straight edges, which will have to be filled with Bondo and sanded smooth for painting. Also note that the inside of the foot has a curved surface (on the right, in this picture). Because eighth-inch styrene isn't that flexible, Andy added two panels with thin styrene to the kit for that curve. The problem, of course, is how to get the styrene into the right shape. I noodled on this for a while, and after trying to just bend it with my hands, I MacGyver'ed a solution. Using lots of tape, I wrapped the panels around the nearest broom handle, and let them sit for a few days.

While I waited for the panels to accept their new shape, I started work on the insides of the feet. The shells are essentially decoration, covering up the actual hardware that keeps RD-22 "on his feet." Following Victor Franco's lead, I built a set of feet out of half-inch plywood. Victor's are labeled temporary, but mine are probably semi-permanent... at least until I figure out that plywood isn't going to support the motors. The center foot was first, since it was the easiest. You can see below that it's pretty simple. There are two outer panels that roughly match the shape and angles of the shells. Between these two panels is a spacer near the top, to support the bolt that will attach the foot to the center leg. Attached at the bottom is another panel, this one to support the caster.

With the outer feet, there needs to be a bit more "beef," since they will end up being the driven feet. The construction of the inner foot, however, is basically the same as with the center foot. Two outer panels were cut to the dimensions of the shell, and a spacer was added near the top to support the bolt. However, for the outer feet, I'm using scooter wheels instead of a caster. So, there is another spacer near the bottom, to support the two bolts that hold the wheels in place. As you can see from the picture below, the wheels are from two different scooters. Also, the one on the left has been taken apart. I glued the upper spacer in place, but it was too close to the pivot point on the outer legs. So, I couldn't get the bolt holes to line up, necessitating a rebuild. Ah well, you can't get everything right the first time!

When the foot panels had sat overnight for a while, I untaped them from the broom handle and attached them to the feet. While the use of the broom handle worked well, the glue that I used didn't set up fast enough to keep them in place. It's not obvious in these pictures, but the curve that was imparted by the broom handle unrolled a bit from the top, so there is an obvious gap all along the inside of each outer foot. I foresee a lot of Bondo action in my future...

Next time, I hope to have RD-22 on his feet!

Bob
January 4, 2008