Tuesday, August 24, 2010

Final road test

The Kalamazoo is done, more or less. And it works, more or less.

It takes more effort to drive than I expected. The steering isn't very stable, despite the caster effect, which means I really only have one hand left to pump with. It's not going to be a very practical vehicle. Oh well.

I redid the horn mounting tonight, accounting for the change in primary driver position. Tomorrow I'll disassemble the entire thing and stain the wood. That's when I'll mount the etched brass builder's plate I made. I drive it to Spokane Friday after work in pieces, re-assemble it there, load it into my dad's Burning Man trailer, and head for the playa Sunday morning. Whew.

Sunday, August 22, 2010


When originally conceived, I planned on wrapping the Kalamazoo in el-wire. It's for Burning Man, after all, and everything there is wrapped in el-wire. But as work progressed, I kept adding more and more subtle, classy design details. By the time I got to seriously thinking about lighting, the idea of adding el-wire seemed really... tacky. I played with the idea of the solar-powered fake lanterns you can get as lawn decoration, which seemed to fit the evolved look better. But they're seriously not cheap, and, well, fake. So... why not real lanterns?

I ended up going with two at the front and two hanging under the pump-arm tripods. The forward pair hang from (custom, natch) smithed hooks. I went with a pigtail curlicue instead of the same 2D spiral I've used everywhere else. As well as adding some variety, this also helps control the swing of the lanterns.

The two under the pump arm hang from some cheap brass chain.

I let one of the lanterns burn for an hour tonight to gage fuel consumption. I put in 150 ml of oil at the beginning, and at the end I poured out... 150 ml of oil. So I don't think taking enough fuel will be a problem.

Road test #3 happened yesterday, with decent results. I tightened the chains today but didn't have an opportunity to take it out again. Running out of time to make modifications, but at least my to-do list is getting quite short.

Wednesday, August 18, 2010

Monday, August 16, 2010

Road test #2

Spent the last week designing and building the new steering mechanism for the Kalamazoo. After last week's disastrous road test, it was critical that this problem be solved. And while what I came up with isn't pretty, it looks like it will work okay.

In short, I bolted on a lever to the side, which connects to the caster via a connecting rod and ugly universal joint system. The motion is actually pretty nice, even when stationary. (On a nice smooth concrete slab, anyway.) I need to offset the lever above the deck to make it easier for the driver to reach, but other than that it's a much nicer interface than I expected. That was always a driving motivation for the old differential braking system -- how do you pump and steer at the same time? While not perfect, the lever approach is pretty decent. And it feels very awesome. Part rudder, part steam locomotive control. Not bad.

Today's road test did conclusively show that only controlling one caster was not enough. Particularly with any back-and-forward motion it was very easy to get in a bad state where the uncontrolled casters was out of sync, sometimes to the point where the Kalamazoo was completely stalled. It will be easy enough to add a tie rod over to the other caster. I always figured this might be needed, but decided to be lazy and try it this way first. Very little work wasted.

The other big issue coming out of the first road test was the failure of my hacked-up fixie wheels under load. So this week I threw a gob of cash at the problem and bought new ones. Unfortunately, no one makes real 20" fixie wheels. But I got a system the bike store people thought might work. Today's road test showed that, no, it doesn't work. This leaves only one palatable option -- I need to switch to full size bike tires. I only went with 20" because I wanted to keep the deck lower for stability (less of a concern now that I've been on the thing for real) and because I was using 12" pneumatic casters in the front. I might just have to live with an A-Team-van-style raised back end, or shim the front casters by a few inches. We'll see.

Overall, while the broken fixies were a big disappointment, the second road test went pretty well. I was even able to drive (slowly, jerkily) up a slight slope, showing the gear ratio changes are helping. There might be one more improvement there, if an ebay shipment arrives in time. I also have a big hunk of lead strapped to the crankshaft to improve its flywheel effect, though I'm unclear how much that actually helps at these low speeds.

On the way back down to the garage I road it and mostly let gravity do the work while I steered and counter-pumped for braking. This worked great, until it got to the steep section and I had to navigate several parked cars. At one point the rear end lost its grip and I fishtailed most alarmingly towards a well. No control authority, just suddenly riding along on the world's stupidest surf board. Important lesson: don't drive the Kalamazoo obliquely across an incline.

Sunday, August 8, 2010

Road test #1

Tony, Rob and I pushed the Kalamazoo up to the road from the garage today to do some real testing. As the video shows, the results were pretty bad.

Time for me to eat an entire murder of crows: differential braking for steering does not work here. At all. I now have a bit over two weeks in which to design and build something completely different.

The action is really jerky, with a massive clank at the top and bottom of the stroke. Haven't quite figured this out yet, might be related to slack in the chain drive. I know how to minimize the noise, at least, but I really want it running smoother than this.

Less seriously, but still annoyingly, we broke the fixed gear connection on one of the drive wheels. Hopefully I can just pay to get some real ones made up at Recycled Cycles. A cash-soluble problem, as I like to say. If that fails, I can always flip that one wheel around. It would break the symmetry of the drive chains (grrrr), but then it would be turning in the correct direction at least when driving forward. I cut the keyway extra long on that shaft precisely to handle this contingency.

I won't deny it, I'm now worried about getting this working in time. Particularly with the Laser Medusa Helmet work I also want to get done. Overall I'm really proud of the work so far, just have to get these last problems sorted out. We'll see...

Saturday, August 7, 2010

Chain tensioning

Not a lot of visible progress after a very frustrating week. It's looking very encouraging that I'll have this thing finally working for real tonight or tomorrow, but I thought I'd share this today.