Monday, July 12, 2010

Pump arm

The pump arm is done!

After planning from the beginning to use ~2" pipe, I started to have second thoughts as the time approached. Yes, the pipe would have made for some easy handlebar attachments and central pivot points, using pipe tees. But it would look so cheap. It wouldn't fit the rest of the look at all. And it would make attaching a nice pivot for the pitman arm really annoying. So instead, I got 6 feet of 2" x 4" rectangular steel tubing. (I wanted 1.5" x 4" but they were out. Luckily the extra width doesn't make too much difference to the visual weight in context.)

Last week was spent cutting the arm to shape and drilling the mounting holes for the handlebars and pivot rod. I ended up making all of them 3/4" for convenience. That's a bit narrow for a handlebar, but I'm going to add some grip pads by wrapping leather strips around them later. The arm itself will eventually be painted, probably a dark grey. (All the raw steel will be painted, of course.)

As can be seen in the picture above, the rods were then welded in place. But I'm horrible at welding, you say? True. But Gabriel Cain was kind enough to lend me his MIG set, which sure makes it a hell of a lot easier. I'm really, really going to have to buy one of those for myself.

The mounting of the pillow blocks onto the support struts isn't finalized yet, but it was good enough for a test mount of the pump arm. It works! It pumps! The action is very smooth. Without any resistance, anyway, pumping feels very natural. Was very exciting to stand there and finally get a sense of what piloting this contraption will be like.

Next up: finishing the pillow block mounts, now that I have the arm to get aligned properly. Going to need quite a bit of shimming there. And then it's on to making the drive wheel brackets -- more welding! With those done I'll have the final placement for the wheel chain sprockets, and can get the keyways cut. It's coming together surprisingly quickly, with a good month and a half left. Want to leave plenty of time at the end for road tests and shakedown cruises. Not to mention I need time to work on Laser Medusa Helmet Mark II! Starting to get very excited about the Burn. Attoparsec is going in style this year.

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