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disgusting brown electrolyte
Tuesday, February 19 2008
I wanted to put good strong spokeless wheels on my firewood transporting cart, whose 19 inch bicycle wheels clearly hadn't been up to the punishment I had in mind. The largest spokeless wheels I'd been able to find had been 16 inches in diameter and came with nineteen millimeter axle bores - perfect for my cart. Today the wheels arrived and I was dismayed to find that their central axle bores were actually 18.5 millimeters, while the axles themselves proved to have diameters of 20.1 millimeters. For some reason I'd assumed these things were like in any other industry: strictly standardized on certain numbers, but this was more like the days when everything was whittled out by hand or made custom at down at the smithy. My predicament was definitely pre-Industrial: somehow I had to figure out a way to grind 1.6 millimeters off my axles. I started out with sand paper, moved up to a mechanical sander, and even tried using a bastard file for awhile. But reducing an axle diameter by 1.6 millimeters (that is, removing 0.8 millimeters from its curved surface) amounts to an awful lot of sanding, particular when all you have to work with are tools held in the hand. And there was no way I could improvise a lathe; the axle was welded to the frame of the cart itself and to lathe an axle would have meant spinning the whole lopsided contraption.
In the end I decided to "reverese-electroplate" the axles. In conventional electroplating, metal in solution is built up on the work layer by layer until it forms a thin crust. What I wanted to do instead was strip layers off the axle. To do this, I attached it to the positive pole of the electroplating circuit. Over time, what I expected to happen was for the iron to corrode off the axle and be deposited on the negatively-charged copper wire at the other pole of the electroplating circuit. I started up the process tonight and could tell it was going to be slow going, but at least I wouldn't have to do any actual work. Strictly for entertainment purposes, periodically I'd fire up my MAPP gas torch to burn off the bubbles of hydrogen gas forming on the surface of the disgusting brown electrolyte. If they were big enough they'd disappear with a loud pop and a burst of orange fire, a tiny Hindenburg sans swastika.
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