Shim, Shimery

Leo Stone reminded me of the Zen and the Art of Motorcycle Maintenance-derived adage "One man's beer can is another man's shim stock."

Well, I had some shimming to do, and I didn't have any shims in the house, so I went out and bought me a can of Rainier shims....

I had noticed a while ago that the front disc on my commuter bike was not true. This was undesirable, as it meant I couldn't have the pads as close as I'd like without them rubbing. You want the pads close, so you can brake as hard as you like without the brake levers bottoming out, especially so with road bike levers.

I finally got around to it and took the wheel off the bike, put it in my truing stand, and measured the lateral runout with the nice dial indicator Dad got me for Christmas. (Or maybe for my birthday? Hmm. It's been a busy winter....) Lateral runout was 6 mil. That seemed like a whole lot. I pulled the disc off, and the mounting face had less than half a mil runout. So definitely the disc, but what to do about it?

So I asked around, and that's when Leo hit me with his adage. (Good thing it wasn't an adze.) So I bought a can of Yakima's finest hops from the local Wino Convenience Store. After disposing of the, um, packing, I was left with an ample supply of 4.5 mil shim stock. (The picture shows my digital caliper. I would have used my vernier caliper, but then the picture would have been hard for you, my loyal reader, to interpret, at the resolution available.)

Now, how to make a few doughnut-shaped shims, otherwise known as washers? It was then I remembered Nick Carter admonishing me to read up on Jig and Fixture Design. The key to a good jig they say, is a lively tune, but what do they know? The key to a good jig, as Ed Hoffman asserts, is locating the work. If you can't locate the work, then how can you work it? It seems prima facie obvious, but there you are.

How shall we locate washers? By their holes shall we find them, I say. [To be continued.]

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