Tuesday, October 21, 2008

Brackets and Rods: Precise Machining Required

On October 12 Amos and I got together one more time to work on the pedal project. By the end of the day the pedals would be assembled, standing on their own two feet, ready for wiring.

The first step, though, was dismantling all three pedal units. Amos stripped them right down to the bare minimum, removing all the parts that were bolted on, and some of the parts that were riveted on as well.

He needed to do this in order to drill four very precise holes in each pedal platform. These holes needed to line up with each other, because half-inch steel rods would slide through them to hold the entire assembly together. If any of the holes didn't line up, the pieces wouldn't go together. And if there was any slop in the holes, the pedal platforms would move around when the pedals were pressed.

In addition to the three pedal platforms, there were two brackets, one on which end, to which the legs of the pedal unit would be attached. These, too, had to slide onto the half-inch steel rods.

So Amos had a lot of very precise drilling and hand reaming to do. Since the drill press on hand wasn't really accurate to get these holes dead on, he came up with the plan of carefully slotting the rear holes in each platform and bracket by hand, just enough to allow the two steel rods to go through.

Here are some photos of the completed assembly. He did it! There's no discernable play, yet the pedal platforms and brackets slide freely on the steel rods. Awesome work.

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