Saturday, December 29, 2007

The Countershaft

The lathe's countershaft is an improvised replacement. It's some manner of hard steel rod. It was perfectly suitable except that it was 5" too long and was protruding from the pulley that connects to the motor (hereafter known as the drive pulley.) To make matters worse, the last 6" of the rod was threaded. I decided to address this unsightly safety issue.

The smooth part of the shaft wasn't long enough which left the drive pulley sitting on threads. This didn't seem sensible to me. I determined the shaft's proper length and cut the excess off. That was a good start but it left the threads under the drive pulley. I removed them by turning the last inch or so of the shaft down to 1/2" from 3/4". Then I made a sleeve that would bring the diameter back up to 3/4" by boring a 1/2 hole in an aluminum rod. I pressed this to the shaft. It was a tight one-way fit. Finally, I turned the sleeve to the proper diameter, faced the end of the shaft, and broke the corners.

This was the first press fit of this size that Marco and I had ever done. It could be likened to monkeys doing math.

If I'd had the steel, I would have made the sleeve from that. We'll see how long the aluminum lasts.

Here are pictures of the countershaft in place.

While I had it all apart, I decided I didn't like the retaining collar on the right end of the countershaft and the pulley on the left end rubbing against the casting. Didn't seem too make a lot of sense. As an experiment I cut some washers from a plastic jug. We'll see how long they last. I don't expect they'll have too much pressure on them.

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