Work this week mainly involved turning the conveyor rollers on my lathe. Last week I welded a plug in one end of each roller, but did not weld a plug in the other end. This allowed me to chuck up on the outside of the unwelded end, with the tailstock center in the center hole of the plug on the other end. This would allow me to turn the outside of the shaft for about 46 inches of the overall 51 inch length. The pictures below show the first shaft being cut on my lathe.

I used my 6 - jaw scroll chuck to concentrically secure the left end of the piece. The right end was centered up by using a "live" (roller bearing style) center mounted in the tailstock. Note that the tailstock is protruding slightly off the end of the lathe bed. This is right at the length limit of my machine.

I had to turn the pieces at 80 RPM and a feed rate of 0.012 in/rev. To cut the 46 inch length at this speed and feed took almost 50 minutes per cut. The limiting factor is the diameter/length ratio of the roller conveyors. At any higher RPM the tool would "chatter", creating a rough surface. Chatter is simply the sympathetic vibration of a rigid element that is subjected to an energy input while rotating at a resonant frequency. Since I wanted the end result to be a smooth, round cylinder I took light cuts. It took three cuts on each roller to get them the way I wanted them. I measured each roller after the final cut and gained a new appreciation for my lathe. The cylinders didn't vary in diameter more than 0.002 inches anywhere along the length.

The end result left about 5 inches on one end that needed to be finished.

I cut off the unwelded end of each roller to a uniform length of 50.5 inches. I turned two more plugs and welded them into the end of each cylinder. Next week I plan to turn down the other end of the rollers, bore out both ends to 1 inch diameter, and make the inner shafts.

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