What's the most low tech way to make wooden bearing balls for a wooden ball bearing?
Last century I read an auto-biography by a back-to-nature man who needed to transmit power from a stream paddle wheel to his cabin by belts. He said the hardest part was making a ball bearing. He carved the balls out of oak with a knife and roasted them brown near a fire. These lasted a long time. How did he do that -- or how could he have done it using low tech?