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?

Make them very roughly ball like, and then run them between two flat rocks, preferably sandstone, better yet a rock called Millstone grit.

Steve
rickharris5 years ago