I have read that certain greek temples in antiquity, had doors which opened automatically, with the rising of the sum. Other writers mention statues that rotated on pedestals, powered by some kind of hot-air driven fan/turbine. I also read that the greek astronomer Andronikos of Athens, constructed a water clock in the 3rd century BC, installed in the “tower of the Winds” in Athens. There is also the mysterious “Anticthera machine”, found by fishermen in the waters off the island of Anticthera in 1911 (the Yale astronomer Derek de Solla Price ivestigated this machine in the 1970’s). So, were the ancient greeks capableofbuilding fairly complex machines? How would a 3rd-century BC, greek artisan go about making gear wheels, shafts, and bearings? If these machines were in fact real, why didn’t the greeks go ahead and make the industrial revolution 2000 years before it happened?
Hie yerself down to the local library or bookstore and find a copy of Ancient Inventions by Peter James and Nick Thorpe. It details all kinds of ancient machinery that the Greeks and others had. As for why these things never became the seeds of an ancient industrial revolution, it basically boils down to the fact that the Greeks and Romans saw no use for such things, since they had a ready supply of slave labor. If they had began to make use of the labor saving devices, they would have had to figure out what to do with the slaves, and since slaves equaled wealth, few people would have been willing to give up their slaves.
Doc Nickel or Miller could probably better tell you than I as to how the Greeks would have made gears. The Greeks had lathes, and while gears are commonly made on milling machines (which I’m not sure that the Greeks would have had), I’m fairly certain that one could make gears on a lathe, if you had ample time. Shafts can be easily made on a lathe, and the bearings probably would have been little more than blocks of soft metal (lead, most likely) with animal fat for lubrication.