09-27-2012, 07:02 AM
Precision is more a function of machine condition than the shape of the ways. Most modern CNC mills use a form of flat ways called box ways and they are very accurate and precise (repeatable). Part of the problem with the old Atlas and Craftsman lathes is that there was no oiling system and unless they were well maintained, they wore out prematurely. Modern machines with box ways have internal oilers that keep the ways bathed in oil at all times.
Tom
Tom