at the end of the day, i was looking at the single driver tb6580.? i think... then i was pushed toward m542. (eyup budget change).lol i want a machine that i can learn from atthe min.) was even gonna go the route of threaded rod as the lead screw... thats changed.. now looking into sprockets, rack n pinion. ive got time no were to build it yet. or put it.. workshop is only just starting...