My first machine waa a modified JGRO - in use until very recently when I started cannibalising it for its replacement. I used 3nm Nema 23 motors from Zapp. I used M752 drivers which worked fine but have been obsolete for a while now (I built the machine around 4 years ago); the new machine will use the same motors but with EM806 digital drivers - OTT for a JGRO but great for the mk2! Zapp also sells trapezoidal leadscrew.