Been spending the last couple of weeks building. I wanted to build a Joe 2006, but without a CNC and without cash, I figured JGRO was the way to go. I did, however, implement Joe's changes that makes the unit a little bigger.
I have most things figured out. I'm using the Hobby CNC controller, but I found some 160 in-oz steppers at Marlin P Jones for only $12.95 each, so I decided to go with those even though it will affect my speed. My lead screws are 5/16 threaded rod, which fits nicely in the skate bearings. I fashioned some motor couplers from 1/2" aluminum rod, which is drilled and tapped, then I used 1/2"ID rubber hose and hose clamps to fasten them together.
Things are mostly good, but I'm fighting with the bearings on the long Y axis. I just cannot get one bearing on each side to make contact. I was pretty sure my pipe was flexing in the middle, and I think supporting it there will help, but I'm thinking I am going to have to take it apart and shim to get everything to make contact. X and Z were mild problems, but I could adjust the pipes enough to tighten things up.
Here are a few pictures on my progress: