Glad to see you working on this! I am using my machine. Still not happy with the speeds, but I deal with it for now. I still have problems once in awhile with one axis or another stalling. Sucks, but I've not ruined a part yet. Usually, it ends up with the EM cutting air. I would like to figure it out, but I don't know how much money I want to sink into this machine. I'm contemplating converting the big mill to CNC or 1/2CNC, and comparing the cost of upgrading that mill or making this one more usable. Doesn't look like ball screws can be added to the Sherline/Spectralight without some major work. Haven't seen any retrofits online, either. A new saddle is the biggest hurdle. Don't want to shell out more for the saddle from A2Z than I paid for the machine to begin with. In fact, that's one thing that amuses me about these little machines. Don't get me wrong; to each his own, but I see so many people who bought the machine, and then spent more than that upgrading it to a Monster Mill one piece at a time! I am considering designing a new X/Y, though around linear rails/bearings and ballscrews. We'll see how that looks.
According to the Spectralight slick, X is 8.5", Y is 4.5", and Z is 5.5".
Dave