Almost finnished the z-axis nut carrier now, so here it is so far. Essentially it is a spindle with the two ballnuts trapped inside so when it is spun, the ballscrew will move, hopefully taking the milling spindle with it. The first few pictures show the insides - a bored cylinder to trap the nuts and hold the bearings on. I managed to drill the clearance holes for the ball-returns on the rotary table. If I never had that, I guess it would have been a file job since the piece was too big to offset in the lathe. This part is made from 2.5" dia 2024 aluminium since that was what I had on hand.