The ballscrews arrived today - I paid for them on 08/06 and I requested different end machining (longer portion for pulley and same machining on both ends of screw) so I think that's good service. He also charged me $447 in total even though I ordered the 25mm screws, so $72 less than originally quoted. The ballnuts backdrive easily and they seem nice and smooth.

I will start working on the rotating ballnut mount soon. I'm currently doing one last 3D drawing. I will use 5/8" aluminium for the plates that hold the bearings with some aluminium 'posts' to hold the plates together parallel at a fixed distance.

I made a mistake with the bearings and bought open not shielded so I'm going to have to put some sort of enclosure round them. I got them on eBay, one SKF and three SBC 7207.