Hello

[Jonathan]

Sorry for the late reply...

Jonathan - if you are still keeping an eye on this thread - I have seen on other threads that you have successfully developed a rotating ballnut system. I was wondering if fixed ball screws held in tension along my x axis would make sense here as it would eliminate whip? Do you sell your spinning ball nut mounts?! :) presumably the arrangement shown in the previous post could be used to drive two ball nuts mounted on the y axis gantry?

Tensioning the screw helps, but you need a lot of tension to make a significant difference to the stiffness and most CNC router frames are not strong enough to apply that much tension. On mine I had the ballscrew machined the same on both ends with a thread. Nut on one end clamps the screw and the other end can be used to tension it a bit. It works well...
I do sell the rotating ballnut mounts, 1500mm is about the threshold where I would say it's worth considering a rotating ballnut, fixed screw setup. You'd certainly get a higher feedrate, but the question is do you actually need it? If you're mainly cutting wood/plastics then you can certainly take advantage of higher feedrates, but if the machine is mainly cutting aluminium then the difference in overall machining time is extremely slight.

Jonathan have you drilled your housings with a holesaw?

No, I milled those housings and bored the hole for the ballnut in the lathe.