after a bit of redrawing last night I had a thought that the fk/ff bearings (which I have just stumbled across) may be a better option for the x axis that the bk/bf ones. I am trying to determine the exact length of the ballscrew I need and cannot tell if the bearings in these units are flush to the back of the mounting plates or they are set in? does anyone have or know a link to some accurate tech specs for these bearings? Because the design of the axis uses a plate either end of the frame to sandwich the x axis ballscrew between two bearing units and I need to know the length of ballscrew I need to order otherwise there will be play or it will be over sized!

Alternatively if I were to machine up my own bearing blocks for the x axis, the floating end is straight forward, what does the fixed end comprise of? angluar contact bearings? sizes?