Hi Ben - You need to get busy in CAD There's lots to sort out. Your lengths are not too long for ballscrews just depends on what speed you want to run them at... You need to define what plenty of Z is as this will determine a lot of things. The Z axis size and gantry size (100x00x6 is too small to cut aluminium over 1500mm efficiently) will determine lots of things.. CAD sorts that out and the Shark Tank here will sort the rest. Peter