Quote Originally Posted by Jonathan View Post
I would mount the stepper motor to a block of aluminium since the posts are not particularly strong, wont conduct much heat from the motor and also look like a grandfather clock. Also you might have difficulty fitting the belt/pulley between two posts? It would certainly limit your choice of ratios.
Probably negligent, but instead of making the ballnut mount match the circular profile of the nut, I'd make the mount closer to a rectangle so it fixes to a greater area of the bed since that should be stronger.

fair points, i will certainly be changing the ballnut mount but the screw mount is, although debatable in need of more thought (access to y axis gib screws has been somewhat compromised)

cost also needs to be taken into account so i may well use standoffs just to get the machine running and then cnc a new mount