Quote Originally Posted by Voicecoil View Post
Tramming's not such a bad thing as might appear - the vertical blocks that the Z-axis Hiwins are attached to have increasing clearance hole diameters from 6.1mm (bottom) to 6.6 mm bot( top) to allow some side to side movement at the top to get it square.
In that case, you are bending the ball-screws because they are fixed to the top plate while the bottoms are fixed to the upright plates which your moving causing a twist on the screw. Also, the ball-screws must stay aligned perfectly parallel to the rails which they cannot do this way because you have them fixed to the top plate.

This design fails the golden rule of DIY to me.? Which is build-in Adjustment, adjustment, adjustment and bit more adjustment just for good measure?

Quote Originally Posted by Voicecoil View Post
And they make the Z-axis plate seriously chuffing rigid top to bottom-wise.
Pointless if they cause vibrations through the spindle, which they will do compared to if they were fixed directly to backplate like on conventional design. You could also use a similar supporting strip on the rear plate if felt it was needed on conventional design but without causing vibrations.