Rod flex under carriage weight

[MechaBits]

I can't work it out from your edit but assume it's probaly half the flex in your rods, maybe even less due to the shorter rods. (but then I do have a little extra weight on the end of the rods/ preload) though they are probably more likely to bow than sag, or just tilt the arm, but the bed is level relative to the arm so it all looks ok at the moment.

Maybe if he arm/rods is tilting it doesnt bend?, and the tilt is compentated for in the bed, but no doubt it will try to tilt a little more as the head reaches the end of the arm, y backup plan if this happens is to add a counter balance, wires at the end of the arm up & over the Z-axis, so it looks more like a Crane, or just add the second Z-axis.