need help with Z axis (1 reply)

Hi,

First time of posting so bare with me

I have built this [www.thingiverse.com] . or at least used it as the basis. However the z axis seems to be flimsy and can be lower away from the rail than in to the rail. if you get what i mean, It tilts away from the rails and belt but the platform support was printed flat and level. now the levelness I can compensate with the level screws and springs under the build platform but it changes depending which way it settles to the min stop. up or down.
Also the movement of the z axis is less at the top than when say over 2mm down away from home.

I have not used a belted system before and cant seem to get the belt really tight. over all is a screw thread system more accurate. would I be better with a z platform held at 2 sides instead of one or maybe 2 drive screws on opposite corners and 2 rails on the other corners. although that would be tricky to build now I had to cannibalize the other printer to try this build.

I may have missed some info thats needed to help but let me know.

Mike