Unresolved Homing on Z axis is inconsistent

Hello,
Recently I have had some trouble properly homing the z axis on my ROBO 3D R1+. When I enter G28 into the gcode terminal the extruder of course homes to the center of the bed. But when I enter G29 into the terminal the coordinates given from auto calibration for the z axis were way off. They were in no way consistent or even close to being consistent. An example of the homing coords would be something like this:
Bed x: 15.00 y: 20.00 z: 4.51
Bed x: 110.00 y: 20.00 z: 8.51
Bed x: 205.00 y: 20.00 z: -0.98
Bed x: 205.00 y: 125.00 z: -1.10
Bed x: 110.00 y: 125.00 z: 0.27
Bed x: 15.00 y: 125.00 z: .60
Bed x:15.00 y: 230.00 z: 6.59
Bed x: 110.00 y: 230.00 z: 10.59
Bed x: 205.00 y: 230.00 z: -1.08

Are these numbers normal or are the inconsistent z values the problem with the print? I really don't know why the homing is inconsistent (not to mention it is inconsistent for prints as well) for i am still new to this 3D printer. Could someone please explain to me why the z axis is so out of whack? If you could guide me through how to fix this, I would greatly appreciate it.

 

I'm having the same issues (randomly) . Though not that far out from what you posted ..but mine is not consistent at all either, and I don't know why.

Have you read through this post http://community.robo3d.com/index.php?threads/read-me-my-robo-doesnt-auto-level-correctly-faq.4664/

?

 

Yes manually everything moves quite smoothly, without any problems. The bed seems to be in its proper position. But every time i try to auto calibrate either when printing or using G29 in the Gcode terminal, the Z axis always seems to be very inconsistent. I can put up more details about the printer, so just tell me what would be needed for further analysis.