How could be rod almost vertical when the head is half way to the tower? Ok, maybe you can call about 14° agnle almost vertical.
Anyway it looks like you are geting about 0.25 mm Z-error when you move half the maximum possilbe distance (ie 50%) from center to a side. I do not know about rostock mini, but a clasical old rostock can be calibrated to move withing 0.05 mm z-height area when moving 75% possible distance to a side. So it should be possible to calibrate better. The point is that the more to the side you are the more precise your calibration needs to be to keep given maximum z-height error.
Since you have different Z-height when you arrive to the same spot from different locations, your problem is primaryly not a calibration problem (and probably not some software bug either). I actualy observed this on a rostock here. But the problem was only temporary and never caused a bad print. Just after homing when I moved head down to the bed and moved from center to a side, measured z-height, returned back to center and went back to the side and mesured the z-height again; then I got a different z-height sometimes. The difference was typically about 0.1 mm. The difference was not always there. Whenever I measured this, the problem disapeared when I was moving for a while just above the bed (mostly I just did a circle around outer side of the heat bed). From that time on, the data from z-probe were consistent withing ±1 microstep (±0.0125mm). I did not find out why was it happening. My guess would be that belts somehow needed to settle to the puleys or maybe ball joints needed to settle somehow (they are quite tight). GT2.5 belts are used.
Edit: only spelling.
Anyway it looks like you are geting about 0.25 mm Z-error when you move half the maximum possilbe distance (ie 50%) from center to a side. I do not know about rostock mini, but a clasical old rostock can be calibrated to move withing 0.05 mm z-height area when moving 75% possible distance to a side. So it should be possible to calibrate better. The point is that the more to the side you are the more precise your calibration needs to be to keep given maximum z-height error.
Since you have different Z-height when you arrive to the same spot from different locations, your problem is primaryly not a calibration problem (and probably not some software bug either). I actualy observed this on a rostock here. But the problem was only temporary and never caused a bad print. Just after homing when I moved head down to the bed and moved from center to a side, measured z-height, returned back to center and went back to the side and mesured the z-height again; then I got a different z-height sometimes. The difference was typically about 0.1 mm. The difference was not always there. Whenever I measured this, the problem disapeared when I was moving for a while just above the bed (mostly I just did a circle around outer side of the heat bed). From that time on, the data from z-probe were consistent withing ±1 microstep (±0.0125mm). I did not find out why was it happening. My guess would be that belts somehow needed to settle to the puleys or maybe ball joints needed to settle somehow (they are quite tight). GT2.5 belts are used.
Edit: only spelling.
