> For the complete documentation index, see [llms.txt](https://arpes-1-2.gitbook.io/arpes-1-2/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://arpes-1-2.gitbook.io/arpes-1-2/manuals-arpes-1-2/starting-the-experiment/multiax-manipulator-control/calibration-of-manipulator-axes.md).

# Calibration of manipulator axes

How to change the reference positions of 6 manipulator axes

In case of problems with communication between the MultiAx program and the manipulator it can happen that calibration of the axes is not correct anymore.

Recalibration is performed axis by axis. To recalibrate one axis go to Settings tab and type in the password (provided by the beamline scientist), then press the **Unlock** button.

Select the axis and press **begin calibration.** \
Set the **actual position** as determined from the rulers on the motors or visually from the camera image:

* Move x and y to 4 mm on the rulers --> recalibrate x=0, y=0; \
  Alternatively, read the values on the rulers (arrows mark positive direction, 4 mm mark is 0)
* Recalibrate z according to the value on the z ruler;
* Use tilt to position back side of the manipulator head vertically --> recalibrate tilt=0;
* Align the 2 vertical wires (left camera screen) by polar (correct for backlash) --> polar=0;
* Rotate the sample towards the camera by polar and use azimuthal rotation to make sample holder top edge horizontal (correct for backlash) --> azimuth=0.

Press **confirm**. 

After this axis coordinate will be saved and calibration panel will be locked automatically.

After recalibration your saved positions will not be precise anymore because of the errors in determination of the positions. Center of rotation for polar map XY-corrections may be also slightly shifted.