Unfortunately, this does not make too much sense:
Depending on the probe / clone model:
- The distance between retracted pin and nozzle tip should be between 2mm and 4mm. Actually you should follow the recommendation or it can lead to vastly crappy readings
- With the calibration you exactly determine the difference between the probe’s trigger point (as determined during
G28) and the nozzle being at first-layer-height (typically determined with the infamous paper test)
As per logic this distance cannot be negative unless something is very screwed in your setup (or I’m completely missing something)