[BUG] When using the Move Axis feature to manually set Z height, the user can inadvertently lower the nozzle all the way into contact with the print sheet.

[jack-21409]

Printer model

MK3.9

Firmware version

6.1.3+7898

Upgrades and modifications

None

Printing from...

N/A

Describe the bug

[BUG] When using the Move Axis feature to manually set Z height, the user can inadvertently lower the nozzle all the way into contact with the steel sheet by selecting the minimum value of "0". If the user then uses the Move Axis feature to move the X or Y axis, the nozzle scrapes the sheet causing damage to the sheet. In previous versions of the hardware (e.g., I3 MK3s+) the nozzle would not contact the sheet at the minimum Z value.

Link to download video:

https://1drv.ms/u/s!AqTta7XkUq3OhddGXU91OMl_tFwaYw?e=7qcELn

How to reproduce

Install a steel sheet on the print bed. Auto home the printer. Use the Move Axis feature to lower the Z height to the minimum value. Observe that the nozzle comes into contact with the sheet. Observe that there is slight deflection of the heated bed when this occurs.

Expected behavior

The minimum possible Z value for the Move Axis feature should be a safe value that ensures the nozzle will not come into contact with the sheet when the user is using the Move Axis feature to manually change X, Y or Z positions.

Files

No response