Solution: Printer crashes into bed after bed probe with USB


Staff member
We have discovered a small bug in the Marlin 1.1.1 firmware which causes your print head to crash into the bed after the probing sequence when printing via USB.

Note this only affects people printing over USB from Simplify3D, Cura or Pronterface.

The solution is easy. If you want to print from USB, remove the SD card.

It turns out if you have the SD card inserted while printing from USB, the Z offset is cleared out. We tried this on several machines and from Cura 2.7, Cura 3.03, Cura 3.04, Simplify3D 4.0, and through Pronterface.

Even simpler if you connect to the printer from a host, we used Pronterface, and run the code below, the x/y/z coordinates are output after the bed probe. Make sure to run M114 after the bed probe has complete:

Our results without an SD card inserted but from USB:
X:384.00 Y:398.00 Z:14.99 E:0.00 Count X:30720 Y:31840 Z:5528
The exact same setup only this time we inserted the SD card:

X:384.00 Y:398.00 Z:0.00 E:0.00 Count X:30720 Y:31840 Z:-2147483648
The Z position is cleared out in the second one with the SD card inserted. This causes the head to dive into the bed after bed probing. The weird thing is, you can print from SD with the USB plugged in with no issue. You just can't do it the other way around. We apologize for any inconvenience. This problem has already been addressed in the newer Marlin builds, post 1.1.1, and it will be included in our next firmware update.