This happens in 2 scenarios

(1) Due to improper calibration and level adjustment. The height of the idle nozzle is too low so turn it up. Please move the build platform to the top of Z-Axis, adjust the height of two nozzles according to the gap between the print head and the platform, tighten the idle nozzle by wrench and make it a little bit higher than the other one.

(2) The printing flow is too high causing the actual layer thickness to be higher than the original setting. After a while, the object is over high and touch the main nozzle. Please turn down the printing flow.

Posted in: Mankati Fullscale XT