Overview: the advantage of 3D printing is that each printed piece constructs one layer at a time. This means that each layer is independent, and the nozzle can move freely to any position of the platform. At this time, the print is still under construction, which provides many opportunities. You may see that the nozzle will leave traces when it moves on the surface of the previous layer, which is most easily seen on the upper surface of the print. This scar occurs when the nozzle is moved to a new position and dragged over the previously printed plastic. The following chapters will explore several possible causes and provide corresponding suggestions on which settings can be adjusted to avoid problems.
Solution 1 Extrude too much plastic (first of all, you need to make sure that your extruder does not extrude too many consumables. If you extrude too many consumables, each layer will tend to be thicker than the preset. This means that when the nozzle moves through each layer, it may drag the previously extruded consumables. Before you check other settings, you need to make sure that you have extruded too many consumables.) After confirmation, we reduce the traffic of slicing software.
Solution 2. Vertical lifting (Z lifting)
Instructions for setting the lifting height of the z-axis of the fallback in the slicing software: if you are sure that the amount of extrusion consumables of the extruder is correct, but still encounter the problem of dragging the nozzle on the upper surface, it is necessary for you to see the vertical lifting setting in the slicing software. Turning this option on means that when the nozzle moves again, it will rise a distance above the previously printed layer. When it reaches the target position, the nozzle will move back to its original height for printing. By moving a certain height upward, the nozzle can avoid scratching the upper surface of the print. To turn on this function, click tool - Open expert setting - there is a "z-axis lifting height during retraction" in the return wire, which is generally set at about 0.3mm. For example, if you enter 0.3mm, the nozzle will always lift 0.3mm before moving to a new position. Please note that the lifting will only occur during the retraction action.