Combing will reduce the chance of defects on outer surfaces of the print by recalculating all nozzle travel moves to stay within the perimeter of the print. This results in greater travel distances, but with a reduced need for material retraction.
If combing is disabled, the material will retract and the print head will move in a straight line to the next point.
Combing disabled (left) has retracted travel moves that move outside the print’s boundaries. Combing enabled (right) has unretracted travel moves within the print’s boundaries.
Avoid printed parts
By enabling this setting, the print head will avoid printed parts when traveling. When the shortest route from one point to another in the print is obstructed, the print head will move around it. This decreases the possibility of coming into contact with parts of the model that have already been printed, in turn reducing the chance of surface defects or material mixing. To use this setting, you must first enable combing.
The travel moves in both images start and end at the exact same location. Avoid printed parts is disabled for the model on the left, and enabled for the model on the right.
This setting defines the distance (in mm) between the nozzle and the print when avoid already printed parts is enabled. A greater avoid distance means a reduced chance of contact with the printed model, however a large avoid distance will significantly affect the length of the travel moves, impacting the print time, and chance of oozing.
Layer start X-Y
This setting defines the position closest to these coordinates to start the next layer. The setting is normally set to the far-right corner because that is where the Ultimaker 3's switching bay is located.
Note: This is a different setting than the Z-seam. The z-seam alignment setting only adjusts the start position of the outer wall, where this setting normally starts at the infill.
Z-hop when retracted
With this setting, the build plate will move down by the set value when a retraction is performed, allowing the print head to travel over the print without the nozzle touching it. This prevents the nozzle from hitting the object or leaving “blobs” or scratches on the print surface. Please note that for prints with lots of retractions/travel moves, this can increase the print time.
Z-hop only over printed parts
The 'Travel' category includes the option 'Avoid printed parts'. When this is enabled, the nozzle will avoid these parts when possible in order to reduce scratching the model’s surface. When there is no way to avoid the part, the printer will perform a Z-hop when traveling over the part.
This setting specifies the height (in mm) at which all Z-hop moves are performed during the print.
Z-hop after extruder switch
This feature will trigger a Z-hop when the nozzle moves to the switch bay, reducing the chance that oozed material will come in to contact with the printed model.
Continue reading about Cooling settings.