I noticed a problem with the combing feature. When I print the first layer with combing set to “not in skin” the extruder does not retract on the first layer. That leads to ugly oozing strings in the visible parts of the prints and also to other problems. E.g. if I want to print a model with tiny circles in the first layer (like for screw holes) the circles get easily pulled away because the extruder is not retracting. At first I thought I’m having sticking problems with the first layer, but I improved that a lot and my prints are perfectly fine now, when I turn off combing completely. In that case the extruder is retracting as desired and the circles stay in place. But turning combing off isn’t always a good option. Sometimes large prints take so much longer and may even have little marks in the visible surfaces where the retractions happened. So I don’t want to turn combing off completely just to be sure the first layer is okay. I saw this behavior with a lot of different models now, so I’m sure, Cura doesn’t always handle the first layer as skin. Setting combing to “not in skin” does definitely not help.
Here are two pictures of the first layer of a print. The first one with combing turned off. You can see the light blue travel lines which mean, the extruder is retracted. And the second one with combing set to “not in skin” where you can see the dark blue lines. The extruder is not retracted there which produces the described problems.
Updated question to answer:
Thanks a lot for explaining that to me. But I’m afraid the problem still persists. The value of “retraction minimum travel” was at 0.8 mm, which should be fine I assume. Now I’ve set it to zero, just to be sure. The extruder does still not retract as you can see in the picture below.
But when I turn combing off completely, the retraction is happening. So I think it is a problem with the definition of “skin” for the combing mode “not in skin”. The bottom layer doesn’t seem to be treated as skin. By the way, I’m running the latest version of Cura of course (4.6.1).