unwanted extrusion instead of retraction

[beguggamin 0]

Hello,

I have a strange probleme with my UM2+ Extended: Sometimes (Not everytime on the same position) the feeder is pushing material out instead of retracting.If its haapening, it is realy pushing out material. You see it very well on the attached pictures. I swaped the extruder stepper motor, changed firmware, reduced exdruder current, sliced different models. But nothing helped so far. If somebody has an idea, it would be greatful to have an idea where to find the solution of this problem.

In this Image the line in the circle and the bulb in the middle of the object ist the Problem.

Best regards Beguggamin

Edited October 29, 2017 by Guest

[gr5 2,071]

What slicer are you using? In Cura 2.* you can enable "combing on bottom layer only". This will take care of that single line through that circle on the right. It will also take a little longer to print as it will avoid going across open areas but when it does go across open areas it will retract the filament.

[beguggamin 0]

Hello,

I had this problem already with 2.7 now its the same on 3.0. (at the momen with standard stettings. The image was taken from the second layer. It's not only at first layer. It apears all over the high randomly. Have you seen the big bulp in the structure? where the line starts? The lines in the empty room are not the big problem, but his part in the Structure is anoying alle layers after comming. Because the nozzle hits again. (Material on structure)

When problem appears, I hear the feeder working hard.

Anyway I'll try this option.

BR

Edited October 30, 2017 by Guest

[gr5 2,071]

On one hand it's important to have our parts stick to the print bed and the best way to do that is to overextrude the bottom layer so we really push the filament into the glass hard.

On the other hand if you are overextruding you get these blobby areas.

After a few layers it should all fix itself.

I'm not sure how to fix this overextrusion yet still have parts stick consistently. Especially larger parts like this (more than 40mm across). But I suggest you try something in between. In other words try moving the glass a little farther from the nozzle. But if the parts come loose while printing you moved to far.

Also if you have the patience to level perfectly then you could try a thinner bottom layer. 0.1mm bottom layer height can work quite well. That way when it over extrudes it tends to strip the filament a little bit instead of overextruding yet you still get the part to stick well on the bottom layer. By the third layer there should be no overextruding.