Cura skipping retraction on some layers

[BlueMaster 0]

I had some issues with oozing, and tried to print 5 tubes. I figured out that Cura is retracting fine, but in some layers it just ignore the retractions and travel freely between the 5 tubes.

In Cura I can see that the layers where it don't retract has a darker blue.

Here are two images, one of Cura, and one of the printet tubes. The blue travel lines in Cura corrolates to the oozing on the print.

It's about layer 19-26, 45-51 and 71-75. The model are 75 layers high.

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Edited December 6, 2017 by Guest

[gr5 1,072]

Retraction is a complicated issue. there are several settings related to retraction. The one you care about is to try to prevent the filament from grinding. I have done prints with 500 Meters of retraction. In one print! That's a half kilometer! I have found that if the same piece of filament goes back and forth 10X through the feeder it is always fine but around 20X or 40X through the feeder and your print can fail.

Because of this there is a parameter that keeps you from retracting too much. I forget what it is called but something like "minimum extrusion before retraction" or "maximum retracts on same filament". Something like that. They have changed the name and I lost track.

There is *also* a parameter that prevents retraction if the gap that you have to pass over is smaller than a given distance. This is unrelated to your issue above but good to know about.