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Cura not retracting correctly

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Posted · Cura not retracting correctly

It would appear that I have been having this issue for over a year with multiple versions of Cura.

The part I am printing is a name plate. It is 2mm thick with the name cut through it. It is bonded to another part that you can see through the letters that provides a contrasting color for the lettering.

For letters like o, b, d that have an island in them I add a small bar across the letter to tie the island back to the main part that is 1mm thick.

When I print this the skirt prints, I can hear the retraction, it moves over to the main part, with no strings, and starts printing, and there will not be another retraction until layer 6, and I get strings pulled all over the place, which detracts from the appearance of the print. What is unique about layer 6 is that it is the first layer that no longer has that little bar in it. But retraction only occurs when moving between the islands, and from the main part to and from the islands. The rest of the part still has strings pulled all over it.

On layers 1 to 5 the print looks like one part, but layers 6 and up look like multiple parts. It would appear that Cura will only retract if it is moving from one part to another, or between isolated areas. Looking at the part in Cura layer by layer you can see that this is how it intended to do the job.

Any thoughts on how to correct this?

Steven

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Posted · Cura not retracting correctly

Hi, can you provide a screen shot or the model? I can't really envisage the problem from your description (sorry).

 

Good point.

This is a test part to better show the problem than the real part.

Slide1.thumb.JPG.638f556cbda4a48839a051e336d5603a.JPG

The islands that I refer to are in the larger circle, triangle and square, and you can also see the small bars. The small circles are just there to force more travels.

Looking at the first layer you can barely see that at the end of the skirt the travel line to the main part is a lighter blue, it would appear that this means travel with retraction. All the remaining travel lines are dark blue, which seems to mean travel without retraction. In the photos as they appear here, the dark blue looks more like a dark gray.

Slide2.thumb.JPG.91162d4a71028651ea1a3e1bd4b2efc7.JPG

Going to layer 6 you can see that all the travel lines are dark blue, no retraction. Also note that no travels ever cross into an open area, they go to and leave the islands on the bars.

Slide3.thumb.JPG.679c54a71111a0fe0d52fea5c76b59a3.JPG

Now going to layer 7, the first layer without the bars. Now the travels to and from the islands are the lighter blue, which seems to indicate we have retraction (when it prints I can hear the retraction happening, and this is where it occurs while printing), but the remaining travels are still dark blue.

Slide4.thumb.JPG.335f19056c1feff8b333344154aa009a.JPG

The remaining layers are the same.

So it looks like Cura will only do a retraction if forced to cross an open area. All this leaves a lot of strings which detract from the appearance of the print.

So how is this fixed?

Steven

Slide1.thumb.JPG.638f556cbda4a48839a051e336d5603a.JPG

Slide2.thumb.JPG.91162d4a71028651ea1a3e1bd4b2efc7.JPG

Slide3.thumb.JPG.679c54a71111a0fe0d52fea5c76b59a3.JPG

Slide4.thumb.JPG.335f19056c1feff8b333344154aa009a.JPG

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Posted · Cura not retracting correctly

OK, thanks for posting that extra info. I think you just need to disabled combing over skins (settings / travel / combing mode). Personally, I never use combing over skins and when using PETG I disable it completely. Hope this helps.

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