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Rectract Before Outer Wall not working - ZScar issues

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Posted (edited) · Rectract Before Outer Wall not working - ZScar issues

Hi,

I'm having some issues with the zscar, I already try most of the possible combinations with Cura settings and I am continuing having problems as we can see in the image below.

Screenshot_4.thumb.jpg.fc0cb833ea7206c7b61d0bf517df5788.jpg

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I think the main problem that is causing the issue in the image, is the lack of pressure inside the extruder when it starts extruding the outer wall. Before the outer wall, the extruder does a long travel move, and during this travel move some pressure (filament) goes way from the extruder.

Also this long travel move is strange since the the "Z Seam Aligment" is "Shortest".

After analysing the gcode, I found that the "Rectract Before Outer Wall" setting is not working as we can see in the next image.

Screenshot_3.thumb.jpg.1aa0e17387e11c174f7e9d46424ed0b2.jpg

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What I intent with this setting is to hold the pressure inside the extruder soon after the last extruder path (in the below layer), and then ensure that when it starts extruding (on the next layer) it will not have underextruding issues.

I also found that if the "Retract at Layer Change" is activated the rectration will occur in the same x y position where the outter perimeter will start, this situation contributed again for the loose of the pressure in the extruder.

Screenshot_2.thumb.jpg.156f22962af4d2e33d7f572747f84a0a.jpg

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This two settings "Retract at Layer Change" and "Rectract Before Outer Wall" in order to be more eficiente must happens on the end of the last extruder path (yellow arrowhead in the gcode images).

Cura 2.7.0

Tks

Screenshot_4.thumb.jpg.fc0cb833ea7206c7b61d0bf517df5788.jpg

Screenshot_3.thumb.jpg.1aa0e17387e11c174f7e9d46424ed0b2.jpg

Screenshot_2.thumb.jpg.156f22962af4d2e33d7f572747f84a0a.jpg

Edited by Guest

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Posted · Rectract Before Outer Wall not working - ZScar issues

It seems that the "Rectract Before Outer Wall" sometimes is made.

Screenshot_6.thumb.jpg.31e2b924eae68405cffdc6a6613c3704.jpg

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Posted · Rectract Before Outer Wall not working - ZScar issues

Thanks for the gcode - I've found the bug (it's not one of mine!), it's triggered by the combination of retract before outer wall and outer wall printed before inner walls both being enabled and the end of one layer being some distance away from the start of the new layer. I will submit a PR that should fix the problem to the Cura devs.

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Posted · Rectract Before Outer Wall not working - ZScar issues

Hi @ghostkeeper,

The issue with the "Retract at Layer Change" that is happeing in the same x y position where the outter perimeter will start (that contribute for the loose of the pressure in the extruder) was not solved, only the "Rectract Before Outer Wall" was corrected.

As you can see in the image, after the last extrusion (and here is where the retraction must occour) there's a long travel move, then a retraction happens, goes to new layer and prime, all this on the exact same place.

Screenshot_2.thumb.jpg.be253d05fc80619f89dd16bf8100b738.jpg

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Screenshot_2.thumb.jpg.be253d05fc80619f89dd16bf8100b738.jpg

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Posted · Rectract Before Outer Wall not working - ZScar issues

Just doing a quick test and it's working for me. This image shows the retracted travel move (yellow) to the start of the outer wall. Will continue to investigate.

Screenshot_2017-11-09_17-26-50.thumb.png.cc07949573db59332b11ed44f5ac31f4.png

Screenshot_2017-11-09_17-26-50.thumb.png.cc07949573db59332b11ed44f5ac31f4.png

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Posted (edited) · Rectract Before Outer Wall not working - ZScar issues

Edit - no, I was wrong it's actually working OK (duhh, I forgot to turn on the retract before outer wall setting!) So at the moment, it's working OK for me.

Edited by Guest

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Posted · Rectract Before Outer Wall not working - ZScar issues

And, guess what? You made the same mistake! In your gcode file it has the evidence:

travel_retract_before_outer_wall = False

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Posted (edited) · Rectract Before Outer Wall not working - ZScar issues

In this gcode I was not using the "Retract before_outer_wall" option (but I know that it's already working), I was testing only the "Retract at Layer Change".

Edited by Guest

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Posted · Rectract Before Outer Wall not working - ZScar issues

I have modified the mod we made earlier to take into account the retract at layer change setting. A quick test appears to do the right thing so I will create a PR and then the Cura devs can decide whether to incorporate it or do something different.

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