[Bug] "Retract before outer walls" does not work.

[thanhtacles 1]

I found a bug where the feature to retract before the outer walls flat out does not work. There is no retraction when moving to printing the (red) outermost wall. What the programmer did wrong was that the interpreted all walls as outer wall, including the (greenl inner wall that shouldn't count. The retraction step needs to happen right before the red outer wall.

 

You can see it for yourself in the printing process. And the fix is really easy, You just have to rearrange the insertion of the retraction.

Edited March 17, 2020 by thanhtacles

[burtoogle 513]

Hi, please attach a project file that illustrates this.

[thanhtacles 1]

Here. You can clearly see where it retracts every time it goes to the (green) inner wall E8.40884 -> E5.90884

 

G1 F1320 X96.067 Y75 E8.40884
G1 X96.167 Y75
G1 F2400 E5.90884
G0 F10800 X95.882 Y75
G0 X74.088 Y88.273
G0 X73.818 Y88.543
;TYPE:WALL-INNER

where instead it SHOULD be retracting before the OUTER WALL. Youll notice there is no retraction step from the transition of inner wall to outer wall. Retracting before you go to the inner wall does absolutely nothing to your seam because that's not where your seam is. It's your outer wall that determines your seam, and thats where you want to retract to have perfect seams. 

To prove this, I tried setting wall line count to 1. This tricks it into behaving like the expected behavior of wha this setting was meant to do. So that way it would go from infill immediately into outer wall (no inner wall) and it creates absolutely stunning perfect seams. I honestly think whoever wrote this made a mistake and meant to have it retract right before outermost wall.

SimpleSquare.gcode

Edited March 17, 2020 by thanhtacles

[burtoogle 513]

Please provide the project file, thanks.

[burtoogle 513]

BTW, the reason it's not retracting on the move from inner to outer wall is because the distance is less than the value of retraction minimum travel. Try reducing that value to below 0.566 mm.

 

There's something weird I spotted, it looks like you are using a negative extra prime value, is that so?

[thanhtacles 1]

@burtoogle in S3D, there's this absolutely crucial setting called extra restart distance and I can't find anything equivalent to it in cura. I searched the GitHub and only found that people have attempted to put in a negative number for "Retraction Extra prime amount" in an attempt to emulate how S3d does it but I dont know if that's correct (it turns orange when you enter a negative value) but I figure I might as well have on. It's a very clean and intuitive way to implement this, and I think CURA would serve to learn from it. Unfortunately I'm still getting blobs at the seam start.