Coasting in Cura on Layer Change

[SellAndBuxY 0]

Hi guys

 

I'm always experiencing little blobs on a new layer when printing with Cura with PETG. But this thread is about a software problem. I'm working with coasting (coasting volume 0.35mm3 and minimum coasting distance 0.375mm3 with my 0.8mm nozzle with 0.4mm layer height). It gives me really nice results, no blobs and no gaps in the print and almost no strings, even with fan completely disabled. However, on a new layer, I noticed I will have either strings or blobs which will make the print not so perfect. So from an analytical view I thought this must be something software related and so I checked the gcode for this attached 3mmBox.stl.

 

So, for the WALL-INNER(Line 316 and Line 317) in the GCode you will see there is no E command so coasting is working. But at the end of the layer (Skin, Line 385 and 386) you will see that it extrudes till the very end and makes a retraction move. So, since there is no coasting happening then, I will get these blobs at the layer change. How can I achieve in Cura that coasting is also done at the end of the layer?

 

Please don't give me hardware tips retraction does not work for PETG like it works for PLA on a bowden printer so I do need the coasting setting and not something else.

 

I just unchecked for fun the setting "Retract at Layer Change" so you can see this setting makes no difference in the GCode, besides on the comments.

 

I hope I don't need to implement my own plugin to fix this problem?

 

Thank you for your help

CCR1_3mmBox.gcode CCR1_3mmBox_nr.gcode 3mmBox.stl

Edited June 13, 2020 by SellAndBuxY

[burtoogle 508]

This is because the layer ends with skin or infill, neither of which heed the coasting settings. Only wall lines are coasted. There is a recently active issue about this (https://github.com/Ultimaker/Cura/issues/3843).