Outer Before Inner Walls - gaps at the beginning wall

[jiberan 0]

I have problem, when I use Outer Before Inner Walls, then I get gaps at the beginning of every outer wall. Rest is ok. When I print inner wall first, then is no problem, but for the exact size I need outer wall first. Look like lack of material after retraction and traveling on beginning outer wall.

I tried Z Seam Alignment: Random, but it just spread gaps randomly around.

Complete setting in attachment

CFFFP_valec 50.3mf

[burtoogle 510]

Hello @jiberan, the problem is that it is doing a relatively long travel move without retraction immediately before the outer wall is started. There are two settings in the travel category that can help you here. You can either enable Retract Before Outer Wall or you can set Max Comb Distance With No Retract to a value such as 10 which will make all combed travel moves longer than 10mm use retraction. Hope this helps.

 

[jiberan 0]

1 hour ago, smartavionics said:

Hello @jiberan, the problem is that it is doing a relatively long travel move without retraction immediately before the outer wall is started. There are two settings in the travel category that can help you here. You can either enable Retract Before Outer Wall or you can set Max Comb Distance With No Retract to a value such as 10 which will make all combed travel moves longer than 10mm use retraction. Hope this helps.

 

 

 

Combing mode have no effect. Combing mode: Off - the exactly same like before.

 

Combing mode: Not in Skin + Retract Before Outer Wall - (on pictures down) gaps at the beginning little shorter, but still missing material at the beginning outer wall. I think in this case not help this setting, but only the shortest travel distance.

 

 

2CFFFP_valec 50.3mf

[burtoogle 510]

Perhaps it needs more retraction or slower retraction? Sorry, can't think of anything else.

[Camaro 0]

Hi everyone,
I think i got the same Problem here, or a similar one at least. As I'm printing inner walls first, the issue occurs at my first inner wall, which results in a gap between top skins and the perimeters. The image shows this gap.

I tried a lot of different things, to get more extrusion for the first inner wall, but nothing seems to work. When I use Retraction Extra Prime Amount with about 0.05mm³ i see a slight blob at the start of the inner wall line, but than it goes back to the underextruded line.

 

My printer is an Hypercube Evolution with an E3D Titan extruder an about 650mm bowden tube. The printing speed for the inner walls was 50mm/s and 40 for the outer walls. Top skin speed was 30mm/s. The prints were made without combing and with 2.5mm retraction at 35mm/s. Support and Infill were also printed with 50mm/s and were equally bad. As i slow down this gets a little better, but 50mm/s isn't that high to begin with. The material is white PLA at 200°C and 55° bed temperature. The flow was set to 90 %.

 

If you need more information let me know. I attached the project file for the part shown in the photo.

 

Thanks for your help

 

SpeakerCableholder.3mf

[burtoogle 510]

2.5mm of retraction for a 650mm bowden is rather low. Personally, I am using 4.5mm of retraction on approx 500mm of bowden tube and retractions are very good (no oozing, no air bubbles).

[Camaro 0]

Hi,
Thanks for your reply. I thought so too, and had about 4mm at first, which resulted in underextrusion due to a partially clogged nozzle. But 2.7mm are even enough for PETG.I do not have any problems with stringing or oozing with smaller parts. (didn't try bigger parts with long travels yet.) I printed the hollow pyramid as a retraction test, and it worked perfectly appart from the underextrusion on inner walls and my part fan which is much to week for small details. (I broke it to test strength and have a look inside to see the inner walls. I can print another one and post an photo)
Quiet possibly I will need more retraction on bigger parts.

[Camaro 0]

But I guess it is due to some missconfiguration in my retration settings or something with my extruder hotend assembly. I printed another part, which came out pretty ok for my experience, but still has the same under extrusion problem on walls after retractions. On small details, where there is no inner wall, the under extrusion occurs therefore on the outer wall. (second image, this is how it came out of the printer, except for the tree supports i removed)
The weird thing is, that i didn't have any stringing or blobing during the travel to the small "pillar". I do not have a clue where the missing plastic could have gone.
The problem is less present, when using Simplify3D, but this introduces other problems (Overextrusion on Layerstart, which I couldn't fix yet). Additionally my Cura profile is tuned better, and I'm used to it. As I said, I'm pretty happy with the quality of the part except for the under extrusion. Maby someone had this problem already and was able to fix it?

Thanks for your help.

Edited November 12, 2018 by Camaro