Camaro

Yes, I would say so too. but that makes it really hard to find a solution for it. I also would guess that this is some kind of configuration issue, as I already swapped out every possible component, but nothing really worked. The last thing I changed were the Stepper drivers. I previously had TMC2130 on XYZ and MKS LV8729 for my Extruder. Now I use TMC5160 for all axis. They are total overkill but at least it reduced the issue further. However, this couldn't have been an issue on its own, because a friend of mine used the same combination and had no problem at all. I am on high-end hardware for the whole extrusion system now but still have the problem on higher speeds. @gr5 Are you printing with a direct extruder? But with 150mm/s printing speed, I guess it's a bowden. And if so, how long is your bowden tube? I will report back if I have done further testing on this issue. Until then I'm printing slow (<65mm/s), which is kind of a shame for a CoreXY..

Hi, yes 'max comb distance' brought some improvement for me too. Even better worked enabling 'connect infill lines' and turning off combing completely. (this is similar to what slic3r does by default) This results in slightly more filament used, but improved my print quality a lot. I also experimented with the Linear Advance feature in Marlin. My bowden tube is about 60cm in length, which resulted in a huge K-factor for the algorithm. This in turn slowed my printing speed down a lot (probably due to other not optimal settings made in Marlin) and made the extruder quite noisy. At those speeds the quality was acceptable even without LA and at least the extruder was quiet. I also tried the Pressure Advance feature in Klipper, which also caused the extruder to be noisy, and mainly fixed the overextruded edges. So I turned it off again until I could fix the main issue. Hope this helps someone with similar quality issues.

As kulfuerst mentioned, Extra Prime didn't solve this issue, but also led to blobs on other parts of the print. I dried my filament and played with 'Equalize Filament Flow' but wasn't able to improve the issue. I will probably revisit this setting though later on. As I had this problem with any slicer and a freind of mine has a similar setup I thought about what about my hardware is different from his: than it occured to me, that I'm running an 8-bit board with a 0.9° extruder motor on the E3D Titan and use 1/16 micro stepping on my extruder which led to about 800 steps per mm. I changed to 1/8 microstepping which massively improved quality. I guess the necessary step rate for driving the extruder on the retracts simply exceeded the one my board was possible to generate. I'm not a 100% sure about this explaination, but reducing the microstepps worked for me. This also wouldn't explain why this problem didn't appear after each retract. As a next step I want to exchange this board with an 32-bit one. After that I will try increasing the microstepps again and if I'm right the problem shouldn't reoccur.

Thank you for your fast response. I will try your suggestions and report back on any new findings. 😉

Hello, I think I'm having the same issue for about half a year now... My printer is a Hypercube Evolution. At some point I switched to a Titan Extruder as you did, which as you said didn't solve the problem. I also tried different slicers All had the same issue. The problem can be minimized by disabling "Outer before Inner Walls" in Cura, effectively hiding the issue inside. This however works only for large "islands" on every printed layer. Further i switched to a original V6 hotend, changed the nozzle, tried different heatbreaks (PTFE Inlay, full metal and titan) and replaced the bowden tube multiple times (currently I'm using a Capricon bowden tube ~60cm). Your theory about the small parts could be right. I also see over extrusion on some parts or a blob at the end of an extrusion right before a retraction. Did you find a way to fix this issue? Or have you tried other slicers too? Im really frustrated over this issue.. Would be nice to finally have a fix for it. Thank you for your help

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.

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.

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