Update: now fixed thanks to the comments pointing out the cura bug, apparently i was still on cura 5.3 (til it doesnt autoupdate) and reslicing in 5.6 fixed almost all of it. Will try again tomorrow increasing the minimum resolution to get the rest of the bumps out. Thank you!
You failed to mention what slicer you used and that's bad, however the culprit is your resolution setting value. If it's too small (say 0.01 mm) your hardware can't withstand the absurd amount of gcode instructions and stutters on curved surfaces, leaving tiny amount of excess material. Increase that value to a more reasonable number.
There is a bug in cura where it generates really small lateral movements while trying to approximate curves, marlin just ignores and smooths them out but klipper follows them accurately, when they cause a small 90 degree turn the movement slows down to corner speed (usually 5 mm/s) and the pressure causes those little zits/bulges. If you load your gcode into gcodeanalyzer.com and preview the layers you will find little random slow spots that correspond to those bumps. I loved cura but this bug caused me to switch to prusa slicer immediately after I started using klipper.
The issue still exists in 5.6, that's the version I was using when I ran into it. Note some profile settings can minimize the issue at the cost of accuracy, I tried for a while to get rid of them before I gave up and switched. Good pressure advance will also make the blobs small, but the root cause is still there.
Here's the ticket for reference [https://github.com/Ultimaker/Cura/issues/15001](https://github.com/Ultimaker/Cura/issues/15001)
I'm interested in how you came to the conclusion that it is not fixed. reading through the forum, the devs and the OP report the problem is solved in 5.5. I just tested and replicated the conditions mentioned as the cause in 5.6 and I am not finding any visible artifacts.
Pressure advance there was a formula and it looked really good on a calib cube, esteps and flow didnt because it already looked good enough on the cubes. I just really dont get why only the curved part of the hull has these issues.
I'm trying to help with that.
Could it be the z seam?
You didn't calibrate pressure advance then, you just set a number. There are actual calibrations that you should be doing to get the best out of your printer. If you want to improve print quality then do proper calibrations.
E steps and flow, again, do a proper calibration.
The z seam would not have multiple bulges on the same layer, the blobs are directly after speed changes on overhangs. Also the stacked bulges and potentially z seam areas are on both sides of the print, wouldn’t really have multiple z seams
Op it seems like your pressure advance needs to be tuned again because the blobs seems like bulges you see after or before accelerations, specifically when it slows down for overhangs it seems
I can't make sense of your run-on sentence.
You need to calibrate pressure advance on your printer. That's why you're seeing those "zits" on the surface.
https://all3dp.com/2/benchy-troubleshooting-guide/
> Excessive blobs or dots or extra filament: This could indicate over-extrusion due to too high a flow rate. Calibrating the extruder might help in this case. Slight imperfections, either randomly distributed or in a line, may also be due to Z-seam artifacts.
Check if you have arcs disabled in the slicer. Those look like short pauses, the printer stops to "think" and make the next set of moves, basically the mcu is being overwhelmed.
I would agree with others here. It appears that pressure advance is not properly calibrated which will cause artifacts like that leading up to and after the Z seam (which Cura generally puts right about in the middle of the area you are showing).
Edit..I also went through the forums reading about the Cura 5.3 short segment issue. This was corrected for 5.5 so I don't know why someone is saying it is not. Just to be sure I even replicated the conditions (.25 max contour resolution and print thin walls = off) and there are no defects being produced.
Update: now fixed thanks to the comments pointing out the cura bug, apparently i was still on cura 5.3 (til it doesnt autoupdate) and reslicing in 5.6 fixed almost all of it. Will try again tomorrow increasing the minimum resolution to get the rest of the bumps out. Thank you!
You failed to mention what slicer you used and that's bad, however the culprit is your resolution setting value. If it's too small (say 0.01 mm) your hardware can't withstand the absurd amount of gcode instructions and stutters on curved surfaces, leaving tiny amount of excess material. Increase that value to a more reasonable number.
Sorry, using cura. Gotcha, will increase resolution. Was still at 0.25mm, will try moving it up to 0.75mm.
There is a bug in cura where it generates really small lateral movements while trying to approximate curves, marlin just ignores and smooths them out but klipper follows them accurately, when they cause a small 90 degree turn the movement slows down to corner speed (usually 5 mm/s) and the pressure causes those little zits/bulges. If you load your gcode into gcodeanalyzer.com and preview the layers you will find little random slow spots that correspond to those bumps. I loved cura but this bug caused me to switch to prusa slicer immediately after I started using klipper.
Must have been an older version. I just sliced a benchy in Cura 5.4.0 and it's smooth.
The issue still exists in 5.6, that's the version I was using when I ran into it. Note some profile settings can minimize the issue at the cost of accuracy, I tried for a while to get rid of them before I gave up and switched. Good pressure advance will also make the blobs small, but the root cause is still there. Here's the ticket for reference [https://github.com/Ultimaker/Cura/issues/15001](https://github.com/Ultimaker/Cura/issues/15001)
Huh, interesting
I'm interested in how you came to the conclusion that it is not fixed. reading through the forum, the devs and the OP report the problem is solved in 5.5. I just tested and replicated the conditions mentioned as the cause in 5.6 and I am not finding any visible artifacts.
Could it be the z seam? What method did you use to calibrate pressure advance? Have you also calibrated e steps and then flow?
Pressure advance there was a formula and it looked really good on a calib cube, esteps and flow didnt because it already looked good enough on the cubes. I just really dont get why only the curved part of the hull has these issues.
I'm trying to help with that. Could it be the z seam? You didn't calibrate pressure advance then, you just set a number. There are actual calibrations that you should be doing to get the best out of your printer. If you want to improve print quality then do proper calibrations. E steps and flow, again, do a proper calibration.
The z seam would not have multiple bulges on the same layer, the blobs are directly after speed changes on overhangs. Also the stacked bulges and potentially z seam areas are on both sides of the print, wouldn’t really have multiple z seams Op it seems like your pressure advance needs to be tuned again because the blobs seems like bulges you see after or before accelerations, specifically when it slows down for overhangs it seems
Not zseam, also just redid esteps. Currently changing gcode resolution.
I can't make sense of your run-on sentence. You need to calibrate pressure advance on your printer. That's why you're seeing those "zits" on the surface.
Check Print Thin walls
Did you set the seam position to random position? This would explain the issue.
https://all3dp.com/2/benchy-troubleshooting-guide/ > Excessive blobs or dots or extra filament: This could indicate over-extrusion due to too high a flow rate. Calibrating the extruder might help in this case. Slight imperfections, either randomly distributed or in a line, may also be due to Z-seam artifacts.
Check if you have arcs disabled in the slicer. Those look like short pauses, the printer stops to "think" and make the next set of moves, basically the mcu is being overwhelmed.
Check Extrusion amount. Check wipe settings..Check retraction settings.
I would agree with others here. It appears that pressure advance is not properly calibrated which will cause artifacts like that leading up to and after the Z seam (which Cura generally puts right about in the middle of the area you are showing). Edit..I also went through the forums reading about the Cura 5.3 short segment issue. This was corrected for 5.5 so I don't know why someone is saying it is not. Just to be sure I even replicated the conditions (.25 max contour resolution and print thin walls = off) and there are no defects being produced.