Prusa XL Filament Flow Inconsistent
I just got the Prusa XL a week ago and I'm having this issue while printing. When it first started (second or third print) the filament stuck sensor kept tripping and the print would stop when printing, the filament almost looks like it isn't being pushed through the nozzle consistently. I noticed that it seems to only happen with extruder 1 and 2. No clicking noises. The idler screws were loosened just in case it was too tight. No real noticeable change. The perimeters seem to print fine (right side of the black item 3 shells), but within the perimeter the issue arises. Here are my printing specs:
Nozzles: Original 0.4mm
Filament: Overture PLA (Dried)
- Per Overture, print specs are 190C to 220C temp, speed 40 to 90.
Temp: 210C first, 205C all else
Speed: 90 max
Flow width: 0.40mm max
Nozzles have Overture PLA (also dried) as well, but differing colors. Seems to print fine. Nozzle 5 has Gizmodorks PVA and it prints perfect every time. In the picture above, the clear material is the PVA from Nozzle 5. I'm at a loss. I've tried restarting the printer, nd recalibration the Z-Axis. I've experimented with flow widths, speeds, overlap percentages. I'm at a loss. I could really use any help at this time.
Thank you for your time!
Best Answer by blauzahn:
The nozzle is definitely too deep for the amount of filament it squishes onto the sheet. On my MK3S I'd lift z-live. On the Nextruders driven by the buddy firmware as mentioned before.
Please measure the diameter of your filament in several places. Watch out that its bending does not yield in a biased diameter. In case this spool has a diameter on the plus side, you can increase the filament diameter (for this spool only) or reduce the extrusion factor e.g. to 0.98, probably even lower.
The sheet looks fine now.
Give the print sheet a thorough clean and degrease and try again.
Cheerio,
RE:
Please clean the nozzle. Try to do so right before the nozzle cleaning dips. Prusa's firmware is a bit picky about clean nozzles because it determines the first layer height. We observe that on the XL as well as on the Core One or the MK4s. If your filament were too humid, it would ooze more.
Wavy pattern across filament lines indicate a nozzle that is too deep. If needed, you can apply a z-offset by pressing the button longer. On the textured sheet, the first layer has to be squished into the "valleys" as well in order to get large enough surface for adhesion. Since I got my satin-sheet on my MK3S I have not used the textured anymore. My textured sheet for the XL is unused.
In addition to what @Diem said: Please do not touch the sheet with your fingers directly. Use a paper towel and a ceran board scraper with slightly rounded edges. The latter exclusively for the printer unless you want to degrease it all the time. Let the sheet cool down before bending it just enough to get the parts of with ease.
RE: Prusa XL Filament Flow Inconsistent
Thank you for replying!
I cleaned the satin sheet and the nozzle. The problem became much better but I'm still, ultimately, having the same issue. I re-ran the input shaper calibration in case it was an issue with the vibrations. The perimeter is printing fine, but the interior of the first layer is wavey. On the left side of the picture you can see the printer is almost.... weaving.... the filament together. Thoughts?
Thank you for your time!
RE:
The nozzle is definitely too deep for the amount of filament it squishes onto the sheet. On my MK3S I'd lift z-live. On the Nextruders driven by the buddy firmware as mentioned before.
Please measure the diameter of your filament in several places. Watch out that its bending does not yield in a biased diameter. In case this spool has a diameter on the plus side, you can increase the filament diameter (for this spool only) or reduce the extrusion factor e.g. to 0.98, probably even lower.
The sheet looks fine now.
RE: Prusa XL Filament Flow Inconsistent
Thank you for your insight! By holding down the dial on the xLCD mount and waiting for an audible beep, it allowed me to live adjust the z-distance. Like you said, it was too deep. I ended up lifting the nozzle by 0.062mm and now all my problems have been fixed! I am curious, though... will the adjusted z-distance offset stay in place with every print? Or will I be required to make the adjustment on the first layer of every print? Why does the Point Probing not catch this distance issue at the beginning?
RE: Prusa XL Filament Flow Inconsistent
Please check whether the nozzle is properly seated vertically and fixed with the grub screw. Maybe it is a little loose and slips downwards when at printing temperature when the filament pushes from above. Please unload filament first. Be careful not to overtighten the screw as that may deform the nozzle tube. You might also try to recalibrate the load cell. A proper working load cell will catch this.
I very rarely have to use the z-offset at the XL. I think, there it is temporary unlike at the MK3S where it is essential. In fact I still like the way the MK3S does it.
RE: Prusa XL Filament Flow Inconsistent
Thank you for that! The nozzles are confirmed clean and in the correct orientation/position.
I was carefully watching my printer today and I think I found the cause of this issue to begin with. One of my toolheads has PVA loaded. Since the PVA is the first filament that needs to be printed (when used), the printer uses the PVA toolhead to calibrate the z-offset. However, the default calibrating temp is set to 170C, and this temp causes the PVA to SLOWLY ooze out of the nozzle. I did a little more research and found that a possible solution is to add a gcode modifier to line M109 that controls the initial temps of each toolhead, depending on the filament type. Currently, PVA is not listed in line M109 so I believe the printer is defaulting to PLA temperatures, which causes the oozing. Do you have any experience in modifying gcode? Or do you have any other insight?