MK4S - Circular Prints Failing
Hi All,
as you can see from this image, when printing any circles on my MK4S, which has recently been upgraded from a MK4, has suddenly started printing like the image below.
I have re-calibrated the gearbox cover and also checked the idler arm tension.
This filament isn’t that old and works fine on my other PRUSA MK4 (not yet upgraded to the ‘S’). The issue occurs on any board type, any filament (all PETG) and using generic PRUSAMENT Slicer setting - nothing changed.
Any suggestions?
RE: MK4S - Circular Prints Failing
That looks to me like poor adhesion to the bed and/or printing too fast. For reasons of inertia, the filament has a tendency to keep an straight trajectory. When we draw a circle, if the adhesion to the bed isn’t good enough or the speed is excessive, the thread of filament strays from the curve and takes the shortest path, as in the picture. You may argue that on a MK4S printer, the Z offset of the first layer shouldn’t be an issue. In real life this isn’t always the case, because of imperfect calibration of the load cell for different reasons. Even if the Z offset is correct, when the bed isn’t spotless, adhesion may become poor.
To be fair, I don’t see signals of a dirty bed on that picture. Besides, if the filament is PETG, adhesion shouldn’t be a problem even on a textured bed, provided that the Z offset of the first layer is correct,
If you have no problems with your other MK4 printing with the same settings, it looks like a Z offset problem. Nevertheless, I’d try to use adhesive and/or printing slower and see what happens.
RE: MK4S - Circular Prints Failing
Hi,
Are you using filament profile for mk4S ? I've used by mistake filament profile based on mk4 profile and print failed with similar problems (adhesion,...).
RE: MK4S - Circular Prints Failing
Hello, thanks for the speedy reply! I agree, I don’t think the bed adhesion is the issue here but I would say that the print speed is probably too fast! After listening to the printer print, there is a slight clicking noise as it prints and I have read that this can be to do with the idler tensioning.
I will also double check the tension of the belts.
Surely the presets of PRUSA PETG using PRUSA PETG Filament should work as that’s what they have based their settings on? And as long as I haven’t modified any of the settings, I can’t see why it wouldn’t be the same.
I’ll give it a go turning the speeds down but I don’t see the point in having a High-Flow Nozzle and MK4S if in reality you have to turn the speeds back down.
RE: MK4S - Circular Prints Failing
I'm not sure what the issue might be, but I've done the upgrade to the 4S and have been printing with PETG and have not seen this issue.
Are you sure your nozzle is seated correctly and that you have not overtightened the thumb screws that retain the nozzle.
Did you run back thru all of the calibrations and tests as well as changing the printer model to the mk4s in the printer settings?
RE: MK4S - Circular Prints Failing
Interestingly… I have just run through the calibration menus from the start and the Y-Axis has failed. I double checked that it is set to MK4S and it still failed. Hmmm. Belt tension issues?
That was a good reminder to follow the basics so thank you. Any ideas why the Y-Axis could fail?
RE: MK4S - Circular Prints Failing
What is this clicking noise? I had checked inside the gears, then performed a calibration and still this clicking noise exists. The idler tension screws don’t protrude the two holes as followed in the instructions.
I also can’t see any signs of a clogged nozzle, but I did a cold pull anyway and that hasn’t helped (it’s a brand new HF nozzle).
note: the issue only seems to occur at the back of the prints.
Check the Y axis idler is not clogged or damaged.
Check the part is printing completely flat to the bed. You may fix it with a thorough bed clean but if not save your project as a .3mf file
Files > Save Project as
Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.
Cheerio,
RE: MK4S - Circular Prints Failing
Interestingly… I have just run through the calibration menus from the start and the Y-Axis has failed. I double checked that it is set to MK4S and it still failed. Hmmm. Belt tension issues?
That was a good reminder to follow the basics so thank you. Any ideas why the Y-Axis could fail?
Maybe the new belt tensioners are out of alignment or something. Maybe go back over that section of the upgrade instructions to make sure everything is good.
RISPONDI: MK4S - Circular Prints Failing
You could also try a cold pull (best with Prusament PLA), might be a partial nozzle clog, which
may result in problems you wouldn't expect. I had a similar issue. Turned out, the nozzle temperature
in the manufacturer profile for Prusa Slicer was about 10 deg. too low for the new CHT nozzle coming with MK4S,
which resulted in partial clogging and random problems I wouldn't have associated with extrusion in the first place.
After a cold pull and increasing nozzle temperature, my problems dissapperared.
Keep in mind, that all profiles in Prusa Slicer except Prusament probably haven't been upgraded by manufacturers for MK4S, yet.
Alternatively, it might be idler tension, indeed.
Here is a good guide on how to dial it in: https://www.cnckitchen.com/blog/how-to-set-extruder-tension
RE: MK4S - Circular Prints Failing
After 2.5hrs on a live chat to PRUSA going in circles, I decided to disassemble the entire print head and start from fresh. It looks like the issues have sort of fixed themselves but myself and the PRUSA support still can’t identify where this “clunk” noise comes from (see video).
Video: Filament Clunk Noise
It’s during the filament unloading and highlights an underlying issue perhaps with the Extruder Motor?
Please note I have used default PRUSAMENT settings, a brand new PRUSAMENT filament reel opened just yesterday, and had my g-code checked by the support team.
Honestly baffled! Thanks for everyone’s support and advice so far! 😁
RE: MK4S - Circular Prints Failing
UPDATE: Just printed a nozzle replacement tool using g-code directly from printables and it printed perfectly. Despite the clicking, I wonder if there is something wrong with my slicer? I have deleted and re-installed on Windows 11 but I have used the configuration wizard to delete and reset (hopefully) my settings. Let's see how this goes.
RE: MK4S - Circular Prints Failing
I'm glad someone else pointed this issue of the clunking extruder when unloading filament. Mine is doing it as well after I installed the MK4S kit. It doesn't sound healthy at all. If you ever resolve this, I am keen to know what's going on.
I have checked the teeth of the extruder for slipping/stuck filament and double-checked the idler installation, beyond that I don't know what to look for. It's done this ever since the upgrade.
RE: MK4S - Circular Prints Failing
Kinda sounds like the extruder skipping steps. Must be jamming somewhere. I suspect maybe some alignment issue in the Nextruder.
Do you have the alignment tools? Did you run the alignment calibration with the screws loose m
RE: MK4S - Circular Prints Failing
@brian-12, yes, I ran the alignment calibration with the screws loose when I installed the kit. (I bought my printer as a kit so I have the alignment tools) Maybe I should do that part again, if this isn't normal behavior. Would you suggest that?
RE: MK4S - Circular Prints Failing
@brian-12, yes, I ran the alignment calibration with the screws loose when I installed the kit. (I bought my printer as a kit so I have the alignment tools) Maybe I should do that part again, if this isn't normal behavior. Would you suggest that?
Couldn't hurt.
RE:
I too have heard the clunk happen while unloading. It did it consistently directly after the upgrade, and after I re-greased and recalibrated the planetary gears again it's happened less. No other failures, and things are printing well otherwise. I've printed some PETG, PLA, and mostly TPU, although not in high quantities. My printer only runs occasionally, so it hasn't been a bother.
I suspect this is unrelated but I did notice that the extruder gear isn't perfectly aligned with the filament path, and I couldn't see a way of improving it when I had it open. All the parts go in as expected and there isn't room for shifting anything.
-J