"Nozzle Cleaning Failed." Error  

RE: "Nozzle Cleaning Failed." Error

I use a brass wire bush.  Got some from Amazon.  YMMV.  Running 6.0.0 on my MK4.  Don't have this problem (have others, though).

RE: "Nozzle Cleaning Failed." Error

Nozzle is clean, and I don't see the cleaning as the root cause for this error.

Looking at the sensor info screen and there at the values of the load cell value, the numbers are constantly fluctuation. Right now they are around +1000 even without any load. 

Then, doing a new loadcell calibration and the values are in the -50 range. Intressing that the "tab" needed to be firm in order to pass the test. Clearly there is something going on on the hardware side and som possible interference with the printed nextruder parts. Otherwise I would expect values staying in a specific range in order to be accurately interpreted by the sw. 

RE: "Nozzle Cleaning Failed." Error

On latest firmware, levelling works as expected. Likely you have a faulty loadcell, or the connection to the loadcell is loose.

RE: "Nozzle Cleaning Failed." Error

I just had the same error with my 3 weeks old MK4, with PLA. 

retry didn't help.

After purging some material out and retry it worked well.

RE: "Nozzle Cleaning Failed." Error

Hello everyone,

I have now converted my MK3s+ MMU3 to 3.9 and have had problems with the nozzle since the first print, nozzle cleaning failed.

I can't find a solution, I've tried everything imaginable that has been written everywhere.

Should I turn on support?

Thank you.

RE: "Nozzle Cleaning Failed." Error

Based on what happens, Prusa is sensing some kind of elasticity during the taping of the nozzle. If you bed is not strong enough and defects slightly, the mechanism is failing. Make sure, your bed bearing and all related parts are ok and not moving. There is a reason, whi the testing points are on the side with the two bearings.

RE: "Nozzle Cleaning Failed." Error

It helped me:

Start loadcell calibration

Push with a certain constant force on the nozzle even before the beep (try which one)

Press harder when it beeps.

According to me, in the first phase it detects the signal from the strain gauge when the nozzle is free and then takes this value as a reference for the actual contact of the nozzle. And since the value from the unloaded strain gauge fluctuates strongly, it will evaluate some spikes as touch. My procedure achieves that the noise with a free nozzle will be completely below the limit level.

For me, very often the nozzle did not even go down and was clowning around at different heights, as if it were directly above the plate. Everything is ok now.

RE: "Nozzle Cleaning Failed." Error

Hi, yes yes it work like this. Thank You.

Posted by: @ivo-z

It helped me:

Start loadcell calibration

Push with a certain constant force on the nozzle even before the beep (try which one)

Press harder when it beeps.

According to me, in the first phase it detects the signal from the strain gauge when the nozzle is free and then takes this value as a reference for the actual contact of the nozzle. And since the value from the unloaded strain gauge fluctuates strongly, it will evaluate some spikes as touch. My procedure achieves that the noise with a free nozzle will be completely below the limit level.

For me, very often the nozzle did not even go down and was clowning around at different heights, as if it were directly above the plate. Everything is ok now.

RE: "Nozzle Cleaning Failed." Error

For those that, like me, have issues only with PC, here how I did solve the issue.

Again in my case PLA and PETG work flawlessly, PC Blend oozes a continuous stream of material making the cleaning impossible.

Go to the "printer" section, select "custom G-Codes", search in the first window for the two lines below. You see that I did change for the PC filament type the temp decrease number from -25 to -50 and this fixes my problem.

M104 T0 S{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 50) : (filament_type[0] == "FLEX") ? 210 : (filament_type[0]=~/.*PET.*/) ? 175 : 170)} ; set extruder temp for bed leveling
M109 T0 R{((filament_notes[0]=~/.*HT_MBL10.*/) ? (first_layer_temperature[0] - 10) : (filament_type[0] == "PC" or filament_type[0] == "PA") ? (first_layer_temperature[0] - 50) : (filament_type[0] == "FLEX") ? 210 : (filament_type[0]=~/.*PET.*/) ? 175 : 170)} ; wait for temp

This is also the same section where you would change the purge line position to avoid creating a track on the plate (see my entry in GitHub for PrusaSlicer-settings)

RE: "Nozzle Cleaning Failed." Error

I have had this issue with one printer.  It is intermittent for me.  

RE: "Nozzle Cleaning Failed." Error

I rarely get the error. I had it only a couple of times with the old 5.x.x FW.

I realized that the issue is created by small dots of material still on the nozzle. They should be 100% removed. I am always maniacal during the startup.

• I check that the nozzle is clean. If not, I set the temperature and with a brush and a clothe clean it until there is nothing.
• On the startup, I wait the 170° and look at the nozzle. If I see any leak, I remove with a flat tweezer.
• When it is about to starts the purge line, and the material starts leaking, I move the leaking material just on left out of the bed with a tweezer, so that when it starts and lows the nozzle it helps to stabilize the purge line.

When I experienced the issue, I had forgotten to clean some leakage from the previous print, and so when it started to probe the bed, the very small amount of plastic attached to the nozzle caused the error. I don't believe the Nozzle cleaning phase really works. I easily cleaned the nozzle since it was still hot, and restarted the process. But with my surprise, there was no way to complete the probe without the error even if the nozzle was cleaned.  I realized that was the FW that messed itself and the load cell values.

I pushed the RESET button,and the printer restarted. I waited it cooling down, and then just restarted the print and it worked.

So, when you have that I suggest:

• Clean deeply the nozzle.
• Leave it cool.
• RESET the printer
• Restart the print.

Regards

RE: "Nozzle Cleaning Failed." Error

Allow me to try bringing some structure to this discussion, as I have the strong feeling we are mixing really different problems/experiences here:

- clearly state when the problem manifests, e.g., always or only with specific filaments
  if always, a procedure like the one described by @Antimix in the previous post or recalibrating the load cell makes sense, if only with specific filaments a temperature adjust in the custom g-codes seems to help more

- hw platform, e.g., mk4, mk3.9, mmu as the machines are really different

regards

RE:

I forgot to mention that is absolutely critical on MK4 that at the start of every print, there should always be some slack for the filament between the extruder and the Filament guide of the spool. Otherwise, the filament tension slightly pulls the extruder up, which will affect the Nextruder Load-cell readings during the mesh bed levelling.

I always  pull the filament from the spool and create a loop of filament just above the Nextruder to avoid that a negative pressure tension is applied to the Nextruder.

I have done this since day zero of the MK4 so automatically, that I even forgot to mention. 😀 

RE: "Nozzle Cleaning Failed." Error

I am being hit by this occasionally in general, but especially when printing TPU or TPE.

I really think forced workflows and UI that overrides the user's judgement is absolute trash. It reminds of the messed up sensor Boeing used on the 737 Max, leading to the crashes. It's less dramatic with 3D print failures, but the same principle applies. I have noticed it now with nozzle cleaning, but there's the same logic with the filament runout sensor. The UI forces you into a workflow that assumes the sensor is 100% working correctly and doesn't allow you to use your judgment. They force you to open it up and inspect the sensor mid-print, even if you would rather steamroll ahead and revise it later, for example.

The hardware, I love, but these fw & sw decisions truly suck. 

RE: "Nozzle Cleaning Failed." Error

I have not had this issue.  How is your filament traveling, and is it in a PTFE tube?

Posted by: @antimix

I forgot to mention that is absolutely critical on MK4 that at the start of every print, there should always be some slack for the filament between the extruder and the Filament guide of the spool. Otherwise, the filament tension slightly pulls the extruder up, which will affect the Nextruder Load-cell readings during the mesh bed levelling.

I always  pull the filament from the spool and create a loop of filament just above the Nextruder to avoid that a negative pressure tension is applied to the Nextruder.

I have done this since day zero of the MK4 so automatically, that I even forgot to mention. 😀 

RE: "Nozzle Cleaning Failed." Error

(@cwbullet) Yes, the filament spool is in a DryBox and exit through a PTFE tube, and then it exits just above the printer on a custom bracket that holds the tube.

Then the filament reaches the Nextruder freely (no tube).

I did not had issues with the old filament box model where it was rotating in the axial centre of the spool, since it had almost zero friction; but then I replaced all the boxes, since the spool itself was able to autorotate and unwind the filament inside, due to the elasticity of the filament itself, messing all the spool. I hate the messed spool; I like the spools factory winded like the Prusament filament, very precise. So to avoid messing the filament in the box, I changed the dry boxes with a new model that I designed that has the roll resting on the lower tubes, like the original Prusa MMU3 spool holders.

Now this model requires strong force to roll the spool (like the MMU PRUSA spool holders) and so prevents the spool auto-rotation and auto unwinding. Unfortunately the force to roll axially a 1Kg weight is well far from few grams, and I suspect it is between 500g and 1Kg itself. As result the filament between the spool and the Nextruder is constantly tensioned.

RE: "Nozzle Cleaning Failed." Error

Hello,

Apologies for hijacking the ongoing discussions but I very often have the same "nozzle cleaning failed" error when starting a print and I thought I'd write here rather than opening a new topic.

I only print PLA (prusament rPLA) ; everytime the nozzle cleanup process is performed,small plastic dots are left on the bottom left part of the build plate, where the nozzle is touching the build plate to "clean". My feeling is that the more diligent I am in cleaning that area up , the less likely I will have a nozzle cleanup failure. 100% if I do not clean that bottom left area after a successful print, the next one will fail with the "nozzle cleanup failure".

Does this line up with other people's experience? Do you also always clean that area up between prints? I find pretty difficult to clean (I've never managed to get it back to "as new" state in that area) and it completely removes the option of popping a print off the plate and starting a new print (not a huge deal, just an observation).

As an aside, I've ran through the steps described here: https://help.prusa3d.com/article/nozzle-cleaning-failed-mk4-mk3-9_689429 so hopefully that is handled.

Thank you

RE: "Nozzle Cleaning Failed." Error

Yes I have a feeling it is related to those "dots" as well, although I always rub them off with a spatula. 

It feels like Prusa decided to be fastidious on this point because of the risk of bed levelling errors if there's loose filament. That makes sense.

It's the lack of menu options to allow the user to exercise their own judgement, even making it impossible to disable nozzle cleaning with a line of gcode, which irks me.

RE: "Nozzle Cleaning Failed." Error

The bed should be pristine. I am maniacal on my MK4 about this. 😉 

The point here is that the only factor between the nozzle soft touching the bed during probe, and the nozzle destroying the bed with too much motor pressure, is the extreme sensitivity of the pressure sensor, that should not be fooled by uneven surface and material dots. Only in this way it can output a very precise surface layout that is the base of the perfect first layer.

That is the basic concept of Nextruder. It has pros and cons. On my MK3.5 it has still the old SuperPinda and it does not care of those details, but when I change the metal sheet or i replace a Revo nozzle, I need to re-check the first layer.

RE:

Thank you for the replies @Daniel and @Antimix.

I'll make sure to get that area as clean as possible (the rest of the surface is as well) and I'll report in a while with the progress.

I also had the problem that once during probing points around the surface at pre-print, the nozzle was pushed so hard into the bed that the whole assembly bent (just for the duration of the press, I hope) and ruined that side of the sheet so ... I have become a bit superstitious since then (I complain but despite these things, the prints come out good every time when the print actually eventually starts and that is ultimately the most important part).