Missing extrusions and clunking noise: can't figure out cause
 
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Missing extrusions and clunking noise: can't figure out cause  

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davidr91
(@davidr91)
Active Member
Missing extrusions and clunking noise: can't figure out cause

This has been driving me nuts 

  • Ruled out the material (happens for Hatchbox PLA with different temps and the included Pusament PLA). Including drying.
  • Ruled out the nozzle (it started with 0.6 Obxidian but it also occurs with stock 0.4)
  • I've inspected the gears, cleaned the nozzle, used cleaning filament too. (It's not clogged or even partially clogged)

And I just cannot get away from this 'clunk' noise coinciding with missed extrusions. Videos:

Prusament PLA with 0.6 Obxidian nozzle

Prusament PLA with 0.4 stock nozzle

Different models both sliced with Prusa Slicer 2.9.2 

All of this is with the SPEED profile - sometimes it seems like it only happens with high-speed moves, but as with the first video, it's actually doing it on almost every line after the first layer.

Any suggestions on how to proceed - is the speed profile just generally busted or is there a physical hardware issue I have not checked?

 

 

Posted : 04/05/2025 3:55 pm
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

I've created a model that consistently reproduces this for my printer: https://www.printables.com/model/1285853-fast-continuous-extrusion-test

Sliced with the speed profile this clunks out and creates a result that is missing half of its material.

With the 0.25mm structural profile the result is perfect.

So is the speed profile intended to be unusable for scenarios like this, or is my printer defective and it should be working at these speeds/flow rates.

Posted : 04/05/2025 8:30 pm
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

Looks increasingly likely I'm headed toward returning my printer. 

Support helped me do a cold pull and re-calibrate the gearbox (and also detach the gearbox without opening it to check for debris etc.) and the behaviour is still the same. On several occasions the implication was that this is just an issue with the speed profile and not a hardware issue, but I've also now had this on the structural 0.4m profile too.

This is a great shame because I actually really like this printer, but randomly losing extrusions on functional prototypes makes it unusable for me

Posted : 05/05/2025 8:26 pm
Biomech
(@biomech)
Estimable Member
RE: Missing extrusions and clunking noise: can't figure out cause

Try to print Benchy models included on the USB. They are sliced with speed up to 300mm/s. If they print ok, then it's probably issue with slicer setup. Are you using high flow nozzle printer profile and print profiles? The stock 0.4mm CHT brass nozzle is high flow.

Posted : 06/05/2025 9:17 am
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

Yeah everything is configured and sliced high flow.

All the slicer config is completely stock and unmodified using the built in profiles. The most I’ve ever really changed is enabling supports. 

The trouble with the included models is that they’re so small - and even when they’re larger like the alpaca, they don’t tend to have long lines or outlines. That seems to be what reliably triggers my problem.

Which is a big issue for me, because all the parts I prototype are eg panels and grills with large outlines 

Posted by: @biomech

Try to print Benchy models included on the USB. They are sliced with speed up to 300mm/s. If they print ok, then it's probably issue with slicer setup. Are you using high flow nozzle printer profile and print profiles? The stock 0.4mm CHT brass nozzle is high flow.

 

Posted : 06/05/2025 9:42 am
Diem
 Diem
(@diem)
Illustrious Member

I've rarely seen such a filthy print sheet.  Give it a good scrub with dishwashing detergent (dawn/fairy) and very HOT water.

Cheerio,

Posted : 06/05/2025 6:08 pm
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

The first video was immediately after being IPAed and it was pristine. I haven’t paid much attention to cleaning it since then because bed adhesion doesn’t seem to be a factor in this (eg if put the Z offset up and print into thin air, it still fails to extrude and makes the same noise after a certain point)

Posted by: @diem

I've rarely seen such a filthy print sheet.  Give it a good scrub with dishwashing detergent (dawn/fairy) and very HOT water.

Cheerio,

 

Posted : 06/05/2025 6:19 pm
Diem
 Diem
(@diem)
Illustrious Member

The first video was immediately after being IPAed and it was pristine.

There is clear fingerprint first layer breakdown of the first layer, bottom left at 0.05s

There must be IPA insoluble residues to shift.

I haven’t paid much attention to cleaning it

You must make a religion out of cleaning your print sheet.  Do that and come back if problems persist.

Cheerio,

 

Posted : 06/05/2025 7:11 pm
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

OK, so some positive progress on this: after systematically checking every possible component on the printer to rule out hardware problems, I realised a pretty simple issue:

Speed and the other profiles get faster after the first layer. The default filament settings either leave the temperature the same after the first layer, or they even decrease (e.g. for Hatchbox)

When I significantly boost the temperature after the first layer instead, the extruder can keep up, and my test model prints fine on 'speed' without any clunking. And the result is reasonable too.

I'm waiting to hear back from support on whether there is any possibility of this being unusual (e.g. is my thermistor actually offset) - but assuming it's fine: This makes sense, but it is a little frustrating that Prusa Slicer does not automatically account for this- especially when using Prusament. But I am pleased my printer seems to be working properly.

TLDR: Get hotter when the print transitions to going fast 

Posted : 07/05/2025 7:47 pm
2 people liked
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

I've un-marked the above answer as the solution because I've still experienced missing extrusions even with high temperatures.

I've also now replaced the extruder motor with assist from support, to no avail.

Today while testing a print I also experienced an unexplained sudden homing to the front left corner (video) in the middle of the print, which then shifted everything afterwards so it printed in mid-air.

So I've actually asked for a replacement now, I think this unit just has issues

Posted : 17/05/2025 7:55 pm
Diem
 Diem
(@diem)
Illustrious Member

There's no sound on that video so I can't tell whether there was a head-crash - did you clan the print sheet properly? and how are you drying your filaments?  What does the printer log say?

Cheerio,

Posted : 18/05/2025 5:23 am
Ratlet
(@ratlet)
Trusted Member
RE: Missing extrusions and clunking noise: can't figure out cause

I wonder if jump over to the corner is related to the lateral shifts described here:

https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4637

Di you have 'avoid crossing perimeters' checked on that one?

Possibly an issue with the board/driver rather than the stepper motor so Hopefully you will get the unit replaced, you don't really want to end up with a Core One of Theseus wher you have almost an entirely new printer from replacing various components to try and rectify.  Best of luck!

 

Posted : 18/05/2025 7:24 am
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

Plate was pristine and the first layer was perfect. Filament in a dedicated dryer.

It did make a strange noise - my best guess is that the missing extrusions created bits of plastic that stuck upward and it got caught and the head couldn’t move (maybe caught on the fan shroud). And then it overcorrected?

No errors, no log events, nothing on the UI at all, as far as it was concerned the print continued normally 

Posted by: @diem

There's no sound on that video so I can't tell whether there was a head-crash - did you clan the print sheet properly? and how are you drying your filaments?  What does the printer log say?

Cheerio,

 

Posted : 18/05/2025 9:49 am
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

Yeah seen the crossing perimeter stuff - isn’t enabled for these prints, all stock settings except for supports.

And you’re exactly right, want to avoid swapping and fixing every component, this is the end of the line for this specific unit IMO

Posted by: @ratlet

I wonder if jump over to the corner is related to the lateral shifts described here:

https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4637

Di you have 'avoid crossing perimeters' checked on that one?

Possibly an issue with the board/driver rather than the stepper motor so Hopefully you will get the unit replaced, you don't really want to end up with a Core One of Theseus wher you have almost an entirely new printer from replacing various components to try and rectify.  Best of luck!

 

 

Posted : 18/05/2025 9:51 am
Diem
 Diem
(@diem)
Illustrious Member

Plate was pristine and the first layer was perfect. Filament in a dedicated dryer.

Excellent.

It did make a strange noise - my best guess is that the missing extrusions created bits of plastic that stuck upward and it got caught and the head couldn’t move (maybe caught on the fan shroud). And then it overcorrected?

There are a couple of other possibilities - now it's worth looking at the geometry you're printing:

Please 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,

Posted : 18/05/2025 1:03 pm
davidr91
(@davidr91)
Active Member
Topic starter answered:
RE: Missing extrusions and clunking noise: can't figure out cause

Well, it looks like my printer is returning to its home planet. Awaiting packaging info for putting it back into its box.

Interestingly, when I initiated a return I had to opt for a return+refund - a replacement was not an option. I guess that's because of lead times and they're pushed for available stock? Thought it was a bit strange though. 

Overall very frustrating experience. I really like this printer but this issue has driven me nuts and I can't trust it to actually print anything.

Posted : 24/05/2025 4:05 pm
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