My MK3S+ Extruder motor keeps skipping backward and clicking  

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Posted by: @cwbullet

@obsessed

When you say failed - stopped extruding or broke award from the plate?  

Both. It depends on the print. Generally the first.  It stops extruding (starts clicking).  Sometimes it starts again, but by then it has skipped a layer or two and it fails due to that.  Some suggest says stop lifting (turn off lift z) and then it just bulldozes pieces off the plate, but that is less frequent.  I turned lift Z back on, so most everything is back to default now, as I'm going "back to the basics."

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

Have you done a cold pull to fix your extrusion issues and do you have cleaning filament?  

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

Email is a total waste of time. You need to chat with them; and yes, it means sitting in a queue for 15 minutes. It also means rehashing some of what was mentioned here. 

Your other option is to buy a spare extruder motor from Prusa and see if that is the issue. The problem is it might also be the Einsy failing. Without an oscilloscope looking at the signals when the clacking happens, it is all guesswork. And, not being in front of the printer, it might be as simple as the idler door screw being too tight or the Bondtech gears not meshing well because one of the sets screws isn't properly placed on the motor shaft flat.

Just so many possible things that can cause what you are seeing - it's almost impossible to run through them all remotely.

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

Actually - your last reply to Chuck made me think --- are you seeing filament being chewed up? Dust and flakes in the Bondtech cavity? Eaten away spots on filament unloads?

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Look at the image in Tim's last post.  If it looks like that, your idler might be too tight.  

I concur with Tim also.  Wasting your time with email.  eShop chat is the only what to efficiently converse with support.  

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Posted by: @obsessed

Posted by: @cwbullet

@obsessed

When you say failed - stopped extruding or broke award from the plate?  

Both. It depends on the print. Generally the first.  It stops extruding (starts clicking).  Sometimes it starts again, but by then it has skipped a layer or two and it fails due to that.  Some suggest says stop lifting (turn off lift z) and then it just bulldozes pieces off the plate, but that is less frequent.  I turned lift Z back on, so most everything is back to default now, as I'm going "back to the basics."

This is the part that confuses me.  Unload the filament after a period of several bouts of clicking and look for a chewed-up place.  

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Okay, another update.

I can 100% confirm, beyond a shadow of a doubt, that the bondtech gears are not the issue. They are meshed/aligned perfectly, grub screws on the flat spots of the armatures, and I have tried the full gamut of tension (from barely screwed in to torqued down quite a bit) and it still behaves identically. I'm not seeing any chewed up filament or anything of that sort.

I also installed a new hotend fan (an 8CFM version, it moves a LOT more air by feel alone), as well as an extruder motor fan.

It still does it. Same exact behavior, same exact outcome.

Prusa emailed back, said I'm printing too cold (said for PLA I should be at 220-225 at least, and suggest that I lower my room temperature to 50 degrees.  Whether that is C or F he didn't clarify, but if it's C it's obviously too high, and if its F it's impossibly low.

I'll try the chat option but I don't get anything pop up for me, so I'll poke around more trying to find it.

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Posted by: @cwbullet

Posted by: @obsessed

Posted by: @cwbullet

@obsessed

When you say failed - stopped extruding or broke award from the plate?  

Both. It depends on the print. Generally the first.  It stops extruding (starts clicking).  Sometimes it starts again, but by then it has skipped a layer or two and it fails due to that.  Some suggest says stop lifting (turn off lift z) and then it just bulldozes pieces off the plate, but that is less frequent.  I turned lift Z back on, so most everything is back to default now, as I'm going "back to the basics."

This is the part that confuses me.  Unload the filament after a period of several bouts of clicking and look for a chewed-up place.  

Here is a picture of the cold pull immediately after the failed print:

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

That looks normal to me:

https://help.prusa3d.com/en/article/cold-pull_2075

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Chatted with Prusa. They want me to run a print without filament to see if it behaves the same to rule out extruder motor or Einsy board issues.

Starting a print now.

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Well the "print" finished just fine without issues. I guess it's heat creep.  Not really sure what to make of it.

Just to test the theory, I have a 60x20mm fan laying around. I drew up an adapter for the heat break fan and printed it.  I'll play around with this a bit to see if it solves the issue having massive amounts of air moved past the heatsink.  I can't imagine that is the issue but I literally am out of ideas. Nothing else I get some CAD practice.

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Well the "print" finished just fine without issues. I guess it's heat creep.  Not really sure what to make of it.

Just to test the theory, I have a 60x20mm fan laying around. I drew up an adapter for the heat break fan and printed it.  I'll play around with this a bit to see if it solves the issue having massive amounts of air moved past the heatsink.  I can't imagine that is the issue but I literally am out of ideas. Nothing else I get some CAD practice.

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

I am glad it was successful.  Heat creep is pretty frustrating.  I had in on one mini.  I did a disassemble and reassemble and it went away.  

Fingers crossed that it is gone.  Keep us updated.  

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Stupid question, but on all default Prusa filament settings, is the "Flow" supposed to be set to 95? I have the extrusion multiplier set to 1.0 (as it is all default) yet the flow is set to 95.  I understood these to be the same setting...are they not?

So far I have printed 3 PETG parts with my giant fan on the heat break and it hasn't given me issues yet. I'll try Silk PLA later today.

Pic of the current setup (don't mind the multiple extruder motor cowls, That's obviously not there now.) 😀 

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

I have finished my modifications; I'm running a print now that has failed 3x in the past and have never successfully printed it.

Here is what the printer looks like now.  I have a heat break fan manifold that adapts it to a 60mm fan.  This particular model is an extremely high flow, so I have it turned about 2/3 up for this just to test the theory of heat creep.  I also have a small intake cowl if you will that helps not pull the hot air right on top of the bed.  If needed, I have a longer version that actually reaches all the way out front of the build plate if it comes to that.  I also modified the filament sensor cover to allow for cable tying the motor wires from both the heat break fan as well as the extruder motor fan.

Probably a bit overkill, but again, want to test the theory. Maybe if this works I can actually finish the enclosure I'm building for it (as an aside, yes I know the enclosure is only useful for some prints and is mostly a bad idea for others; I'll be leaving it open the majority of the time depending on filament I'm using).

Thanks again to everyone for their suggestions!

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

Tool Time Tim Taylor type of approach - More Fan!  I am interested to see how the pans out.  It should cool more, but the limit is going to be how much air will go through the limited air space around the hotend.  

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Good morning,

I have the same issue on my 3 weeks old prusa mk3s+. At the beginning, the printer works perfectly. But during the last prints, I heard the random clicking noises from the extruder. Sometimes directly at the first initialization line at the bottom/left of the heat bed. Sometimes I only have a single click, which causes an underextrusion (see the picture), sometimes its clicking like hell and the print fails. 

I have never printed something else like PLA (geeetech, prusa which comes with the printer, redline and prusament). It doesnt matter which filament I use, Ill have the clicking extruder. Yesterday, I followed the guide and did a cold pull at 85°C  (see picture). There is nothing unexpected. The bondtech gear is perfectly aligned. I have no idea what else I could do to stop the extruder from clicking.

An other question. When I was following the guide, there was one step:

5. Once it has reached 270 °C, insert PLA filament manually into the extruder and push it in until it starts pouring out of the nozzle.

If I feed the extruder manually, how much pushing force is required until the filament starts to pouring out of the noozle? Should it go very easy, or just with a little pressure? Or do I have to push it in a bit more? I felt I had to press a little harder to get the filament out of the noozle. therefore I would not be surprised if the extruder motor skips stages.

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

Posted by: @cwbullet

@obsessed

Tool Time Tim Taylor type of approach - More Fan!  I am interested to see how the pans out.  It should cool more, but the limit is going to be how much air will go through the limited air space around the hotend.  

Well, to close this out, it fixed my issue, 100%.

I have printed some of the more troublesome prints I've done, without issue. Zero clicking, zero under-extrusion.

I have printed PLA, Silk PLA, and PETG successfully for a few days straight now. I don't have anything I need to print currently with TPU but I'm confident the issue is fixed, as Silk PLA was the one giving me most issues (although the others did it too).  I have printed 2 11 hour prints, and about a half dozen 2-3 hour prints, all of which I have had fail previously.

I think I'm good to go! Now I'm working on wiring the fan more permanently. I'll run a transistor off the 5v hotend fan to trigger the larger 12v so it is auto on/off like the stock fan.

In terms of amount of cooling, I've had zero issues running it at 6v for short prints and 8v for the two longer prints (just to play it safe).  The fan is a 12v fan so I'm only at 2/3 "throttle" if you will and having plenty of cooling.  It's enough that you can feel the airflow on your hand from 8-10" away from the "exhaust" side of the hoat sink. The benefit of 20mm thick fans is much better performance on static-loaded airflow. 

Thanks again to everyone who stuck with me through all this! I truly appreciate it!

RE: My MK3S+ Extruder motor keeps skipping backward and clicking

@obsessed

This is not poking at you.  But I wonder what is different for what you are printing or your printer that requires a bigger fan.  

I am glad it is working.  I could feel your frustration.