More clicking, no extrusion  

RE: More clicking, no extrusion

I can't diagnose that from the description. It would help if someone with experience could take a look at your printer.

Check PrusaWorld if you can find someone near you who offers tech support.

RE: More clicking, no extrusion

I appreciate your response, lichtjaeger.  But I don't see that helping... I know this thing is assembled correctly.  This is a known issue, and I'm not looking for diagnosis... We know the problem.  I'm looking for someone to share how they have beaten this issue. So far, the only answer I've seen is to change to a standard E3 V6 heatbreak. I want to know if I can stick with the prusa heatbreak and have this work. What does this machine require to reliably print PLA at resolutions of .1mm or less, and for print times greater than 2 hours?

RE: More clicking, no extrusion

Posted by: @chris-d39

[...] I bought my i3 mk3s pre-built, but, I've rebuilt the extruder assembly at least 1/2 a dozen times now (trying to solve this issue). I'm sure everything is assembled correctly.  I've replaced the PTFE tube 3 times, I've replaced the stepper motor (because it was getting extremely hot, but the new one still gets every bit as hot), I've replaced the heatbreak, I've gone through 3 brand new nozzles, and tried numerous filaments.  The worst performing filament by far is Prusa PLA. Including the very expensive premium filament.  But, I have used PLA from at least 4 different brands, and the problem is almost as bad.

It sounds like you've tried the most common fixes, but specific things to confirm you've done:

• Verified the filament path. When starting cold (before any heat can build up), if you open the extruder tension screw, can you push filament through the nozzle manually when it hits print temps? If so, the path is likely good.
• Verify the extruder idler gear can rotate freely.
• Have you tried applying thermal paste between the heatbreak and heat sink. Don't apply between heat break and heater block. I really wish the names weren't all so similar.
• It might be worth trying the non-Prusa E3D heatbreak just to confirm this fixes it.
• If you're using an enclosure, open it up for PLA. The E3D V6 hotend is rated for 40C ambient temps. Any warmer and the efficiency of the air cooled design is reduced which can lead to heat creep. Direct a fan at the heatsink area as a test.
• I've increased retraction speeds to 50mm/s but decreased deretraction speed to 25mm/s. I suspect soft PLA has a non-Newtonian fluid characteristic, and hammering it down when soft may cause back-pressure.
• Nozzle swap can't hurt. Actually, trying a larger nozzle would be interesting as that would reduce back-pressure.

These problems usually come down to "heat", whether up top where the extruder motor heats up or down near the transition zone where the 2.2-2.0mm heatbreak choke occurs. In either case, PLA can soften prematurely and jam. One easy test would be to try PETG. Since PETG melts at higher temps, it's less prone to this problem. If PETG works, you know it's a heat problem.

I know it's frustrating. Keep in mind folks here are volunteers sharing their own experiences. There may be some repetition, but we're trying to help you through it. Good luck with it!

RE: More clicking, no extrusion

@bobstro,

Thank you for the reply.  You offer many suggestions, most of which I have done, but  lease me address them one at a time for the sake of clarity...

Verified the filament path. When starting cold (before any heat can build up), if you open the extruder tension screw, can you push filament through the nozzle manually when it hits print temps? If so, the path is likely good.

Yes, I've done this.  This is part of a standard cold-pull.  The filament slides through without undue resistance.

Verify the extruder idler gear can rotate freely.

Yessir, I can confirm that they both rotate without undue resistance.  I can also assert that I'm positive that I have a clear path on the  knurl of the bondtech gears so that the filament goes through that channel precisely in the center and in perfect alignment with the PTFE tube.

Have you tried applying thermal paste between the heatbreak and heat sink. Don't apply between heat break and heater block. I really wish the names weren't all so similar.

Yes, I have done this. It is a standard step in replacing the heatbeak, which I have done.

It might be worth trying the non-Prusa E3D heatbreak just to confirm this fixes it.

Yes, I'm thinking so, but I'm not sure what to hope for here.  If it works, then it means I've thrown away $300 on the MMU.  Just because I prove that the problem lies within the prusa heatbreak (which seems to have already been proven by others), doesn't mean a solution is immanent.  I haven't seen anyone offer a silver bullet on the many other threads that struggle with this same issue. Most have no intentions of,  or have given up hope on, using the mmu.

If you're using an enclosure, open it up for PLA. The E3D V6 hotend is rated for 40C ambient temps. Any warmer and the efficiency of the air cooled design is reduced which can lead to heat creep. Direct a fan at the heatsink area as a test.

I'm not using an enclosure, and the ambient temperature is only 67 degrees Fahrenheit.

I've increased retraction speeds to 50mm/s but decreased deretraction speed to 25mm/s. I suspect soft PLA has a non-Newtonian fluid characteristic, and hammering it down when soft may cause back-pressure.

This is interesting to me... are you saying that you have beaten this issue by using the settings you mention here? It is good and novel suggestion... I will look into this.  Thank you.

Nozzle swap can't hurt. Actually, trying a larger nozzle would be interesting as that would reduce back-pressure.

I'm on nozzle #3 (which happens to be an olsson ruby).  It hasn't helped anything.  I suspect that moving to a nozzle with a larger aperture would help... but a larger bead is of little use to me.  The vast majority of my prints require detail to remain within tight specifications.

I agree, I think that heat is a large part of the issue, and i know that there is a heat shroud someone created (on thingiverse) to put on the extruder's stepper motor (which, as stated, gets quite hot). I don't know if it will help, but I will try that too.  It just seems to crazy to me that I should have to resort to such a hack... but if it works...

Thanks again for your suggestions bobstro. I appreciate the time you took to enumerate them.

-Chris

RE: More clicking, no extrusion

I followed this thread very closely and the one thing that wasn't discussed is hot end temperature.  I've experienced this with filament of different colors from the same manufacturer.  The silver prints just fine on the default settings and the reds and yellows need a higher...much higher temperature hot end.  It is the boring and the engineering of the heat break that causes this. 

This video can better explain  the causes and a solution that is working for me:

RE: More clicking, no extrusion

I could stop the clicking doing these three actions:

1- thermal paste on the heat sink thread.

2- more pressure on the tension screw (the references for the position on the MK3, MK3+MMU2, and MK3S are differents).

3- changing the retraction parameters to:

Length: 0.4 mm

Lift: 0.2 mm

Retraction Speed: 20 mm/s

Minimum Travel After Retraction: 10 mm. After I tried to reduce and now is all right with 2.

There are now more than 10 days without problems with 10h of prints every day.
In the next days, I will try to return to the standard values.

RE: More clicking, no extrusion

You also could add a second fan on the extruder, this cools the extruder, the fan should blow to the top, now heat creep should be less a problem, except maybe in a hot summer. This helps a lot to cool it down. If I was you I would try this. See on thingy verse for a model, attache the cable on the outside of the cableholder, so you do not need to disassemble all the cables, i used a prusa 5 volt fan, this one is very light, and you need a 5 volt DC.

I have a mk3, no S, i did the extra fan on a separate power suply, and i did a heatbrake exchange to E3D, i have a enclosure, and a extra fan to blow in de top of the enclosure for in a hot summer, doors are open wen printing PLA,PETG, with ABS they are closed, except wenn it reaches 40 C in the summer.

RE: More clicking, no extrusion

@gutenbar

Your settings worked for me!!!!

My problem with clicking and jams arose when I started to print higher quality prints earlier this year. I moved from the default 'quality' setting up to the highest setting and thats when i experienced jams. I wonder if this issue is actually related to quality settings and these triggering the fault in the heatbridge part with its 2.2mm to 2mm transition???

RE: More clicking, no extrusion

@jeremy-d9

Today, I believe that is more related to temperature control above the heat block. This combined with low-quality filaments and printing at high speed for long times.

If the heat break and the heat sink can not cooling down the filament, it will turn in a kind of rubbery and slowly remains will stick on the inner walls. After a while, this will prevent the rest of the filament from passing through.

Once I dismounted and, even at 280 °C, I needed a lot of strength to remove the mass formed in the heat break. So, I changed the brand and the problem was very reduced. It does not stop completely because I still needed the high-speed, so I still needed the reduced retraction.

RE: More clicking, no extrusion

You said that it happens at the same time, 2 hours into prints, but are you always trying to do the same print? If you have a lot of little details that cause a lot of retractions one after another (from a bunch of individual thin columns or something), that could cause the problem. I've been successful turning the knob on the printer to slow the print down to 75% or so through the parts with all of the retractions, so that the heatbreak has time to cool down a little before the next retraction happens. 

This probably won't help at all unless you keep getting the problem during parts of prints with tons of retractions in small intervals, but it could just be you're trying to print something that's hard on the printer at full speed. 

RE: More clicking, no extrusion

@chris-d39

Might I offer a humble opinion of what I have experienced. 
Let me first start off by describing the problems that I had that were similar to yours.

I am printing with PLA Prusament as well PLA filament I purchased from Filastruder.

I was able to get a few prints completed that were at the most 2 hours in print time.

I then switched to the filament from Filastruder and my extruder started clicking and not wanting to feed my filament.

So I helped guide the filament into the extruder to help my idler.  Well the beginning filament extruded, but then when the print started the extruder would start to print the first layer and then all that would happen is filament would stop being extruded.

I then checked with customer assistance and the forums as you have and `addressed the following resolutions from responders:

Suggestion - Idler screws to tight

  Action - I then lossened them and repeated prints and same problem arose.

Suggestion - Temperature not hot enough for filament

  Action - I raised the temperature for the PLA filament which resulted in filament oozing out with no problem on loading but then clogging up in extruder without even a first layer along with clicking and inability of the idler to unload filament.

Suggestion from Customer Service was to refer to manual to remove clogged filament by means of heating extruder to highest setting then disabling stepper motors to push clogged fialment out. 

  Action - This did remove filament but did not solve clicking problem or filament to extrude or allow idler to unload filament. 

After repeating the same procedures and feeling discouraged I would stop trying and leave the printer for a few days.  I had even resorted to posting on the forum that I was selling my printer because I was upset that my printer was not working as it should be.

After pondering the problems I happened to look at the manual and re read instructions for installing the idlers and hotend.

By studying the steps I noticed a had missed one tiny procedure.

Now what I am about to tell you has completely relieved me of the problems in the extruder area of the printer.

When reading the steps I noticed on the idler pulley attached to the stepper motor had a tightening screw that holds the idler onto the stepper motor shaft.  I then remembered that in my spare parts there was a tiny brown screw that I wondered where it went.  I was frantic hoping that it had not fallen out of the spare part bag.  Low and behold it was in a separate back in my spare part bag.

I realized that when I attached the idler to the motor shaft I incorrectly slid it on so that the beveled part of the shaft was not in line with the beveled part of the idler hole.  When I attached it wrong it held tight but once the printer was assembled and after a few prints the idler on the motor shaft was no longer tight but loose.  Now when the extruder would try to feed the filament, there was no problem for both idlers to feed the filament until there was resistance against the filament (either from filament on the spool not easily able to unwind or temperature of the hotend not melting filament quick enough.  Once there was resistance the idler on the shaft would just spin as I could see through the hole when I would raise door of the free idler.

Solution;  I disassembled the extruder to expose the motor shaft with the idler attached.  I then used my needle nose pliers to carefully hold onto the idler and pull it off.  Once I was able to free it I then reattached it in correct alignment and screwed in the locking screw to lock the idler in place.  I then assembled everything back together and it has been working with none of the following problems:

Clicking has stopped completely

Idler now feeds the filament with no problem

Extruder extrudes filament with no problem and does not glob.

Filament easily unloads with no problem.

In retrospect.  Even  the most experienced users in 3d printing with all their knowledge cannot conclude an adequate cause for some thing as a little screw tightening an idler on the shaft.

I almost was going to go the route of buying the hotend upgrade and thermal paste break as many others have as well as other suggestions offered.  But low and behold; "Ye little screw was thy mighty vain of my many wiles to find thy answer".

I might add!  Another suggestion from the owner of Filastruder when I contacted him about my issues with their filament getting stuck in the nozzle.

Suggestion - Increase the nozzle temperature and make sure to dry out the filament as it may be to moist.

  Action - I live in the desert southwest of the united states and even in winter humidity is non-existent and the printer is in my bedroom.  The filament was not moist as it prints with no problem now. 

I have surmised that patience, taking a step back from the problem and giving my mind some time to absorb the issue on a clear head results in the best solution.  That solution kept me from ridding myself of my printer. 

Yes I have become grieved as father to his child towards my printer as it is obstinant with newer problems but as I calmly address the issues with patience, I come to learn about my printer and begin to view it as a adolescent child.  Yes it is an inanimate object, but the reulsts it gives me when I guide it back into proper form and function are the closest joy I could experience from a child to his father.

Hope this helps!

RE: More clicking, no extrusion

Same problem here. MK3S stops extruding mid-print, with the extruder motor clicking.
It took me several weeks but I think I just figured out what is causing the problem.

In hindsight things seem much clearer:

- It only happens with PLA or other low temperature or soft materials. It never happened with ABS or ASA, even in a closed enclosure.

- It happens a long time into the print, or right at the beginning of a second print without cooldown.

- It has something to do with retraction. Lowering retraction length or speed in the slicer may help but not always.

- Jams mostly happen when prints are getting complicated, like the roof posts of a Benchy. I have a box full of Benchies of special rare filaments without roof.

- I replaced every single part of the extruder (except the stepper motor) to no effect. Butterworth Design R4 printed parts, genuine E3D heatbreak, titanium heatbreak, copper heatbreak. All parts were defect free and correctly assembled.

- The extruder stepper motor is very hot after a failed print.

- My printer is in a Lack enclosure.

We were all looking at the wrong end.  This is what I think happens:
- Extruder stepper motor gets quite hot during print.
- Extruder gears heat up the filament, especially when touching it three times during retractions.
- Filament is deformed by extruder gears so it jams at the upper end of the PTFE tube.

What we have here is a pre-hotend jam. It is enough to press the filament slightly flat (oval cross section) so it will no longer fit into the round PTFE tube. At high print speed the chamfer at the top of the PTFE tube may reshape the hot filament back to round but this puts more load on the stepper motor. This is when the clicking starts. Later at low print speed the filament cools down between gears and tube and creates a solid jam.

Additionally I have seen filament S-shaping (5 to 15 mm wavelength) inside the PTFE tube which indicates that the filament got too hot and deformed from the pushing force. Not sure if this can cause jams inside the tube but it may be another source of failure from the same root cause: Extruder gears too hot.

The interesting thing is that I do not remember the extruder stepper motor getting so hot when I got the printer a year ago. I am printing a lot so there may be some wear that increased heat production in the motor. Or I am running different slicer profiles now. Or the firmware changed.

Here is my solution:
* Take your printer out of the enclosure (or at least open the doors). Print in a colder room.
* Reduce extruder gears spring pressure. Clicking is not caused by too little force but by too much.
* Install a cooling duct and fan for the extruder stepper motor. Like this or this. Make sure fan is blowing up, so no deflectors needed. No strong fan required, a 40x10 mm is good. Just a bit of airflow is much better than none. Get 5 V power from Einsy board.)

I have done the first two steps and had no jams for two days. Just waiting for a fan to test with more difficult prints.

RE: More clicking, no extrusion

I only replaced the heat break with the same bore through it eliminating the change to a tighter bore half way through the factory heat sink.  I can print a lower an much more appropriate hot end temperature as a higher temperature makes the PLA thread between retractions.  No problem and I've printed at least 48 hours after heat break replacement.

RE: More clicking, no extrusion

@chris-49

Thanks for your great post.  I did all that you mentioned including the fan to cool the extruder stepper (it is now much cooler than before).  Instead of taking the printer out of the enclosure, I have a fan aimed at the open door of the enclosure. Previously I had replaced the heat break with a standard E3D heat break, which did not relieve the issue.  I'm still getting these jamb-less jambs.  I'm beginning to think that it is retraction-related (too many changes in direction of driving the filament).  It happened twice on a print that has a rather large support for an arch.  If the problem continues, I'll have to start experimenting with retractions. 

I still wonder why this started for me back in December after the printer/enclosure combo worked very well since I got my MK3 in March of 2018.

RE: More clicking, no extrusion

I have had some modest success using some very small retraction settings. I do not use an enclosure, so that is out of the picture.  While Chris-49 has some valid tips, I'm not sure that this covers the issue entirely.

There is no question that the stepper motor that drives the media gets too hot (Chris-49's suggestion should help with that).  That coupled with inadequate cooling at the hot end has heat creeping too far up the heatbreak, raising the temperature of the filament to the glass transition (or slightly beyond).  There is a wider bore (as shown in cross-section in one of the videos I posted initially) in them middle of the Prusa heatbreak (that is not there in the standard E-3), which allows for better media swapping for those of us who use the mmu.  The overly-warmed filament deforms and adopts the contours of this bored-out section effectively giving it a 2.2mm "collar", and hardens just enough to not be able to get through the 2mm portion after the 2.2 bore.  This is why Prusa says the "solution" is to print PLA hotter than should be needed... because it causes the heatbreak to heat up so much, that the filment won't be able to harden as it moves through that bore. It is a compensation for the problem in the design.

I submit that the Noctua fan that cools the heatbreak is not powerful enough to do the job with the given heatsink.  If we can keep the filament cool from the beginning (as Chris-49 suggests), and have it adequately cooled at the heatbreak (so the heat doesn't creep up), theoretically the filament should not hit glass transition, and remain 1.75mm as it passes through (until it hits the nozzle).  I don't have a sure-fire solution, but I'm pretty confident I understand the issue now. 

Raising print temperature, reducing retraction (and printing without an enclosure) seem to be the best defenses against this issue on an un-modded MK3s.  The other thing worthy of note is the resolution at which you print.  Higher resolutions (.05 and .1) are more likely to exhibit this issue than settings of .2 -.3mm because the filament spends less time in the heatbreak when printing at lower resolution settings. In fact, at .3, I've never had this issue occur at all. I like to print most things at .1mm, which is why this problem has vexed me for so long.

RE: More clicking, no extrusion

@moonglum

Thank you for your response.  Think I might consider replacing the Noctura, due to your point that it may not be performing to standards.  

RE: More clicking, no extrusion

I can't guarantee that that, in and of itself, will be enough.  I think Chris-49 makes a very good point with the pre-hotend part of it.  I think there is just too much heat buildup all around the head.  Anything that can reduce the heat before and at the heatbreak would probably be a good thing.  Some people have also suggested making sure you have the proper amount of thermal paste... which is probably also a good idea.

The only other option (as prusa suggests) is to overload the heat, to keep over-heated filament pliable enough so that it can be jammed through the nozzle even if it takes on the contour of that bore.  But you inherit other issues with that workaround.  I remember when I first got this printer, how surprising it was that they suggested a temperature of 215F when most printers print pla around 195-200...  I found out why the hard way.  Prusa does a lot of things right, and I'm a big advocate, but I wish they would own up to this issue a little more.  Maybe they painted themselves into a corner with trying a one-size-fits all heatbreak for mmu users and non-mmu users. Perhaps they should ship with a standard heatbreak and include this version with the mmu2. I don't know.  Hopefully in the next iteration this issue would be solved.  It is a bit of an elephant in the living room. I wish I had more time to test possible solutions -- but I just don't.  Now days, I use my prusa primarily for PETG, and print PLA on my other printers for any jobs that take more than a couple hours.

Good luck.

RE: More clicking, no extrusion

Posted by: @moonglum

[...] Maybe they painted themselves into a corner with trying a one-size-fits all heatbreak for mmu users and non-mmu users. Perhaps they should ship with a standard heatbreak and include this version with the mmu2. I don't know.

I think it's a case where most people are not having the issue compared to the number of MMU users who have problems. I printed with my Prusa-style heatbreak for 18 months without issue. I can do extended printing with PLA, PETG, and other materials, including 24hour + detailed prints with thousands of retractions using PLA through a 0.25mm nozzle at 190C without problems. I'm using 50mm/s retraction and 25mm/s de-retraction speeds. Based on a lot of posts I see on this topic, it sure looks like part of the problem is filament being mashed in.

I am still curious whether non-Newtonian filament characteristics come into play. Did you experiment with de-retraction speeds? I was testing maximum volumetric rates attainable through my hotend and was very surprised to discover that PLA hits a definite top-end regardless of temperature. This is even the case with larger 0.6 & 0.8mm nozzles which have less backpressure, so it seems to be strictly a rate (speed) limit. 

[...] It is a bit of an elephant in the living room. I wish I had more time to test possible solutions -- but I just don't.  Now days, I use my prusa primarily for PETG, and print PLA on my other printers for any jobs that take more than a couple hours.

Do you see the issue when printing PETG on the Mk3, or just with PLA? In addition to printing at higher temperatures, PETG flows much more smoothly through the hotend at all temperatures. In my throughput testing, PETG was able to maintain a rate of roughly double the rate of PLA without problems. 

RE: More clicking, no extrusion

@bobstro

I haven't played with de-retraction... but I have calibrated my steps/mm, which should get the flow just right.  I'll have to pay with MVS... I just don't have the time now, or for the foreseeable future.

Yes,  I did mention, this is much less of a problem with PETG.  Because of the issue with PLA, my Prusa is used almost exclusively for PETG prints an it usually works great with this material.