i3 Mk2S Extruder gear/motor clicking  

Re: i3 Mk2S Extruder gear/motor clicking

Hardened steel nozzles usually require higher print temps. Try printing even 15c hotter than normal to see if that helps at all. If it helps, but you start to see stringing, drop the temp a couple degrees at a time to find the sweet spot.

Another place I've see a hard to cure "looks like a plugged nozzle but isn't" is the heat break itself. Debris falls down into the PTFE and heat break, collects, then at some point during a print settles into a cold log jam that keeps the filament from moving. When you back out the filament, the log jam resets, and the process repeats. I was only able to cure this by removing the nozzle and blowing compressed air up through the heat break.

Re: i3 Mk2S Extruder gear/motor clicking

Heyas,

Thanks for the reply.

With the steel one i've been printing at around 250°C at some users recommendations (which is really the highest id wanna go). Sadly, same results.
Really wouldnt explain why i can print perfectly fine with 215°C, up to a point where it just jams up for some reason. :s

This one is a bit hard to check, ill admit. Every time i want to clean my nozzle, i take apart my entire extruder. (nozzle, thread, heatbreak, tube etc)
I make sure its all clean etc. Though ill admit, it looks fine when taken apart. I will need to check this again later in the week i guess.

Any further help/suggestions is much appreciated 🙂

MAD

Re: i3 Mk2S Extruder gear/motor clicking

Okay - here's a checklist (brain dump, really). Anything not tested, or anything tested that isn't on the list?

On the logical side, a "no extrusion" condition is a pretty simple issue. It can be taken down to these basic facts:

1) Nozzle must be hot enough.
2) Sufficient force must be applied to the filament to feed the filament through the nozzle.
3) The nozzle outlet must not create back pressure.

#1 - Nozzle temp is monitored and can be checked while printing. If we assume you have been present at a fail, and nozzle temp was okay, we can rule it out.

#2 - In the extruder path you have these things that can affect force:

1) spool holder and filament path
2) guides
3) gears: alignment and tension
4) PTFE
5) heat break
6) nozzle
7) motor torque

Can we assume you don't have an MMU? Or if you do, the PTFE Bowdens are all clean and in like new condition (not dragging)?
-- Old MMU PTFE Bowden tubing has caused jams.
Has the general filament path changed? New spool holder, filament sponge, etc?

Guides are (almost) never an issue (see discussions of MK3S extruder housing path alignment).

Gears are easily serviceable and teeth full of debris easy to see. However, gears do WEAR and need to be replaced when the sharpness is questionable. Filament must pass through the center of the gear teeth. A visual check of filament path is generally adequate. Tension is also easy to check. If you see teeth marks in filament pulled out of the extruder, there is tension.

PTFE is short, drag unlikely, but with a loose collet PTFE can be sucked up into the Bondtech gears and reduce force applied to the filament.

Heat break is generally fool proof, but there is a theory some Prusa heat breaks have a step that allows heated filament to back up into a 2.2mm diameter section and cool, which causes a jam because cold 2.2mm filament won't move back into the 2.0mm diameter of the last heat break section and nozzle. Plus my pet theory of debris packing the cold section of the PTFE or heat break and causing a Chinese Finger Trap jam.

Nozzle is easy to verify. A few cold pulls generally resolved a blockage. And replacement ensures damaged brass at the tip isn't aggravating plugs.

Motor torque is affected by power and magnetics. Since other motors appear to be running well, we can probably rule out power supply. A driver issue would be hard to find without crash detection - but I believe would manifest in other ways. A broken motor wire has been known to block extrusion, but generally there are no associated noises; but still possible. A test - not foolproof, but easy - extrude 100 or 200 mm of filament and aggressively wiggle the extruder cable harness - if any visible glitch in the extrusion is apparent, more diagnoses if needed. And why be aggressive? It is already failing - but intermittent - and you are trying to make if fail permanent so you can find the cause.

#3 - Back pressure is something that normally varies quite a bit. There are a couple of things that increase it.

1) Nozzle temperature
2) Filament type
3) Layer height
4) Nozzle wear and damage

Nozzle temp, again, is easy to check. But a short delay in heating caused by a broken wire may go unnoticed, but start a jam event. These should be intermittent gaps in flow. Not a continuous stoppage.

Filament brands all have different formulations. Some flow more readily that others. Some have fillers that also affect flow, even collect and plug the nozzle. As long as the orifice size is adequate for the fillers, and temperatures are adequate for the compound...

Layer height reductions increase back pressure. Like holding a finger against a garden hose, the smaller the layer the higher the pressure required to maintain a given flow volume. And FDM printing depends on adequate volumetric flow. It doesn't appear that you are printing ultra fine layers. Part warpage can allow a part to lift from the bed and it begins reducing layer height, eventually even contacting the nozzle. Fat spots in perimeters is one of the indicators of this. A variation of filament diameter can also have an affect here. A large diameter will increase the volume being extruded, stressing everything in the path. Changing filaments should test this.

Nozzle wear is a bit subjective. As a filament extrudes, it can leave additives along the heated path. These can build up and reduce the orifice size. Cold pulls remove most of this buildup in most of the nozzle hot zone, but in the orifice itself it is rather hard to keep fully clean. Also, as the nozzle extrudes material, the hot filament abrades the orifice and nozzle tip. In the orifice, this help keep the nominal diameter open. Particles in the filament, mica, copper, tin, oxides, increase the abrasion and wear. The highest wear is generally apparent on the external tip; where it is likely the tip comes into contact with cooled and hardened filament extruded in prior passes. These unintended contacts damage and wear the tip. This tends to cause initial layer height errors, but subsequent layers are mostly unaffected. Nozzle damage can also cause issues like stringing, due to the way filament flows off the tip, and in extreme cases affect jams. Easy to test by replacing the nozzle.

Re: i3 Mk2S Extruder gear/motor clicking

And one other question. You've change nozzles multiple times. When you've done this, I assume you have been careful to ensure the heat break and nozzle are the contact point for tightening the nozzle in the heater block. That is, the HEX of the nozzle is well above and not in contact with the heater block.

Re: i3 Mk2S Extruder gear/motor clicking

Heyas Tim,

Thanks for the reply.

1.

Mhm, was present at multiple failures. All seems to gi smoothely and with the quality i've come to expect, just suddenly slows down extrusion (as in, less material) till it grinds in and clicks etc. Pushing out air.

2.

1) spool holder and filament path : nice and loose, spins well enough.
2) guides: Not sure what you mean by this for the i3 MK2S :p (not a native speaker)
3) gears: alignment and tension: See this worries me. All of it seems to be in perfect condition but i have no reference to say otherwise.
4) PTFE: is new
5) heat break: should be clear, though i may just get a replacement just in case.
6) nozzle: new
7) motor torque: same as with the gears, i have no reference of ever seeing one that didnt have enough power (while ening in high ower mode)

i have a single material version only 🙂
Nothing of my setup has changed, i still use the 'on top' spool holder that came with the MK2S.

Gears: i get pretty anal about it being centered and there are clear tetth marks on my material. I regularly clean the teeth out with a toothpick as to not damage the gear ever since i noticed the gear had been digging into/scraping off the material at times.

Ill try the motor test again to see if its wiring is faulty, though i had done so before :s

3.

* I spend an afwul amount of time doing 'first layer' tests, even more than i really feel comfortable in admitting :s I just want everything to be satisfactory and will often recheck if a previous setting was more optimal. (we all have our quirks :p). I've seen your description of a layer not adhering to the bed, curling and messing up the nozzle however. It's something i'm aware of and actively try to avoid. Happy to say that with my current setup (z offset, and keeping the bed as clean as i can) they stick rather well and actually give me a nice, clean and even surface (as my previous pic suggests, i hope).
Those 'fat spots' is a good tip however, i've seen those before.
* Filament diameters: i have measured my current spool (first one ive used) and its diameter is 1.79mm, the second one i bought when buying the printer was still boxed up and also measures about the same. the spool i bought only recently (prusament) i havent measured, though all three net me the exact same result as before, despite setting Slic3r to 1.79mm.

* Nozzle is brand spanking new:
https://e3d-online.com/nozzlex-v6

Though, what worries me is when you say the nozzle's hex isnt supposed to touch the heating element?
I'll admit i'm largely self taught (due to commitments from our other departments, we are frequently expected to pick up the slack on our own where i work and that usually requires a lot of self tutilage.
Mine currently is fully hilted to the heating element while heated (enough to fasten it, never over tightened), then i screw in the heatbreak and assemble the rest. I let it cool, insert it into the block, assemble that part and then heat it up to load in the filament.

The heat break and nozzle are always securely screwed into each other however. I've had an issue with that before and it caused massive spills. So i always make sure of that.
Interesting that you mention this, since i'm starting to feel like a twat for doing something wrong and not even knowing about it.
Could you offer an insight as to why this is? How much should the nozzle be away from the heating element? (i assume that once that is done, 'then' the heat break goes in etc as i normally do?)
I have been trying to look this up. And seem to find more and more people making clear that this should be the case, but hardly why or just how much etc.

Here's to hoping this is my issue :p

MAD

Re: i3 Mk2S Extruder gear/motor clicking

3) gears: alignment and tension: See this worries me. All of it seems to be in perfect condition but i have no reference to say otherwise.

Are the teeth sharp? Can you see marks on the filament? Unload filament, let things cool, open the idler door and shove some filament into the heat break and then close the door and set the idler tension. With power ON, so the motor is power up but not running, can you easy pull the filament from the extruder?

Gear wear - so depending on how many years/hours/ meters of filament you have extruded, maybe you have reached gear end of life?

Filament grinding is a precursor to the weird heat break jamming issue I worry about. It only takes a few minutes to remove the nozzle and blast compressed air up the path.

Setting 1.79 in Slic3r reduces flow 5%... while not likely an issue, I leave mine at 1.75 and use Tune to make fine adjustments. But probably not causing you problems like this.

Not all fat spots are warp; but when you see them it's good to check. There's a recent thread where a few of us beat the subject to death and agreed there was something odd happening when print area changed between layers. Not sure we decided on a cure, but slowing down seems to help.

HEX against the block. Okay - this is a serious problem. It should look like this:

https://wiki.e3d-online.com/E3D-v6_Assembly
https://e3d-online.dozuki.com/Guide/Changing+Nozzles/45

E3D says at least 1/4 turn off the block.

The nozzle tightened against the block almost ensures the heat break isn't tightened properly. Insufficient contact between the two - I''m guessing a bit here - allows filament to cool inside the 2mm zone in the heat break, where it gets too sticky and refuses to move.

Nozzle flow doesn't start and stop instantly. Instead, the printer tries to maintain a constant fluid pressure to ensure even extrusion. LINEAR ADVANCE is one of the ways the printer does this when starting and stopping a track. But there are times when the extruder moves more material than others: short strokes where it doesn't get up to speed, compared to long strokes. These differences in demand lead to different nozzle pressures and theoretically to hot filament backing up into the cooler sections of the heat break. Some Mk3 heat breaks have a 2.2 mm diameter section, and while I've never seen a cold pull with that diameter, there's a suggestion if melt reached that step, a plug is imminent.

My thinking is the melt gets far enough up the heat break where it is just cool enough to cause problems - a tight fit helps keep the lower heat break at the melt point. A loose fit allows the entire heat break to be cooler, including the section in the heater block.

Enough chat: while it requires pulling the whole hot end, you do need to fix the nozzle depth issue.

RE: i3 Mk2S Extruder gear/motor clicking

Hey Tim,

Only just been able to get back to you (the site seems to have gone under some changes...). 

I have done as you suggested and did the following:

• Screw in my nozzle and turn it back out between 1/4 and 1/2 turns. (when it was at 215°C)
• insert my heatbreak while still heated.
• tightened my nozzle against the heatbreak
• assembled my extruder completely
• i went through the trouble of going through my entire calibration process again, including making sure my pinda was set at a correct height.

I'm sad to report i get the same issues again during my first layer. 

I may just do it all again when i have the time this week, just to make sure it isnt the issue. 
Though i will admit, just scrapping my MK2S back to a bigger nozzle and buying the new model for detail use does seem more tempting by the day :p

I only hope that even with the stock nozzle, i dont get the same issues again...

If you or the rest of the community have any further suggestions, i'm all ears. 

Thank you so far for helping me already!

RE: i3 Mk2S Extruder gear/motor clicking

That is an IMPRESSIVE list of what you have tried to remedy your problem.

There is one more thing to try that has not been mentioned yet. Mk2.5s upgraded printers are prone clogs caused by insufficient hotend (heatsink) cooling and heat creep up through the filament. Given the slower filament flow, this would be amplified with smaller nozzles and smaller layer heights. Make sure the air flow is unobstructed and that the printer, if printing PLA, is not in a hot environment (enclosure?). The colder the better. Possibly upgrade your 40x40 mm fan to a more powerful one.

RE: i3 Mk2S Extruder gear/motor clicking

Hi Vojtech,

Like i mentioned earlier, i get pretty anal about fixing a problem :p 

Seriously....?  Damn, I wish i knew that beforehand...

Its weird how only after a good year this started to happen though. I'm really trying to scratch off a list of possibilties here and somehow it doesnt make sense :s issues started from last summer, all the way through winter etc. But the room its in is set to have a medium temp of 21°C at all times. No enclosure, though a smaller nozzle and the preset layers for that on the best detail. i do print a lot in batches though. As soon as something is done, i peel it off and start it again without cooling, that could explain the heat build up maybe? Though i suppose as soon as she flows again, won't that be evidence of there being no clog? I mean, i could see an issue when i leave her warm, peel it off and start her back up again straight away and it not printing out material. 

I guess all the more reason to get the newer model and keep the older one for igger prints with the stock nozzle...

I'm going to try and clear it out again and do a full check up of my printer, just to make sure. 

But i guess im buying a new one and some better fans :p  (sigh....)

Need to buy my new house first though.

MAD

RE: i3 Mk2S Extruder gear/motor clicking

I just replaced my heat break with a new, unmodified E3D-V6 version.  Very happy I did.  The Prusa version, as it turns out, was jamming when printing large parts with lots of small print regions (lots of retraction and z-lift).  I confirmed it was the long duration of retractions that lead to a cold zone plug in the heat-break, exacerbated by the Prusa design modification, a step in diameter just above the melt zone.  Sufficient retraction would pull melted filament up into the larger diameter, and then cool; done enough times, the fat spot grew large enough the motor could no longer push material. Just clicking.  That said, this defect doesn't usually affect first layer.

I used to think this defect was fantasy, but printing a 75 hour platter size model of Riems DOM, it happened enough I became a believer; and found evidence of the 2.2 mm plug on multiple cold pulls.

Generally - something that used to work that stops, is pretty simple to fix.  So I would hold off on a new printer... though, it does sound like a great reason to spend money: "It's broke, I need a new one!"

Can you take a photo of your first layer and post it here. It's now drag and drop, just be sure to select LINK TO MEDIA from the options.

RE: i3 Mk2S Extruder gear/motor clicking

Heyas Tim,

See below for my first layer 😉
Like, perfect, smooth and ideal first layer in my opinion.
(If it makes me smile and feel relaxed, its usually a good thing :p)
But then clogs up somewhere and you hear that dreaded 'click' acting up and rapidly picking up frequency...

I mean, i'm willing to try a lot of stuff to make it work without this issue again (ive already spent over 100 bucks just to get it fixed so...). 
If that means getting a new stock extruder and better fans then i'll try that. 

Did you guys get the ones from the prusa store? (new parts/upgrade kits?)
Or just from manufacturers?

Kind regards,

Mad

RE: i3 Mk2S Extruder gear/motor clicking

@Mad - the symptom of a plug happening so early in a print is 99% something in the filament ... and a cold pull always fixes it. Your print looks like a solid nozzle plug.  It's the basic theory a particle in the manufacturing process less than 1.75mm, but larger than 0.4 mm will stop in the nozzle.  A spool of filament that is bad (lots of these specks), if used in two nozzles, even a new one, can cause grief.

One question: have you ever printed with a filled filament (glitter, metal flake, glow in the dark, wood, carbon, etc)?  Or shared a filament after installing the new nozzle?  

Try this: raise the extruder to mid level, about 100mm or higher above the bed. Preheat the nozzle to print temps, 215c for PLA: then use the Settings>Move Axis>E-Axis and extrude 100 to 200 mm of filament as fast as you can (rotate the knob POSITIVE only, if you overshoot 200, let it go).  Just roll the number as fast as you can, and let the printer catch up. Watch for any stutters in the extrusion, or clicks.  If it is a common nozzle jam, it should happen with this test. 

The possibilities reiterated: 

• Non-melting object/debris in the nozzle hot zone
• PTFE collet is not locked or is broken
• Material inside the heat break cold zone collecting and constricting the filament
• Improper Bondtech gear tension (filament drive).
• Worn Bondtech gear teeth
• Filament movement is being restricted above the extruder

RE: i3 Mk2S Extruder gear/motor clicking

Hi Tim,

I have never used any of the above in terms of materials. 

Only my 2 spools of Prusa Grey PLA (the default from a while back) , of which one i had been using since day one and the other who had until recently still been sealed in its packaging. And a spool of freshly bought grey Prusament. Never used any metallics or anything else. (i like to paint my models so using anything shiny is a waste on my part :p)

Even on my new nozzle, with the new Prusament spool (which was the first i had used on that nozzle) i get the issue :s

I'll be looking into getting that new stock heatbreak (non prusa) and trying out your suggestion about just checking the flow on the weekend. 

I don't think the MK2S uses the bondtech variant of the gears though, i could be wrong?

Looks like this one: https://shop.prusa3d.com/en/3d-printer-parts/126-mk2-extruder-hobbed-pulley.html

Kind regards,

MAD

RE: i3 Mk2S Extruder gear/motor clicking

Correct, that's not a Bondtech geared pulley, it's the older system. Although there are people that consider it superior and replaced the Bondtech gears with this on their Mk3's.

RE: i3 Mk2S Extruder gear/motor clicking

@Mad - Misplaced the fact this is a 2... it still comes down to the basics.  It is possible you have a bad spool of gray.  I had some Prusa Beige that had something in it, though it only plugged once. Looked like a piece of glass when I pulled it out of the nozzle. Had a horrid time with Prusa glow-in-the-dark.

Can you confirm these problems are with your hardened 0.25 mm NozzleX.  Can you confirm it was a V6 nozzle for 1.75 mm filament?

And if you have tried swapping to a stock 0.40 mm brass nozzle, just as a benchmark?  

The process is so simple any lack of material being extruded has only a few possible causes. 

• Chunks plugging the orifice -- easier to do with a 0.25 diameter
• Filament jammed at the collet -- unlikely, and rare
• Too low a temp -- this won't happen instantly - but steel doesn't heat as well as brass
• Worm gear not biting the filament -- not something that stops and starts
• Extruder motor stalls -- clicking heard in the motor, but filament is mostly motionless
• Broken wires -- unlikely, and I think you said you've wriggled wires during the print and not seen effects

Way back when - I had a similar start/stop problem on early layers. I was also suffering a rash of fails mid part.  It was about the time I was printing glow, and mostly went away when I changed filament. But it fully disappeared when I blew the cobwebs out of the heat break. 

RE: i3 Mk2S Extruder gear/motor clicking

Hi Tim, 

Typing this in between my work, so may not be as responsive as i was when i was on holiday.

I have used 2 0.25mm nozzles now, though i couldn't tell you what material my first one was, as it was a gift from a friend. (excellent prints made with that one, was amazed :p)

The new one (steel) was fresh out of the box and game me the exact same issues at the same intervals. 

Both first layer, as well as mid prints. 

All my materials provide me with the exact same issues. I would have difficulty convincing myself that all three spools would be faulty right out of the box :s 

As far as my 'clicking' goes, you can visibly see the gear slowing down as it grips, and then 'skips' back along the wire, unable to push it down. its like the motor internally decides that its better to just skip the gear back internally than to force it to a halt or grind away at the material. 

Kind regards,

Mad

RE: i3 Mk2S Extruder gear/motor clicking

When you've finished the 200mm extrude test, post up the results.

If that passes, this is less likely, but... I'm now wondering if the thermistor has started failing and is providing incorrect feedback; telling the controller the nozzle is 215 when it's really 185.    

Have you done a PID calibration recently?  It might be worth the time to try another one.  Also, it wouldn't hurt to do a basic minimum extrude test. Same as the 200mm test, except you use lowest extrude temps and only try to extrude a few mm at a time - any clicking and you move to the next temp.  Start with the nozzle set to 150c, and see if you can get extrusion. Then step temp up 5c, and repeat.  You're searching for the melt/flow point of the PLA.  It should be 20c to 30c or so below the print temps listed on the PLA spool. If the melt point is way off, it's a hint the thermistor is questionable. An ohm meter is another test ... 

RE: i3 Mk2S Extruder gear/motor clicking

heyas @tim-m30  ,

Just did the 200mm test, not a jam or clog, not even a stutter. Just a clean extrusion that coiled itself on my bed.

Doing a big surface print to test the first layer, so far so good tbh. (i know that i kinxed it, i just know it :p) 

Ill keep you informed on how it goes.  

Printing at 215°C  and a 60°C for the bed. PLA (my original spool of grey Prusa PLA 1.75mm, normal settings from Slic3r for my nozzle)

Mad

RE: i3 Mk2S Extruder gear/motor clicking

Well...

Wouldn't you know it, just as i was typing 'Thunk....Thunk, thunk'

I dont have time to do the full clean up and switch to the original nozzle, as a benchmark ( i just got a massive 2 day deadline for a big presentation due on tuesday...so kind of stressing over that first). 

But i will be trying that out after tuesday. 

Mad