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Almost always missing layers / underextruding


Nicolinux

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Posted · Almost always missing layers / underextruding

I think Illuminarti and others settled it. But now I show what speed you should be able to do at each temperature.

Be aware that you need to keep the extruder close to the loosest setting possible although I think yours is a tiny bit too loose - so tighten it until the white thing starts moving the tiniest bit down. Probably. Maybe. Hopefully that will help.

Also I have noticed that partial nozzle clogs usually result in a symptom:

When extruding in air the PLA curls very hard and touches the nozzle tip. Even if I pull down and have 50mm of PLA hanging straight down in gravity, if I extrude more it curls and touches the nozzle tip. I little scraping with a needle moved in a circle path through the nozzle tip can usually fix this. Don't scratch the outside of your nozzle though.

If you see this strong curling then the problem is a partial clog. More likely your extruder just needs slight tightening.

 

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Posted · Almost always missing layers / underextruding

So I took the extruder apart and checked it for any problems.

Here's how it looks disassembled:

Notice the screw on the top left is way to far down. I don't know if it was me or if it was like this from the begining.

extruder 1

So the white screw holder with the spring pushes the L shaped white part down wich in turn pivots around the bottom right and presses the ball bearing even stronger against the filament.

extruder 2

 

When one unscrews the screw at the top, the white part with the spring move down increasing the pressure.

extruder 3

And here is the knurled bolt. The left screw is the original one which was already in pretty bad shape when I disassembled it. I guess it was overtightened during initial assembly. I wanted to use the right one (I have a few of these spare), but it was too long. Also tried to shorten the screw but failed misserably.

knurled bolt

 

After I put everything back together, I adjusted the extruder and moved the white plastic square one notch down (so now the extruder should be tighter and have more grip). I then ran illuminarti's extrusion test with no retraction enabled.

extrusion fail

 

On the left I let the spool on the original spool holder. So nothing changed. Extruder is still to weak. I'll try to tighten it more although I don't know when things start to "break" or what other downsides there are to a too tight extruder.

On the right I put the spool on a new ball bearing spool holder (link). Much better but still no where near illuminarti's result.

I don't know what to do/try next. I could call it a day and never print over 4mm^3/s or 7mm^3/s volume but this will just defeat the purpose of owning a fast Ultimaker.

 

 

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    Posted · Almost always missing layers / underextruding

    Sadly the extruder clicked right before I saw underextrusion. I also tried once to "help" him by pushing the filament in.

     

    If your extruder clicks then it is probably assembled correctly and working correctly and the problem is more likely in the nozzle although I suppose you could increase the current. Supposedly the command to increase the current works now in the latest firmware. But I don't recommend it as you could start to get grinding of the filament.

    I suppose one last test would be to insert the filament only a little ways into the bowden (not to the print head), then put weights pulling down on the filament and driver the extruder slowly until it suddenly slips out. If you do this test then I will repeat it on my machine. If you don't know the weight of your weights you can measure them after you find the right amount that makes the extruder slip backwards.

    On the UM1, it can pull about 22 pounds.

     

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    Posted · Almost always missing layers / underextruding

    Argh! This printer sucks big time right now. I started another print and it stopped extruding right in the middle of it. The filament was ground down to the point where the knurled bolt didn't have any grip. Upon removal the lower part of the filament broke off and the rest was stuck inside the extruder. So I had to take the extruder apart and clean the mess. I then adjusted the extruder tension back to factory settings (all the way up - no tension).

    @gr5: I guess the test isn't necessary any more. The extruder is strong enough to grind filament down. Besides, I don't know what would happen if we find out that our extruders pull different weights. What would that mean? That my board was set to provide too little curent to the extruder motor?

    By the way, after putting everything together and inserting new filament, I now see the phenomena you described earlier about filament curling at the nozzle tip. I don't see why a partial clog would occur right now, but who knows.

     

    Oh and I ran another extrusion test. Fails at 7mm^3/s (no retraction) with the filament on the ball bearing spool holder.

    extrusion test 1000

     

    So here I stand, axe in hand, ready to "fix" this thing for good :evil:

     

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    Posted · Almost always missing layers / underextruding

    Looking at the photos of the filament tension adjsuter, I'm still not sure how it's supposed to work.

    I see that if the white part is lower, then it presses down more on the lever. But what makes the white part move down? Why does changing the length of the screw cause the white part to move? Surely that requires that part of the screw be held captive somewhere, so that it pushes the white part down as the exposed screw lengthens.

    Is it just that the screw head is supposed to be held in place in that tiny space where it narrows - as it is in Nicolinux's first picture above? If so, that seems like it could very easily fail - turning a sharp-edged screw, under pressure, against a small lip of plastic?? Surely that's not it. Or does the screwhead press against the inside of the enclosure at the top, or what? Am I missing some part of the mechanism? But it looks to me like once the screwhead is in the upper larger space, as in Nicolinux's last picture, it's never going to push the white indicator block anywhere??

     

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    Posted · Almost always missing layers / underextruding

    Exactly, the screwhead does press against the inside of the enclosure at the top. The white part houses a nut so when you unscrew, the white part with the spring moves down which in turn pushes the lever that pivots around the bottom right point. This moves the ball bearing to the left and thus adds pressure to the passing filament. However there is very little place left between the bottom of the lever and the bottom part of the enclosure. So I am not sure if adjusting the extruder to max strength would be able to move the white squares piece with the spring, all the way down.

    But as the extruder grinds filament at even the slightest adjustment, I doubt that it is relevant.

     

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    Posted · Almost always missing layers / underextruding

    Hmm. Mine doesn't press against the enclosure... The head of my adjustment screw is about 5mm below the outside of the enclosure. So it think it's caught in the smaller chamber below - also looks like not all the head cap is visible, so I guess it's molded into a domed top there for the screw to press against? Still not convinced it's a great idea though for long term performance.

    Also, I'm not sure about the grub screw length in the knurled bolt. I'd have though the longer one might have been ok... mine sticks out a couple of mm. Looks like it would be ok to go slightly longer - so long as it's less than the 2.9mm gap to the cut out for the indicator mark.

    My UM2 Extruder

     

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    Posted · Almost always missing layers / underextruding

    Bear in mind also that when there's no filament in the extruder, the lever will always be at its lowest point - pressing against the bottom basically - provided there's any tension at all in the spring. It's the act of inserting the filament that pushes the roller to the right, and lifts the level off of the bottom and so compresses the spring to supply the working tension.

     

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    Posted · Almost always missing layers / underextruding

    Hmm. Mine doesn't press against the enclosure... The head of my adjustment screw is about 5mm below the outside of the enclosure. So it think it's caught in the smaller chamber below - also looks like not all the head cap is visible, so I guess it's molded into a domed top there for the screw to press against? Still not convinced it's a great idea though for long term performance.

     

    Maybe it was a mistake while it was assembled and someone screwed it too far. Or maybe it is planed to be "parked" there. Since seemingly no other UM2 hast another extruder setting, it may have been designed to be adjusted but then it turned out that's not needed

     

    Also, I'm not sure about the grub screw length in the knurled bolt. I'd have though the longer one might have been ok... mine sticks out a couple of mm. Looks like it would be ok to go slightly longer - so long as it's less than the 2.9mm gap to the cut out for the indicator mark.

     

    I tried it but the grub screw sticks out too far. The mantle of the knurled bolt is very thin (maybe 1mm) and does not take in the screw too far. With the longer screw, the bold wouldn't turn and bumped against the extruder case.

     

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    Posted · Almost always missing layers / underextruding

    Ok, yeah, looking at your photo again, I see where the screw is supposed to live now - the case is thickened more than I realized up at the top. So, yes, that's the right place for it. Never mind.

     

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    Posted · Almost always missing layers / underextruding

    Hey guys,

    Another day, another oddity. I have followed a killer tip from user Takei Naodar and added a drop of oil to the ball bearing inside the extruder. Also changed filament to orange. The extrusion test went through very well (no retraction). The retraction version failed at 7mm^3/s. So deffinitely an improvement. But then I just changed the filament (back to Ultimaker Silver Grey). This time the no retraction test failed directly at the begining (extruder started slipping). Now every time I hear it slipping, there is underextrusion at once.

    extrusion test filament change

     

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    Posted · Almost always missing layers / underextruding

    Ok, I think I'll stop debugging here. My printer seems to be broken. I wanted to print something and when I switched it on I saw this:

    temperature fail

    Then I did't it Windows style and after a restart it started as usual. I then changed filament. Usually when I do this, the new filament flows out of the nozzle smoothly. This time it barely came out - a good indicator that the temperature sensor is failing.

    I'll contact support. I am sure they'll tell me to check all cable connections and maybe do the 90° drop of water test. I'll do this in advance.

     

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    Posted · Almost always missing layers / underextruding

    Maybe that's a good sign... Perhaps you've been having temperature issues and that's why your extrusion rates have been suspect.

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    Posted · Almost always missing layers / underextruding

    Yes you are right. I hope so. Will have to put up with the inevitable down time, but let's hope the issue is solved then. I'll let your extrusion test on my sdcard and you can bet that will be my first print when it is fixed :)

     

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    Posted · Almost always missing layers / underextruding

    At least you get an ERROR code to tell you something is wrong!

    I wish I had that instead of trying to fix everything and wondering what it might be.

    Before you submit that ticket or send it back to Ultimaker, make sure to check where the heating element plugs into the main control board. That is, if you haven't already done so..

     

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    Posted · Almost always missing layers / underextruding

    You can also check if both cables are still inserted in the back of your printhead?

    And if that is the case, have you made any modifications to the electronics or something downstairs?

    If you remove the cover, can you check if the red-silver wire is still properly connected and also they are still inserted in the header? I have seen one or 2 cases where they came out.

    I am guessing it is either one of these causes.

    And yes.. also do the water test ;)

     

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    Posted · Almost always missing layers / underextruding

    I'm not getting anywhere near illuminarti's results. Today I spent time stripping the hot end down and cleaning it all out and that improved things greatly.

    extrude2.jpg

    I also upped the temperature to 230C for the above. The extruder gear is not slipping on the filament, it's just that the motor jumps backwards and that is when it under extrudes. I'm as sure as I can be that the extruder motor is under powered. Is there any way to increase this? A gcode instruction maybe?

     

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    Posted · Almost always missing layers / underextruding

    Woofy... I've no idea if this will make a difference, but try doing a 'factory reset' from the maintenance menu, and see if that makes any difference. The stepper current settings are stored in EEPROM, it looks like - I guess if those got corrupted, or old values got stuck in there, then the motors might be under-powered. The reset will reload the settings defaults from the firmware.

    Note that it will take you through the filament load and bed leveling again, I think... so be sure and take the filament out before you do it, other wise it could get messy. :-)

     

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    Posted · Almost always missing layers / underextruding

    Thanks, I'll try that when I get back.

    I'm now away for a few days holiday (chasing the northern lights, of all things) :)

     

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    Posted · Almost always missing layers / underextruding

    Hey guys,

    Another day, another oddity. I have followed a killer tip from user Takei Naodar and added a drop of oil to the ball bearing inside the extruder. Also changed filament to orange. The extrusion test went through very well (no retraction). The retraction version failed at 7mm^3/s. So deffinitely an improvement. But the I just changed the filament (back to Ultimaker Silver Grey). This time the no retraction test failed directly at the begining (extruder started slipping). Now every time I hear it slipping, there is underextrusion at once.

     

    I said a tiny drop.... if you are not carefull and some of the oil get on the filament things could get real messy very fast.... depending on the exact oil you use it will not vaporize in the head and you can start a real nice cleaning session ^^

     

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    Posted · Almost always missing layers / underextruding

    It was a tiny drop - swear!

    But I'll have to take the head apart anyway to check the temperature sensor. In the process I'll clean everything.

    They way you are saying it, it sounds like you are no stranger to this issue :)

     

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    Posted · Almost always missing layers / underextruding

    Nope.... i am luckily.....

    But i have run several scenarios in my head how it would turn out if i would fuck up.

    Also i dont think you took to much. first you need to fix the temp-sensor.

    If the oil got on the filament you will notice anyways so why not try before cleaning everything without reason.

     

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    Posted · Almost always missing layers / underextruding

    You can also check if both cables are still inserted in the back of your printhead?

    And if that is the case, have you made any modifications to the electronics or something downstairs?

    If you remove the cover, can you check if the red-silver wire is still properly connected and also they are still inserted in the header? I have seen one or 2 cases where they came out.

    I am guessing it is either one of these causes.

    And yes.. also do the water test ;)

     

    Ok, status update. Took the head apart, checked for a clog, cleaned even if there was no need to. I then ran the extrusion test again (spool on the back of the printer and on a lazy susan). I also took the dustfilter off. That made a bit of a difference but not much. Printer still fails around 5mm^3/s

    extrusion test again

     

    The temperature sensor is correctly connected (also took a peek under the electronics cover. Here's how it looks on the back of the head:

    head back

     

    Also did the wather boiling temperature test. The temp. sensor seems to be off by 2-3°. I saw tiny bubbles (and heard the faint boiling sound) at around 102-103°.

    I also changed filament. Then I noticed that all my Ultimaker filament spools are marked like this one - temperature up to 260°

    Photo 243

    Except for two (Ultimaker Gold and Grey Metallic - the one I mostly use for tests because I don't like the color). This one goes up to only 220°

    Photo 241

     

    This is not the reason for the failings, but I wonder what's up with this filament. Low temperature PLA only? Or incorrectly labeled?

     

    However, what could I try next? Obviously I'd love to spend more time printing real models without underextrusion than debugging stuff. I fell like the time with the UM1 all over again :/

     

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    Posted · Almost always missing layers / underextruding

    I hate to beat a dead horse, but can you check the gap between the teflon and the milled fitting again?

    When my prints were failing everytime, the only change I made was to the space between the teflon and milled fitting. (Posted in this thread somewhere) Since then my issues of under extrusion are gone. I don't understand why, other than the transfer of heat in the form of conduction is very accurate where the heater, nozzle and milled fitting all sit together.

    Or maybe I just got lucky and failing mechanical parts are now working? Very Unlikely

    Everytime I use the Orange PLA from the Ultimaker store I got a clog almost instantly. I did buy some cheap white PLA off of ebay which is printing better than all of the colors I've tried so far(go figure).

    I hope you find the solution!

     

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