gr5

Here's my list of things that can cause underextrusion on the UM3 and some quick diagnostics to eliminate about half of the possibilities quickly: As far as underextrusion causes - there's just so damn many. none of the issues seem to cause more than 20% of problems so you need to know the top 5 issues to cover 75% of the possibilities and 1/4 people still won't have the right issue. Some of the top issues: 1) Print slower and hotter! Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers) and .4mm nozzle: 20mm/sec at 200C 30mm/sec at 210C 40mm/sec at 225C 50mm/sec at 240C The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA. Note that your "print speed" may be 40mm/sec but it may be printing infill at 80mm/sec so CHECK ALL SPEEDS. 2) Line Width larger than nozzle. In cura 3.X search in settings for all line widths. If any of them are larger than the nozzle diameter this can cause underextrusion. There are 8 of these in cura 3.2.1. 3) Curved filament at end of spool - if you are past half way on spool, try a fresh spool as a test. 4) curved angle feeding into feeder - put the filament on the floor -makes a MASSIVE difference. 5) Bad core. Try a different core. It could be clogged, or something more complex like the temp sensor in the core. 5a) clogged nozzle - the number one most suspected problem of course. Sometimes a grain of sand gets in there but that's more obvious (it just won't print). Atomic method (cold pull) is the cure - from the menu do a few cold pulls. The result should be filament that is the exact shape of the interior of the nozzle including the tiny passage to the tip of the nozzle. If it doesn't look like that you need to pull at a colder temperature. You can do it manually instead of through the menu if it's not working right but learn through the menu initially. 95C is roughly the correct "cold" temperature for PLA. Higher temps for other filaments. Simpler cold pull (3dsolex cores only - doesn't work on ultimaker cores because you can't remove the nozzle): https://www.youtube.com/watch?v=u07m3HTNyEg 5b) Temp Sensor bad - even the good ones vary by +/- 5C and bad ones can be any amount off - they usually read high and a working sensor can (rarely) fail high slowly over time. Meaning the sensor thinks you are at 220C but actually you are at 170C. At 170C the plastic is so viscous it can barely get out of the nozzle. You can verify your temp sensor using this simple video at youtube - on you tube search for this: mrZbX-SfftU 6) feeder spring issues - too tight, too loose. You want the tension such that you can clearly see the diamond pattern biting into the filament. You want to see at least 2 columns of diamonds. 4 columns is too much. You usually want the tension in the center. If the white marker isn't in the center, make sure the adjustment screw actually moves the marker. If not then someone put the feeder back together wrong. 7) Other feeder issues, one of the nuts holding UM2 and UM3 together often interferes with the feeder motor tilting it enough so that it still works but not very well. Other things that tilt the feeder motor, sleeve misaligned so it doesn't get a good grip. Gunk clogging the mechanism in there. 😎 Filament diameter too big - 3mm is too much. 3mm filament is usually 2.85mm nominal or sometimes 2.9mm +/- .05. But some manufacturers (especially in china) make true 3.0mm filament with a tolerance of .1mm which is useless in an Ultimaker. It will print for a few meters and then clog so tight in the bowden you will have to remove the bowden from both ends to get the filament out. Throw that filament in the trash! It will save you weeks of pain 8b) Something wedged in with the filament. I was setting up 5 printers at once and ran filament change on all of them. One was slowly moving the filament through the tube and was almost to the head when I pushed the button and it sped up and ground the filament badly. I didn't think it was a problem and went ahead and printed something but there was a ground up spot followed by a flap of filament that got jammed in the bowden tube. Having the wedgebot (link below) helps you feel this with your hand by sliding the filament through the bowden a bit to see if it is stuck. https://www.youmagine.com/designs/wedgebot-for-ultimaker2 9) Extruder mis calibrated. Maybe you changed equipment or a wire fell off. Try commanding the filament to move exactly 100mm and then measureing with a ruler that it moved 100mm within 10% accuracy. If not adjust the steps/mm (this is done by editing a json file on the UM3). 10) Z axis steps/mm. it's easier than you might think to double or half the Z axis movement as there is a jumper on the circuit board that can be added or removed. If the Z axis is moving 2X you will get 50% underextrusion. Your parts will also be 2X as tall. 11) Crimped bowden. At least one person had an issue where the bowden was crimped a bit too much at the feeder end although the printer worked fine when new it eventually got worse and had underextrusion on random layers. it's easy to pull the bowden out of the feeder end and examine it. Similar to 8b above - use the wedgebot to feel how much friction there is in the bowden. 12) Worn Bowden. After a lot of printing (or a little printing with abrasive filaments) the bowden resistance can be significant. It's easy to test by removing it completely from the machine and inserting some filament through it while one person holds it in the U shape. Preferably insert filament that has the pattern from the feeder and fight the movement by applying 2kg force on both ends at the same time and then seeing how much harder you have to push it on top of 1kg force. UM2 feeders can push with 5kg force. UM3 can push quite a bit more. 5kg is plenty. 13) Small nozzle. Rumor has it some of the .4mm nozzles are closer to .35mm. Not sure if this is actually true. I'm a bit skeptical but try a .6mm nozzle maybe. This shouldn't be a problem on the UM3 which has very good quality control but try a different core. 14) CF filament. The knurled sleeve in the extruder can get ground down smooth - particularly from carbon fill. 4 spools of CF will destroy not just nozzles but the knurled sleeve also. Look at it visually where the filament touches the "pyramids". Make sure the pyramids are sharp. 15) Hot feeder driver. I've seen a more recent problem in the forums (>=2015) where people's stepper drivers get too hot - this is mostly a problem with the Z axis but also with the feeder. The high temps means the driver appears to shut down for a well under a second - there is a temp sensor built into the driver chip. The solution from Ultimaker for the um2 is that they lowered all the currents to their stepper drivers in the newer firmware. Another solution is to remove the cover and use desk fan to get a tiny bit of air movement under there. This doesn't seem to be a problem on UM3 even though it's the exact same circuitry but they lowered the current in the firmware. But it's worth considering if air temp is 30C or hotter. It would probably happen only after printing for a while (air heats up slowly under the printer). 16) third fan broken. This tends to cause complete non-extrusion part way through a print. In the door of the head. You can hear it come on when cores get above 40C. Without this fan several things can go wrong. It can take a while as usually you also need several retractions to carry the heat upwards. There are a few failure mechanisms and I don't understand them all. One of them is probably that the molten PLA spreads out above the teflon and sticks to the metal in a core or fills the gap at the base of the bowden in UM2. Later it cools enough to keep the filament from moving up or down. 17) Spiralize/vase mode. This is a rarely used feature of Cura but you might have left it on by accident? In this mode the wall of your part is printed in a single pass. So if you have a .4mm core and the wall is .8mm thick it will try to over extrude by 2X. This is difficult to do and may instead lead to underextrusion. 18) too many retractions (this causes complete failure) - if you have too many retractions on the same piece of filament you can grind it to dust. 10 is usually safe. 20 is in the danger zone. 50 should guarantee failure. You can tell cura to limit retractions to 10 per a given spot of filament. Do this by setting "maximum retration count" to 10 and "minimum extrusion distance" to your retraction distance (4.5mm for UM2 and 6.5 for UM3). 19) Brittle filament. Espciallty with older PLA but even brand new pla can do this. If you unspool some (for example if it's in the bowden) for many hours (e.g. 10 hours) it can get extremely brittle and it can snap off into multiple pieces in the bowden. It's not obvious if you don't look for this. Then it starts printing just fine and at some point one of those pieces reaches the print head and gets hung up somewhere and the printer suddenly stops extruding for now apparent reason. This usually happens within the first meter of filament - once you get to printing the filament that was recently on the spool it should be fine from then on. 20) The "plus" feeder can have an issue where the filament doesn't sit properly for one print and it permanently damages the arm inside the feeder as shown by this photo - the hole is ground down asymetrically: http://gr5.org/plus_feeder_issue.jpg 21) Filament tangle - the end of the filament can get tucked under a loop on the spool and this tangle can propagate from then forever to the end of the spool until you fix it. It will cause many many jam ups and slow then halt extrusion. Repeatedly. The fix is to remove the filament from the printer, unroll a few meters and respool and put back on the printer. Never let go of the end of the filament spool until it's in the bowden. =======

1) What Torgeir said about the steps/mm. 2) The bondtech is skipping? Really? Is the tension half way up the scale as described here? http://www.bondtech.se/wp-content/uploads/2018/08/Bondtech-DDG-Ultimaker-V1.0.1.pdf Is it possible the filament is slipping through the feeder and the stepper isn't actually going backwards? 3) When you use the i2k you should cut off part of the teflon part by the same amount. So if the i2k is 1mm thick then slice off 1mm from the teflon part. If you don't do this - particularly on the "plus" series printers like yours, that aluminum spacer can't compress and you have MUCH too much pressure on the teflon and it tightens/pinches/grips around the filament. 4) Is your teflon part new or old. You say it is "PTK" but I'm not sure what that means. There is the Ultimaker spacer and the 3dsolex spacer - both are great but need to be replaced regularly (like every 200 to 500 hours of printing). The easiest way to diagnose is to put the filament half way down the bowden. Have the extruder move it forward with MOVE command and then fight that with your hand by pulling down on the filament just below the feeder. You should be able to pull 5kg or 10 pounds of force without the feeder skipping. If it skips then something is wrong with the extruder. If it doesn't skip then it's the print head. I suspect the print head but it could be either.

To get a "fresh install" you really have to delete all the user folders. I believe they are in two locations and one of the locations is here (IOS is first): $USER/Library/Application Support/cura/<Cura version>/ (OSX) %APPDATA%\cura\<Cura version>\cura.log (Windows), or usually C:\Users\\<your username>\AppData\Roaming\cura\<Cura version>\ $USER/.local/share/cura/<Cura version>/ (Ubuntu/Linux) That's probably (hopefully?) the only configuration folder you need to remove although there is definitely a second folder. I have no idea where it is on the mac. If you can get cura started you can go to the help menu and it opens both of the config folders for you. No need to reinstall cura - just exit cura, purge the folders (for all cura versions) and then restart cura. It will rebuild those folders in a way that is safe (won't crash cura). However you may be right and the issue may have something do to with other IOS related updates. Either way if you still can't get it to start, please post the log file (found in the same folder above).

@thanks1976 - I think you misunderstood Nallath. There is a parameter called support horizontal expansion. I think you will find that has a value of about 3mm when you support with a second extruder. There is a good reason for this. If you have PVA support, PVA doesn't print on top of PLA very well. But if you do some horizontal expansion, then you can print PVA all the way down to the print bed and you are more likely to get a successful print. You can change this parameter yourself if you think you are smarter than Cura.

The UM2+C has I believe two computers in it - an arduino based computer that controlls the steppers and accepts gcodes from... the second, more powerful computer (think cell phone). The gcodes are all interpreted by the more powerful linux computer which then sends some of them as is over to the arduino based computer. The display is controlled by the linux computer and the M0 requires more complication because the display and touch screen need to pop up a message and when you tap the screen the printer needs to continue. Also it's nice to have the ability to control temp, maybe even change the filament, all while it's "paused". So really the linux computer has to convert that M0 into an upward movement (so the hot end doesn't melt the part) and it needs to display a message and when you continue it needs to move back down and continue the gcodes. My point is the M0 never gets to the arduino-like computer because if it did it would be bad (there wouldn't be any way to continue). I think no one at Ultimaker has written all this code yet. It's written for S3 and S5 I think but not UM2+C. I hope they do it soon but I wouldn't hold my breath. Ultimaker seems to be convinced that most of their clients (think for example factories making parts for the factory itself) don't need to pause a print and say insert a nut or magnet. Many employees realize that "pause" is very very useful to many many clients but I don't think the entire management team is on board with this idea. I'm not sure but that's my feeling. Often writing the code and getting it working is the easy part - then you have to test the hell out of it (does it break if the heated bed is off? should you cool the nozzle a little bit? And heat it up again? Do you want to implement a fancy filament change feature? Or just make them slide the filament out and in? Do you want to implement the MOVE feature to purge the filament? Do you do a retract at pause and unretract at continue? If they purge do you do a retract after purge? And so on).

I'm pretty sure Nallath is referring to the little red arc in the picture that shows your model mostly as blue and white. There should be no red. It might not matter. But that red area is non-manifold in some way. You may or may not have to fix that small spot.

I'm pretty sure it's because the model is too thin there for your settings. As a quick check - set the nozzle width to half of what it is now to see if that helps. If it does then it is related to those thin areas of your model. You can also try the option print thin walls. Check that box in cura. If that's not enough try lowering you line width parameters. If your nozzle is 0.4mm you can go down to 0.3mm line width without a severe loss of quality. Certainly 0.35mm is fine. As a general rule, any wall you print needs to be 2X the width of the line width parameter. Or at least 1X if you check print thin walls. If I'm completely wrong and this makes no difference then please post your project file (do menu "file" "save project..." and post that here).

I have good news for you - I believe that the new Cura beta (alpha?) version 5 does this (aka Arachne). Try it out. There is a good reason that cura has never been able to do this but I don't want to get into it unless you really want to know. Just trust me that it's a pretty good reason. But what you ask for has been asked by so many thousands (millions?) of people. And now I believe (I'm not certain) that Arachne can do this. Maybe. By the way you *can* print 0.4mm walls with a 0.4mm nozzle using Cura if you choose print thin walls but it still does 2 passes.

So in short - you are using the printer beyond it's expected abilities. Add a fan to your filter or just get rid of the cover. Or don't print PLA (but PLA is the easiest and the best material). That cover is bad for PLA but won't hurt if you are printing PETG and is actually helpful for Nylon (but now you are printing too hot and the teflon part in the print head won't last nearly as long). Ideally stick with PLA and remove the cover but if you really want the cover then add a fan to the filter.

If you do remove that outer wall then those very thin walls may fall over. There are several different support pattern options: grid, lines, etc. Did you play with that? It looks like you chose lines Well I tried to duplicate your support structure and I can't. I tried a whole bunch of support settings and mine don't have those walls. Please post your project file (it will contain your model, your printer settings, your profile, and your setting overrides). Go to menu "file" "save project..." and post that file here. Also what version of Cura are you using as I have to use the same version or newer otherwise the project file won't open for me.

@Smithy - does UM2+C have pause feature? I think UM3, S3, S5 all have it but not sure about UM2+C.

Sorry I've never used the backup plugin. I don't save my settings in "profiles" but instead save them in "projects" and those get backed up along with everything else I care about on my computer.

@Torgeir I don't understand what you are saying. To review, things are better when combing is turned off (more retractions happening, more hops happening). Are you saying that because the print job is slightly slower (with combing off) that the printer has more time to keep the nozzle hot? That seems unlikely - the difference in print speed is pretty small (11 minutes out of almost 4 hours).

just cut 2mm off the end of the bowden and then put it back in. No need to buy a new bowden. The S5 bowdens are significantly longer than the UMO,UM2,UM3,S3 models which have the same length bowden. Also since you are doing this on the feeder end, you should maybe chamfer the inside of the bowden using a countersink drill bit. Or even better just use an exacto blade to cut a chamfer inside the bowden to help guide the filament into the bowden. Either way, clean it up with an exacto as you don't want a tiny piece of PFA tubing making it's way to your nozzle and causing an annoying clog only fixable with a cold pull (I'm not certain but PFA probably melts at a much higher temp than PLA). The white collet has 4 metal blades in it. If after cutting 2mm off the end of the bowden, the bowden still has keeps popping off then you need a new collet. These are easy to find at reprap/3d printing sites. Make sure you get one for 1/4 inch I.D. tubing (6mm O.D.?) meant for 3mm filament and not for 1.75mm filament bowdens (4mm O.D.?). 3dsolex in Norway sells these collets for next to nothing. Plus they sell S5 bowdens (which come with the clips and collets) that have been pre-countersunk. Plus those bowdens are made of teflon so are super super slippery and can improve your printing performance.

It should print in the center by default. When you add an STL it should put it in the center. Is it printing in the corner? If so then... Go to left side of screen in PREPARE mode. Click on your printer, then do "manage printers" then "machine settings", Uncheck "origin at center". Also check the dimensions of your bed - for example, if it says your bed is 100mm wide but it is actually 200mm wide then it will be printing on the left half of your print bed. The dimensions should not be the actual dimensions of your print bed but the range of motion for the axes which may be smaller than your print bed.

Most likely you need to lower minimum layer time. By the way this is a relatively good feature - quality can go down if you don't give the previous layer time to cool but I think lowering it to 3 seconds should be okay.

Oh!! That changes everything. Do you have one of those $10 IR temp guns? point it at the back of the printer and let us know the air temp if you can. Yeah don't use an enclosure with PLA. It's hard enough to keep things cool with the side fans at full blast but a top cover and a heated bed can result in air temps around 100F which is just too hot for a UM2 series printer. I mean that's great for printing higher temp materials but not for PLA which gets soft at 52C (130F). Inside the teflon part and I think even just above you are seeing temps above 52C and that is causing the problems. You could lower the temp. I like to print much cooler (180C) when printing 0.25mm nozzle. And limit retractions. And try to get more cooling. .25mm nozzle is tricky - like geert says, the slower printing volume causes problems as you aren't feeding nice cool filament at the same rate as with e 0.4mm nozzle. Typically 4X slower (volume of PLA - not print head speed). Also doing thick(ish) layers is good. I'd do 0.1mm layers. People often want to scale down the layer height when they scale down the line width but that's a bad idea in your case. Thicker layers will increase the volume per second of PLA which helps to keep things cooler in the upper part of the hot end (where your problem seems to be). COVERS Why the cover and air filter? That's fine for ABS but you don't need it for PLA. Did some article scare you about particles in the air? I'm pretty sure PLA is relatively safe. If you read all those reports about PLA particulates carefully you will see that the original research also mentioned that candles, bacon, burger frying and french fries all create very similar particles in much higher concentrations. So worry about breathing the air in a McDonalds or burning a candle in your home or frying bacon in your home long before you worry about a few printers printing PLA. Don't get me wrong - ABS is nasty. And ABS will benefit from the higher temps that a cover will create. ABS doesn't get soft at 52C like PLA. It gets soft at 99C and you can even pour boiling water into an ABS cup and it's fine. Not PLA, lol. News agencies only make money if you read their articles so they tend to be scary: "Is your 3D printer creating dangerous particles?" Then you read the details of the article and it's like "Okay so each printer is like one candle? Pfft."

I don't have any Creality printers so I can't help you there. I don't actually sell Ultimaker's but I do sell nozzles. I know you think it's Cura but you've managed to convince me it's not Cura. Something like millions of people use Cura and I *do* listen to the issues and I understand why you are convinced it's Cura. Your thinking is quite logical. But it's not Cura. I was actually hoping it was Cura and that you found a new bug but you managed to convince me it's not Cura especially now that Greg tried your print with an Ender 3. Most likely it's a combination of underextrusion and shrinking, cooling plastic that warps an upper block off of a flat region. I've seen this in my own prints but only for ABS which has much worse layer adhesion and much worse cooling/warping. Fixing the layer adhesion issues fix this for me with ABS. Fixing the underextrusion (which may be impossible on your 2 printers) would solve this for you. Combing off means you have more retractions which means less leaking and helps out a tiny bit with the underextrusion. Raising your temp 20C may fix this for you - maybe your temp sensors are off quite a bit (or maybe your PLA just needs higher temps). But it's not Cura. I'm sorry you got crap advice in the past - where people had you fix things that didn't help your printer. Underextrusion can occasionally be a real bastard as there are dozens of possible causes. I had one brand new printer that did it and it was so frustrating. I never did figure out what the problem was (although I had an ugly solution - increase flow) and ended up returning it. Even Greg mentioned making your axes perpendicular - that's not going to fix underextrusion.

So this is a great thread! Okay so I didn't notice the Z hop but I see it now in the gcode. At first I was - it has to be the zhop because... well it does *more* hops if you turn off combing so that doesn't make sense. And I checked and there are hops on the layers below as well! So that doesn't make sense. But in general, zhop should only be used on delta printers. I strongly recommend you turn that off and if you think you need it, let me know why you think you need it. For example sometimes the head hits other areas of the print but there are other solutions to fix that. But after more thinking it's probably not zhop (unless you have it backwards and combing fixes the problem, lol, I guess not very likely!). I hope greg sheds more light on this with his test print(s). Maybe I'll print these myself but it will be on an utlimaker if I do. And none of my machines undrextrude so... I'm sure it will be print fine - well maybe not with zhop - I found that zhop turns my prints to shit.

"sponge" sounds like "underextrusion" and has too many causes. I mean here are some examples for a different printer but many of these will be relevant for your printer:

Bugs/errors will be ignored if you are the only one experiencing it. People have to duplicate it first. I have no trouble with combing and I print a LOT of parts. Your issue is very unique to me. I think the shape of the part exacerbates the problem as you have this large flat layer and then smaller parts just above that are long enough to have warping. But I don't know for sure. I'm hoping you will come up with a part that only takes an hour or two to print and experiences this issue because I don't want to print a 5 hour print to find that my printer has absolutely no issue with it. Oh good. 🙂 Looking forward to it. If I don't respond within a day please direct message me as I tend to stop checking threads that have no activity for a week.

I noticed you have 5mm of retraction. That seems like too much. On the much bigger Ultimaker 2 I use 4.5mm of retraction and that is a LONG bowden compared to the Ender 3 bowden. About twice as long. I would think around 2.5mm or 3mm would be about right? You want it to retract just enough so that the filament doesn't come out of the hot end. If it does then air goes into the nozzle and you get overextrusion for maybe 10 seconds as the air heats up in the nozzle followed by underextrusion for maybe 10 seconds when the air bubble is the only thing extruding. Although this would probably have nothing to do with your experience as you said you did better with combing off (more retractions).

@Ste_297 - this is the slowest conversation ever. Please note that I usually stop reading a thread after about 7 days so I'm adding this note just to keep it going but after another 7 days you can reply and I probably won't notice unless you send me a direct message.

lol! No I meant let it try to boot for at least 10 minutes. when you upgrade sometimes the upgrade procedure reads all your matieral profiles and translates them (or something) to the latest format for the latest firmware. That step can take 5 or 10 minutes for some reason. But seriously - severaly people have had problems with upgrades but when they power cycle the printer 2 or 3 more times suddenly it is working fine. I have no idea why.

What is the air temp in your room? Is it like 25C (too hot!)?