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Is this the newer UMO with the white circuit board? If so it is expecting a PT100 temp sensor. And kind of temp sensor is this? There are so many types. For example a lot of people use thermistors for heated beds because they tend not to get much hotter than 150C and many thermistors can't handle temps over 150C. Or some people use PT100 or some use thermocouples. It matters. And although every PT100 out there has the exact same table that translates resistance to temperature, that is not true of most thermistors. Company A might sell 3 different types of 100K thermistor and company B will almost certainly sell a thermistor with a 4th type. They are almost all different. You need to know exact brand and model number of the thermistor and then make sure the UMO firmware has the right temp table.

That's underextrusion because the nozzle is too far form the glass. Simply turn the 3 leveling screws CCW 1/2 turn to move the glass closer to the nozzle. Don't bother rerunning the leveling procedure.

Try cutting the end of the PLA filament to a point using two angled cuts with a wire cutter. I'm guessing it's just getting hung up at the transition to the teflon or the transition from teflon to block. that happens to me all the time if I don't cut the tip to a point.

I've never used the sheets. Can't help you there. Can you show a photo? I don't understand the question about support structure being knocked out of place. If you print ABS on glass I recommend a layer of pva glue - for example hair spray, wood glue mixed with 10 parts water, or glue stick cleaned up with a wet tissue leaving an almost invisible layer behind. Glass in the freezer works well because glass doesn't expand much when heated compared to ABS or PLA (why are you using ABS by the way? Maybe PLA will fit your requirements? PLA is pretty amazing stuff and much easier than PLA). These sheets probably *do* expand/contract with temperature so putting them in the freezer probably makes no difference.

You have support turned on. You don't need it on this part. More importantly you don't *want* it on this part.

This is pretty normal. The wave effect means you are too close but you want to be "too close" because if you don't squish the first layer well then the part won't stick. that stringing is so thin you can whisp away thousands of those to nothing in 1 second with a heat gun. If you still get lots of stringin on higher layers possibly lower the nozzle temp by 5C to 10C but that stringing looks pretty minor. You should see more typical stringing, lol, which can be a pain to clean up.

Okay. Well underextrusion is not so obvious on walls. It still looks like underextrusion so here's my list. Look through it. If your printer worked fine for a while but then started doing this then it's probably #3. CAUSES FOR UNDEREXTRUSION AND HOW TO TEST FOR THEM AND REMEDY THEM 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. 2) Shell width confusion. Shell width must be a multiple of nozzle size (in cura 15.X. In cura 2.X it doesn't matter as much but still makes a difference). For example if nozzle size is .4mm and shell width is 1mm cura will make the printer do 2 passes with .5mm line width which is possible but requires you to slow down much more to make a .5mm line out of a .4mm nozzle. If you really want this then set nozzle size to .5mm so it's clear what you are asking Cura to do for you. 3) Isolator - this is most common if you've printed extra hot (>240C) for a few hours or regular temps (220C) for 500 hours. It gets soft and compresses the filament under pressure. It's the white part touching the heater block. It's very hard to test when not under full pressure (spring and bowden) so sometimes it's best to just replace it. Also if you notice parts of it are very soft (the blacker end where it touches higher heat) then it's too old and needs replacing. 4) Curved filament at end of spool - if you are past half way on spool, try a fresh spool as a test. 5) curved angle feeding into feeder - put the filament on the floor -makes a MASSIVE difference. 6) UM2 only: Head too tight? Bizarrely MANY people loosen the 4 screws on the head by just a bit maybe 1/2 mm and suddenly they can print just fine! Has to do with pressure on the white teflon isolator. 6b) UM2 only: Bowden pushing too hard - for the same reason you don't want the bowden pushing too hard on the isolator. 6c) Um2 only: Spring pushing too hard. Although you want a gap you want as small as possible a gap between teflon isolator and steel isolator nut such that the spring is compressed as little as possible. 7) clogged nozzle - the number one problem of course - even if it seems clear. There can be build up on the inside of the nozzle that only burning with a flame can turn to ash and remove. Sometimes a grain of sand gets in there but that's more obvious (it just won't print). Atomic method (cold pull) helps but occasionally you need to remove the entire heater block/nozzle assembly and use flame. I found soaking with acetone does not help with caramelized pla. Even overnight. Maybe it works on ABS though. 8) 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 9) feeder spring issues - too tight, too loose. On the black UM2 feeder 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. On the white UM2 plus and UM3 feeders you usually want the tension set in the center. 10) 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. 11) 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 11b) 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 "plus" upgrade or using the IRobertI feeder helps you feel this with your hand by sliding the filament through the bowden a bit to see if it is stuck. 12) Hot weather. If air is above 30C or even possibly 25C, the air temperature combined with the extruder temperature can soften the filament inside the feeder such that it is getting squeezed flat as it passes through the feeder - this is obvious as you can see the problem in the bowden. The fix is to add a desk fan blowing on the back of the printer. Not an issue on the UM3 or UM2 "plus" series. 13) 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. 14) 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 i nsert filament that has the pattern from the feeder. 15) 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. 16) 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. 17) 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 - maybe there is a temp sensor built into the driver chip? The solution from Ultimaker 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. TinkerMarlin lets you set the currents from the menu system or you can send a gcode to lower the current. Ultimaker lowered the default currents in July of 2015 from 1300ma to 1200ma for X,Y,Z but left extruder at 1250. Other people (I think the support team of a major reseller but I forget) recommend X,Y,Z go down to 1000mA. M907 E1250 Above sets the extruder max current to the default - 1250mA. So try 900mA. This will only change until next power cycle so if you like your new value and want to save it use M500. You can just put these into an otherwise empty gcode file and "print" this and it will change. Or get tinkergnome marlin! You will wonder how you lived without it: https://github.com/TinkerGnome/Ultimaker2Marlin/releases M907 E900 M500 18) third fan broken. This tends to cause complete non-extrusion part way through a print. In the rear of the head for UM2 and the front of the head for UM3. 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. 19) 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 nozzle 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. 20) non-standard or bent fan shroud. Sometimes people print some fan shroud off of thingiverse or youmagine out of PLA or ABS. Some of these are great but most of them are crap. One needs to do good air flow modeling. Also if it's PLA it will slump and direct air differently. Air directed at the block or nozzle can cause severe underextrusion and also sometimes HEATER ERROR. Put the original shroud back on or just turn off the fan to prove that the fan is the problem.

I've found PLA is quite good. I have PLA items a few years old and they still seem as good as new. I really don't know for sure but maybe it's only if you bend the material severely that it ages. I guess I *have* heard people say you can't for example use PLA as a link in a chain that will hold something up for years. The stress I guess after many months becomes a problem. But if you are printing a knob that only withstands large forces for a few seconds per day (like when opening a cabinet with a knob) you should be fine. Or a model that just sits on a desk. Maybe butter knife that you use for an hour ever day to spread butter would be a problem?

Can you show a photo or screen shot of what you are talking about please? Is the problem visible in layer view or is it fine in layer view but you can see the problem only after you print it?

Here's another thing - in Cura - with ABS profiles, it lowers the fan to about 50%. That's great for UMO and UM2 but for my UM3 that is the exact same fan speed as 100%. My fan speed doesn't start dropping until around 10%. so for ABS on UM3 you need about 3% fan. On a UM2, 3% fan won't even rotate. There's just lots of details like this.

colorfabb sells 2.2kg spools. I put them on the floor. It's really not that hard to pause a print and change filament - just practice once. It took me at least 20 prints in ABS (after 1000 in PLA) to get prints that weren't totally useless. ABS is a whole other level harder than PLA. You really need to enclose the printer to bring air temp up to 35C minimum (or a bit hotter). And you need the bed at 110C and I can't get mine that hot without enclosing the whole printer. You need to squish really well into the glass, you might need a few days of messing with the glass to get it really really flat in the corners - if you don't do that one of the rear corners will lift. You need to get temperature PERFECT. ABS has a very narrow print range. 5C too hot and it clogs the nozzle and print fails (you can recover a failed print if you keep the bed hot while you repair things). 5C too cold and the part looks just fine until you drop it 1 inch and it cracks because layer bonding sucks. Too much fan and layer bonding sucks. Not enough fan and it doesn't bridge well and overhangs suck. Basically things are hard enough with PLA but printing a full size print with ABS I would say 98% chance your print will fail within the first 4 tries. PLA is so much easier - you always want 100% fan. There is a 40 degree temperature window. It sticks better and warps less. It's still tricky to get the bottom layer squished nicely so it sticks to the glass well.

Cura 3.* doesn't print through USB anymore [edit - not true. Cura still does]. So you have to save to a SD card or you have to use other software like pronterface for that step.

It looks like under extrusion but it could be you don't have enough top layers. It's about 50% underextrusion if that's the problem. How many top layers do you have? If it's doing ugly walls also - with some holes - then it's an underextrusion issue and I'll give you my complete list of possible causes.

That's cool. I use OpenSCAD sometimes. I didn't know about the import function. I might do that next time I need to edit an STL.

Okay well then some of the mess on the robot is support but the main issue is underextrusion. 60mm/sec at 220C and .4mm nozzle with 1mm shell (.5mm forced out of a .4mm nozzle for two passes) and assuming .2mm layer thickness - well that's too much. Try forcing cura to do .4mm line widths and make your shell either .8mm or 1.2mm. Usually the 1mm default works fine so I'm not sure what cura defaults are. Anyway try messing with the TUNE menu while it's printing the robot and cut the speed down to 50% and then try 25% and then 10% and see what speed it prints fine at and report back. You may have something wrong with your printer that is causing underextrusion or it might have just been a bad slicing. But I won't know if the printer is exceeding it's ability unless I know layer height as well. Basically I know at a given temperature what the volume can go up to. So at 220C you should be able to print PLA around 3 to 5 mm^3/sec through a .4mm nozzle. 5 on a brand new printer but 3 is still reasonable. If you can only print 1 cubic mm without getting underextrusion then something is definitely wrong and we can go from there.

If you want it really clean it's best to disassemble and remove the Z screw and clean it with WD-40 above newspaper and then dry it well and then add one drop (one pea sized drop) of grease. Best to clean the Z nut as well.

The middle two photographs show horizontal layer lines. Random layers that are over extruded (stick out) or underextruded (stick in or even have holes). This could be caused by varying width filament (extremely unlikely) oscillating temperature (slow oscillation - over one minute oscillation) also not particularly likely, or Z issues (most likely). Try cleaning the top of your Z screw (the part used for the first 3cm of printing a small part) to see if that helps - realize that it is a triple helix so only following one thread with a q-tip and you will miss the other 2. Not that a q-tip is the best tool necessarily. Your fingernail or a toothpick and some tissues are a good start. Below is a before and after with just ONE MINUTE of cleaning:

Well the first 2 images could be non-perpendicular axes - look straight down from above on the head and see if visually the 2 thin rods that go through the head are perpendicular. Push the head to the 4 sides and make sure the wooden blocks stop the same distance from the sides. But more likely the problem is play. The last 2 photos are definitely showing play aka backlash (you can look it up in wikipedia as it is a technical term). On UMO play is usually caused by loose belts (I know you printed tensioners). It can be caused by anything too loose. So gently push the nozzle around without letting the belts move and see how much the head moves. It could be a problem inside the head itself. But usually it's the long belts. Also paradoxically this can be caused by belts too tight or too much friction. The end caps on the 4 large rods can be too tight making it difficult for the head to move. Push the head around and feel the friction. Clean the rods with cloth or tissue and put one drop of oil on each rod. The two axes should have identical friction and you should be able to move the head easily with one finger on the left block and one finger on the right block for example. This leaves the long belts. Sometimes the printed tensioners are not enough. If you put the head in the corner and pluck the belts and use a guitar tuning app on your phone pitch should be around 100 to 200 Hz. More details on why backlash causes what you see in the final photo: https://ultimaker.com/en/community/2872-some-calibration-photographs#reply-15474

Did you set infill to 100%, and if so why? 20% is usually very strong. I guess it would help to show the model. I have never printed > 30 hours but many people here have printed 4 day prints and longer. I don't recommend printing something that big the first 100 prints as there is a lot to learn about using the printer. A lot of things can go wrong and that would such a waste. Better to do 100 prints that take less than an hour to slowly become an expert. Also consider breaking the print up (can you show a photo of it?) into multiple parts. You can change filament part way through a print. But you should practice that. I haven't tried it but I think you go to TUNE and then PAUSE PRINT and then while it's paused I think there is an option to change material or you can just pull it out and put in a new one and prime it.

@Tomhe - any comments about the above post and the post further up with close up of filament showing cracks? In particular: What makes filament brittle why when one straightens the filament for 8 hours or so does that make it suddenly brittle Why is older filament more brittle (is it water related, age, outgassing, micro fractures?) An experiment on UM filament that is very interesting (watch the 40 second video): https://ultimaker.com/en/community/17102-why-did-the-filament-break#reply-120629

So it looks like the X axis is probably moving fine (and the extruder and Z axis) but the Y axis appears to not be moving much. I think it's probably a loose pulley set screw. The Y axis has 6 pulleys and 3 belts. These are the ones on the left and right side of the printer that run front to back (that's 4 of the pulleys) and then 2 more on the short belt to the motor in the back left corner. Usually the problem is on those 2 that are harder to get. Hopefully you have the hex screwdriver or an L shaped allen wrench that fits those set screws. You can push the head around until the set screws line up. Then tighten them hard. Very hard. If you are using the green and black hex driver you can probably use your full strength. If you are using the little L shaped wrench your fingers should hurt after you tighten them. That hard. You can also take a sharpie and mark the shafts and pulleys on the short belt to prove that they are slipping. Your's seem to be slipping so bad, with power off you could try pushing the head to the front and rear of the printer and notice that the stepper doesn't always rotate.

Would this help? https://ultimaker.com/download/272/Ultimaker%20Original+%20Assembly%20Instructions%20v2.pdf

Oh. mind blown. Okay I guess maybe it's not a loose pulley after all. I really need to see this from a few more angles. Maybe the bottom view? It looks like part of the part is straight and another portion is crooked? That doesn't make sense - usually crookedness happens because the printer shifts a little on each layer. But here it looks wrong on a single layer. I'm confused now. Did you look at this part in layer view by the way? Does it look fine there? @neotko's suggestion of tilted X/Y makes sense - except the bottom half of the part looks straight? Or is it just a strange camera angle fooling me? You can see the tilt easily by looking straight down and pushing the head to the 4 sides and looking at the two rods that go through the head and also checking if the end blocks hit at the same time when you push the head to an extreme.

Most of my data comes from this amazing research here: https://ultimaker.com/en/community/17102-why-did-the-filament-break#reply-120629 But after reading that my experience completely agrees - usually the problem only happens on older filaments and only the portion of the filament that was straightened for a few hours. Sometimes it cracks a few times in the bowden but most often it cracks right where it goes into the feeder. In my experience. All locations where the filament has straightened. Having it crack in the bowden is bad because it usually gets stuck when the crack area gets into the print head. My solution is to not allow old filament to stay inside the bowden overnight.

Yes. Exactly what I suspect as well. And parts made from old filament seem fine but I haven't done any mechanical testing on old filament versus new. I've done lots of mechanical testing but not on old filament.