gr5

This is a common problem and easy to fix. One thing you can often do is bend the fan back in by squeezing it but from the photo it looks like it's all the way in. The other cause is the homing switch - it may have moved recently. Push the head around by hand and when it is all the way to the left you will hear a click. That's the homing switch. Locate it - it's in the left top rear corner. Just above it are 2 screws. They may be loose. Loosen the screws a bit and slide the switch to the right and re-tighten. This homing switch sets how far to the left the head will go - the max position. You can also bend the metal part of the homing switch. But it can break so do it carefully. You can also glue something on to that metal tab of the homing switch - like a few sheets of paper or a toothpick or something 1mm thick (you only need to move the head to the right by 1mm when homing to avoid scraping).

@Paul-G - it's quite easy to search for the letter "Z" in the gcode as the Z is only moved about once per layer (unless you have z hop turned on) and also burtoogle is extremely competent at this sort of thing. So I'd say you would have been find to print it.

Maybe the log from cura would be more helpful than the event log. Also when you first run Cura it installs a lot of files and when you uninstall it those files are not deleted. They are in %appdata%/cura or similar location. If you want a "clean install" all you have to do is exit cura - destroy that folder tree - and rerun Cura. No actual install necessary.

second thought - could the heavy stuttering be doing tiny infills all around the cylinder and not from the skin walls? If so there are improvements in that area also in the burtoogle version of Cura. You could give that a shot.

Yeah I'm used to Ultimakers with 5000 to 9000 acceleration. Bowden printers have much higher accel as the print head is light weight. Can you upgrade the firmware on the printer to do 16 gcode look ahead? Or even better, put a duet controller on there - are you familiar with duet? Very nice controller - easy to use - very easy to setup for a new printer. It's just a delightful interface. I'm told (I don't have one). Or possibly resign yourself to printing 35mm/sec max speed. Or use prusa slicer. Or.... there is "max deviation" and "max resolution". Try doubling those. It might reduce quality. Really it's better to reduce resolution in fusion. I'd look at the STL in some other software to see what they actually look like visually. I wouldn't be surprised if the resolution is still 10X higher than needed in your current STL. @burtoogle - I don't play with "max deviation" and "max resolution" but wasn't there some improvement you made recently? Or Ultimaker did? If there is an improvement - did it make it into the latest Cura?

Seems like the right track to me. Seems like we are thinking it's the same or similar thing. It could be the prusa slicer does this better (reduces gcodes).

Look at the gcode for a known stuttering circle (a known layer where it does it - I predict it won't do it every layer). How many gcodes for a circle and how big is the circle? You wan't the buffer length of the printer (really? Only 8?) to be long enough that the printer can go from full speed (e.g. 70mm/sec) to stopped in that distance. It depends on the acceleration. Say it's really slow - 1000mm/sec/sec. You can get 0 to 70mm (or back) in 2.45mm. So you don't want more than 8 gcodes in a distance of 2.45mm. This is almost surely the problem. If the acceleration is 2000mm/sec/sec you can get from 70 to 0 in just 1.22mm (wow - I didn't expect it to be linear). If you want to go 35mm to 0mm with acceleration at 1000mm/sec/sec you only need 0.61mm. Wow - again it appears to be linear. Not what I expected. Anyway you get the idea - having half the buffer length and possibly lower acceleration can make a big difference and cause stuttering. So in your cad you could just output fewer triangles to the STL. I've seen some crappy STLs where hundreds of triangles converge on one point (on a cylinder part). Most cad won't do that. But you can have 100 short gcodes just above and below that point all within 1mm. Makes the printer almost completely stop.

Interferometers? Here's my interferometry video channel. Some of these videos are better produced than others but I put dozens of hours into all of them. Except the shortest one. These interferometers measure telescope mirrors to test them - it's for people grinding their own mirrors (small market worldwide). https://www.youtube.com/channel/UCvz4goKtjouHwmS-qAjp8Tw/videos

Did you follow the instructions in the link then? PC or MAC? do you get the 2 tones mentioned in the link? What com port number does it show up as (latest cura *seems* to have trouble with com ports > 10 or so? Not sure).

@Tafelspitz - if this happened to you once, it will happen again. It's not hard to get nylon to stick very well to heated glass. Key elements are: 1) higher bed temps are better up to around 100C - usually 80C is plenty hot and that's what I do. Nylon gets softer and softer the higher the temp but still quite firm (like putty) and then eventually melts around 120C. 2) Squish - this is most likely what you did wrong - see video 3) Use brim 4) Use one of 3 PVA glues (if you use glue stick - you must thin it to get extra good sticking but thinning shouldn't be mandatory for Nylon except maybe extra large parts or if you aren't using brim) Better details here:

If the brass got red hot then beware that it will be softer going forwards which doesn't affect printing but means you have to be careful when changing nozzles. Try not to go over 1 Nm of torque. For example if you use a 7mm socket but no wrench - just socket in your fingers - 1Nm is about the limit of torque an average adult can produce using absolutely all your finger strength. I can't quite get 1Nm.

That's not good. That just speeds things up. This is called stringing and you shouldn't get any stringing for most filaments including PLA. I find white PLA (and all white filaments) string more than others but I usually get zero stringing. Settings that affect stringing: retraction - you want to retract just enough to relieve the pressure without letting any air into the nozzle. Around 4-8mm for bowden printers (more for longer bowdens) and around 2mm for direct driver printers. Temperature - lower temperature is better - more viscous - less leaking Nozzle size - smaller nozzles drip less print speed - higher print speed means higher pressure which means you need more retraction - it's best to just print slower and not mess with retraction

Well I've been very happy with my UM2 series printers (I have 3 that I use regularly).

You should never have to go above 20% infill with line width set to 0.4mm so I'm not sure how setting it to 40% changes anything. Anyway you can use variable infill - it's a great feature in cura that saves lots of time (zero infill then gradually it steps up to the max infill you desire which can be 40% or just 20% or whatever).

I don't know much (anything) about your particular printer so I'll give you the list for the UM2. 80% of these items relate to other printers. Particularly issues about room temperature, too many retractions, printing too fast (volume, not speed) and so on. CAUSES FOR UNDEREXTRUSION UM2 AND HOW TO TEST FOR THEM AND REMEDY THEM One can quickly check the feeder (it takes seconds) so I would always do that first. The feeder on UM2+ and UM2 can push with 10 pounds (5kg) force easily so first thing is to lift that lever (if um2+, if um2 regular do move material) and insert filament so it is only part way into the bowden (e.g. half way). Then move the filament with "move material" command in menu so the feeder is energized and then pull down on the filament under the feeder. You should be able to pull with 5 to 10 pounds force without it slipping. Then have it move the material up while you pull down. 5 pounds force (2kg) is enough to make decent prints at moderate speeds listed below but you need 10 pounds (5kg) to print fast (e.g. 0.2mm layers and 60mm/sec) 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. Simpler cold pull: https://www.youtube.com/watch?v=u07m3HTNyEg 😎 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. 21) Firmware settings - for example UM2+ firmware on UM2 or vice versa will cause 2X over extrusion or 2X underextrusion. Downgrading or changing firmware can mess up steps/mm and other settings - so if you updated firmware and then problems started then do a "reset to factory settigns" which corrects all the steps/mm values. 22) 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 and 8mm for S5). 23) 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. 24) 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 25) Other feeder issues. You can test the feeder by putting the filament only part way down the bowden and with the feeder electrically turned on (or moving) pull very hard on the filament until it slips. You should be able to pull with about 5kg or 10 pounds of force before it slips. 4kg is acceptable. 2kg is a problem. If the stepper motor isn't engaged you can try going into the move menu. After a minute or so power is removed again from the feeder stepper. 26) Meduza - some people who install the Meduza feeder upgrade (2x the pushing power versus standard black UM2 feeder) make the belt so tight that the printer starts underextruding - typically as the circuitry heats up the extruder driver has less and less power and extrusion gets slowly worse over the course of 10 minutes or so.

I don't recommend Cura for USB stuff. What are you trying to do? Print through USB? Doesn't that printer have an SD card slot? It's much more reliable to use the SD card for printing. But if you must, then use prontrface/printrun instead and let us know your issues. usb debugging:

Isn't that good? Are you saying it prints top layers but you don't want it to?

OMG - Why is @FendrychDesign and I the only people who see this serious problem!!!! I complained about this issue A LOT early on when Cura 2.X came out. It STILL DRIVES ME CRAZY. Okay here is the problem with keep/discard. It is unclear if the question is asking about the new profile or the old profile. That's it. That's the entire problem. Let's say I was on profile A. I changed the temp. Now I load profile B. It pops up the keep/discard question. It used to be worse - the wording is better but still confusing. So here are possibilities "Keep" will modify profile A. Is that what it does? No. It makes sense that this is what one would expect though. "Keep" will copy the overrides that I just did into profile B. Is that what it does? No. "Keep" will load profile B and override the same settings you did on profile A. Bingo! "Discard" will leave profile A alone (not save changes). True but that's not the intended meaning. "Discard" will not apply overrides/changes to profile B. YES - this is what actually happens. Instead it should say something like "discard/Apply" or "transfer". "Apply will apply/transfer your customizations to this new profile without actually updating the new profile permanently". The key thing missing in the whole description is which profile (a or b / new or old) is being modified.

I'm guessing your normals are backwards. If so, the post above should hopefully fix it. It's possible you also have missing surfaces. In blender - did you put inner *and* outer walls in the tube of the bong? You specify the wall thickness by having two cylindrical surfaces. If you only have one surface then the bong is infinitely thin. So in summary, there are two critical things: 1) Make sure the part is manifold (no holes). 2) Make sure all the normals are correct. Here's another explanation of normals. Normals tell you which side of a surface faces air and which side faces plastic: https://www.sculpteo.com/en/tutorial/prepare-your-model-3d-printing-blender/

if using blender - here's how to fix your model

Yeah this is a hardware issue of some type. What kind of printer is it?

The bottom of the nozzle has a flat area around the hole. Like an iron. so if you overextrude (up to around 200%) it will still flatten it out (if it fits) such that the bottom layer is no thicker than it's supposed to be. I suppose in practice it's possible that the bed/stage is pushed down a bit and the bottom layer is thicker. But I don't think there is enough pressure through that tiny nozzle tip to do that so mostly the filament should slip a bit in the feeder to compensate for some overextrusion. I personally compensate for the "elephants foot" by using "initial layer horizontal expansion" set to a negative value. This allows the bottom layer to be squished nice and hard for good adhesion yet avoid the elephants foot. For a 0.4mm nozzle I set this to about -0.25mm but it matters how much you are squishing that bottom layer and you have to be aware that if your part has small features on the bottom layer they might not get printed at all which will give very bad results (second layer printed over air). So check the bottom layer in PREVIEW mode. The second layer is usually fine for me without any flow adjustment.

I'm not certain but I think you can completely remove the white PCB and hook it up only through the USB and it should still power the arduino and also program it. I know someone who had a UMO was able to remove the arduino (it's socketed) and program it and put it back onto the printer and got it working again. I'm not sure this works with the UM2 but probably it does. If you own any arduinos ($5 on ebay) you can plug one into your computer and usb cable and program it up using the arduino IDE or you could get an arduino mega2560 (probably more like $20 on ebay) and try to load the UM2 firmware onto it (won't hurt anything). This will verify that the software/drivers/computer/cable are all working and it's something with your UM2.

Well it sounds like you somehow destroyed the arduino chip on your PCB. This seems so unlikely from your description but it's the explanation that makes the most sense right now. You can get crappy (in that it's more work - you have to buy separate servo drivers and tweak their current without damaging them) but cheap UM2 boards from China or you can get the real thing from igo3d.com in Germany.

I do a LOT of printing of parts that use M3 screws (3mm diameter metric steel machine screws). The same button head screws that are used in the Ultimaker printers themselves. I typically make the holes too small, drill them out and then let the screws self tap. If the screw is longer than 1.5cm I usually go half way and do another screw and then come back to it. With the electric drill. This gives the heat time to enter the steel screw and prevents it from melting the PLA too much. I also have a "real" tap but don't often use that. It makes it much easier to screw in and out later if you have to tighten and loosen a screw often. I have sold about 30 laser interferometers. Each with 4 self tapped screws in PLA. And stages - those also have an additional 2 self tapped screws. I have one interferometer for myself and I've loosened and tightened some of these screws 100 of times over the last 2 years and I haven't had a problem.