gr5

Those "internal supports" have two names: The primary name is "skin" and it's also called "top layers". You can simply increase top layers. You can also make the skin *wider* - search for "skin" in the settings and you will instantly see a lot of settings - the only one that won't show up is "top layers". You can also use "gradual infill" to make the infill density low or even zero for most of the part and then get more and more dense as you approach a side wall or top wall. I love this feature - it tends to reduce print time and weight by about 20% yet keep strength and good top layers/skin. For starting out try: infill density 50% gradual infill steps 6 gradual infill step height 1mm (or less!)

Call them "cores" please, not heads. 🙂 When the "bad" core is printing try pushing up or down on the glass bed to make sure we understand the issue. I'm expecting the right core is too high off the glass and so it doesn't stick unless you push up on the glass? Also if you grab the lever on the right side of the head and slide it towards you and away from you repeatedly does the right side core go up and down? Maybe I don't understand the problem in the first place so more photos/video might help me understand better.

Note that you probably logged in as ultimaker/ultimaker but you can also log in as root/ultimaker and get access to all the python files there. But I think you found what you are looking for. I'm pretty sure those the the correct values. I don't know why those are defaults when travel moves have a jerk of 50! And accel travel can go to 5000mm/s/s. It seems like you would get more accuracy with maximum jerk and accel. But you get less ringing with lower jerk and accel (ringing is visible and ugly but vanishingly small compared to other sources of dimensional errors). So I suppose it's a tradeoff - higher accuracy versus more beautiful. There are quite a few differences between the nicest looking profiles and the most dimensionally accurate profiles. Have you seen the new profiles in the beta cura? Anyway, bulging corners are caused when the printer slows down for the corners yet the pressure is still high. The simplest way to fix this is to lower the print speed down to around the jerk speed although 30mm/sec should be slow enough. Other ways are to crank up the jerk and accel. It also makes a lot of sense to cut the corners in the CAD model (and other modifications like make all vertical holes 0.4 to 0.5 larger in diameter than desired). Just bring in the corners to compensate for what the printer does. If you think it's bad for FFF printing you should see what it's like - all the crazy changes you have to do - to create an injection mold. If you want 90 degree corners the CAD model actually has to be <90 or >90 (I forget which). I assume most European and USA mechanical engineers don't deal with this as the CAD modifications tend to be done in Asia. But for FFF printing it's done usually in-house and you have to do these tweaks.

This may also help. But I didn't mention it because for 90% of prints you want this at the default 3mm for very good reasons. I guess the quick summary is that pva sticks to the glass bed well but not to pla very well (it sticks, just not well). So you want the pva portion to have a path all the way to the glass. "support horizontal expansion" often (usually? sometimes?) fixes this issue and makes a disaster print into an excellent print. Depending on your model.

By the way, errors in Z screw, Z stepping would affect both left and right nozzles equally because they are both controlled by the same Z movement hardware. So parts will be the same scale height (with a possible tiny offset < 0.3mm). Any offset > 0.3mm will not allow the print to print the bottom layer at all (either too close and bottom layer is transparent or too high and the filament won't stick to the glass at all - get dragged around).

The answer depends what printer you have. UM3/S3/S5. If you have a UM3 then I recommend you disable automatic leveling and do a careful manual level. However I suspect this is an S5. Something is going wrong with the autoleveling I think. The second head is too close or too high off the glass (you can verify by pushing up or down on the glass while it prints with the second head and filament should stick nicely). Autolevel failures are usually caused by spring issues. You basically need the spring in the cores to be stronger than the spring in the bed. This is a simplification but often one needs to make the core springs stronger or the bed springs weaker. You can weaken the bed springs by moving the bed up a bit so the 3 springs are compressed less. Try 10 rotations of each of the 3 levelling knobs, then redo manual level. You can test the cores by putting the nozzle on a postage scale and pushing down until you first start to see a tiny bit of movement. This should happen at 1.0 kg (or higher). Less than 1kg force needed means the core may have vertical calibration issues. Which model printer do you have?

Make sure "support x/y distance" is around 1mm or even higher - this will move it away from your walls. Also "support distance priority" might have to be changed to "x/y overrides z" depending on your part shape.

I've never heard of a long thin shape lifting off the bed in the middle. Usually it's the ends. Do you mean "the middle" vertically? Or half way between the two ends of the part? I guess I would reheat the part above it's softening temp (for pla dunk it in water that is around 80C (pour boiling water into a pan or dish) for about 1 minute - for ABS leave on heated bed at 110C under a towel for about 1 minute) then put it on something flat and hold it in position for 2 minutes while it cools back down into the right shape. So the layers adhere well? By the way I would never print ABS on a 95C print bed. 100C minimum. You want to be above the softening temp of ABS but if it's sticking well then 95C is fine.

The machines are more similar I think than their profiles. I would check all the settings and see what is different. Make the speeds the same speed for all printing speeds (on both UM2 and UM3). For accuracy, disable accel and jerk control on both machiens. Make sure line width is the same - pay attention to the "outer before inner walls" - make sure they are the same. Speeds the same. Temperature the same. And if you are lucky the shrinkage for vertical holes will be the same. I usually increase my hole diameters by 0.4 to 0.5 in cad and leave it at that. Another choice is to drill out the holes after. It's very easy to drill out holes when they are already within 0.3mm of desired size.

No! That's much more complicated. There are 4 screws higher up on the head. Perfectly symmetrical in a square. Remove the 2 towards the rear. That will not do much other than give you the ability to remove the rear half of the top of the head. It's a small flat rectangular piece of plastic - similar to a battery cover. That will give you access to a connector - if the cable comes partly loose (very common with UM3!!!) one possible failure mode might be the front fan not working. If the front fan doesn't work then one would expect the filament to overheat above the heat break (after a while - maybe 10 to 40 minutes) and swell up and get jammed. Especially if there are lots of retractions which help move the heat upwards in the core.

The front fan is a very serious issue and could explain everything. Remove the rear 2 screws on the print head and the rear cover will pop off easily. Push down firmly (with the head in a corner so you don't bend the rods) on the connector in there and see if that fixes the fan. Also how many hours are on that core. The teflon may have gotten old if it's say 2000 hours or more. Under 500 hours I'd say no way.

Your issue is that you aren't squishing the bottom layer enough. Squish is the most important thing to keep your part sticking to the build plate. If it was properly printing the bottom layer they wouldn't come apart like you show in the photo. I don't know how to alter the leveling on a prusa but if it has auto leveling maybe you need to turn that off and stick with manual leveling.

If you do that make sure you "play" the beginning of your print job using layer view and the horizontal and vertical sliders to see the first few moves in layer view to make sure nothing will hit your part. Note that the gantry is probably less than 127mm tall on many printers so you have to realize that your gantry may hit your part as well as the hot end (and fans, etc) because it will have to level the bed before starting your print.

There are many possibilities but most likely is that you have an error in your model such that it is skipping a layer there. Please look at the part in preview mode and step through the layers carefully and see if maybe it's skipping those 3 layers that you highlighted in red. If so then there is a problem with your model. Did you create it? If not you can just try to fix it with netfabb repair service. A free service on the web but you have to create an account. YOu could also click in the left upper corner where it "view type layer view" and change to xray view. Anything red in xray view is definitely a problem with the model but just because there is no red doesn't mean there is a problem. What cad software did you use? Most cad software will not let you create non-solid models. But a few will and they have their quirks and maybe someone here is an expert in your particular CAD.

It's actually pretty easy to dry PVA since you own a UM3. Put the spool on the print bed, set the temperature of the bed to 70C, cover it with a towel, and leave it overnight. Going forward always store the pva spool in a 2 gallon zip lock with some big 45 gram, rechargable dessicant packs.

To potential buyers: Looks like it shifted in Y only. Pretty easy to fix. It's usually a loose pulley set screw (there's 6 pulleys on the Y axis) - and usually the one on the motor/stepper which is the hardest to get to but if you have a long hex driver you can get in there without taking anything apart. Tighten the hell out of those set screws. However since this machine may have sat idle for months - I'd try cleaning the 6 rods in the gantry with an oiled rag or paper towel and lubricate with a light oil (any light machine oil will work - e.g. sewing machine oil, or 3-in-1 oil). one drop on each of the 6 rods. In theory the center 2 rods don't need oil and will just gum up the ball bearings but a tiny bit of oil can help.

I would ask on a google chrome forum how to change protection of a downloaded file to enable execution.

I don't know but I suspect cura doesn't run on chrome os. Anyway - are you sure you know the admin password? To be safe do this: sudo -s Then you should have to enter a password. Then make sure the prompt changes (ending with # instead of $). Now do an "ls" command to make sure you are in the right folder: ls Cura* then if it's there do the chmod command. Then to run it you do: ./Cura4.AppImage (or whatever the file is called).

Is this object on thingiverse? did you design it? Can you post an STL file somewhere? Or even better, do a "file" "save" from cura and post the 3mf project file somewhere. It looks solid in "prepare" mode so I'm pretty sure it will be solid in "preview" mode as well unless you tweak settings in cura (for example enable spiralize but there are other ways as well).

@super811 - what cad software are you using? First look at the settings in mesh fixes. Secondly, if this is not your model, it's actually normal to design a solid vase like this and expect people to fool with the settings. You probably want to check the "spiralize" checkbox which is designed to turn solid vases into vases with sides and a bottom but no top. Read the comments about spiralize (hover over the feature for a popup that describes what it does). Spiralize is meant for vases and cups mostly.

okay. Strange. Let's clarify: 1) Do you export 2 STL files from autocad? 2) Are the two files exclusive? I mean in the image just above the blue cylinders pass through "holes" in the yellow part, right? At no point are both materials occupying the same space? if not then you need to do a boolean operation where you subtract the blue part from the yellow. 3) I suggest you play with all the "mesh fixes". Please make all mesh fixes options visible and then look at each one and toggle the value if it even remotely might have something to do with this. Looking them over, any one of them could be related but the most standout one: "alternate mesh removal" is very likely involved - you probably want to uncheck that. Read what that does - it sounds a LOT like what is going on here but it should not be a problem if there were no bugs.

When printing ABS I recommend using "abs glue" which is a mixture of abs filament and acetone. let the acetone dissolve the abs for a while in a sealed container like a glass jar. Then paint it on the build plate with a paint brush and let it dry. Almost as good is to use PVA wood glue - just any version of elmer's wood glue mixed with about 10 to 20 parts water. Paint that on clean glass and turn on heated bed to 100C and it will dry long before temp gets to 100C. Leveling with gauge is not ideal - you want the bottom layer to squish a bit - so I tend to level low. The harder it squishes the bottom layer, the more it sticks. Regarding underextrusion/grinding this is more complicated as it could be the feeder or many other things. Unfortunately I have a very long list of things to try and test. Here's the list (yeah - it's long). Brittle filament is indeed one of the possibilities. Printing too fast is another. I'd start by trying a different core. CAUSES FOR UNDEREXTRUSION ON UM3 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. 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. 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. =======

I thought "give it a shot" possibly meant you were going to just print it blindly. I'm glad you know about preview mode.

To potential buyers again: A 2 year old UM3 is just fine - it doesn't age if you don't use it. Just wash the glass thoroughly with glass cleaner. Yes the filament can get a little more brittle but I've learned to deal with that and regularly use 2 and even 5 year old PLA. Also the PVA will need to be dried but that's easy - put it in a box on the UM3 heated bed, set to 70C, cover in a blanket or towel or something and leave it overnight.

"give it a shot"????? You should know about "preview" mode at the top center of cura. In preview mode you can see what your printer will be doing and you can see if a setting in cura has properly taken place. Use the slider on the right side to view the bottom few layers to see if infill will be visible or if the bottom layers will be sealed. Never print something without checking it in preview first.