gr5

It's somehow getting the max acceleration or max speed of E or Z axis confused with XY axis. It looks at the distance it needs to move in XY, E and Z. It tries to figure out which axis is the limiting axis and it usually correctly identifies XY axis and it uses that axis accel/jerk limits and applies this to all the axes (for example if XY jerk is 20 and XY is limiting axis then XY axis moves with jerk of 20 but E axis may be moving 1/10 as far so it's jerk is set to 1 and D axis may have be moving 1/2 as far in this move so it's jerk is set to 10 in this move. Then it does a similar thing for the accelerations and max speed. Somewhere in this logic it messes up and instead of limiting XY jerk to 20 it sees that E jerk is 10 and then says XY moves 10X as far so sets the XY jerk to 200. Or similar with the acceleration. Something like that. The code is complex and confusing. If you set jerk to 200mm/sec then it will go from 0mm/sec to 200mm/sec instantly (infinite acceleration, infinite true jerk) which won't work and it will skip steps. It would be easy to fix if I understood the problem - I think setting feedrate to 1mm/sec might fix the problem. Or better to just not move 4 axes all at once. Ideally it would be best to understand the bug 100%. The code is here: https://github.com/Ultimaker/Ultimaker2Marlin/blob/master/Marlin/planner.cpp I think around line 840-860 but I could be totally wrong and it's a bug somewhere totally different.

Yes. You can also "easily" calibrate and determine the K value by printing a bottom layer pattern on glass and taking a photo. I would draw a large open square with 3 90 degree turns and do this at various speeds (10mm/sec, 40mm/sec, 150mm/sec). It's known what the jerk and acceleration values are so knowing that and the speed and looking at the line widths you can figure out K. You could also add a few extra lines like ruler lines to help judge the scale (near the corners of the square. You want a large square to get up to pressure before you hit the corner. Alternatively (maybe simpler?) you coulddo a 10mm/sec line and then go around a 90 degree corner and do the second line at 50mm/sec. With that huge speedup you should see thinning of the line at the corner just like the previous pattern would have thickening at the corners due to slow down. Anyway from a photograph of that result you could measure line widths and get a good approximation for K. Then turn on "the feature" with that K value. Alternatively you could do several patterns with 3 different K values and have a user say which pattern looks the best at the corners (left, middle, right pattern). Then use the best K value going forward.

No there is almost certainly a bug in Marlin. Is there a way to have fewer axes moving at the same time? Or just lower the feedrate (speed) to the maxv of the slowest axis on multiaxis moves? I think Marlin is ignoring one of the "max" parameters - either max accel or max speed - but only on multiaxis moves. Usually X and Y are the limiting speed factor because usually the extruder hardly moves at all compared to those axis and the Z axis usually doesn't move at all or in spiralize it moves a very very small amount. It's only when Z or E axis moves longer distances and simultaneously X or Y move very small distances. I assume. Right?

That's the X motor but you do have a point about the pulley.

Actually you don't need retracts at all if you implement this properly. It's kind of built into the whole thing. There's two ways to implement "advance". Most people get the idea to modify the extruder such that it accelerates faster than the head accelerates and decelerates faster and so on. But alternatively you can have the extruder run at a reasonable position and have the XY lag instead - have the XY accelerate *slower* than the extruder and so on. Have the XY pause briefly while extruder builds up pressure and so on.

You have underextrusion on some of those layers - the layers that split and also the layers of lighter color - second picture from last above. That's probably causing all of your issues. Lots of things can cause underextrusion. The most likely are: 1) The white teflon coupler - consider replacing it - you should have gotten 2 spares with your printer or you can get some at 3dsolex.com - not expensive. But if you print only ABS you might want to get the IPM. 2) spool of filament getting near the end - with the higher curvature towards the end of the spool it takes much more force to get it through all the parts. consider moving the spool to the floor and printing more slowly (half speed). 3) Change in settings - did you recently speed up your prints? Or lower the temperature? I assume not - but it's also possible your temp sensor is falling apart very slowly - they tend to read high (higher resistance is higher temp and if the connection is loose they tend to read easily 10C high or 20C high or even worse meaning the nozzle is much cooler than you think). You can test with this video if you have a piece of PLA laying around:

Oh - well the old forum is still there so if you want me to delete something let me know. It's read-only but perhaps I'm allowed to remove photos: http://oldforum.ultimaker.com/

foehnstrum is giving a talk in my home town about his tool changer! Check it out: http://www.fab11.org/workshops/ops304/ Maybe I'll crash it and ask some difficult questions?!

No - those are different. Fan speed can be set in cura and it puts fan speed gcodes in the gcode file that goes onto the SD card. You can open it in a text editor and see that. When you go into TUNE and look at fan speed it shows you the current fan speed - you can change it. But as it goes through the gcode if it hits a fan speed command it will obey the gcode and change the fan speed at that moment. Also your material settings on the UM2 series has a fan % that modifies the fan speed by that percent I believe - I'm not sure how that works as I always do 100% (PLA - really only ABS needs lower fan speeds). Temperature is same as fan speed - there is a gcode or you can change it in the tune menu but if you used a plugin that modifies fan speed the gcode will change the fan speed back. Also by default the fan speed comes on slowly on each layer until it gets to 100% so if you turn fan to 100% on first layer it will probably go back to whatever gcode sets it to on the next layer. diameter is usually set on the machine, not in cura - at least it does in "ultigcode" mode. When you tell cura your machine is UM2go it assumes you want "ultigcode" which doesn't specify filament diameter - instead that is set up on the um2 in filament properties. it should default to 2.85 which should work fine - I haven't touched that ever.

That's normal. The 3 parts on the left have relatively easy bridging but that hole in the right 2 parts (I know I'm counting the same part twice) is extra tricky. Can you flip these parts over and print them the other way or some other direction down? The trick for these "bridging" issues if you have to do it is to use lots of fan, print a bit cooler and use an extra good quality filament but this is actually pretty good - I've seen filaments that do much worse. You could put in some support - for example a cylindrical wall that supports that round hole would help the layer that looks bad - and if you do it right (maybe it's just .2mm below with a gap) then you might be able to just break off the support. But like I said - best to rotate a different side down.

That's interesting but you shouldn't think about it as a simple lag time there actually is zero lag time as the speed of sound through PLA from feeder to extruder is negligible - you should think about it as controlling the pressure. You want a higher pressure when you are printing faster and a lower pressure when printing slower. You need to add extra pressure depending on the extruder acceleration. But you need to modify the pressure instantly if you change the acceleration instantly and Marlin only allows instantaneous acceleration changes (no true jerk control). Marlin allows some instantaneous velocity changes but it's limited to the "fake jerk" parameter. Just read Bernhards stuff linked above - it's very interesting. Especially the graphs. But keep in mind that the Y axis is velocity not position - this takes some time wrapping your head around it. I think you could do it possibly on an arduino if you put some of the smarts into the slicer. But the slicer and arduino would both have to know a constant for how much extra velocity you need on a given acceleration.

Like he said - embed img tag inside url tag. The problem is now I have to first upload all my images somewhere before posting to ultimaker. It only takes 30 seconds but it's an extra step I'd love to skip.

These printers turn from rectangular box like shape into parallelogram shape during shipping. This often affects the print quality. if one corner is higher then the 4 bars over head are probably not in the same plane but are in a saddle shape. When printing large parts and printing the brim or skirt - some times you can't get it quite level because 3 points leveling is not enough. This can be caused by the rods not being parallel/perpendicular. this can be fixed by loosening the panels and pushing it back into shape. Alternatively your rods may all be in the same plane but they may look like a parallelogram from overhead. This causes square prints to be parallelogram shaped from overhead view. Again - loosen all the panel screws and push by squeezing on the long diagonal until it is back to square.

There are several places for the filament to get stuck along the path - where the bowden ends, where the peek part starts and ends. Usually if you just pull it out a few inches and push it back in it gets past these lips or edges or catches. But to avoid this I always cut the end of my filament to a point before feeding it in.

I've never set flow other than 100% in cura but I just played with it now to find your answer. There is no gcode to set flow so what Cura does is it just increases the "E" or extruder distances by the flow amount. The flow value on the control panel will increase it even more! Or decrease it. So a flow on the panel of 100% is nominal but you can increase it or decrease it. For example if you print with 110% in cura and 91% on the panel you are now back to 100% flow (1.10 X 0.909 = 1.00).

I have so many of those "rabbit" things in my yard - just like the photo above. I probably have 10 living just in my yard alone. Plus another 40 that wander over for a visit occasionally. You should see the fencing my wife had to put up around her garden - it goes underground. It is very strong! I could make a LOT of rabbit skins and no one would mind. But me. Not interested. Plus my dog would probably tear that skin apart. He may look cute here - but the rabbits don't agree! The rabbits fear this dog big time.

3dhubs.com has the best printer comparison information. I strongly recommend them - it's pretty easy to find from their main web page - only one hover and one click. (start with "learn" menu). dual extrusion only on the UMO. Not sure that UM2 is any better than UMO+. Both printers have had lots of advances - UM keeps improving both of them. To see the kind of quality you can get go to this thread and be prepared to be blown away: Start with this page and go backwards - only looking at pictures until you see something you like: https://ultimaker.com/en/community/view/1467-post-your-latest-print?page=336

To do "advance" correctly I've come to realize you need a bit more powerful computer (not much more) than an arduino. For example a beaglebone. Most printers out there are not bowden printers and the few that are (e.g. ultimaker) don't seem to think this is a priority. :(

Works fine for me in Chrome. Try a different browser. I "proved" I'm not a robot and then it just started downloading. Must be some javascript thing that is blocked in some browsers maybe. Both for an older version and for the current version of Cura.

I haven't figured that out yet either - it should be that if you click on the picture you get full size. I mean that would be how *I* would do it.

That's very common. You are seeing it skip back on that first layer. The feeder has limited current - it's supposed to skip back rather than grind the filament to dust. The feeder can put out about 5kg (10 pounds) of force but in your case that's still not enough to overcome all the various resistances (pulling on filament from spool, friction in bowden, friction in teflon coupler, pressure in head). Normally at 1mm^3/sec you would expect only about 1 pound of force needed. So something is causing massive friction. Now it's hard to say for sure because sometimes it only does this on the bottom layer - the bottom layer is typically .3mm thick so you may be printing 3x more volume there although it looks to be moving slowly (around 30mm/sec?) also sometimes the head is too close to the glass and it slowly builds up pressure because there is no place for the filament to go. So I guess I would wonder if it does this on layer 2 also. Anyway I'm going to assume your leveling is fine. That means you have serious underextrusion. Check to see if filament tangled first - heck here's a list... #10 is not your issue as that doesn't do the skip back. #1 through #6 are most likely. Try to rule these out one at a time. 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): 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) Isolator - this is most common if you've printed extra hot (>240C) for a few hours or regular temps (220C) for 100 hours. It warps. It's the white part touching the heater block. Test it by removing it and passing filament though it by hand. 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) 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. 5b) Bowden pushing too hard - for the same reason you don't want the bowden pushing too hard on the isolator. 5c) 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. 6) 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. 7) feeder spring issues - too tight, too loose 8) Other feeder issues, one of the nuts holding machine 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. 9) 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 9b) 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. 10) 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.

and while you have it apart test the teflon piece by pushing filament through it to test the friction.

well a new nozzle can often do wonders - it's worth trying.

The above link works fine for me. It takes me to here: https://ultimaker.com/en/products/cura-software Then there is a link to older versions: https://ultimaker.com/en/cura-software/list

Oh - nocen - you are in USA so if you decide to get an IPM you get it at my store: gr5.org/store/