DrR1pper

Is it just me or does it look like the UM3 has addressed the zebra stripes issue?

By any chance have you tried the mod/hack yet @lancelet? Also, very nice looking print. What was the print speed?

I'm really sorry about that. Do you think it best that i start another thread? I think my bed springs are tight already. When i first calibrated the bed, i made sure to thoroughly tighten them and apart from re-leveling the bed a few times before i got the height just right at the beginning (with each time making sure that i had to tighten the springs if i needed to change the level rather than loosen then), I've not needed to re-level the bed since. I have tried this before but not with this model. I can do that though, no problem. I'm not so sure if i noticed any significant changes in the appearance of minor banding lines though by doing this. More testing would be required. I agree it's kinda weird. The best theory i can come up with based on the evidence thus far is that it might be due to inconsistent extrusion, with it cycling between under to over extrusion (in perhaps a sinusoidal manner) and then repeating itself over the course of a print. The two facts that printing the same test object with the same slicer settings except halving the speed did nothing to change the frequency of the banding lines and secondly that enlarging the test object just enough so that each print layer requires twice the time to print (for the same print speed and slicing settings) caused a doubling in frequency of the banding lines, the only possible culprit i can think of is that it has something to do with the extrusion rate being inconsistent. Be that due to hardware or software, i don't know for sure but i am more inclined to think it'll be hardware given the two aforementioned observations. I have not but this is a good idea/test to perform as it would either break my theory or reinforce it's probability of being the right theory. If i use the 0.8mm nozzle on the same test object and if my theory is correct, i should expect to see the banding frequency halve compared to the 0.4mm nozzle print. I will test this soon. Thank you for the idea @SandervG!

Has anyone ever experienced this before and know how to fix it please?

Very interesting developement. I modified the tower to double the perimeter length (by increasing the x and y dimensions 41.4%) which should roughly double the print time per layer and used all the same slicer settings as before and the layer banding doubled on that print in frequency. Take a look.... I'm thinking this is caused by inconsistent extrusion rates now caused by some sort of inconsistent feed per revolution of the either the knurled feeder gear, extruder gears or extruder motor itself (or if i should be so lucky, all the above, lol). Thank you @neotko for suggesting bangbang mode as a possible cause as that spurred me on to discover this.

It's printing right now, but i totally forgot, i made two prints from the um2+ remember. One at 40mm/s and the other at 20mm/s and in both examples the banding frequency was the same. Also, just checked on print and looks like no change to banding pattern and frequency. :( I'll do the print with double print area to test if it might be something with the extruder gear, but i noticed the other day that there is 1mm of momentary play when changing filament travel direction. But thanks for the suggestion of possible cause.

Just started the same gcode now with bed temp manually set to 0*C.

hmm. Interesting theory @neotko. So if it's caused by bangbang mode, then the frequency of the banding lines should match the frequency of the oscillations from bangbang mode, right? I can test this theory by simply printing without bed temp, right?

Oh right. Thanks @gr5. So you're saying if a repeating layer banding problem were to be caused by the z screw, it should be at least 3 times the distance between each of the banding lines seen on my prints? Any ideas what might be causing it then? Or is this typical of um2+ prints for whatever reasons? Thanks again!

So with the zebra stripes related post out out of the way, here are my results from my test designed to observe how print temperature and print speed might affect the visibility of layer lines/banding on all my um2+ prints. The test object consisted of a 75mm tall, 30x15mm rectangular tower. On both printers, printed with only 1 bottom layer, two perimeter wall and hollow for the m200 and only a few percentage grid infill for the um2+ prints (as i printed the um2+ prints first only after to remember that the lowest infill setting available for the m200 is equivalent to something like 30% for the um2 but since i don't think this matters much i did not bother to repeat the um2+ prints with truly zero infill). A layer height of 0.20mm on the um2+ and 0.19mm on the m200. Print speed was "Normal" for the m200 and 40mm/s and 20mm/s for the two um2+ prints. In both um2+ prints, the tower was divided into 5 printing temperature zones along the z axis starting with 220*C for the first 15mm, then 210, 200, 190 and lastly 180*C for the last 15mm. Temperature control on the m200 was not possible but also not a variable i needed to test as the m200 does not have a layer line/banding visibility issues with the unchangeable presets in z-suite anyway. Here are two pictures of all four test print objects first taken with 50% lit ambient room lighting. From left to right, z-abs, z-ultrat, PrimaValue PLA 40mm/s, PrimaValue PLA 20mm/s. UM2+ prints were sliced with s3d and prints speed was set to constant (i.e. same infill, outter/inner perimeter speeds). I also created a video to try and demonstrate the layer line issue better. I forgot to conclude in the video that print temp and print speed appeared to have no affect on the visibility of layer lines/banding on my um2+. Here is another video demonstrating the visible play in my z axis. Looks like it's around 1mm. Conversely the m200 has zero visible play here (but not shown in the video). Not sure if this could be an indication of the z axis being the problem or not. When the bed raises and lowers, the lead screw seems rather straight. I do remember it spinning off center when i first received it but it seems to have straighten up on it's own over time. Odd but not sure if relevant. And here is one of the um2+ prints next to the z axis lead screw. Is it just me or does it look like the distance between each of the larger layer banding lines on the print matches the pitch of the lead screw? Lastly, i printed this object for a friend last night with 0.3mm layer height. I'm including these because they highlight the randomness of the visible layer banding lines when in the right lighting (full ambient room lighting with camera flash in the second and third photo down) and during printing... Notice in the last picture vs the second last, there is a shadow being cast onto a small section at the top of the print which makes the layer lines looks very neat compared to when there is lighting shining upon it (and almost everywhere else on the printed object) then the layer lines/banding is very visible. Finally, photos of each with a single direct camera flash and very low ambient room lighting does a very good job of reducing the visibility of those layer lines on the um2 print compared to the m200 print (last). (I snapped off the top of the first print...not relevant but just so you know it's the same object as above). But put them all side by side in the same non camera flash and well light room lighting and the layer lines/banding on the um2 prints really stick out. Sorry for that wall of text, photos and videos. I just wanted to be really thorough and try my best to leave no stone unturned. The question i wish to ask is whether these banding lines are in fact quite normal/typical of ultimaker 2/2+ prints? I've done some looking around online of the print quality on other um2's and from what i can see, i'm somewhat inclined to believe it is typical (however much i wish it not to be the case). I've actually come to really like (dare i say love) this printer for many reasons. I think it looks really freaking cool, i love how quickly the hot end heats up and cools down when needed, large build volume, oh and it looks really cool (did i say that already?). But to me it doesn't print as nice a surface finish as compared to the m200 which is a bit of a big deal to me. However, I've still really come to love it in many ways for many reasons, even if it leaves a lot of stringing in my prints also. Anyways, I'd really like to hear an honest take on whether what i am seeking from the um2+ is in fact unattainable or not because if this is not how the um2+ prints should turn out, then i wish to rectify it ofc. Big thanks in advance for any help/light you guys might be able to shed on the matter.

Hi everyone, I was going to post this into a new thread (as i know that I have hijacked this thread long enough...sorry about that) but i've decided to posted it here as a portion of it actually relates to this threads topic at hand. If you would prefer that i remove it though and post it someone else, please let me know. So, I performed a really simply print test yesturday to see what the affects of print temperature and print speed have on the visibility of layer lines/layer banding on practically all of my um2+ prints. I also printed one on the m200 so that i had something to compare against and to my surprise, i believe that i am seeing zebra stripes on this m200 print. Something i had checked for in the past and not observed. It was printed in z-abs and here is that z-abs print (on the left) next to one printed in z-ultrat (on the right). I don't believe i have ever noticed zebra stripes on the m200 before but it could very well have been there in many prints only i just never noticed it (though i'm finding it hard to believe to be probably however possible as it's not exactly subtle, at least not in these prints). I've printed the benchy and the other test objects shown in this thread that presented noticeable zebra stripes on the um2 and other printers on more than one occasion on the m200 and could swear that i never saw any zebra stripes of any kind in the slightest. But I'm starting to doubt myself, so i'll run a battery of test soon to double check as i threw those old prints away.

ah ok, thank you Torgeir. Can i try your version of the gcode you used to print the file on your um2 please?

@cloakfiend Thanks for that. Regarding... But that's just the thing. On the m200, i've not experienced these lines on any of the prints whether small or large, complex geometry or simple geometry and with all their filaments (except for pc-abs that i haven't tried).

After i've ran your gcode though (if you don't mind sharing it with me please), what do you think i should do to try to fix the problem then? Do you think it's the z axis as well or something else? Thank you again. People weren't kidding when they said ultimaker has the most amazing and helpful spirit within the ultimaker community. I have to say, as promising as your pictures are Torgeir, i still have this hint of skepticism that the printer can really print as well as you've shown there despite showing clear evidence that i can. That print just looks too good to be true LOL. But trust me...i want it to be real and you've given me the extra impetus to try and achieve it so thank you as well as the others whom have been so helpful too!

Btw, how these prints are oriented in this photo is not how they were printed. The bottom of each print is the right vertical face on each in this photo.