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Top Layers not touching - UM2


Nicolinux

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Posted · Top Layers not touching - UM2

I am not _sure_ as Daid could be since he wrote the stuff, but the description of the setting "Bottom layer speed" reads:

"Print speed for the bottom layer, you want to print the first layer slower so it sticks better to the printer bed".

So I guess only the first layer prints slower.

 

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    Posted · Top Layers not touching - UM2

    I thought it did too.

    So does the power on the fan speed, usually they are on around 5th or 6th layer I believe?

    I am going to print it tomorrow and do a comparison.

    What happens when you finish the print? Will it continue to go wider?

     

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    Posted · Top Layers not touching - UM2

    I thought it did too.

    So does the power on the fan speed, usually they are on around 5th or 6th layer I believe?

    I am going to print it tomorrow and do a comparison.

    What happens when you finish the print? Will it continue to go wider?

     

    No at some point the lines reach a "weird width" and stay there. It is not visible with the object I provided the .gcode file, since by the time the lines stabilize, the object would print 5% infill. I'll print another box with 100% infill and see how it goes (but I remember that it was like that - lines reach a constant spacing and stay like that).

     

    The lines look dense enough, just too much space in between.

    What value is your infill overlap (%) in expert config?

     

    It is at 15%.

     

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    Posted · Top Layers not touching - UM2

    @Nicolinux: I checked your gcode file. These are the speeds I found:

    1st layer: 20 mm/s

    2nd layer: 27 mm/s

    3rd layer: 35 mm/s

    4th layer: 42 mm/s

    5th layer: 50 mm/s and stays there for the following layers...

    So it really might be good to see if the effect continues from the 5th layer on, just to exclude the speed as a factor...

     

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    Posted · Top Layers not touching - UM2

    Ohhh, good to know. Sorry for persisting though.

    I did another test - just a flat rectangle (high enough to have more than 5 layers) with 100% infill. Will post photos tomorrow. But the strands do look evenly spaced apart - yet there is another twist - some strands are thinner then others.

    Here is the link to the .gcode file:

     

     

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    Posted · Top Layers not touching - UM2

    Hi,

    I took some closeups of the test print (don't mind the fisheye on the first pic - that's just the cheap lens I bought for the iPhone).

    1

    2

    3

    4

    5

    The pattern of the line spacing changes over the its area. Top left, the lines are thinner but closer together. Bottom right, the lines are thicker (or two lines are together followed by a space).

    And here is a "real life" example. The strands are quite far apart. I have the impression that it is getting worse with every print. This way I'll never be able to print a water tight vase (apart from the visual impact).

    real

     

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    Posted · Top Layers not touching - UM2

    Can you please measure the distance with calipers? Maybe take 10 lines and measure this distance...

     

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    Posted · Top Layers not touching - UM2

    You mean the gap between the strands? Ok, can do.

     

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    Posted · Top Layers not touching - UM2

    Nope, can't do it. Tht tip of my digital caliper is not fine enough.

     

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    Posted · Top Layers not touching - UM2

    Hmmm... I meant, please measure the thickness of a bunch of ten lines (should be 4mm, shouldn't it?)...

     

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    Posted · Top Layers not touching - UM2

    That's not so easy to measure. But it is around 4mm.

    The line and spacing pattern changes from bottom right to top left. On the bottom right two lines are touching followed by a gap. On the top left the single lines are evenly spaced (and still not touching).

    pattern

     

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    Posted · Top Layers not touching - UM2

    Ok. Nothing wrong with line spacing, neither from the gcode or what the printer makes out of it. It's quite obviously not enough material coming out of the nozzle.

    Just to check a few things:

    - Temperature is sufficient for the speed you print? 210°C or similar? Does it actually get better if you increase temperature?

    - Did you play around with steps per mm? I guess not, but just to exclude it...

    - All flow settings are on 100% (Cura, UM2...)?

    - Have you tried an atomic cleaning yet? I think it might be a particle hanging somewhere inside the hotend blocking the nozzle partially. btw: make sure you extrude a bit manually before using the atomic method; push at 80°C, not at 90°C

    - Which feeder do you use at the moment? The stock feeder? Robert's feeder?

    - What are your retraction settings?

     

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    Posted · Top Layers not touching - UM2

    That's not so easy to measure. But it is around 4mm.

    The line and spacing pattern changes from bottom right to top left. On the bottom right two lines are touching followed by a gap. On the top left the single lines are evenly spaced (and still not touching).

     

    Which part was printed first? The single lined one or the double lined one? Does the effect repeat on other layers?

     

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    Posted · Top Layers not touching - UM2

    Do you think if there was something in the feeder, it would be so consistent and the lines would be so clean?

    I am bound to think it is something in Cura, however it is strange that it only happens to Nico (or nobody else notices it).. or it is something mechanical. But it means he would have received 2 UM2 with the same thing which nobody else experiences. Based on that I would think maybe it is something in his workflow?

     

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    Posted · Top Layers not touching - UM2

    Hi,

    I was just about to start an indepth analysis of what I could be doing wrong and write a lenghtly post about my workflow when a thought struck me. The problem is mechanical and very sucky because I am not going to take entire UM2 apart to fix it.

    The strands are not touching because the small rods (where the head moves onto) are not parallel to the X/Y rods.

    I printed an axis align tool and checked it on all axes.

    align tool

    When I latch it onto the 8mm rod and slide the head so a small rod fits the outmost notch (6mm) and then move the align tool up - the small rod doesn't fit into the notch because it is farther away than at the bottom.

    axis not parallel

    axis not parallel 2

     

    Unbelieveable but I am really that guy with a huge amount of bad luck when it comes to 3D printers :mad:

     

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    Posted · Top Layers not touching - UM2

    Ok, I spent most of today trying to fix this issue.

    1. Axis Alignment

    I re-aligned the short rods which took ages because the pulleys on the long rods are hard to reach and tighten (the fine gentleman who assembled my UM2 didn't care to align the pulleys so the screws face in the same direction).

    While doing so I found out that he also messed up assembly and fitted the wrong plastic spacer on the x-axis (front right when facing printer). This lead to a problem where the belt sractched the corner of the pulley.

    missing spacer 1

    missing spacer 2

    Um2 assembly fail

     

    Here is a video of the issue (the belt bends weirdly when the slider block approaches the pulley:

     

    I printed a new one and it works fine (hopefully the friction won't produce that much heat as for the spacer (PLA) to soften)...

    2. Possible Underextrusion

    After aligning, I printed a test cube and the pattern of the non touching lines changed. They are evenly spaced now:

    after axis align

    Printed another one and set flow (gradually) up to 150%

    after align flow 150

    Then I remembered what you guys said about possible underextrusion. I used a Taulman 618 sample to perform a through nozzle cold pull. (read about nylon to be very useful for that here is the - http://bukobot.com/nozzle-cleaning).

    And indeed, there was some gunk in there. The tip of the Taulman filament looked like this:

    coldpull1

     

    Then it was clean for a couple of pulls:

    coldpull2

     

    But then all of the sudden (I barely could pull the filament out), it looked like this:

    coldpull3

     

    Continued with cold pull and finally concluded with PLA cold pull:

    coldpull pla

     

     

    Conclusion

    The strands do not touch (it seems to be worse on the top right half).

    after align coldpull

     

    I still think it is something mechanical. When a print starts, after the preparation and initial extrusion, when the head moves into position - the sound it makes is a bit unusual. It sounds strange - like it would resonate through the entire frame and amplify the movement of the head. I don't remember this sound characteristic from the other two UM2's.

    I am past anger and disappointment now and start to not care any more. If this continues I'll put the printer on ebay and be done with it for good.

    I'll try one more thing (check the pulleys on the steppers for the x/y axis). Since most pulleys were not tightened properly when I got the printer, maybe those on the steppers have been overlooked too.

     

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    Posted · Top Layers not touching - UM2

    Pulleys on the steppers are fine. I had to tighten them a lot, but the problem persists.

     

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    Posted · Top Layers not touching - UM2

    Somehow the asymmetry in the line spacing reminds me of the uneven prints I had on my UM1 before I replaced both the pulleys and the 8mm rods.

    The bores of the pulleys were off center by up to 0.3mm and the rods were not straight.

    Do you think it could be something similar with your UM2?

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    Posted · Top Layers not touching - UM2

    Could you check if the hole in the pulley are centralized?

    Any idea is a good idea and I am really eager to find the reason of this.

    Hopefully you have some energy for it too.

    Besides the infill, it prints fine?

     

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    Posted · Top Layers not touching - UM2

    Did you check the actual height of the printed layers? It looks to me that, for whatever reason, the layer height varies and so the lines get thinner/thicker hence... taller/shorter. Correlated with the peculiar noise, this may indicate a mechanical problem, somehow related to Z axis.

    LE If not uniform in layer, then a X-Y assembly issue still exists. Once a mechanical problem has been already identified, and since s..t never happens only once, I would suspect a bed geometry of X-Y assembly.

     

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    Posted · Top Layers not touching - UM2

    @Dim3nsioneer: Well that's why I ordered the better pulleys from user foehnsturm a few months ago when I still had the UM1.

    @Sander: Is there any chance to not have to take all rods out and all pulleys? Because that's a b**ch to do :/

    Apart from that, I have other problems. Printed a thin walled object and the surface looks bad. It should be smooth and not riffled:

    thin wall1

     

    Also had some underextrusion (printed at 210° and round 40 speed).

    thin wall2

    I did run the underextrusion test again (at 230°). It looks fine and fails late, but here again - underextrusion and then it is fine again:

    extrusion test

    @3Dmaker4U: I did measure it (because a layer was sticking out on a print). It was close to 0.2mm so this should be fine.

    ----------------------------------------------------------------------------------------

    So I did a few more tests. Printed the standard cube and paused after every layer to take a photo:

    L1

    L2

    L3

    L4

    L5

    So there is always a pattern - a part of the layer is printed almost fine, and the other part is bad.

    I re-leveled the bed and made it to be a little closer than usual but it didn't make a difference:

    after leveling

     

    Then I printed at 230° and the problem is almost gone. That's not good though because I'd really like to print cooler to reduce stringing and all kinds of other effects:

    230 degrees

    Next things to try:

     

    • pulleys (don't want to but I can't rest if it does not work)
    • firmware reset/update

     

    Here are a few notes about my workflow. I don't think I am doing anything special. Printing with Faberdashery white. I use Martin's loose filament spool holder and the standard UM2 spool holder:

    Um2

     

    The printer is in my living room now and sits on a flat, low table:

    workflow1

    workflow2

     

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    Posted · Top Layers not touching - UM2

    I would suggest printing a larger cube aligned with the bed edges and with the infill at 0 degree.

    The idea is to "separate" X from Y and see where the issue appear, on a wider perspectiive.

     

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    Posted · Top Layers not touching - UM2

    Hi Nico,

    Usually you have to print white at a slightly higher temperature then other colors.

    Have you also tried other colors and with what temperature it disappeared?

    Maybe, because the hot end on the Ultimaker 2 is different, you should not hold on too

    tight to the profiles you used to create for the Original.

    For example, have you tried printing http://www.thingiverse.com/thing:8757 model and see if you had any stringing?

     

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    Posted · Top Layers not touching - UM2

    And I remember you used to fail at 4'3'mm/s. 13 is really good and I think you should be glad with those results.

     

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