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Irregular gaps on top/bottom shell

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Posted · Irregular gaps on top/bottom shell

Here's how I solved my thin line issue:

I had thin, detached lines a few nights ago using Ultimaker blue PLA filament. Not just the 1st layer. Every layer had clearly aligned and unified gaps between the lines, the end points weren't all touching the walls and the walls were all separating. Had a few days of printing white ABS from iMakr.com with no issues whatsoever, so this seemed completely out of nowhere. Was like the hole in my hot end was clogged a little bit, only letting 1/2 the normal amount out. So I cleaned out the head and poked a .4mm needle through the opening and that did nothing. Same result. I upped the material flow under the tune menu as high as 350% with NO change. (later found the http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#underextrusion that explains how upping the material flow is not going to do anything)

I then remembered that I had upped the width of my material settings on the U2 a few weeks ago to 2.92 to match some new filament. I checked the width of the blue PLA filament and it was just shy of 2.85mm. Changing the material width on the U2 back to 2.85 solved my issue completely. The blue PLA is now printing wide enough to touch each other on flat areas and the separating wall issue is gone as well. bed: 60c, hotend: 210c, speed: 25mm~30mm, layer height: .08mm.

If your material setting is wider than the filament, you will get thin, detached lines. If it is set thinner than the filament, you will get over-extruded lines.

Hope this helps!


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    Posted · Irregular gaps on top/bottom shell


    Their shipping is pretty expensive so I ordered three. Want me to send you one instead? I can put it in the mail tomorrow.


    Really appreciate the offer dude, but let me see if I can find another supplier now that I know the specs since with my luck I'll break it and need another anyway. :wink:

    Btw, 5% off Voxel until Sunday. Discount Code: NewVoxelFactory


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    Posted · Irregular gaps on top/bottom shell

    Well, this is starting to get extra weird now. First off, I exchanged the bowden tube, but that didn't change anything.

    The only thing I hadn't done yet was raising the tension in the feeder. I didn't really think about that as I never changed that and, as I said, everything was fine before. Anyhow, I cranked up the tension a lot and Heureka! prints come out almost perfect! No more underextrusion, no more unclean walls, top layers filled perfectly.

    So far so good. After the first successfull print I decided to print the other part I had in the queue. Same settings, same material, I didn't even touch the spool between the prints.

    And.... Heureka.... we're back to zero. Uneven walls, underextrusion, some perimeter lines not touching.

    On the left: The one that looks as I expect it to look.

    Right: Problems came back


    Print settings, just in case (used the same profile for both)

    Layers: 0.15

    Walls and bottom/top: 1.2mm


    100% Flow


    The two little cubes are my testcubes. The one on the left was printed before the big part on the left, the right cube was printed after the underextrusion came back. It's even missing the whole 3rd layer.


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    Posted · Irregular gaps on top/bottom shell

    pm_dude - that is definitely underextrusion and happening in a pattern of good/bad with a cycletime of maybe 30 to 90 seconds.


    4. I then set the bed temp out from 60C to 0C and then I started having a more uniform surface


    Try going back to firmware from before 14.06. Somewhere around 14.06, 14.07 Daid has been making changes in both nozzle and bed temperature controls. These changes in the firmware I believe are causing these problems. In particular the bed is now in "bang bang" mode and it makes total sense that the bed is now turned on and off about once every 30 to 90 seconds (in older firmware it's about 20 times per second). This changes the power draw drastically when the bed is on versus off and somehow seems to affect nozzle temp.

    There are other changes to nozzle PID software - in a recent firmware change Daid increased the PID loop frequency by quite a bit so it adjusts power level to nozzle much more often. Not sure if this is better or worse than before.

    The fan may be part of the problem but I never used to have these kinds of problems until I updated the firmware.


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    Posted · Irregular gaps on top/bottom shell

    The problem started in marlin 14.04. I have refused to update my Marlin because of this issue quite a few people had. It looks like the same issue as yours pm_dude (post #37):



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    Posted · Irregular gaps on top/bottom shell

    Yes I was going to try with 14.03. I'll do it as soon as I can which will hopefully be before changing to the custom block :)


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