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Cura settings for round holes (poor print quality)

Tim Warren

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Posted · Cura settings for round holes (poor print quality)

Hi All,


Using Cura 3.2.1 and Ultimaker 2 Extended. 0.8mm Olsen nozzle.


I am having issues with screw holes in a printed PLA part. Where the screw holes are supposed to be, Cura switches to using circular printing pattern, but the gap between traces seems too wide and I am having issues with the adjacent traces not bonding to one another. I also had issues with infill not bonding to wall, but this was solved by adding 50% overlap. What setting should I adjust for the round holes? Please see picture.


I think the same issue affects other part of the model. See second picture of a supporting tab, with screw hole and rounded outside. It's been turned to mush.


Thank you in advance.


2018-03-20 13.28.21.jpg

2018-03-20 13.27.56.jpg

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    Posted · Cura settings for round holes (poor print quality)

    That looks like underextrusion to me.  Massive underextrusion - like you are only getting half as much filament out through the nozzle as desired.


    Is it possible you accidentally tried to print this with a 0.4mm nozzle?  As that would explain everything.


    Your settings look fine.  You dont' show how many walls in settings but I can see 3 walls in the print so with a shell width of 2.1 and 3 passes that averages 0.7mm per pass which is < 0.8mm which is fine and 0.2mm layer height is fine with a 0.8 nozzle and your speed of 50mm/sec is quite doable (50mm/sec * 0.2mm height * 0.7mm width is 7 cubic mm per second which is very easy even with a non-plus ultimaker 2.  With the plus it's very easy with a 0.8mm nozzle (hard with a 0.4 though!).


    Well something is seriously wrong.  I still like my 0.4mm nozzle theory.  Or maybe you are printing non-pla filament but at pla temperatures.


    The strange thing is that the top layer infill looks fine - only the shells look bad.  Are they supported underneath?  They should be identical on every layer.


    I guess I'd like to see more settings - I want to see inner/outer and infill line widths.  I want to see qty of walls (it sure looks like 3).


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    Posted · Cura settings for round holes (poor print quality)

    I thought about it some more.  Maybe each layer isn't sticking to the layer below.  That would explain a lot.  Try to level the bed again.  Maybe you should clean the glass off in a sink and then apply a very thin layer of PVA glue - for example glue stick and then take a wet tissue and spread the glue around.  Oils on one spot of the glass or a lower spot of glass may result in part of the first layer not sticking and then it never recovered.

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    Posted · Cura settings for round holes (poor print quality)

    Hi GR5,


    Thanks for the input. I've actually just realised as a result of your post that my printer is actually an UM2 externded and not the UM2+ Extended as I had configured in Cura. Would that make a difference in this case? I notice if I select the correct printer that the total print time increases significantly, but settings look the same, so I guess the printed choice is limiting the speeds somewhere. I shall kick off another print with the correct printer and report results.


    Printer came with the Olsen block from the factory (fitted myself). The nozzle is definitely 0.8mm in both settings and reality.


    I am fastidious about cleaning the glass printer bed. It gets wiped down with isopropyl alcohol before every print until it is squeaky clean. I've never had issues with adhesion. Though having said that, the print in the photo above did have an issue on the supporting arm labelled "minor pitting" above where it lifted from the print bed, but this must have happened after that part of the model had finished printing as the top layers are fine and external quality looks good. I took those photos above half way through a print. I've adjusted the bed slightly to allow a thicker first layer for the brim as it looked a bit thin in places. I shall see if that makes a difference for adhesion. 


    The filament is ColorFabb PLA 2.85mm. Printer settings are Flow 100%, Extruder 210C, Bed 60C, Fan 100%. I do not seem to be able to see / change material settings in Cura though. Material temperature settings are hidden due to the setting in "Enable Nozzle Temperature Control", but this setting is non existent despite looking and searching. How do I change this?


    Attached is another screenshot with more settings, plus the Cura project which i hope contains everything(?).


    Thanks again,






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    Posted · Cura settings for round holes (poor print quality)
    On 3/20/2018 at 3:00 PM, gr5 said:

    Is it possible you accidentally tried to print this with a 0.4mm nozzle?  As that would explain everything.

    I also have this problem, although it's not quite as bad as Tim's, and I also have a 0.4mm nozzle.  I don't understand your explanation as to why a 0.4mm nozzle could be the culprit.

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    Posted · Cura settings for round holes (poor print quality)

    Try Optimize Wall Printing Order, it does several lines around holes all at once with leaving and returning. 

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    Posted · Cura settings for round holes (poor print quality)

    (Forgive the cross-post but this problem seems to appear several times across the forum but I've not seen a solution)

    I have this problem as well, all the time, with Cura. I don’t experience it when testing other slicers. I don’t know what’s causing it, but I know what it isn’t (and I’ve searched and combed through various forum threads with no solution). Here's what I've eliminated so far:


    —"Optimize Wall Printing Order" does not fix this problem for me, whether it’s checked on or off makes no discernible difference to this.


    —It happens with curved lines/circles, but doesn’t happen with straight lines. So, amping up the flow rate/extrusion on walls does not fix the problem, because to see any difference I would have to turn it by 25% and by then all other walls (straight lines) become massively overextruded.


    —It’s not a speed issue. I have tried printing at 20mm/s, 40, 60, 100—it happens at all speeds (it’s slightly worse at very high speeds, but it’s bad always).


    —It’s not a gcode flavour mismatch; I’m running Marlin and have set Cura to Marlin firmware (as I have any other applicable slicers I’ve been using to test). Note: this was also happening on stock firmware, which is why I switched to Marlin in the first place.


    —It’s not my hardware, given that the problem is limited to Cura slicer.


    —It’s not layer height; I have tried 0.1mm to 0.4, and the only difference is how many layers have gaps, not the size of the gaps.


    —It’s not nozzle width. I’m careful to set my nozzle width properly and have tried 0.2mm to 0.6mm nozzles. It persists on all of them (only the size of gap changes).


    —It’s not wall width. I can set that to 5mm, it still will form a gap around the 5mm curved line.


    —It’s not temperature; it happens across the range. Also, I’ve tried different cooling amounts (fan speeds).


    —It’s not the filament; it happens with PLA, PETG, and ABS, and across manufacturers.


    —If the solution is retraction/combing/coasting settings (big "if), then it’s some very precise combo of those three. I’ve tried a range of retraction/comb/coast settings on the above filaments and the issue persists across those ranges.


    —I’ve tried "ironing" the top surface but this is a bandaid solution—the gaps exist throughout the print, just not in that one top ironed layer. So it can produce an okay surface, but it doesn’t fix the underlying structural problem.


    —It’s not ambient moisture. Filaments are printed direct from a drier or from the spool holder if recently dried.


    —It’s not the enclosure around the printer; it was happening before I put an enclosure around it (which I thought would help solve the issue).


    —It’s not bed adhesion or leveling. This has happened across multiple levelings and in any case, it happens even at the top of tall prints where the circular hole is only in the top few layers.

    Any other likely candidates for what might be causing this? Such a shame that an otherwise great piece of software would have trouble with such a basic thing.

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