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Tim Warren

Cura settings for round holes (poor print quality)

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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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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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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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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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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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