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Nett

Printing issue with 0.4 and 0.25 nozzles

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Hello,

 

I have an issue when print with 2 different nozzles, 0.4 and 0.25. For some reason I get a border when start to print with 0.25 nozzle (yellow color). Border appears equally on both sides, inside and outside of the model. I've done required XY-offset calibration when installed new 0.25 nozzle, and it seems to be OK.

I've attached stl files, project from Cura and picture of a model I've got. I've splitted origin STL model in Netfabb, and then combined in Cura.

Could you please help me to clarify this issue? Is there a way to get rid of those borders? I'm going to create cutters for polymer clay, and this border spoils final result when cut a polymer clay model.

Thank you in advance!

UM3_Square-30-0.25 - Square-30-0.25 (repaired) (Cut 1).curaproject.3mf

Square025.jpg

Square-30-0.25 - Square-30-0.25 (repaired) (Cut 1).stl

Square-30-0.25 - Square-30-0.25 (repaired) (Cut 2).stl

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12 hours ago, yellowshark said:

Have you checked that in Cura the x/y dimensions of the two models (before combining) are exactly the same after being cut in Netfabb?

Hello, @yellowshark. Thank you for reply ). 

I'm sorry, but I dont quit understand. Could you please tell me how do I check x/y dimentions before combining?

I thought those models supposed to keep dimensions regarding each other, when cut. 

When I combine those models, and switch to 'layer view', Cura does not show anything strange. But, you are right, because final result looks like the top is initially bigger than it should be.

Thank you.

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I'm having a hard time seeing the issue from the image, but if I could clarify, the walls of the yellow box are thicker than those of the grey, just that yellow overhangs the grey both on the inside and outside?  If that is the case, is there any possibility you are looking at effects of different nozzle thickness to line thickness, such that the walls are actually coming out a bit thin on the grey?

 

Is there any way you can get a set of calipers on the yellow and grey walls to measure their actual thickness against expected? (might be a challenge for the grey due to the starting layers)

 

Also, could you indicate what material you are using, and if it is the same material, is it roughly the same age and humidity?  I recently printed a project with an older spool and found it out of tolerance (vertical holes were too tight for the inserts), reprinted it with a fresh roll and it was perfect.

 

Just some guesses, hopefully something of use in there....

 

John

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Yes the two models should be identical dims on exit from Netfabb; but if Cura has bugs so can Netfabb,I am sure they are the same but you do not know:). On the Cura screen select one of the models and the on the left side of the screen you will see a vertical set of icons. Select the Scale icon and you will see the x/y/z dims of the model. Repeat for the other model.

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1 hour ago, JohnInOttawa said:

I'm having a hard time seeing the issue from the image, but if I could clarify, the walls of the yellow box are thicker than those of the grey, just that yellow overhangs the grey both on the inside and outside?  If that is the case, is there any possibility you are looking at effects of different nozzle thickness to line thickness, such that the walls are actually coming out a bit thin on the grey?

 

Is there any way you can get a set of calipers on the yellow and grey walls to measure their actual thickness against expected? (might be a challenge for the grey due to the starting layers)

 

Also, could you indicate what material you are using, and if it is the same material, is it roughly the same age and humidity?  I recently printed a project with an older spool and found it out of tolerance (vertical holes were too tight for the inserts), reprinted it with a fresh roll and it was perfect.

 

Just some guesses, hopefully something of use in there....

 

John

Hello, @JohnInOttawa. Thank you for reply).

Yes, yellow overhangs the gray from both sides (inside and outside). Materials are new, I think, yellow ~ 2 weeks, and silver ~ 2 month old. Type - PLA.

As I understand, printer should print model as it presented in slicer. But Cura does not show anything during slicing process.

Thank you!

 

 

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@JohnInOttawa  has some good points. It might be that you need to change the x/y dims of one of the models to compensate and get them to line up. You would use the Scale icon to do this. It would probably take several goes and whilst you may get the external dims to match if the walls are different thicknesses then you may not fix that. Also when you scale up or scale down that will, I assume, modify the thickness of the wall on that model but maybe not noticeably. Maybe worth a try. 

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Filaments all tend to have different flows, they are affected by the colouring dyes. So when get down to the nitty gritty I guess a small variance in line width might occur? Maybe you could try reducing the temp. of the yellow extruder to restrict the flow a bit. Yes one would hope the printer should print as per the instructions from the slicer - but your settings can affect the flow of the filament, as can the filament itself and indeed the hardware accuracy of the printer.

It might be worth trying two other filaments and see what happens; maybe then pick the two filaments that seem best matched.

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I tried to open your project in cura, but it's picking up my settings. Can you tell me what line widths and layer heights you are using?

 

Also, the cura model looks different than your photo.  In cura (and your latest screen shot), the grey section has sloped sides, whereas in the first photo, the walls all look more vertical.  What am I missing?

 

J

Edited by JohnInOttawa

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12 minutes ago, JohnInOttawa said:

I tried to open your project in cura, but it's picking up my settings. Can you tell me what line widths and layer heights you are using?

 

Also, the cura model looks different than your photo.  In cura (and your latest screen shot), the grey section has sloped sides, whereas in the first photo, the walls all look more vertical.  What am I missing?

 

J

@JohnInOttawa, my latest screenshot demonstrates impact of scale, applied to model which should be at the top.

And yes, the model has sloped sides, I print not full height, not to spend lots of time for each print iteration. That is why I've uploaded project and models I have. 

Layer heigh is 0.1mm, for both extruders (unfortunately Cura does not allow to set different layer height for each extruder). Line width is 0.35 for 0.4 extruder and 0.23 for 0.25 extruder, actually default settings.

 

Thank you!

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On 2/25/2018 at 5:05 PM, Nett said:

Just tried to apply scale to top model, and merge objects.The result is unexpected )), I've attached a screenshot.

CuraScale.jpg

 

Just by going by this image it looks like your upper model "yellow" does not have it's origin centred correctly. In other words the 0,0,0 of the yellow model isn't in the centre, ensure your model is zero'd out and centred in your modelling application first before exporting.

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It could be that you just need to do the manual bed calibration again.  It could be that the printer misunderstands the height of the .25mm nozzle.  The very last step of manual bed calibration calibrates the second core and you must use the EXACT same technique that you used to calibrate the first core such that when you print they are printing at the exact same height.

 

If the yellow nozzle is printing slightly lower it will overextrude the first printed layer and give you a little tiny ridge.

 

Also - do you want the gray and yellow walls to line up perfectly on the outside?  Or inside?  Because I don't think you can do both since the nozzles are different.

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On 27.02.2018 at 7:59 PM, cdrose said:

 

Just by going by this image it looks like your upper model "yellow" does not have it's origin centred correctly. In other words the 0,0,0 of the yellow model isn't in the centre, ensure your model is zero'd out and centred in your modelling application first before exporting.

Hello @cdrose, model is ok, that screenshot shows how top model changed it's position after I scaled it in Cura. If a join models without scaling, whole model joins without any issues.

 

Thank you.

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On 01.03.2018 at 2:19 PM, gr5 said:

It could be that you just need to do the manual bed calibration again.  It could be that the printer misunderstands the height of the .25mm nozzle.  The very last step of manual bed calibration calibrates the second core and you must use the EXACT same technique that you used to calibrate the first core such that when you print they are printing at the exact same height.

 

If the yellow nozzle is printing slightly lower it will overextrude the first printed layer and give you a little tiny ridge.

 

Also - do you want the gray and yellow walls to line up perfectly on the outside?  Or inside?  Because I don't think you can do both since the nozzles are different.

Hello @gr5,

I thought UM3 does bed calibration automatically. Printer runs 'Active leveling' procedure before each print, because UM3 specs mention that this process is automated.

Do I still need to do manual calibration on my own?

I would like to line up walls on the inside of the model, it's more important in this case.

 

Actually I've tried to reduce the temprature for 0.25 core, to 190C, like @yellowshark suggested. And I've got better result, only one side of the model has small ridge inside of model.

Anyway I'm still looking for other solutions. Already tried to set 0.1 first layer height. Maybe, I could change model, that way, so last layer of bottom model could match ptint core size of top model.

 

Thank you!

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I've never tried the auto level so I don't know if it does a good job.  I've had my Um3 for over a year and never had any interest in even trying it.  It probably sometimes does a perfect job and sometimes not perfect?  I don't know.  But I know if you mess up manual calibration it will indeed cause the behavior you describe.  So I would try that.

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I took the files, opened them up, assigned core 1 to 0.4 AA and Core 2 to 0.25 AA. Assigned the parts to the extruders and just pretty much left everything to default.

 

The slice is good as far as I can see. I am not printing this out to test it, but if the slice is good and the print has the overhang, it may be a slight mismatch on math between wall count, and wall thickness at the taper/meeting point of edges. But the slice looks good without scaling and such. Everything matched up in all views; Solid, x-ray and slice.

Sliced.thumb.jpg.e5e74a9054aa22aad4976e2e0b8051de.jpg

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