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Michael Bell

Zits and Banding

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Hello everyone,

 

Having issues with Cura with my cr-10. I have read everything I can find joined the cr-10 group on Facebook but I hoping someone can help. The pictures attached show a few of my issues. I have lines and banding always at different heights and also zits. I have printed things sliced in S3D and they seem fine. I want to get this to work with Cura.

 

These are a few of my settings if you want to see the Cura profile let me know.

 

Cure 3.2
eSun Pla
0.18mm layer height
Nozzle 215
Fan 100% after first layer
speed 65
3 bottom and top
4 walls
60% infil
retraction on
coasting on
Walls before infill

IMG_1330.jpg

IMG_1331.jpg

IMG_1332.jpg

IMG_1333.jpg

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This is a pretty good print.  You can do better but there's nothing really easy to fix here.  This is a typical quality.

 

Horizontal banding is usually caused by Z issues where the Z axis isn't moving consistently.  On an old machine this means it's time to clean the Z screw.  It can also be caused by fluctuating temperatures - watch the temperature while you print.  If it varies by more than 3C then that will cause banding issues.

 

But this is pretty good - I don't think you can get this better without buying all different Z hardware.  maybe increasing stiffness of bed.

 

The zits - I think I know what you mean.  Those look pretty damn subtle.  I don't know if you can fix that.  I would try cura 15.X to see if that fixes the "zits".  There are so many changes in cura and it changes so fast -- I think there might be a setting to help with those but not sure anymore.  I think cura 15.X might give you a better surface.

 

It's possible (check layer view) that your model has too many triangles coming all to the same point near those zits.  if so you could remesh the model.  do you have a mesh view of your STL that shows all the triangles in it?  I'd like to see that in the area of the "zits".  

 

If you have the issue I'm thinking of you will see one point on your model with hundreds of lines emanationg out from it.  When cura slices near here it creates dozens or hundreds of line segments all within 1mm.  Printing 10 or 100 line segments within 1mm will give you "zits".  it should be smoothed out - line segments should be at least .3mm long for the most part.  Preferably mostly at least 1mm long.

 

That's 2 of your issues - maybe you could zoom in and circle an issue as we might be talking about different things.

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Thanks for that its good to know that is not that bad of a print.

 

I think I may need to build a enclosure for the printer as the temp where it is goes up and down quickly and its on average around 13C. I zits seem to be on layer changes whats why I tried the coasting and the retraction which is currently set to 15mm and speed of 80. You can see them more on a benchy I will take a picture when I back home on Monday. 

 

Regarding the mesh I know the mesh is super detailed for this. Fusion360 says there is 225532 triangles could the model be the issue?

 

Regards

 

 

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200,000 triangles is a lot.  It's good practice to learn how to remesh.  Read this article.  By the 3rd time you do this it will be very fast.  Also slicing will be faster if you reduce.  Try a 10X reduction but look at the text carefully after to make sure none of the letters were ruined.  you might not have to reduce the triangles so much as move them around so you could try only a 2X reduction as well:

 

http://www.shapeways.com/tutorials/polygon_reduction_with_meshlab

 

What about 13C?  I was asking if the nozzle temperature changed much.  If it's moving 13C above and below the goal temp that - well that's unlikely.  But you fix that kind of thing by fixing the PID values.  the nozzle temp should be very steady - so for example if your printing temp is 210C you shouldn't see it go above 211C or below 209C but it would have to move to around 205C or 215C to see a difference in the walls (horizontal layers).  More likely it's the Z screw that's not perfect such that some layers the bed is moving more and some less.  When it moves less you get more extrusion sticking out on that layer.  When it moves more then that layer would be somewhat underextruded.

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Yeah the temp does change maybe 1/2 degrees up and down. What is PID? 

 

Everything is tight on the bed and screws I will clean the Z and see if that helps and also re mesh to see if Cura is struggling with it.

 

Will let you know after the weekend thank you.

 

 

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I dunno...I had some failures in my prints pointed out to me by experienced hands just a week or so back. So, take it for what it is worth from me; I liked it. But @gr5 is way beyond my level of expertise and experience. His word I would take over mine.

 

But, I do try to remember that this is not injection molding. And even then there is always a clean-up of flashing and/or warping and seams.

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2 hours ago, Michael Bell said:

Yeah the temp does change maybe 1/2 degrees up and down. What is PID? 

 

Everything is tight on the bed and screws I will clean the Z and see if that helps and also re mesh to see if Cura is struggling with it.

 

Will let you know after the weekend thank you.

 

 

 

Cr10 PID is know to not be accurate 

 

https://www.thingiverse.com/groups/creality-cr-10/forums/general/topic:17593

 

https://matterhackers.dozuki.com/Guide/PID+Tuning/6

 

PID is a controlled temperature algorithm so the heat stays as stable as possible. When heat changes or fluctuates the print literally goes up/down microns making a small Z banding. Ofc on open machines like the cr10 that’s normal since heat has everywhere to escape, but tunning PID should help. Ofc mind that since is a very open machine winter/summer room differences will affect 

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1/2 degree temperature should not be a problem.  Any z banding is probably imperfections in the Z screw which I'm guessing are only fixable by getting higher tolerance parts.  I'd not worry about it too much.  Maybe you should just prime and paint your parts to hide the banding?

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I agree with much of what was said - overall it's a pretty good print. If you layer heights are big you could make them smaller a bit, but you kinda don't have to.

 

The only real advice I have that others haven't given is look CAREFULLY at the print preview - many times I think there's an issue with the printer, but hairs, holes, extra segments, blobs, seams, and the rest are all there plain as day on the preview.

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Thanks for all the advice. 

 

Monday when I back with my printer I'm going to try cleaning the Z screw and giving is a little light lube, then try reducing the number of triangles in the mesh and investigate the PID

 

will let you all know the results

 

:)

 

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So today I,

 

Cleaned the Z axis

Remeshed

cleaned nozzle

level bed

 

I tried some reprints and still looking the same I'm going to try printing flat and also standing up and 45degrees and 90degress to current location just in case its a limit in the stepper motor only being able to be accurate down to 0.04mm.

 

The interesting thing is I had a friend slice in S3D for me and I gave it a go. Apart from the print failing due to poor bed adhesion the layers look a lot better. :( its good and bad at the same time I want this to work with Cura.

 

 

54255322027__90340862-1274-4CF8-BC8F-968656C5575F.JPG.jpeg

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