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LePaul

I can't figure what setting to tweak to improve some prints

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I'm not 100% sure combing is the problem some of my recent prints have.

Let me share the most recent ones, where the fill looks a little off (despite 24%) and 0.20 layers. Bottom/Top thickness is 1.2 Shell Thickness 0.8

This cover piece just has these edge artifacts and the surface should've come out smoother

IMG_9753.thumb.JPG.aab52b099b65988f6d8387f11f242e50.JPG

This one, you see the trailing lines which seem to indicate combing. But when I tried a test print with combing off, I got terrible underextrusion

IMG_9752.thumb.JPG.0d43dae7c99d2aee70c0bb897ef1061f.JPG

And on this last print, again you see those odd trailing lines on these support leg pieces.

The fill just seems to be lacking...something! If you click on the photo, you can see it in better detail (I uploaded a larger resolution)

5a33149781eec_IMG_9758L.thumb.JPG.a36f6fa155f8f5f537911f8eaf65eac4.JPG

Overall these prints are satisfactory but I think they could be better.

IMG_9753.thumb.JPG.aab52b099b65988f6d8387f11f242e50.JPG

IMG_9752.thumb.JPG.0d43dae7c99d2aee70c0bb897ef1061f.JPG

5a33149781eec_IMG_9758L.thumb.JPG.a36f6fa155f8f5f537911f8eaf65eac4.JPG

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Well more than retract what I would do to have a clean surface it's to close that holes and drill them. The drag marks are because the flat area has 'holes' so the top layer path isn't 'linear' so the head must fill, move, etc etc. Ofc the other problem if you make that tubes solid it's that because the top layer of the screw areas it's taller, it will make the same problem and marks.

Solutions? I would use another slicer version or different and check the travel paths. What I would really do? I would use s3d that allows to have different processes and I would split the 3d object of the top layer and the upper part on another but to do that you need to really know how the program thinks and make the object with that in mind. Also on s3d you can force the head to almost only move from one position to another by using only the perimeters (because you can tell him how much distance it can use to combing and on cura you can't do that).

Another sollution? Use Z hop to avoid the marks, but that will add small blops and make other problems, specially if you print too hot.

Try the last cura beta 1.99, maybe it has some tools to make that cleaner.

Edit: BTW I'm not sure (low res photos) that the scratches are 'scratches' of the nozzle moving or dripping. If it's dripping forget everything I wrote and just print cooler/slower but check that the nonprinting movement speed it's at least 200mm/s

Edited by Guest

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Edit: BTW I'm not sure (low res photos) that the scratches are 'scratches' of the nozzle moving or dripping. If it's dripping forget everything I wrote and just print cooler/slower but check that the nonprinting movement speed it's at least 200mm/s

 

I suspect the later [dripping].  I have been printing at 208C and 40mm/sec

The travel speed is the default 150mm , so I can up that.

I can also lower the print speed to 30 mm/sec on a test piece and report the results.

Edited by Guest

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If you have an umo/umo+ to improve the quality try lowering the acceleration from 4000 (default) to 1800-2500, and the Jerk to 18 or something like that. For me 1800 works better because some other mods. That removes some of the ripple effects of the movement and will also make the printer shake less. The 4000 acceleration on my umo+ made it shake like a milkshake. But that's for other topic... =)

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On the ulticontroller. Prepare/Motion or Control/Motion I don't have the printer infront of me :D

If you like the result use the save memory option.

More on the topic:

https://ultimaker.com/en/community/16398-how-to-tune-your-motion-parameters

And guide about the menus

Edited by Guest

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@LePaul

My current UMO settings:

Control->Motion->Accel: 2000

Control->Motion->Vxy-jerk: 12

 

I entered these settings and made sure, in Cura / Expert Settings that Combing was bacl to 'All' (default setting)

I also recalled what @gr5 has posted a few times...

Print slower and hotter! Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers):

20mm/sec at 200C

30mm/sec at 210C

40mm/sec at 225C

50mm/sec at 240C

I have a test piece printing now at 40mm/sec and 220 C (ColorFabb seems to like the cool size, so I opted to go below 225C )

I can already tell that the movements are much more fluid and the usual jerking/thrashing I have grown used to is gone. This is a great tip!

I'll post a photo of the test piece once completed.

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Well, problems still exist....ideas?

 

Is this still sliced with Cura? Then you should use the "No Skin" option for Combing. I suggest this as a starting point:

retract.png

In addtion: the extrusion looks quite unbalanced, there is serious underextrusion on some parts of the skin. You mentioned in your first post that this happens after retractions... and gets worse after lot of retractions?

I assume that this is somewhere hardware related.... perhaps some backlash in the feeder...? (i'm not familar with the UO feeder...)

Anyway - you should definitely get rid of this first...

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The scratching on the surface it's just the head moving. But you have actual holes between the infill lines. How many top layers or how height are they? I use to need 3-4 top layers at 0.2 & 70mm/s to have a perfectly close top layers.

Also the quality of the top layers depends on the nozzle flat area. Check the nozzle tip to see if it's really flat. But your printer was very new isn't?

An example from my shop. Printed at 60-70mm/s 3 top layers 0.2 207C s3d. You will see it has zero scratches because also, played with the processes to make it look good.

350194-485905ce552347e89dd8e1837abd0954.png?size=2000

Edit: Also, if you play with the nozzle size and force a 0.38 or 0.39, the nozzle will make smaller movements, and that helps a lot since the flat area will 'flatten' the top layer more making the top layers look better. This won't remove the scratches from the path planning of cura..

Edited by Guest

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