Is this pillowing?

[mark-hale 1]

Hi

Trying to work out if this image is what the trouble shooting guide refers to as pillowing.

I am only using an infill of 20% but my top and bottom layers are set to 1mm but i'm only seeing this on the top layer. When looking at the last few minutes of the print it does seem as if its struggling to fill the infill holes but I had hoped a 1mm top layer might be enough to overcome this. The fans are going at 100% and the temp is 200. in terms of speed its 50mm/s

Any thoughts?

 

[tinydancer 0]

What layer height are you using?

 

[yellowshark 153]

Hi Mark, I am guessing from your settings that your layer height is around .100. I do not think that 1mm top layers is enough, especially at that speed. I rarely go as low as 20% infill, but with 20% and .300 layers I use 1.2mm. I have not done any great analysis/testing of this but it seems to me that with sparse infill you need a greater depth of top layers the thinner your layer height. So in the same scenario, with .100 layer depth I would use more than 1.2mm.

Easiest way to resolve is to print test cubes until you are happy

 

[pm_dude 27]

Yes this is pillowing. Like Yellowshark is saying depending on the layer height you might want to have more or less layers for the top fill.

@Yellowshark your numbers seems a bit weird to me. at .3mm layers you use 1.2mm. This mean only 4 layers are used for the top fill. In the case of 0.1mm layers that would make 12 layers for the top fill which is more then enough. Anything between 8-12 layers should be enough.

Maybe you can try to print the top a little slower using the tweak at z plugin.

In the upcoming version (Cura 15 RCs), Daid submitted a change that have a different top and bottom fill speed. This could be worth trying.

 

[mark-hale 1]

Many thanks guys, yes the layer height is 0.1.

@pm_dude - ok on the plugin, never played with those as of yet. Assume if i leave any section blank it uses the current settings?

The 15RC sounds like it might me a good idea

I have just tried reducing the speed on the final section plus dropped the temp by 10deg as find the white does tend to blob occasionally when I go to slow, this certainly improved matters as now only have one small hole. Reckon another .5 or so would have covered it.

Cheers

 

[yellowshark 153]

Hi pm-dude, to answer your query. There are a couple of basic rules in play here…

 

• 
  It is the amount of filament that is deposited, not the number of layers, that is important. Generally speaking it is probably good to say that at least 3 layers should be used.
   
  
• 
  The thinner the layers used then the more filament that has to be deposited for the top layers; this is exacerbated by sparse infill and I think to a certain extent by print speed also, although I have never done any real testing on this last point.
   
  

To illustrate these points I have pics. These were all done one after the other using Colorfabb’s leaf green.

The base setting was 300 microns at 50mm/s, temp of 210 and fans at 100. Where the layer thickness or speed changed, I adjusted the extruder temp.; the fan% and extruder temp. were stabilised before 25% of the cube was printed. I watched all of the prints continuously to check that there was no under extrusion prior to and during the printing of the top layers – all were OK.

Pic 1: this shows 300 microns at 50mm/s at 210. I used 0.9mm top layer for this rather than the 1.2mm I recommended. As you can see the top layers are pretty good. With the light angled just right you can see slight pillowing (not sure if the photo will show it.)

Pic 2: is the same again but with top layers of 1.2. Zero pillowing.

Pic 3: is for comparison with pic 1. This is 100 microns at 50mm/s at 205 using 0.9 top layers. As you can see poor finish with three holes. This demonstrates the disparity between thick and thin layers over sparse infill.

Pic 4: is the same again but using 1.2mm top layers. Still a poor finish with pillowing but the three holes have disappeared. So with 100 micron layer over sparse infill at reasonably fast speed, even 12 layers were not sufficient.

Pic 5: This is 100 microns using 0.9 layers but using a print speed of 30mm/s and temp of 200. As can be seen an improvement over pic 3, and, just about the same as pic 4. I.E. slowing the print speed helps.

Pic 6: shows the substantial difference between sparse infill and using 40% infill. This is 100 microns at 50mm/s at 205 and 40% infill using 0.6mm top layers (yes that was six). Almost, but not quite a perfect finish. Probably another two layers would sort it.

 

 

[pm_dude 27]

Thanks yellowshark.

What printer have the tests made with?

I'll do some on my side as well and show my results here.

Here is some doc on the subject. Not as detailed as your comments.

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#pillowing

 

[yellowshark 153]

That would be useful/interesting. I have not used the leaf green filament before so the extruder temps were guesses and possibly not the optimum. So it may be that you get some better results than me; although the overall finish was fine so I do not think I was far away from optimum.

Printed on a 3ntr, the A1 not the new A2.

I had forgotten about the section on pillowing in the troubleshooting guide. I know it is for the Ultimaker but I think the statement to use a minimum of 6 layers is a bit misleading. With 300 micron layers I normally use 3 layers, but I normally use 40% infill, hence switching it to 4 layers for the 20% infill