Strange surface pattern - is it ringing?

[Smithy 1,145]

I printed today a quick toolbox with a 0.8 print core, thin walls (1.5mm = 2 walls) and found now on the left side a strange pattern on the surface. I have never seen such a pattern which goes diagonal over the whole surface. Is it ringing? Printed with the Cura defaults for 0.3 layer height.

 

[gr5 2,224]

not ringing for sure.

 

Is this wall 100% perfectly vertically and horizontally lined up?  Or is it tilted (for example wall leans inward or outward.  If the model leans both ways this *could* be zebra stripes but I really really don't think so.  The wall would have to have a very strange wavy lean to it to get this pattern.

 

It could be infill pattern showing through but if soo it's a strange infill pattern (check that in layer view - see if the infill pattern touches the walls in this strange diagonal pattern).

 

Instead I think it's just one of those weird oscillations where the head comes by and when it's thicker the liquid filament sticks and more is pulled out over the previous bump but in the direction of travel so it's slanted.  It's kind of a vibration in the feeder combined with vibrations in the liquid pla in the head.  The best fix for this kind of thing is usually to lower the temperature.  You could play 2ith 3 different temps 1/3 of the way through the print and keep notes and see what happens.  I would go into TUNE menu and lower by 10C 1/3 into the print and if that makes it worse go +10C or if it's the same or better maybe -20C or -15C at the 2/3 point of the print.  or try MANY temperatures and use a sharpie to mark the layer where you changed temperature.

 

[Smithy 1,145]

Thanks @gr8 for your help.

Yes the wall 100% perfectly lined up, vertically and horizontally. It is just a simple box I did myself in Fusion 360.

And it is definitely not the infill, the object is hollow and has no infill, just 2 walls. Line width in Cura 0.75 for the 0.8 core and model wall has 1.5mm.

 

I print quite often with my 0.8 core, but this is the first time I have seen this pattern. But your tip with the temperature is good, because I think it is the first time I printed Colorfabb PLA with the 0.8 core (usually I use UM Tough PLA when printing with .8)

 

Strange is (or maybe not ? ) that this pattern is only on the left side of the object. The right side is perfect. Just the back has also for 1-2cm the same pattern, but directly from the corner of the left side. So when the object was printed clockwise, the front was ok, then the left side with oscillations and from the left back corner on the backside for a short distance also oscillations. Then is looks ok for the rest of the backside, right side and front.

 

I will try it again with some temperature tests.

[Dim3nsioneer 558]

It could be a numerical thing combined with the resolution of the stepper. In that case, rotating the object by 45° will solve it.

[Smithy 1,145]

Thanks Dim3nsioneer for your help.

I also checked yesterday the axles for play and noted that both y axles were a little bit loose. I could hear a little knocking when trying to move them. So I did the whole calibration thing and aligned the axles particular with the axle tool as described on the UM website and tightened the pulleys accordingly. Calibration was successful, I printed a calibration cube afterwards and it was fine, from the surface and also from the dimensions.

 

So I will reprint the model again, same settings, same position to see if the loose axles were the root cause. And if not, I will try to rotate it by 45° and print it again. 

 

Do you suggest to rotate such straight objects generally to 45° on the build plate or only if there are problems?

[mpdoyle2010 0]

@Smithy I am having the same "wavy" issue. did you ever find the root cause?

[Smithy 1,145]

No sorry, with other models it never occoured again or I haven't noticed it.