problem with second layer

[Rosebud635 1]

Hello,

 

My Ultimaker 2+ was working flawlessly for months. I let it rest a couple of weeks while I was waiting for my new filament roll and now everything is wrong.

As you can see, the first layer is perfect but the second one is a disaster.

I put a new nozzle, cleaned everything and it's the same.

Any idea?

[gr5 1,085]

Strange.  Well it speeds up on the second layer so if your second layer height is similar to the bottom layer (typically bottom layer is .27 in cura and second layer is maybe .1mm but if second layer is more like .2 or .3...) then maybe you are just putting too high a volume of filament through the nozzle per second and it is underextruding (which is kind of what this looks like).

 

Or it could be the fan.  The fan comes on starting the second layer.  Maybe it's blowing too much on the print head and cooling it down.  Or maybe the fan shroud is touching the heater block (very common problem on UM2s) and when the fan comes on the nozzle temp drops like a rock.

 

Or it could be the Z screw needs cleaning - although that would not affect the second layer - 3rd layer would be the first possible layer with an issue I think.

[Rosebud635 1]

Hi, thanks for the answer.

Everything seems fine with the fans and I have the same settings as always. Printed hundred of pieces with no issues.

Underextrusion should be there at the start of the print also right?

Everything goes wrong as soon as the second layer starts. Like the nozzle is not calibrated anymore.

 

[gr5 1,085]

Underextrusion can have many causes but basically it's printing too much volume in too little time at too cold a temperature.  Even a partial nozzle clog can be overcome by slowing down a lot.  Thicker layers print with more volume per second.

 

Did you look at this in cura layer view?  It may be skipping your second layer in cura and jumping to the 3rd or 4th layer.  

 

Or any of the things I mentioned before.  ALL of these things are very  easy to test.  You can raise temp from tune menu by 25C to see what happens.  You can cut the speed in half to see what happens.  You can turn off the fans to see what happens.  I'd do all 3 and if it gets better than undo them one at a time.  You can do all of these experiments while it's printing that second layer.  If doing all 3 things fixes it then it's underextrusion related.  If they don't then the z axis moved too far (either slicing issue or z screw issue).

 

But I'd check cura layer view first.

[IRobertI 434]

Unless I missed it you didn't mention what material you were using? Are you using a material that is sensitive to temperature and using a high fan speed on the second layer perhaps? Just a random thought.

[Rosebud635 1]

Just the same PLA I've been using for month with the same setting with no issues at all.

[Rosebud635 1]

1 hour ago, gr5 said:

Underextrusion can have many causes but basically it's printing too much volume in too little time at too cold a temperature.  Even a partial nozzle clog can be overcome by slowing down a lot.  Thicker layers print with more volume per second.

 

Did you look at this in cura layer view?  It may be skipping your second layer in cura and jumping to the 3rd or 4th layer.  

 

Or any of the things I mentioned before.  ALL of these things are very  easy to test.  You can raise temp from tune menu by 25C to see what happens.  You can cut the speed in half to see what happens.  You can turn off the fans to see what happens.  I'd do all 3 and if it gets better than undo them one at a time.  You can do all of these experiments while it's printing that second layer.  If doing all 3 things fixes it then it's underextrusion related.  If they don't then the z axis moved too far (either slicing issue or z screw issue).

 

But I'd check cura layer view first.

Hi, the cura layer view is fine. The thing is I use the same settings as always and it was fine. Also I print quite slow anyway.

[Nicolinux 283]

Check the knurled bolt in the feeder. The first layer is printed very slowly so under extrusion would not be visible there. However a worn out knurled bolt might lead to under extrusion so George would be right with his suspicion.

[Rosebud635 1]

Hi,

Thank you all.

After cleaning again + bed leveling for the 10th time it manage to finish the second layer but some crap keeps building up during the print and make a mess that ends to clog the nozzle.

It's like there is no more retraction.

Is that what you mean Nicolinux?

[Nicolinux 283]

It could be that. Just open the feeder at the back of the printer and take a look at the knurled bolt. If the teeth are worn out, then the printer is not able to sustain the extrusion rate and both extrusion and retraction would be impaired.