Stringing and ringing.

[olhan20 0]

Hello

 

I recently purchased an Ultimaker 2 extended, second hand. It is 6 years old, but It makes good looking prints. However, it does keep stringing, especially whilst travelling over long distances. It also makes tracks on surfaces, whilst travelling over solid objects. I have cleaned the entire machine and made sure that the extruder/feeder is free from debris . I have also tried adjusting the temperature, the retraction speed and length, but no matter the setting, the stringing is the same. Could it be the nozzle or the coupler for the bowden tube?

 

The settings that I have been using is pretty much the recommended settings provided by Cura. The settings that I have fiddled with is:

 

Temperature range between 200-210 degrees celcius.

Retraction length between 4.5-6.5.

Retraction speed between 25mm/s - 30mm/s

 

I have been watching my prints closely and it seems the feeder retracts properly in most areas, but fails to stop the flow of filament from the nozzle. 

 

The attached photos show some objects with stringing in between. The benchy is a test to show the retraction failure, which is visible on the bottom layer between the characters, and on the top layer in the back of the boat, where tracks (from retraction failure) on the surface are visible. A picture from the side of the benchy shows signs of ringing.

 

Any good advice?

 

Best regards

Oliver 

 

[geert_2 556]

Is that material PLA? Some materials do string a lot more than others, e.g. the PET I have, because they are more elastic, while molten PLA is more like yoghurt. So, if it would not be PLA, try PLA first, with a fairly standard speed of 50mm/s.

 

I never played with retraction settings, so I can't say anything on that. Did you enable retraction in the slicer, make sure it is not switched off somewhere (there is a checkbox in my Cura version)? Forgetting to enable retraction would cause the same stringing effect.

 

Also, it looks like your nozzle is too far away from the glass: normally the bottom layer should be much smoother, more squeezed agains the glass.

 

Also, not sure, but the vertical patterns in the benchy might be infill shining through?

 

This is how the bottom of my prints usually looks for normal prints, and for very fine prints:

 

 

 

[olhan20 0]

Thanks for your reply, Geert. The examples are printed with high quality PLA, which I have dried for 6 hours at 40 degrees celcius before printing. I have enabled retraction in the slicer prior to printing as well.

 

As far as the printing speed goes, I do not think it would solve the stringing issue, as it only occurs during travel movements. Perhaps changing the travel speed would help?

 

I see your point in regards to the first layer. The print actually has a bit of an elephants foot - wouldn't that be due to the nozzle being too close to the bed, under normal circumstances?

15 minutes ago, geert_2 said:

Also, not sure, but the vertical patterns in the benchy might be infill shining through?

Unfortunately the pattern showing on the surface is inconsistent with the filling pattern, so I am not sure why it appears. I just corelate it to the stringing issue.

 

BR

Oliver