Stringing: I am about to throw away the printer...  

RE: Stringing: I am about to throw away the printer...

I forgot to point out that I also changed the heat block with a new one, still aluminium (but not Prusa's) having a slightly different geometry. Can be it?

RE: Stringing: I am about to throw away the printer...

a new heatblock, may adjust the relative positions of the nozzle and the filament cooling fan, and undermine the PID settings!

regards Joan

RE: Stringing: I am about to throw away the printer...

Thats a big list what have you all done. What I am missing is something about retract settings extra restart lenght and M900 linear advance...

RE: Stringing: I am about to throw away the printer...

@alexander-s27

I tried different retraction lengths, from 0 to more than 2 mm, it did not affect the final result. Sorry I don't know what M900 is...

RE: Stringing: I am about to throw away the printer...

@joantabb

Thanks, I will try to redo the PID tuning and post the results here.

RE: Stringing: I am about to throw away the printer...

Linear Advance varies per material and also per printer type.

in the picture above you can see that

Generic Flex has linear advance turned off (M900 K0) where as 
Generic PLA has two values for Linear advance, depending upon whether the Printer is Direct Drive extruder (Mk1, Mk2, Mk3, Mk3 with MMU2) or Bowden drive Extruder (Mk2 with MMU1 and probably Mini)

each material can have a different K value, and different extruder configurtions can require different K values... 

regards Joan

RE: Stringing: I am about to throw away the printer...

@joantabb

Hello, I checked and I was printing with M900 K30, since my nozzle is 0.4mm. How can understand if this number is correct?

I also tried to replace the heat break with one in titanium. Tried as above with different settings, still same bad situation: 

And, in the meantime I ordered new heatblock and nozzles...

RE: Stringing: I am about to throw away the printer...

Did you try to dry your filament?

RE: Stringing: I am about to throw away the printer...

@lichtjaeger

Hello! Yes, I tried to dry it and also I bought a couple of new filaments, freshly opened, same result. At this point I will try to:

• change the heat break with a more expensive one...
• change the nozzle with a more expensive one...
• change the thermristor

P.S. I re-ran PID calibration, temperature calibration after every modification... Still no changes. It's driving me crazy!

RE: Stringing: I am about to throw away the printer...

UPDATE: I replaced the heat break with a titanium one and tried with the original Prusa 0.6 nozzle, same results.

Tomorrow I'm gonna try to change thermistor (same 100 KOhm of another brand) and the heat block too.

RE: Stringing: I am about to throw away the printer...

Posted by: @staicontento

I forgot to point out that I also changed the heat block with a new one, still aluminium (but not Prusa's) having a slightly different geometry. Can be it?

What exactly is different? Were other components switched as well? You seem intent on using clone parts which is going to make troubleshooting more difficult. Obvious suggestion is to try an E3D hotend which the printer is designed for. 

RE: Stringing: I am about to throw away the printer...

You know, there are two retraction settings in PS.

There is one in the printer settings and there are overwrites in the filament settings. Maybe your retraction adjustments don't show any effect because they got overwritten by the filament setting.

RE: Stringing: I am about to throw away the printer...

@lichtjaeger

In Filament Settings / Filament Overrides everything is unchecked, so I guess it is not the problem. Thanks anyway.

RE: Stringing: I am about to throw away the printer...

Posted by: @bobstro

Posted by: @staicontento

I forgot to point out that I also changed the heat block with a new one, still aluminium (but not Prusa's) having a slightly different geometry. Can be it?

What exactly is different? Were other components switched as well? You seem intent on using clone parts which is going to make troubleshooting more difficult. Obvious suggestion is to try an E3D hotend which the printer is designed for. 

At the moment only two things are not original:
- heat block
- thermistor

I went back to the original 0.6 mm Prusa nozzle. Same stringing.

I am waiting for a new TCMUK-3D heat block (a v6 clone), even if I do not think that the heat block can affect stringing so much, and also for a new thermistor.
Thanks to everyone for the help, I will keep you posted.

RE: Stringing: I am about to throw away the printer...

I've had this problem in the past, and I successfully managed to get rid of it after reading some articles about stringing:

https://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#pillowing (scroll down to stringing)

https://ultimaker.com/en/resources/19504-how-to-fix-stringing

https://www.simplify3d.com/support/print-quality-troubleshooting/stringing-or-oozing/

Hope this will help.

Ferdinand.

RE: Stringing: I am about to throw away the printer...

Hi everyone! As an update:

1) changed the thermistor with a new one (FYSETC)

2) changed the heat block with a new one, v6 new style (TCMUK-3D)

I re-ran all the calibrations (XYZ, PID, first layer...). Incredibly I have seen no effect on the final product:

Given this,  I am starting to think of some trouble on the control system. What do you think?

How can it be possible???

@Ferdinand, I appreciate your links but every time I am trying at different temperatures and with different retraction settings. This is not a common stringing problem, as I've been printing with different settings for 2 years.

RE: Stringing: I am about to throw away the printer...

I'd definitely try a Prusa or E3D thermistor.

RE: Stringing: I am about to throw away the printer...

I am gonna give this a conclusion:
(Too) many factors are involved in stringing. Apart from the common ones (retraction, temperature, bad filament) there are many others... and I found another two.

1) After changing thermistor I had run PID calibration many times but the results were really bad (see above). Then I followed an advice I read somewhere: run PID calibration keeping the fan on. This was the real breakthrough!

2) The stringing test I was using was too demanding: it had a variable column section, quickly becoming too small for the nozzle that couldn't be wiped enough when going from left to right. Smaller the column section area, more the stringing (as you can see in the previous pictures). Then I switched to a constant column section.

Results
I did the following test using 0.8 mm retraction at 190° (the rest is all standard Prusa settings). The left one is without z-lift, the right one with 0.6 z-lift:

It is not like the old days but still a good result.

Thank you for your support.

P.S. Sorry for the bad photos... I didn't take advantage of black friday... Still an old phone 😭 

RE: Stringing: I am about to throw away the printer...

If you calibrate your filament settings and use dry filament, you should be able to minimize stringing using the standard Prusa hardware. Here are my  results using Filastruder Veracity PETG starting with 0mm retraction and 0 z-lift at bottom left and working to the right and back increasing retraction 0.1mm for each position.