Stringing, can't figure out.  

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Comp
 Comp
(@comp)
New Member

Hi there,

I was wondering if anyone would be able to help. I've done a stringing test and it came out perfect, but when I print a part with the same settings there is so much stringing, it's not funny.

Cheers.

Posted : 12/03/2021 12:52 pm
bobstro
(@bobstro)
Illustrious Member

I've got some notes on the topic here. In short:

  • Calibrating my extrusion multiplier correctly for each filament made the single biggest difference. 
  • Print as cool as you can. Reduce nozzle temp, or increase cooling fan if possible.
  • Be sure filament hasn't absorbed moisture. Dry if needed, or use fresh spool. 
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 12/03/2021 1:08 pm
fuchsr
(@fuchsr)
Honorable Member

What @bobstro said. This looks like a lower temperature should improve it. What material is it? With PETG you may always have some residual stringing (at least I do) but a heart gun can take care of that. This though looks like you need to dial your settings in first. 

Why didn’t you see it in the test model? Who knows. In my hands I didn’t find all these “stringing test models” to be particularly predictive of real world performance. Sure, they can be useful for dialing in settings but 3d printing is far from being a precise science so I’m not surprised to see this discrepancy.

Posted : 12/03/2021 1:51 pm
Comp
 Comp
(@comp)
New Member

Thanks guys for your quick replies. There is some useful info.

I think I resolved the issue for now.

Cheers.

Posted : 15/03/2021 12:10 am
fuchsr
(@fuchsr)
Honorable Member

@comp

May I ask what you did? Always nice to bring issues raised in this forum to a conclusion that may help others with similar problems.

Thanks.

Posted : 15/03/2021 12:25 am
Comp
 Comp
(@comp)
New Member

@fuchsr

Sure thing.

Not as straight forward as I though it would be.

I started by cleaning the nozzle with some cleaning filament I had. Even though the filament when extruded was not curling, apparently it was clogged a bit.

Also I noticed when I was putting a top screw back (the brass one on the heatsink, I should mention that I'm using PrusaMini) it was not compressing the PTFE tube that is inside. I clearly remember fixing that when I was changing PTFE tube, so I repressed it while the hot end was up to temp, I thought maybe it was not depressed enough because of that.

That seems to fix the issue for me. I guess there was a bit of clogging combined with not compressed tube inside the hot end that caused under-extrusion and stringing.

Hope that helps.

Posted : 15/03/2021 12:51 am
fuchsr
(@fuchsr)
Honorable Member

@comp

Thanks for sharing! I have replaced all of the brass connectors with standard PC4-M8 connectors and haven't had any issues since. Plus, with these connectors I find it more convenient to remove the Bowden tube should the need arise.

Posted : 15/03/2021 1:07 am
keithroe
(@keithroe)
Active Member

@fuchsr

Might I ask for a little more detail on which connectors you replaced?  I would like to do this as a preventative measure.

Thanks!

Posted : 15/03/2021 2:40 pm
fuchsr
(@fuchsr)
Honorable Member

The two brass connectors at the end of the Bowden tube between hot end and extruder. I used these PC4 connectors from Amazon:  https://smile.amazon.com/dp/B07QFK7YWP/

I also tried some of the printable adaptors on prusaprinters.org but found them to be not robust enough. One in fact sheared in such a way that I had to replace the hotend because I was unable to remove the part stuck in the thread. 

Posted : 15/03/2021 2:55 pm
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