Stringing Issue Prusa MK3s (PLA)  

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ahnguye3
(@ahnguye3)
Active Member

I've been trying to search for the best resolution to my stringing issue. The PLA filament is fresh out of the bag and new.

 

Users keep telling me to "dry" the filament and put it in a dehydrator. I did the same print on my Monoprice Select Mini v2 and experienced no stringing. That test confirms that it's not the filament being "wet".

These are the settings I used in my PrusaSlicer in regards to my retraction settings. Extruder temps are at 190.

Would anyone have any recommendations on what settings I can adjust to fix this stringing issue? Thank you in advance.

This topic was modified 1 year ago by ahnguye3
Posted : 13/02/2020 2:30 am
vintagepc
(@vintagepc)
Noble Member

try boosting your retraction speed. Mine is set at 80.

Posted : 13/02/2020 12:27 pm
ahnguye3
(@ahnguye3)
Active Member

@vintagepc

I tried the 80 Retraction Speed but stringing still occurred. Any other tips?

Posted : 02/03/2020 5:56 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @ahnguye3

[...] I tried the 80 Retraction Speed but stringing still occurred. Any other tips?

The first thing I'd try is another filament. If there's less stringing, there's some difference between your printers that causes stringing on the Prusa. I'd still try drying the filament simply because it eliminates one possible factor.

The biggest factor in battling stringing IME is getting your extrusion multiplier right. I started trying to nail down stringing myself when I started getting the same sort of fine gossamer threads. I decided to set up a series of tests to nail down retraction and z-lift values. I wanted to make sure there was nothing about the filament contributing to the problem, so I dried it per the PrintDry instructions, did a filament calibration and linear advance calibration and started my prints, expecting to nail down the precise problem. This was my first run using Filastruder Veracity PETG. Here's a run starting in the bottom-left corner at 0 retraction and 0 z-lift, then increasing by 0.2mm for each step from left-to-right, front-to-back. The results were unexpected. 

I recently decided to try again, sticking to PETG since that's usually the most difficult to avoid stringing with:

I realized that beyond 0.2mm, there was little need for additional retraction once I've properly set my slicer filament profile to accurately reflect the real-world measurements of my filament. If the slicer is working from an incorrect set of values, it makes sense the results would suffer. If the slicer is specifying a bit too much filament, it has to go somewhere. It can't go down. It goes outwards on surface walls or up to stick to the nozzle.

I have since settled on using defaults of 0.2-0.4mm of retraction for my defaults, 0.4mm z-lift "because" and have turned off wiping completely. I use 50mm/s for retraction and 25mm/s de-retraction to minimize non-Newtonian fluid effects. This has made a huge difference. I still get some stringing, depending on the specific print, but it's no longer the norm. I also don't get extruder clicks often associated with excessive retraction.

Of course, some filaments (e.g. TPU) don't take to retraction well, so stringing may still be a problem. 

 

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 : 02/03/2020 6:22 am
Clemens M.
(@clemens-m)
Prominent Member
Posted by: @bobstro

.. , so I dried it per the PrintDry instructions ...

Can you please leave a link to that topic?

Best regards, Clemens

Posted : 02/03/2020 7:12 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @clemens-m
Posted by: @bobstro

.. , so I dried it per the PrintDry instructions ...

Can you please leave a link to that topic?

Try here.

 

This post was modified 1 year ago by bobstro
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 : 02/03/2020 7:31 am
Clemens M.
(@clemens-m)
Prominent Member

@bobstro

So now I have ordered a food dryer - will see the difference. Yesterday I worked with a PLA which is about 2,5 years old and open - you can hear some sound during printing coming from "explosions" caused by steam (at least I think that it is like this).

Best regards, Clemens

Posted : 02/03/2020 10:48 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @clemens-m

So now I have ordered a food dryer - will see the difference. Yesterday I worked with a PLA which is about 2,5 years old and open - you can hear some sound during printing coming from "explosions" caused by steam (at least I think that it is like this).

I think it's a good investment. If you save a few rolls of filament using it, well worth the investment. PLA doesn't generally suffer from moisture problems, but it certainly can in some circumstances. Better to have the right tools before you need them! Good luck with it.

 

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 : 02/03/2020 2:01 pm
Mike Daneman
(@mike-daneman)
Estimable Member

Another thing to try is to reduce "Z lift" (I think that's what it's called) in the Printer->Extruder settings to 0.1 or 0.15mm (I think it's set to 0.5mm by default).

Posted : 03/03/2020 8:22 pm
sam.s7
(@sam-s7)
New Member

Recently I had terrible stringing that I couldn't get under control. Tried drying filament, trying different filament, all sorts of retraction settings, new printer nozzle, all without success. Was really at a loss regarding what to do since it was previously working well. I finally replaced my entire v6 hotend thinking that maybe there was something causing some resistance and that completely solved it. Now I'm back to printing without any stringing at all. I looked at the old hotend and didn't see anything wrong with it - could see through and nothing seemed blocked, but that fixed it for me. They aren't that expensive - might be worth a try if you have tried other things first. 

Posted : 17/11/2020 3:59 pm
Tim
 Tim
(@tim-2)
Illustrious Member

@sam-s7

It would be interesting to measure the thermistor of the old hot end when it is near a good room thermometer (22c) to see if it has failed. 

It is always wise to get more than one opinion...
Posted : 17/11/2020 10:13 pm
sam.s7
(@sam-s7)
New Member

@tim-m30

It didn't seem to have failed, at least not catastrophically, though I never measured to make sure it was accurate. I tried both printing hotter and dropping the temperature until I was having even worse print quality and missing layers while I was troubleshooting. I tried several temperature towers but throughout the range of temperatures stringing persisted. 

Posted : 17/11/2020 10:51 pm
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