What Settings Work For PETG to Reduce Stringing?  

RE: What Settings Work For PETG to Reduce Stringing?

I printed a stringing test with various parameter changes. So far, these changes have improved things quite a bit:

Retraction Length  6.2mm

Lift Z .05 mm (Most improvement)

Regards,

Mark

RE: What Settings Work For PETG to Reduce Stringing?

That article comes from times when the only printer they had was direct drive printer (MK3 in this case). Hence the retraction distance being 2 mm.

Use what works best for you. I found that thoroughly drying PETG helped immensely with stringing and overall print quality, I printed few print-in-place articulated toys like octopus and lizard for my colleague's kids because I was lazy to change filament in between printing enclosure parts, and it handled it well. I used Prusa PETG (not Prusament PETG) profile which corresponds with Plasty Mladeč filament, left everything default except for minimum cooling to 20%. If you found that with your filament 6.2 mm is the best, then use it. Increasing travel speed between points also helps cutting strings.

RE: What Settings Work For PETG to Reduce Stringing?

A couple things I have noticed to be quite true:  printing below 0.15mm is a bad idea.  My best results on my i3 Mks are at 0.15 mm.   Bed temps matter : start at 85 , maybe more... then multiply by 0.6 and leave it there until end of print.   I also think that retraction, like anything over 20 mm makes no sense.  All you are doing is stretching out the melt portions in the extruder.  Petg is a high viscous material,  you can't ask it to do things it is not intended to do. In other words makes more sense to do a good z-hop fan at healthy high rate and acceleration up high like 190+ and stop stretching on it for ever.  Now on my mini; man I can't get any strings to stop on any prints.  I did pit a silicon sock on, so the air flow is restricted,  but I also upgraded the fan shroud.   I think I might start leaning to using 0.2 for petg on the mini going forward.... 

RE: What Settings Work For PETG to Reduce Stringing?

It depends on what brand you're using and the polymers they use. Example: Overture PETG with stock "Generic PETG" gives me very pretty results with minimal to no stringing, even the Prusament PETG setting works well (but I notice a bit of bulge at the corners, likely LA difference) when I wanted functional/better adhesion.  Make sure your PETG is dry, a cheap adjustable food dehydrator works wonders.

As far as retractions go: Try a bit lower and a touch slower. Default MINI settings are 3.2mm distance, 70mm/s speed, and 70% before wipe. Try reducing retract to 2-2.5mm, 30mm/s speed, and only say 25% amount before wipe. I found this helped with "Silk" PLAs that seem to have a thicker polymer blend that likes to string and underextrude with stock settings on quick retractions. Reducing those has them printing great. For Z lift, the stock is 0.2mm, could try either moving it up to 0.5mm, or removing lift altogether so it wipes against the part to break the string.

RE: What Settings Work For PETG to Reduce Stringing?

Posted by: @skreelink

As far as retractions go: Try a bit lower and a touch slower. Default MINI settings are 3.2mm distance, 70mm/s speed, and 70% before wipe. Try reducing retract to 2-2.5mm, 30mm/s speed, and only say 25% amount before wipe. I found this helped with "Silk" PLAs that seem to have a thicker polymer blend that likes to string and underextrude with stock settings on quick retractions. Reducing those has them printing great. For Z lift, the stock is 0.2mm, could try either moving it up to 0.5mm, or removing lift altogether so it wipes against the part to break the string.

Hi, I wondered if you would be able to explain why you suggest decreasing the retractions/speed and amount where most other posts seem to suggest that increasing the retractions help with stringing.

I have been having some issues with Prusament PETG on my Prusa Mini, so have been trying various retraction settings.  I started with the stock settings and increasing the retraction by a mm each time. Now after reaching about 11mm retraction the stringing was better BUT it then wasn't extruding enough material and the string towers were deformed.

I then tried using your suggestion of reducing the retraction/speed and amount and my stringing problems have improved vastly, I still need to play around with these more but I would be interested to know the logic/science behind it.

Look forward to hearing from you.

RE: What Settings Work For PETG to Reduce Stringing?

Posted by: @michaelaswood

Posted by: @skreelink

As far as retractions go: Try a bit lower and a touch slower. Default MINI settings are 3.2mm distance, 70mm/s speed, and 70% before wipe. Try reducing retract to 2-2.5mm, 30mm/s speed, and only say 25% amount before wipe. I found this helped with "Silk" PLAs that seem to have a thicker polymer blend that likes to string and underextrude with stock settings on quick retractions. Reducing those has them printing great. For Z lift, the stock is 0.2mm, could try either moving it up to 0.5mm, or removing lift altogether so it wipes against the part to break the string.

Hi, I wondered if you would be able to explain why you suggest decreasing the retractions/speed and amount where most other posts seem to suggest that increasing the retractions help with stringing.

I have been having some issues with Prusament PETG on my Prusa Mini, so have been trying various retraction settings.  I started with the stock settings and increasing the retraction by a mm each time. Now after reaching about 11mm retraction the stringing was better BUT it then wasn't extruding enough material and the string towers were deformed.

I then tried using your suggestion of reducing the retraction/speed and amount and my stringing problems have improved vastly, I still need to play around with these more but I would be interested to know the logic/science behind it.

Look forward to hearing from you.

While in general increasing retraction helps with stringing, I find it better with thicker/stickier filaments like PETG or Silk PLAs, decrease is a bit better. The reason I figure this works is, the melted blob still in the nozzle is sticky, it doesn't want to move anywhere. So trying to pull the filament back fast/far instead just pulls the unmelted filament back and disconnects it from the melted end, thus it stays there to ooze and string. Slowing it down and reducing how far it pulls gives the unmelted filament enough time and grip to pull back on the melted filament enough to reduce the pressure and pull it back from the nozzle enough to reduce stringing, but not enough that when it plunges it back in, it lags and causes underextrusion or other artifacts. You can try increasing the distance a little, to say 4-5mm, but keep the speed lower and see how well that works out. Might be good enough to pull the blob without disconnecting it. 

RE: What Settings Work For PETG to Reduce Stringing?

@skreelink

Thank you so much for your speedy response.  I shall try that tomorrow.  That makes perfect sense now it's been explained. 👍🏻

RE: What Settings Work For PETG to Reduce Stringing?

@michaelaswood

Make sure to update me and let me know how it works out! I might need to do more of my own testing. 🙃 

RE: What Settings Work For PETG to Reduce Stringing?

Posted by: @skreelink

@michaelaswood

Make sure to update me and let me know how it works out! I might need to do more of my own testing. 🙃 

Hi,

Well, I wish I could say it was a quick and easy process... lol  After many hours of printing numerous stringing test models, I would like to say I have cracked it, unfortunately not, although it's getting there!!

So, I've been testing with Prusament PETG, hotend 225.

I have increased the Retraction from your suggested 2-2.5mm to 3.5mm with a z-lift of 0.1mm.  I had previously disabled the z-lift, which seems to be wiping the filament but then leaving blobs and zits.  Retraction speed = 20mm/s, Deretraction speed = 15mm/s, Retraction amount before wipe = 20% 

To confuse matters even more I have very recently swapped out my Mini hotend with a full metal E3D V6 hotend. (As I had been experiencing issues with my Bondtech heat break).

I would be interested to know how these settings work for you...

RE: What Settings Work For PETG to Reduce Stringing?

What settings did you end up with @mark?

RE: What Settings Work For PETG to Reduce Stringing?

Posted by: @jed

What settings did you end up with @mark?

I went back to the default settings in Prusa Slicer. While the stringing can be improved on the test parts, the surface on most real world parts I print got worse by changing the retraction and lift. Drying the filament makes the most improvement and I do get small strings on PETG, but they are easy to remove.

Regards,

Mark

RE: What Settings Work For PETG to Reduce Stringing?

thanks for the reply!  you probably saved me a lot of time lol.  there doesn't seem to be a whole lot of options for stringing when using the bowden extruder.  

RE: What Settings Work For PETG to Reduce Stringing?

I was amazed at how much drying the filament decreased stringing.  I’ve been chugging through a project and had left my PETG on the printer for about two weeks.  It’s winter, dry climate. Didn’t think anything of it.  had to switch to another filament so I dried the PETG before going back to it.  Made a huge decrease in the stringing that I had just assumed had been an artifact of printing a number of small towers in the project.