I’m printing a simple cap with 92 TPU (Paramount) and I get some fine stringing where the new layer starts or ends, pretty obvious in the picture below. The filament has been dried and I’m printing at the higher end of the temp range (220C). I have a small amount of retraction (0.4mm). The rest of the print looks great.
Any tips for reducing this stringing?
Have you tried the “Avoid Crossing Walls” option in the Quality Tab at the bottom under Advanced?
I have not. I’ll give that a try.
“Avoid crossing walls” didn’t seem to have any effect.
Is this new TPU straight out of the vacuum bag or older?
It could have some moisture in it. TPU absorbs moisture too well. Do you have a heated chamber to dry it out for a few hours?
Something like this…
https://www.amazon.co.uk/Upgraded-Dehydrator-SUNLU-Enclosure-Compatible/dp/B09HTJ5HT6
Yes, it’s as dry as I can get it. I dried it in my X1C.
With a retraction of 0.4mm I was able to reproduce your experience.
I increased the retraction value to 4mm it is now clean in my test of your problem. Zero strings.
This is a 50mm diameter tube with a 3mm thickness and a 4mm retraction.
It will likely work with less retraction. Play with that setting to see what you can get away with.
The problem is related to the TPU material stretching under pressure and only 0.4mm of retraction didn’t pull the filament out from the nozzle.
certainly should try with less retraction because 4mm on a direct drive extruder is huge and on longer prints that can lead to heat creep and with it the filament being jammed up in the extruder
Which is what I said.
The point was to show one extreme to the other.
Changing the retraction to 3mm completely fixed the stringing.
I’m glad I could help.
If you can get the retraction figure lower without too much of an issue try that.
I guessed the dimensions of your model to create a reasonable facsimile for my own tests.
Yeah I’ll trying lowering gradually until it starts stringing again. The model is 77mm ID so your guess was reasonably close.
THANKS!
Trying SUNLU TPU in my P1S for the first time and noticed some stringing on the Benchy & the advice of increasing retraction solved my problem with a little tweaking of several parameters. I have gone from 0.8 to 2.0 with Hot End temp of 210C and Bed temp of 35C has produced fine quality, but I’m still chasing flawless by fine tuning fan speeds 
What optimal settings did you find please ?
For myself the SUNLU TPU works the best between 225°C and 230°C on an A1.
I’m using Paramount 92A TPU:
205C first layer, 215C after
Retraction = 1.6mm, 0.4 zhop, wipe while retracting enabled
Max volumetric speed = 3.5 mm3/s
I also increased the part cooling fan speed a little.
But I have also found that another huge factor is how easily the extruder can pull in the filament. I had to put the spool on a ball bearing rolling hub, and also I unwind a lot of filament because it has a tendency to stick together, so unwinding it and winding it back up loosens it up some.
Thank you so much ! You truly helped.
What are your fan settings exactly please ?
Very kind of you ! Thank you so much
Tried this with my Addnorth easyflex tpu and it works wonders!! thank you!
