Lots of stringing but as I understand that's normal for TPU. Printed at 225⁰C on a 30⁰ bed, stock Ender 3 S1. 0 retraction, 0.93 flow, 35mm/s for most speeds
this post was submitted on 24 Sep 2024
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That's better than my first attempt with TPU was, that's for sure. No retraction whatsoever? That's bold.
If your slicer supports it, I recommend enabling "combing" (which is what Cura calls it), or "Avoid Crossing Perimeters" (in Prusa/derivatives) which work slightly differently, but have the net effect of keeping the nozzle within the outer walls of the print during moves when possible, which ensures that any stringing so caused winds up inside the solid spaces in the model where it's not visible.
Edit to add: There are of course some shapes where not crossing perimeters is impossible, which in your case would be the uprights on the Benchy's cabin before the top of the arches meet. Presumably it's designed this way on purpose. The combing/avoid crossing settings do wonders for not causing extraneous stringing e.g. in holes and notches in your print if any exist, though.
I had read that TPU doesn't really like to be retracted. I did a retraction tower and it didn't seem to make any difference really at least in the ranges I tried. I have avoid crossing perimeters on (using OrcaSlicer) with something like 350% detour but that won't help with the archway of course since those lawyers are just completely separate pieces
I'll have to try the combing setting though
The E3 S1 is a direct drive extruder, right? If so, it should produce some kind of results for you although in my experience you have to retract TPU pretty far to get results, like 5-6mm. In my experience it always oozes as least a little bit so long a your nozzle is at temperature and there's any amount of the stuff in the chamber, so you'll never fully eliminate stringing. But some retraction should help, and you can get it down to being very minor.
On a Bowden type extruder, though, it's basically a fool's errand because the stuff is so damn elastic, and is also slightly compressible to boot. The more length of it you have between your extruder gears and the tip of your nozzle, the more its elasticity becomes apparent. I think this is where the "common wisdom" of no retraction on TPU came from. The stuff can kink and then jam in a Bowden tube if you really go at it with gusto.
Anyway, you could also try a fairly long "wipe after retraction" setting.