I am at my wits end with this. I print with PLA, PCTG and TPU. The stringing with PLA is bad, and TPU is unusable due to stringing and constant feeder jams. I have a drier and heated spool holder, so I keep my filaments as dry as possible. PCTG is doing much better after a lot of tweaking, but I cannot seem to get great and CONSISTENT results with PLA and TPU.
This is not the PLA stringing I am used to with my ender 3. This looks like little bits of cotton candy or in some cases peach fuzz. It typically manifests between the travels from part to part, or part to prime tower. Printing cylinders leaves a lot of fuzz on the inside from internal travels. TPU leaves more of your traditional looking strings, but that’s if it is actually printing and not jamming.
I have done the temp tower, Max Flow, Pressure Advance, Flow and Retraction calibrations. For PLA, the retraction test looks the same the whole way up the towers, regardless of retraction length. I have checked the g-code to make sure it is actually changing the retraction length during the test. I have tried higher and lower retraction lengths and I have tried increasing retraction speed to 40mm/s. I have tried z-hop on and off. I would say difference is negligible.
For the TPU jams, I cannot figure this one out. I have tried different tool heads with the same result. I have tried using the spool holder/auto loader and I have tried feeding directly to the back. I have tried various retraction lengths and 0 retraction. Somehow it will jam on the top temp tower every time with 0 retraction, or even a continuous vase mode print like a max flow rate test. How the heck does it jam in the gears with a continuous feed and 0 retraction? The TPU is Overature 95.
For PLA issues, I recommend recording a video to pinpoint exactly where the problem occurs.
For TPU issues: The biggest problem is inconsistent feeding and insufficient cooling. When printing TPU, I set the fan to maximum because I print at a higher temperature than recommended (245–250°C) to ensure material adhesion strength and better flow at high temperatures. Also, printing TPU often triggers an empty spool detection alert, causing the print to stop. I disable empty spool detection as long as I’m sure there’s enough material. When printing TPU, the filament should connect directly to the extruder, minimizing the feed length. The official recommendation is to use materials with a hardness of 95A or higher. I’ve tried it, and if using glossy filament, you need 95A; matte filament can go as low as 85A.
Additionally, if a specific hotend has trouble extruding TPU, you can clear it by feeding PLA or PETG through it.
Good morning, thanks for the tips. For the pla, it’s worst at seams where a travel to another part or purge tower occurs.
For the tpu, yes I am using 95A. I haven’t had an issue with the run-out sensor. When it jams it air prints. When you say hook direct to the extruder, what is your setup for that?
Is this happening with all PLA that you’ve tried or 1 specific brand & color. When printing with a brand of PLA that I haven’t used on the U1 before I start with the generic ola profile then tweak it from there if needed. I find 95% of the time it works just fine.
I’ve printed TPU 95a on mine a few times with only a small amount of angle hair that burns off easily. TPU needs to be printed pretty slow so you might try slowing it down some & see what happens. You could also try bypassing the feeder & see if that helps. I remember back when I had an Ender 3 s1 that TPU gave me all sorts of issues just going thru the runout sensor.
I see, yeah I have tried the direct feed too. Frustrating. I know some have adjusted the set screw for the gears but I don’t want to screw it up for the rest of the filament types.
