Hey everyone. I got a P1S mainly to print Priline TPU which is some pretty stiff TPU at 98A. Everyone I know with the P1P through X1C prints it no issue. I have been trying to print a handle for an electric unicycle and have used a few different models, but they all fail in the same way.
The first time I printed it I used a profile from my group which essentially is the same as the default generic TPU profile, and this is what came out:
The outside face was fine, but the inside face had all those dots everywhere and the bottom surface where the supports were was horrible, although I understand getting a clean support interface with TPU is almost impossible.
Regardless, I did a bunch of calibration prints with benchies, cubes, etc and I got everything set up using the default TPU profile as a base. Here are screenshots of the settings I am using.
At this point I am at a complete loss of what to do. I just dont understand how those gouges form in the side of the print and why everything just looks so horrible.
Im going to print it once more, except in this orientation. Its not optimal in any way but maybe the small radius curves in the bottom layers are causing issues:
I print my very old 85A from Extrudr ± with the Stock Bambu TPU Profile. I calibrated mine with the Orca Slicer. Flow 1, PA 0.016 and 3.2 Volumetric Flow.
But what I see in you settings… why did you print with 0.1 layer height? Is this not so small for the TPU?
From the pictures and your description, filament seems like it is probably “wet”. TPU is very hydrophilic, sucks up water from the air like a sponge. When it goes through the extruder the water heats up and turns to steam, which forces plastic out faster than the filament is being pushed in, so you over extrude. But it also causes poor adhesion and stringing because the filament continues to expand after it’s left the nozzle.
If you don’t own a filament dryer, or you haven’t used it with this filament, that’s your problem. If you do own one and you have used it, you needed to go longer in the dryer. Put it back for a day and try again.
The filament roll is brand new and I had it in the dryer for 24 hours before starting use. The test prints I did before the handle (benchy, cube for wall thickness calibration) came out flawless with no stringing or pockmarks, the main signs of wet filament.
On that run I was printing with 0.1 layer height because I thought maybe overhangs were the issue, so having a lower layer height could help. I have also tried printing at 0.2 and 0.16, all end the same way.I currently have my pressure advance at 0.15 (not 0.015 as you mentioned) but it seems to be no issue as my test prints (benchy, cubes, etc) all print perfect.
Well, the one thing I’ve learned is that it doesn’t matter how long you’ve had your filament in the dryer. If it prints like it’s wet, it wasn’t in the dryer long enough. Put it in the dryer longer. Or maybe your drier isn’t doing the job and you need an upgrade…
If this was heat creep, the effect it would have would be to clog the extruder. How hot the filament is when it’s going in to the extruder doesn’t matter to how hot it is when it’s coming out. But if it gets too hot between the extruder gear and nozzle, it’ll buckle and squash, stopping extrusion completely.
This looks like bad/blobby flow. You can see it clearly in the single extrusion line, here:
I struggled for the last week with Matterhacker Pro Nylon (in colors!). I dried a roll for 24 hours and it still printed like ■■■■. Blobby, stringy, over-extruding. But while I spent a week trying different things, I had a second roll in the dryer. Last night I decided to give that second roll a try and give up if it didn’t print well. It printed beautifully. I put the first roll back in the dryer for another day and now it prints beautifully, too. Still have to tweak retraction and flow a bit, but all the bad artifacts, that looked very similar to the pictures above, are now gone.
Dryer: Sunlu S2 at 65ºC. The dryer reports a RH of about 14% after 6 hours. It didn’t go any lower after another 18 hours. But clearly, the filament was still wet after the first 24 hours or it wouldn’t have gotten better after a second round of 24 hours.
I have a roll of Duramic 95a TPU I got a while ago on Amazon that I had issues with on my P1Ps, I ended up drying for 48 hours then printting from the dryer to the machine and finally got good prints. The 48 hours was a hail marry before I tossed it thinking it was just junk TPU. It prints so well on the gerneric profile that I may buy another roll. Reguardless he should be printing PLA, TPU, PETG with the door ranging from cracked to fully open.
Dryer is definitely doing the job and I am certain the filament is not wet at this point.
The reprint I did standing vertically shows no signs of wet filament, but it has its own array of issues. The layers are uneven and I am not sure why. There are some that bulge out more than others.
Its been drying for about 3 days now, still same issues. The air bubbles on the top were caused by pillowing from using cubic infill, I changed to gyroid and the issue no longer persists. My biggest problem currently is getting supports to work with TPU.
However, the problem still remains that at random places along the overhang the print looks like someone took a knife and stabbed into it. This came out this way and was under the supports.
This is the same thing that keeps happening on all my TPU prints, and this one had ample support and the overhang angle isn’t even extreme. Plus I have overhang speeds slower.
Have you tried to adjust the belt tension and clean the guiding rails ?
I had similar issues and after the quickly done maintenance tasks they vanished.
I will take a look. The rails all look spotless, but the belts I have not touched as the printer is brand new. It printed the 18 minute benchy file perfectly so I would imagine the belts are fine?
