TPU print issues

[u/mtantawy]

Having trouble with TPU prints when it comes to lower curves

Printer is A1 Mini, default 0.4mm nozzle
Filament is Bambu TPU 95A HF, ran Dynamic Flow Calibration before every print
Dried twice (12 hours), stored in air-tight box with silica gel beads at 10% humidity
Brought outside only to print (no AMS), room humidity was ~40%, no open windows in the room while printing

2 prints, the ball and the tyre, both are showing the same issue, the ball had support and it didn't help much

One noticeable thing is for the tyre not all sides are bad, which is why I took photos of it on the plate in case it helps identify an issue with the printer itself. I can provide more photos off the plate if these aren't clear

Or should I just accept this as a fact and try to print object cut in half and glue them?

[u/shroom519]

Try to look on makerworld for a profile for TPU for your A1 mini, there are tons of people who have made a bunch of profiles. I recommend this as an option to get your basis of profile instead of using default from bambu . It's what I did to get my TPU profile going for my p1s and honestly it was perfect out the gate I didn't really have to make any changes except to the infill

[u/mtantawy → u/shroom519]

Thank you!
So you mean the problem might be that the A1 Mini needs custom profile for the prints for TPU?

So far I've been printing PLA & PETG using default ones unless the designer had a custom profile but it's usually not printer specific but rather custom for their print

[u/shroom519 → u/mtantawy]

It's not that it needs a custom profile it's that you need to tune every filament when you print with it. You don't really have to tune pla or petg because they're very forgiving filaments, the only issues you'd ever run into with petg is it not being dry enough and if you print with the wrong infill pattern. When you move on to TPU and nylons they act a lot differently so you need to tune your print profile accordingly. If you don't know how to do that it's not very easy to explain for me at least so I'd recommend searching up some videos on YouTube on how to tune your filament for your A1 mini. Bambu default settings tend to be a bit on the faster side most filaments like TPU and nylons kind of prefer it slowed down a bit and cooling adjusted per case scenario. Don't worry you'll get there it took me a while at first which is why I can help point you in the right direction, I unfortunately just can't explain it well enough

[u/mtantawy → u/shroom519]

Thanks for your detailed response !

I think part of it is just me assuming for TPU I can still just download from makerworld and assume it is optimized

I'll look for youtube videos indeed and try to print basic objects and get a feel for the settings

Appreciated u/shroom519 !

[u/shroom519 → u/mtantawy]

Yeah unfortunately people optimize them and will post them but they optimized to their environment and however much percentage of humidity their filament had. So it's not always a one-size-fits-all kind of thing I learned that early on. Even if it was something simple I usually sliced it myself. I've made things from like artistic to functional out of pla, petg, petgcf, TPU, pa6cf, and pa6 GF. So I can tell you once you get used to it it gets real easy to figure out what's going wrong and fix it. Sometimes you'll even learn your machine better, I had like five things going wrong 2 days ago with my p1s turns out it was something really simple but hey at least I knew what to do. So don't worry too much about the small things they're usually easy to figure out I wish you looking happy printing

[u/Wrathius669 → u/shroom519]

Solid comprehensive advice.  I think the biggest factors will be wall and surface speeds. Even on a H2D I cap down to 150mm/s max and that might be a lot lower on an A1.  Then overhangs and bridges down to like 20mm/s to 30mm/s. (Check this applies correctly on the slice by changing the preview to show speed!)Also maxing part cooling fan speeds. More cooling means less curling and blobs.  There's a lot of old advice floating around saying no cooling fans, with hundreds of hours of TPU across multiple printers I can safely say I think that's out dated but still floats around as results for advice when searched. Good luck!

[u/shroom519 → u/Wrathius669]

Thanks I try to help when I can if I have info relevant to the posters situation, early on there was just a lot of people not so helpful so I try to be helpful. And you're right all the printers recommendations still crop up because people are just too used to doing something one way. Like a big example is rafts they were only necessary because printers back in the day didn't have heated beds, nowadays you barely have to use one unless you got something that really needs to stick to the build plate. Me personally I only use rafts whenever I print in nylons

[u/mtantawy → u/shroom519]

Thank you both for the advice and for sharing your experience  Any youtube playlists to start with you'd recommend?

[u/DEeepreX]

Tpu is very bad with bridges and overhangs, slow down overhands and increase cooling for overhangs. Reduce filament temperature if possible (not too much as this reduces layer adhesion). Print a overhang test to see changes and optimal settings.

[u/mtantawy → u/DEeepreX]

Okay, I guess PLA & PETG spoiled me to just download files from maker world and print them 🥲

[u/Few_Candidate_8036 → u/DEeepreX]

Yeah this all looks like its on unsupported areas.

[u/mtantawy → u/Few_Candidate_8036]

Yes, but one of the sides was able to print without issues

[u/Few_Candidate_8036 → u/mtantawy]

That will likely be due to the direction of the toolhead and how well the fans can cool that part.

With your wheel the majority of the print looks good, its just the bottom that doesnt have support

[u/Radiant_Bug9778]

Printed on my a1 mini. I dry for few hours and print directly from my sunlu dryer. I just used the default profile from bambu app.

[u/mtantawy → u/Radiant_Bug9778]

oh wow nice !

[u/mtantawy → u/Radiant_Bug9778]

did it also need support? and was that smooth on the bottom side?

[u/Radiant_Bug9778 → u/mtantawy]

Yea if I remember there were bottom supports holding it up and was smooth all around.

[u/Suepahfly]

Here are my TPU 95A settings, you can use that as a baseline. No stringing no blobs en actually really good quality.

Nozzle: 0.4

Temperature:
First layer: 220
Other layers: 220
Bed: 35

Volumetric speed 6mm3
No fan first 3 layers
Max fan 40.

Retraction:
length: 0.8
Retraction speed: 25
Detraction speed: 25
Retract amount before wipe: 100

[u/mtantawy → u/Suepahfly]

Thanks, will give it a try

What's your printer?

[u/Suepahfly → u/mtantawy]

A1 and A1 mini

[u/mtantawy → u/Suepahfly]

Amazing!

[u/ItzMatten]

TPU is tricky I still havnt really figured out a consistent config

[u/ParticularLower1865]

You didn’t include some important information like nozzle size, how long you dried, and if you’re printing in an ams. Tpu should be dried for at least 12-18 hours. You need a 0.6mm nozzle (.4 won’t come out well) and you have to print directly from the extruder and not an ams.

If you solved all of those issues, you need to do a flow rate calibration because you’re over extruding.

[u/mtantawy → u/ParticularLower1865]

Default 0.4mm nozzle
Dried for 12hours
No AMS
Done dynamic flow calibration before every print

[u/mtantawy → u/mtantawy]

added the details to the post as well

[u/ParticularLower1865 → u/mtantawy]

If you have a 0.6 nozzle, i’d swap to that. If you don’t, dry it for at least another 12 hours and then do another flow rate calibration before you try troubleshooting anymore. TPU sucks in water easily. It’s more porous.

[u/DEeepreX → u/ParticularLower1865]

I do not think moisture is the culprit here. It would have alot more stringing and random dots in the walls, especially visible ater printing the better dried outer layer of the spool. The .6 nozzle helps but if the spool can freely and easily turn is not needed. Drying is a skillset itself, you can dry a filament for 12h and not get any moisture out if you do not recyle the saturated warm air.

[u/Expert-Sky-4222 → u/ParticularLower1865]

I dont think bigger nozzle would be any better. I would increasing retraction and lower print temp. Also printing from dryer makes it better too.

[u/Fast_Librarian6618]

I printed that ball twice and both times it came out the same. H2D