Printing with TPU, any tips?

[WobblyHand]

Have you tried filament and zhop retraction (distance inputs)? I believe those were some suggestions with my stringing PETG.

I kept the standard retraction lengths for fear of jamming. PETG is trivially easy compared to TPU. I can use defaults on PETG and it comes out beautiful as long as it's dry. My first roll of PETG was soggy and snapped and popped right out of the package. Learned about filament drying that day!

My short run models in TPU are mostly ok with not too much stringing. But the longer, bigger model has quite a bit, so much that initially I couldn't see through the bore of the part.

 

[WobblyHand]

Your close enough to me want me to try it on my Bambu Labs P1S (would need your filament roll, wife not happy with the stack I have now).

I hear a lot of folks with Bambu Labs printers have trouble with TPU. I think my main issue was extruder jamming due to the soft filament and tension settings, followed by having to cap the flow rates. Practically had to set the tension to near zero to get it to work for TPU. Stringing, well it needs more work. The issues I had only showed up on large models, not small ones. Small ones printed fine and had relatively little stringing. Big models take time to print, even with a Bambu.

The filament that worked (Sainsmart TPU) is ~$30/roll, fortunately not the $52/kg stuff. Even so, it takes 69m of filament which is $5.60 for a full part. I have printed the equivalent of 3.5 parts and taken over 3.5 days of printing (24 hrs/day) spread over a week and a half, to get to this point.

So, I wouldn't mind dropping by and saying hi anyways, since you are less than 30 minutes away from me, but I think it would be best to experiment with TPU on your own. Have to say, working with TPU been a humbling experience. Hope to get some GT-3 Sainsmart filament today, maybe it prints easier since it is supposedly a higher speed material. It's only $28/kg at the moment, which isn't too bad for TPU.

 

[keeena]

@WobblyHand - Did you see James' (Clough42) recent video where he made caps for compressed air disconnects? He's using Ninjatek Cheetah flexible TPU on a Mk3s with a Diamondback Polycrystaline Diamond Nozzle. He said it took a bit of tuning, but now it runs reliably and is his go-to printer for TPU. You can see his settings in the chapter starting 9m21s. YMMV. I certainly want to give it a try too since I have some projects I'd like to try in TPU.

 

[toprecyler]

@WobblyHand - Did you see James' (Clough42) recent video where he made caps for compressed air disconnects? He's using Ninjatek Cheetah flexible TPU on a Mk3s with a Diamondback Polycrystaline Diamond Nozzle. He said it took a bit of tuning, but now it runs reliably and is his go-to printer for TPU. You can see his settings in the chapter starting 9m21s. YMMV. I certainly want to give it a try too since I have some projects I'd like to try in TPU.

I liked James video. Makes me want to start learning fusion 360 as quickly as he was making adjustments to his design.

Then I checked Amazon for the diamondback nozzles. I guess for $100 each, it could be worth it if you need it.

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[WobblyHand]

@WobblyHand - Did you see James' (Clough42) recent video where he made caps for compressed air disconnects? He's using Ninjatek Cheetah flexible TPU on a Mk3s with a Diamondback Polycrystaline Diamond Nozzle. He said it took a bit of tuning, but now it runs reliably and is his go-to printer for TPU. You can see his settings in the chapter starting 9m21s. YMMV. I certainly want to give it a try too since I have some projects I'd like to try in TPU.

A decent video from James, he has a good style. His choice of filament and nozzle are not plebian, and seem to be somewhat financed from his youtube earnings. Both are expensive choices. (That might be the secret to success though.) He does make it look easy.

Since his part is relatively small (and he has the fancy high conductivity nozzle) it's less likely for him to run into the maximum volumetric flow issue that I did. He also didn't mention that the extruder tension needs to be reduced. The MK3S+ is a slower printer (I had one and upgraded it to the MK4) so it helps in the case of TPU. An MK4 is not as speedy as a Bambu Labs printer, but it runs into similar issues with printing these types of filaments. High conductivity nozzles would help, as would better filaments with higher MVS, and or better hot ends.

This TPU stuff isn't impossible, especially for the small parts. Big ones where one is hitting max volumetric flow, require additional fine tuning and a whole lot of patience.

 

[WobblyHand]

Fusion360, like many of the CAD programs is a great addition to one's capabilities. I happen to use FreeCAD, but any 3D CAD program will give you extra capabilities to help out making parts, be they printed or machined. It was worth the time I spent to learn the program. Learning didn't come easy, but eventually I persevered.

Yesterday, I looked at my 3d printer's OctoPi computer as it was sprawled on the table. Decided to make a holder/case for the OctoPi to make it a little more organized. Cobbled this together and printed it in PETG last night. Since it was PETG, not TPU this printed in a couple of hours. It's not pretty, but it should be functional. The bottom is a tray for an SSD, and has a cutout for the SATA to USB3 adapter. There are bosses to attach the RPI4 to the middle piece. The middle piece snaps into the tray. The fan module is attached to the top piece, which has cutouts for the fan, the 40 pin connector and a ribbon cable for the camera. It uses M2.5 screws for the the RPI4 and cover, where as the fan uses M3 screws. I'm assembling this together this morning.

 

[vtcnc]

The advice I could gather on this were, “slow and low” as it relates to speed and temp respectively.

The spring tension on the idler wheel (at least for Prusa Mk3 has to be as light as possible.


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[WobblyHand]

The advice I could gather on this were, “slow and low” as it relates to speed and temp respectively.

The spring tension on the idler wheel (at least for Prusa Mk3 has to be as light as possible.


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Yes, that's about the whole story. At least for me the tension was so loose on the MK4 that the only time the springs didn't rattle was when the filament was in place.

I have since printed a spool holder inserts out of TPU with no issues, save for stringing. Due to the part's geometry, there's no large infill areas which are anywhere near the MVS limit. A slow print, but both pieces finished correctly. I'm going to experiment on another set, to see if I can raise the print speed a little. Maybe it will fail, but I can revert to slow and low again. Nothing ventured, nothing gained. I'll print sequentially, so maybe I'll get one good one, rather than too half done pieces.

 

[WobblyHand]

So far, LOL, 4.8 mm into the print, I'm impressed with the GT-3 Sainsmart filament. Supposed to be a higher speed printing TPU. Printing a little faster, and hotter. Knock on wood, doesn't seem to be much stringing. Strangely, the GT-3 was cheaper than the normal TPU for Sainsmart.



Kept MVS=5.0mm3/s
Used Sainsmart TPU as the basic material.

 

[WobblyHand]

Here's a picture of the spool holder insert, still on the sheet. Rather low stringing, at least compared to the other TPU. Nothing that won't clean up with some hot air. Exterior is very good looking. This GT-3 seems to be working for me. Or at least this spool is... Second is now printing on the opposite corner of the sheet.