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CORE One and soft TPU  

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Scott
(@scott-18)
Estimable Member
CORE One and soft TPU

Hello!

I'm currently trying to print TPU (step step from 95A, to 60A) and 85A was very difficult to load without removing PTFE and printing directly from the top extruder.

Does anyone have a tips for that?

Next step will be 70A and then 60A, but I think I will have to modify filament guide inside the head with something like THAT.

I will keep you in touch, 85A Ninjaflex was printed easily just by unscrewing idler tension a little.

Posted : 28/02/2025 2:05 pm
altaic and LarGriff liked
Scott
(@scott-18)
Estimable Member
Topic starter answered:
RE:

Little update:

- 60A is quite impossible to load for 2 reasons:

Filament sensor is very hard for a soft filament like that so I managed once to pass it (even if I bypassed PTFE tube). Once loaded, filament curls everywhere in the print head even with the modified main plate I linked above.

- 70A is quite hard to load because of the filament sensor but a little easier than 60A. I had to bypass the PTFE tube and load directly above the tool head. With the mod I managed to load and purge, didn’t have time to try printing tho.

I don’t like the main plate mod and I changed back to original one.

I will try to print 70A with the original main plate and see if it works.

 

Curiously the filament sensor didn’t feel as hard to pass on my MK4S even without PTFE. I will try to figure out why.

The filament sensor at the beginning of the PTFE (behind the handle) seems even harder.

Posted : 01/03/2025 3:45 pm
andhson
(@andhson)
Trusted Member
RE: CORE One and soft TPU

I am still waiting for my printer but I will follow your efforts with interest, I have a few TPU projects coming up and will need to learn how to print flexible materials on the core one.

/Anders

Posted : 01/03/2025 4:31 pm
Andreas
(@andreas-19)
Eminent Member
RE: CORE One and soft TPU

I can't even get some 82A past the filament sensor and haven't managed to get the PTFE tube out either.

Posted : 15/03/2025 6:53 pm
Brecht
(@brecht)
Member
RE: CORE One and soft TPU

Wouldn't varioshore tpu solve this problem when you need softer parts? I might be looking into printing non slip parts for my rc planes and it's good to know not to try the softer ones. 

Posted : 15/03/2025 7:38 pm
altaic liked
Scott
(@scott-18)
Estimable Member
Topic starter answered:
RE: CORE One and soft TPU

Which filament sensor? 

Removing PTFE is quite difficult, you have to press the black ring down and pull the PTFE.

I managed to get 85A (Ninjaflex) through the entire PTFE and both filament sensor, but I had to cut filament with bezel before.

Posted : 15/03/2025 8:57 pm
Andreas
(@andreas-19)
Eminent Member
RE: CORE One and soft TPU

The extruder sensor and I tried pressing down the ring, but it wont budge.

Posted : 15/03/2025 9:29 pm
Scott
(@scott-18)
Estimable Member
Topic starter answered:
RE: CORE One and soft TPU

It's quite hard indeed. I can't give any other advice than pushing harder on the ring, and pulling harder the PTFE tube ahah.

Posted : 17/03/2025 9:41 am
Andreas
(@andreas-19)
Eminent Member
RE: CORE One and soft TPU

I unscrewed the fitting and was able to load the filament. The print turned out quite nice, but unloading the filament was equaly hard, since the filament formed a thickened end that didn't fit through the filament sensor. Maybe that is because of strange way filament is unloaded, compared to my old MK2.5. I had  to open the idler and cut off the end before I could pull the filament out.

Posted : 17/03/2025 12:28 pm
Scott
(@scott-18)
Estimable Member
Topic starter answered:
RE: CORE One and soft TPU

That's nice the print came out good with 82A filament.
What max volumetric speed (MVS) did you set?
Did you reduce idler tension?

Posted : 17/03/2025 12:38 pm
reinvented.tech
(@reinvented-tech)
Member
RE: CORE One and soft TPU
Posted by: @scott-18

That's nice the print came out good with 82A filament.
What max volumetric speed (MVS) did you set?
Did you reduce idler tension?

I have the same problem with TPU as OP. Without loosening idler screws loading is practically impossible, the filament can't geth through the second sensor. After reducing idler tension it is pain in the ass, but after several tries it is possible.

I am very glad with my Core One as far as speed and print quality, but I am dissapointed with flexible filaments. I didn't expect such problems with loading, although prints on default flex profile are very fine.

Posted : 19/03/2025 8:11 am
Daniel liked
Jürgen
(@jurgen-7)
Honorable Member
RE: CORE One and soft TPU

This sounds consistent with what Prusa recommends for inserting flexible filaments into to XL: Cut the filament to a pointed tip, reduce the idler tension, disconnect the PTFE tube. It takes an extra step on the Core One because the top panel has to be removed to gain access, but otherwise it seems the same?

Posted : 19/03/2025 2:38 pm
Andreas
(@andreas-19)
Eminent Member
RE: CORE One and soft TPU

 

Posted by: @scott-18

That's nice the print came out good with 82A filament.
What max volumetric speed (MVS) did you set?
Did you reduce idler tension?

I used the manufacturers recomendations. So for a 0,6 mm nozzle 7,2 mm³/s. I didn't reduce idler tension, because the problem was the filament sensor. Even with the idler open I couldn't get past the sensor.

I didn't have to remove the top panel. There is just enough space to unscrew the fitting.

Posted : 19/03/2025 9:21 pm
Daniel liked
reinvented.tech
(@reinvented-tech)
Member
RE: CORE One and soft TPU

Thanks for a hint, after disconnecting PFTE tube loading was easy.

Posted by: @jurgen-7

This sounds consistent with what Prusa recommends for inserting flexible filaments into to XL: Cut the filament to a pointed tip, reduce the idler tension, disconnect the PTFE tube. It takes an extra step on the Core One because the top panel has to be removed to gain access, but otherwise it seems the same?

 

Posted : 20/03/2025 7:59 am
Jürgen liked
Daniel
(@daniel-3)
Eminent Member
RE:

Hi,

It seems greater MVS works well with 0.6 nozzle.

I have a Prusa Core One, 0.4 nozzle, and printed very well Polymaker PolyFlex TPU-95A HF with MVS=5 and I feel I can increase it a little. But with Varioshore is almost impossible to have a longer print even if it will easily pass the sensors. I've tried with MVS=4 which works without problems on my MK3s and it failed for both normal (195 nozzle degrees) and maximum foaming (220 degrees). In fact, I can't print it because of a known 'nozzle cleaning error'. If after a few attempts, it passes this error then it will require 'changing filament' - don't understand why!- while after filament changing (with the same Varioshore filament), it will lead to the same 'nozzle cleaning error". One of the problems with Varioshore is a lot of the filament is purged before starting nozzle cleaning and printing. I can't clean it because I can't open the door or if it finally starts printing it will affect the quality of the first layer.

Any other experience with Varioshore?

Thank you!

Posted by: @andreas-19

 

Posted by: @scott-18

That's nice the print came out good with 82A filament.
What max volumetric speed (MVS) did you set?
Did you reduce idler tension?

I used the manufacturers recomendations. So for a 0,6 mm nozzle 7,2 mm³/s. I didn't reduce idler tension, because the problem was the filament sensor. Even with the idler open I couldn't get past the sensor.

I didn't have to remove the top panel. There is just enough space to unscrew the fitting.

 

This post was modified 1 month ago by Daniel
Posted : 22/03/2025 9:27 am
reinvented.tech
(@reinvented-tech)
Member
RE: CORE One and soft TPU

I get nozzle cleaning errors when the filament is not dry enough. Just after drying there are no errors, but when the spool is outside drying box for 1-2 days the problems begin. Dry for 4 hours at 65 degrees celsius and check if you still have problems.

Posted : 22/03/2025 10:07 am
Daniel
(@daniel-3)
Eminent Member
RE: CORE One and soft TPU

Which filament are you using? 

I dried Varioshore in the Polymaker Dry Box for hours till 20% humidity. The same problems. I printed without any problem Polymaker PolyFlex TPU-95A HF without even drying it and with MVS 5.

Posted : 22/03/2025 11:53 am
reinvented.tech
(@reinvented-tech)
Member
RE: CORE One and soft TPU

I've just found the tweak to skip the failed nozzle cleaning problem. At the end of nozzle cleaning pause the printing. After resuming the printer does not clean the nozzle again, but starts probing the bed level. 

Posted : 01/04/2025 2:47 pm
Daniel liked
Daniel
(@daniel-3)
Eminent Member
RE: CORE One and soft TPU

What exactly means "at the end" ? I assume you don't wait for the message "nozzle cleaning error" to appear, isn't it? Thanks!

Posted : 01/04/2025 6:54 pm
Daniel
(@daniel-3)
Eminent Member
RE: CORE One and soft TPU

It worked for me too one time (I tried just one time)

Posted : 02/04/2025 3:47 pm
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