Printing TPU95 lower than 230°

Bambu Lab H2 Series
1

Hi, I used the generic TPU profile to print a benchy and after that reduced the nozzle temp from 240° to 230° and now the prnt has less holes and zits. I was wondering if I should try to keep lowering the temp and also how to do a temp calibration for TPU using Bambu Studio. Also if anyone knows how to do a retraction calibration I would like to know that as well.

2

Holes like this:

IMG_2588
IMG_25881658×1667 179 KB

There was many more of them when printing at 240°.

3

Did you properly dry your filament?

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4

24 hours at 70 degrees. I’m printing at 225° and the print isn’t finished but already I’m seeing improvements.

5

Yeah printing at 220° gave a much better result (except for the overhangs but i won’t print it without supports anyway):

IMG_2594
IMG_25941488×1416 130 KB

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6

That is quite weird to see this. This behavior is usually caused by moisture.

Printing TPU at 240C is normally not a reason for this effect. It might be on the high side though.

But definitely great to hear you get better results.

What brand/type are you using?

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7

Polymaker PolyFlex TPU95. Will try a temp tower now between 210-230°

8

Polymaker sits on the lower end of the spectrum, so 240C was on the high side.

But never seen this behavior when printing TPU, other than moisture.

210 or 220 is best in your case, I presume.

Success!

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9

I was able to get a good print at 230C. Turns out you shouldn’t turn on Flow Dynamics calibration with flexible filament. I was printing with Auto, which means On if you never calibrated before. Only found out after trying to do a manual calibration lol.

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10

Interesting that made a difference for you! I used some TPU 95 on my H2C for the first time recently, and I did leave the dynamic flow calibration on “auto” for the prints, curious to see what it would do. It definitely skipped it… I watched it on several prints. Just kinda wagged the head back and forth a couple times instead of extruding anything, then wiped the nozzle. Printer status briefly said “dynamic flow calibration” during that time and the timing was also correct (compared to other prints). And looking at the machine G-code for all 3 H2 printers I even see where it appears to skip the flow calibration for TPU type filament (not that I’m an expert).

{if filament_type[initial_no_support_extruder] == "TPU"}
    G150.2
    G150.1
    G150.2
    G150.1
    G150.2
    G150.1
{else}
    G150.3
    M106 P1 S0
    M400 S2
    M109 S{nozzle_temperature[initial_no_support_extruder]} ; wait tmpr to extrude
    ....
{endif}

Anyway, probably a good idea to disable DFC for TPU manually anyway. Thanks for pointing that out!

-Max

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