TPU - Impressions (Tina2)

[CrazyIvan]

Having got cocky with printing in PLA, I have a project for which a rubbery material is required and dived into TPU. Heads up (for those who don't already know): printing with TPU is nothing like printing with PLA!

• Lacking rigidity, tall thin structures wobble as the print head passes over them, so more support is required (and the support itself needs to be beefier so it doesn't wobble either);
• Stringing is inevitable;
• Separating support from the actual print is very difficult (lots of adhesion at the support interface, regardless of air gap).

After a disastrous first attempt, I decided to print a TPU temperature test tower (Cura > Marketplace > Extensions > search for "calibration"). Generating and then slicing the test tower (somehow) overrides the user settings and imposes its own temperature profile in the output gcode.

Starting at 225ºC and going down in 5º decrements to 210ºC, there was a great deal of stringing at 225 which improved as the temperature went down and it still printed satisfactorily at 210, so I do not understand why the default for generic PLA in Cura is 228 (with the first layer printing at 238ºC!). I chose 215ºC as the best compromise between stringing and surface defects, but this might be dependent on the specific TPU.

At no temperature did my Tiny2 succeed in printing the bridge. Extruding a thin line of TPU into free space and expecting it to hold is a fools errand.

I shall try maxing the fan speed (presuming it isn't already), but that's clutching at straws.