The curling up happens because the TPU isn't fully melting in the nozzle, and when you put the perimeters down, the cooler core is retaining some tension and causing stress in the model - that pulls on the sharp corners and curls them upwards. The solutions are either slow down the print, increase the temperature, use a nozzle like a CHT or similar that can heat the filament more easily, or if your slicer has the option (Orca does) - use alternating reverse perimeters, so clockwise one layer, counterclockwise the other. That won't remove it completely, but it will spread the stress across both corners instead of just the one and reduce the curling by about half. You see it with other materials too, PET-G in particular will do it when printed at high speeds.
@MyTechFun
7 ай бұрын
OH, this was super useful, especially tip for alternating reverse perimeters. I will use it with other filaments too. Thank you!
@Dramaican88
7 ай бұрын
I think for flexibles lower print temperature means higher viscosity and increased internal stresses. The higher viscocity creates a small delay for when the stress (of the material being squeezed through a small nozzle opening) releases. I think those stresses create the curling up and especially for overhangs because the extruded line is less constrained by the previous layer so it has more space to deform from the released stresses. If you have ever noticed on silk filament that when you extrude in mid air (while loading/purging filament for example) right after the extrusion stops the extruded string of material becomes bigger in diameter and retracts/shrinks in length. That is stress release and you can easily see it because the extruded line/string is not constrained to a previous layer or the build plate. Stress release always happens, but if the material is stiff the previous layer limits the amount of defomation the stress/pressure release forces can introduce. In the case of a flexible material, the previous layer "moves" with the current layer as the material is still deformable even if has solidified/cooled down, because it is flexible...
@karlosss1868
7 ай бұрын
I love the friction test for these types of filaments as its a material property not tested by many other prople (if any).
@MyTechFun
7 ай бұрын
Actually, it was suggested in a very useful comment and I became curious.
@dekurvajo
7 ай бұрын
Here is my idea about the lower temp curling. By printing lower temp, the tpu still sticks to each other, yet the surface tension is much higher than the warmer parts. Its like when you stretching dough. They are curling back on the end. But if you make it warmer (by the waemth of your hand) the tension force is getting lower. So they still flat on the table, and dont curling back at the edges. And i think the extruder is able to push trough the material, even below its ideal viscosity point. So you actually sticking together a kind of flexed strings, and they start tp flexing back.
@diegovd7215
7 ай бұрын
Thank you for your time and hard work testing! :)
@radiotbo4646
7 ай бұрын
Tks for all these incredible tests!!!
@robertgubberiksson2068
7 ай бұрын
Tnx, your videos are really informative and appreciated, keep up the good work mate!
@edufonseca5718
7 ай бұрын
Great! Testing the exact Tpu shore i was looking for.
@hd-be7di
7 ай бұрын
At 220c the layer adhesion fails along the limited surface contact area from the overhang so the problem is both the low temperature and the overhang combination I think. If anyone has other opinions or thoughts please share!
@davidconner-shover51
7 ай бұрын
I've been using 87a, it's been a bit of a challenge
@timhoover1416
7 ай бұрын
I just did a temperature tower with some silk PLA and noticed the same phenomenon about the overhang angle looked better at higher temperatures. The other features improved as well, so I'm not sure why that is...
@itsGeorgeAgain
7 ай бұрын
Give varioshore tpu a try. Its 99A unfoamed, and goes 55A if you foam it at 250c/60% extrusion multi
@frankb5728
7 ай бұрын
I was honestly surprised at how easy It was for me to print the 85A filament I have. It helps if you have a large geared direct drive extruder. I found that I could still enable retraction with a short distance and a lower speed than I would use for normal filament. I also don't believe TPU needs drying.
@MyTechFun
7 ай бұрын
I am sure that TPU needs drying, in my experience, more than PETG (but less than Nylon). Check my Extrudr review video, huge difference after drying.
@frankb5728
7 ай бұрын
@@MyTechFun Saying that I knew I was wrong because it always depends on the relative humidity where you are. In the summer I have to dry PLA sometimes. In the winter I can print anything without really drying it
@szekerespista3758
7 ай бұрын
I like this channel! 👍
@MyTechFun
7 ай бұрын
Me too. And according to your name, this may be interesting too: www.youtube.com/@3dnyomtatas
@szekerespista3758
7 ай бұрын
@@MyTechFun köszi 😉! Sok sikert!
@dekurvajo
7 ай бұрын
Thank you, i know it sounds weird but by look, this is the exact shore/flex ratio that i am looking for. Do you think it would be possible to print with Bowden or its a no-no?
@MyTechFun
7 ай бұрын
Bowden NO, this filament is very flexible. For bowden try some 95A for the start.
@dekurvajo
7 ай бұрын
@@MyTechFun yeah. That's what i use currently.
@iamdmc
7 ай бұрын
try esun 83A tpe
@mikestewart4752
7 ай бұрын
Get yourself some NinjaTek Chinchilla…
@marc_frank
7 ай бұрын
higher stiffness would be more useful, i think
@donr62
7 ай бұрын
In that case you buy a TPU with a higher shore A value. 🤷🏻♂️
@ThePritchett1
7 ай бұрын
More useful for what? Could it be that different applications require different material properties?
@marc_frank
7 ай бұрын
@@ThePritchett1 true but it's a general statement, so the context is general more applications could use a stiff flexible material than a super soft one the instances where using such a material would be better than what is commonly used range from top ⅓ tpu95a to bottom ⅓ pla including the gap in between super soft only covers bottom ⅓ tpu95a more applications -> more useful
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