Compliant tube based headphone pad idea I had while riding a bicycle two days ago. I got the thickness and dimensions dialed for printing and bending, but I either need to setup my old KP3 kingroon with a longer 2040 Z extrusion or print this in 2 pieces. Either way, the joint connection needs more than just the overlap and glue. TPE would probably be better too, although I have no idea what shore hardness this $10 clearance spool of TPU has. The sound quality seems a little tinny and I have no way to tell how loud it is externally, but it is just my first iteration that I can put around my ear and test. TPU is so slow to print and the moisture levels impact the qualities drastically. I actually like the texture and properties of wet TPU more than dry, but it is hard to get it just right. With the design’s compliant bend, consistency is kinda important. Anyways, just another boring project. On the bright side, this seems cooler temperature wise when the TPU pad is against my ear.
I spent all day chasing custom logarithmic infill patterns that might incorporate a compliant bend but only learned about how not to do a thing like that in CAD.
Silly suggestion for testing how loud it is externally; put the headphones on your leg/thigh and test them, it should be a reasonable approximation of your head.
Also forgive my ignorance, but why are you printing this as straight pieces that require gluing as opposed to printing it as a solid circle?
Mostly, the design is motivated by the aesthetics, but also TPU sucks at bridging and supports.
Testing the loudness really needs two sides and a later stage prototype. It is also very subjective without a repeatable testing technique. I personally loath the subjective nature of opinions people have about anything audio related and avoid saying anything about such myself to the best of my ability.
The overlapping joint insert was just a first idea for a design. There is a section at the top of this joint that I didn’t bother to optimise for vase mode but the rest of the print is possible. It would take some tuning to get vase mode fully dialed. I would probably need to use some helix trickery to get the exact stiffness where I need it. Vase mode was and is still likely in the cards.
I also have a design in CAD that I made today. It has an exposed infill pattern and solid shell in places. I used the pictured design to conceptualize how the infill would behave and how much movement to expect. I may never print that one. I still don’t have a way to connect it that I like.
I’m also playing with the idea of covering a print in textile materials and or altering pockets and chambers.
You don’t find many printed headphone pads and the ones that do exist are very ugly IMO. Prototyping in yellow is only just that. I have other colors of TPU on hand.
Overall, this has the potential to dial in many properties from fit to audio properties. The orientation is ideal for the properties of TPU. The abstract concept is broadly universal where this will technically work for the majority of headphones. As is, it doesn’t look terrible in person and I can make this much prettier if I choose.
The pictured setup is an early alpha phase prototype and it is not glued while it is close to the right size so just the friction is holding it together in the pic. I could glue this and it would likely work fine.
Have you ever tried Creality’s HP-TPU? It only comes in transparent and white unfortunately, but I’ve printed it at 150mm/s and had no issues with bridging at all. I don’t have much experience with other TPU, but I’ve liked using that one. The base price isn’t very good, but sometimes they have really nice discounts on it.
I haven’t tried a lot of flex materials. I’ve only used them for things like a few seals. Compliant mechanisms have been a curiosity of mine for a long time, but I haven’t had the intuition to establish an entry point project worth trying on my own.
Like as a totally random aside, if this TPU is super dry like how the one test print that looks super crisp with sharp edges, it appears to be air tight. I see a lot of potential for building cheap pneumatic, cable, or passive force driven actuators while playing around with my thumbs sealing each end.
I intuit that this level of usefulness in mechanisms would be hampered by the low quality of the first bridging layers. Absolutely any moisture in the TPU causes random gaps to form as the steam escapes at the nozzle tip in small bursts. Any larger bridging is going to have some amount of dropped passes as a result. I don’t think this is a real issue if the TPU is very dry on a totally enclosed dry feed path to the extruder, but I don’t like the properties of this material when it is super dry. Overall, my design method in this case is likely oriented in the best way for the properties of TPU and the mechanical best case for compliant design. The layer deposition steps and top/bottom layer properties of FDM are not optimal for compliance in most cases. This particular design is capable of compliance both for the bending form to create the headphones pad, and as a pad against the ear after it is installed.
It is also ~$10-$15 for replacement headphone pads, so making and sharing such a design should be limited to materials most people already have on hand. I’m very tempted to try this with a 98A TPE, but it is just too expensive of a material to justify for this project when I’ve had 3 rolls of TPU banging around for years unused and only got them because they were dirt cheap clearance sale materials. I would do a lot more if I had an IDEX, but I don’t need that rabbit hole money bonfire.
If anything, a dirt cheap foaming TPU could be interesting if such a thing existed. It might be possible to create something functionally similar if TPU could somehow be exposed to a humidity controlled environment at a specific percentage, but I have no idea how moisture saturation works on a deep level, like if the saturation would remain regulated by the humidity percentage or if the exposure would allow the filament to always wick all available moisture where a much more complicated setup would be required to ensure consistent properties. Anyways, my point here is that the best properties for me are not from the super dried TPU needed for bridging and bridging is itself a poor mechanism with FDM. It is best if it can be avoided at the design level like I have done here.