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.
I appreciate the detailed reply! You've certainly spent more time thinking about this than me.
My train of thought so far has been, "I wonder if I could partially notch my ear pads to fit my glasses better" -> "I could probably print something out of TPU" -> "I've seen gyroid only prints with no walls, varying the infill density could be a halfway decent method for messing with how squishy the print will be and without walls air shouldn't be trapped"
On my headphones, the pads snap into the headphones:
My stock pads are starting to fall apart and I have a pair of replacements on the way, so I am considering disassembling them for their rings and clips and gluing the print to that.
And you're right! While I was looking for replacements, I discovered that the stock units are functionally compatible with a bunch of other units although the finish materials are different.
Cool! I love that you are engaged on my level. Today I had a new idea. I thought of the pop-tube kid's toys randomly.
I was combining that with an idea I had yesterday. Yesterday, I properly measured my ear after I glued up a print and actually tested it by listening to music for a few hours.
So first off, my empirical hypothesis is that the sealing properties and the air volume are the primary factors that determine the perception of frequency response. The design pictured in this post adds a little bit of volume overall compared to the original. It doesn't have quite the same bass response but it adds a lot of crisp clarity in the ~200Hz+ range. I think this is just due to the spacial volume.
After measuring my ear and looking at the CAD and print, my first prototype adds enough fore to aft clearance around my ear. It added around 3mm of extra depth. This clears my ear depth by about 1.7mm too far and is primarily from designing in a stiffer material than the original pad. The original pad touches my ear in several places which gets hot and annoying, especially in the summer.
So I started thinking about how I can alter the print to shape it and completely clear all of my ear. The printed pad is already cooler, but adding full clearance could make it even more comfortable. I was perplexed about how to accomplish this though because it would likely require me to replace the base plate if I am going to shape the print further. My present design is just a 9mm single instance of the tube shape with the pattern repeated and a little underlap sleeve added at the end. What I really need is to vary the spacing of each conforming section to control where and how each bend happens. This would likely make the unsolved clasping connector issue worse.
The pop-tube idea might solve my problem though. I don't need to think about the bend joint like a spring. I need to think of it like a bistable switch and design the bends to snap into shape. I'm still mentally sorting out the idea before trying to design it. I'm essentially decoupling the bending from the shape itself. The challenge is how to do this in a continuous print without gaps in a vase-mode like mindset. I'm adamant on the vase-mode approach because I think I can better tune the pad conforming behavior based solely on single wall extrusion properties. Also, TPU is always more ugly for me if I allow z-hops and travel.
Anyways, if I introduce this disconnected level of complexity to my next iteration, I can likely also add something like a recess for glasses too. I have the same issue with my reading glasses and just use ear buds instead when I need them.
I also want to thin all of the walls of the tube and use a mathematical spreadsheet based pattern to stiffen some sections, but that is a secondary objective. My next step is to make a bistable bending action. I'll see if I can make it tunable for a 4 corner topology so that it can work for oval and rectangular designs – not that you should wait or anything like that. I'm fundamentally unstable and unreliable due to my physical disability. Like yesterday was my big cooking day for 2 weeks of food and I'm mostly recovering so far today. I don't know if my back will settle down enough for me to spend competent time designing today, but maybe after lunch and Adderall I'll get an hour or two to mess around if I lay on a heating pad.
I share your curiosity, but I don't have a ton of time to dig into this right now beyond the thought experiment. That's the reason for my slower responses :( Work is busy and the kids eat up most of free time.
You're right - the seal will directly impact bass. This is why the sound on some headphones will change fairly dramatically as you move your head around - you're breaking the seal. For me, the head position most likely to break the seal is turning my neck fully in one direction and looking up, but it can also happen with less extreme head motions depending on the cans. I could see volume also playing a role, since the air volume inside the pad is effectively a resonator and changes in air volume will impact how it resonates. I suspect the material of the cup itself will also play a role. Something dense/reflective, like leather, will likely sound somewhat different than say a suede or a microfiber. That was one reason why I was considering gyroid - it would be reasonably non-reflective.
Sounds like a similar motivator to my "I wish these didn't press on my glasses frames so hard" ;)
A pop-tube seems like it would be hard to print vertically oriented. I suspect it would move around some as you're printing thanks to not being very rigid. It wouldn't hurt to try it. Printing it sliced down the center and laying across the bed horizontally seems like it would be easier. I certainly hear you on the joys of TPU stringing, but if it's limited to the far ends of the print it shouldn't be too horrible to clean up. You could even design it a touch too long and cut the ends off.
Depending on the spacing of the tube crinkles, you might be able to line them up so your frames fit between them. You could also probably make one crinkle stick out a little less and line that up with your frames.
At this point, I have nothing but time. I'm also trying out a pair of 'real' ANC headphones, vs my office drone headset that happens to have defeatable ANC. They have ridiculously sized pads and they're actually pretty comfortable with glasses. I am somewhat tempted to type out a mini-review somewhere here, but have no idea where I would post it.