Pushing the limits of size and resolution

I like my Bose earbud headphones: they stay in my ear when I’m walking or jogging, and don’t bleed sound to folks around me like the stock white Apple ones. I really like the little clip that lets me attach the cable to my shirt, keeping the wires from that point on to my ears at a constant distance; I can turn my head in any direction and won’t be restricted by the wires back down to my pants pocket.

Walking to work one morning, thinking about how nice this clip is, I thought that I should try to make a similar clip for the white headphones, just to see if it could be done. And, of course, I could share it on Thingiverse.

I immediately figured that I didn’t want to print a clip that required a spring like the Bose clip; one-piece, simple, non-mechanical is what I wanted. What could I do to keep the clip locked into place on a shirt, without using a spring or spring-like mechanism. Well, there are buttons on shirts, maybe I could make a button that one could loop the headphones through. No, that would require removing a button, re-sewing a new button on, it would have to deal with washing and drying… A button seemed wrong. Okay, well, I could make the clip slide onto the shirt and have long “arms” that went around the button threads on the front and back sides. This sounded like a plan.

I also knew that I needed to somehow keep the clip locked in place on the headphone wire; it couldn’t slide up and down as that would defeat the purpose of keeping the wires positioned on the shirt.The Bose clip has a tiny arm that wraps tightly around the cable, but I could tell that sort of arm would be impossible to print on a Thing-o-Matic.

I made some measurements of shirt thickness, average cable thickness (I measured the wires on several different brands of earbuds), distance from edge of shirt to button threads; all the usual suspects. Looking at the numbers, I knew I was going to be pushing the lower limits of object size – this seemed even smaller and thinner than the IKEA shelf holder I made all those months ago. Off to SketchUp I went. After 15-20 minutes I had my clip designed.

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It’s impossible to tell from the design view, but this thing is small. The whole thing is only 20mm long and 10mm tall, there’s a 1mm gap between the front and back arms, the little “nub” that holds the cable in place is only 0.5mm tall. Will this even print? Will the generated support actually, well, support? Only one way to find out. I ran the STL through ReplicatorG with a raft, full support, zero shells, and 100% infill. The estimate was 11 minutes and as usual was pretty spot-on.

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It actually printed! But man, is that ugly! The first layers connecting to the raft got all sorts of messed up. Not sure what happened there but it wasn’t pretty. But — does it work?

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Yes! And no.

The clip slides perfectly over a shirt, but the shirt I’m wearing today has a totally different width between the edge of the shirt and the button, making the arms too short (almost by half). However, it manages to stay put on the shirt where I place it, perhaps just by luck.

The headphone wire doesn’t fully fit into the holder area, but once in doesn’t budge; they aren’t sliding up and down anytime soon. The space to slide the wire into really could be another millimeter larger to better slide the cable in, and I think my weird “nub” to hold it in place would work fine.

In the end I’m impressed at the resolution of my Thing-o-Matic; I can print tiny things with sub-millimeter features and get decent results. It’s not perfect, and certainly not pretty, but it’s an idea come to life in a matter of minutes. So, conceptually it’s a win.

Before I upload the files to Thingiverse, I’m going to take a pass at making it better — increasing some spaces here or there, and perhaps re-think the bumps that wrap around the button threads, instead making them go front-to-back.

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