3D printed watch band

A while ago I wondered if it was possible to 3D print a watch band that was not only functional and strong, but also aesthetically pleasing. After smelling what the continual Shenzhen humidity had done to my NATO style watch band in the last month, last night I decided it was time to actualize this idea.

Here’s the sexy results of a few hours of CAD and Makerboting (is that going to become a verb, like xeroxing?)

First off I started by posing my concept: I wanted to use an extrusion-type 3D printer (makerbot) to print out a flexible wrist watch band that is thin and flexible.

My first try was more of an experiment to determine if 2 layers of ABS plastic was strong and flexible enough to act as a watch band. I designed a 1mm thick band, and spec’ed the prototype to test the watch spring bar mounting holes. In the first print there was noticeable curling after the 10th layer, so I stopped the print part way. Additionally, there was a small gap between the two shell layers of the watch band such that it wasn’t properly bonded. I tried to rip apart the first partial print (about 4 mm in width), but I was not able to without help, thus proving that this ABS band would be strong enough!

After adjusting the watch band to be 0.75mm thick ( to eliminate the gap), and printing on a raft to stop the curling, this was the result! This second print proved that 2 layers of ABS were indeed strong and flexible enough to be a watch band, but the watch springbar holes were not fully supported by infill, thus I resized the holes so that they would be set closer to the shell (and hopefully bond with it). Right about now I realized that a standard watch clasp wouldn’t work well for the 3D print (since the clasp would exert force parallel to the ABS print lines, and probably split it and rip right through). So I set about designing printable clasp. I took the concept of a zipper (with trapezoidal interlocks), and made a simple watch clasp out of it. Here is the first clasp design I made┬áThe watch band of the second print was wayyyy to long, so I resized the watch band diameter to fit my wrist circumference (~172mm). The watch band design length was sized according to the length of two arcs (with a radius of 35mm) + a top flat piece that supported the bottom of the watch. After this bit of the design refinement, I printed the third prototype with fingers crossed.

As its said, the third time’s the charm and the third print came out very nicely :D

With a little bit of filing the clasp slid in and out smoothly and snugly, and the watch cuddled my wrist fairly cozily like a koala on a eucalyptus tree.
As always, there little things that can be tweaked. So I made a final fourth revision that reduced the length of the band by 4.25mm so that it would cuddle up a tad bit closer, and eliminate some of the side slack space. Additionally, the way that the male side of the clasp attached to the watch band created an air gap after the clasp. Thus I adjusted the male clasp side design to close the gap an make the clasp more physically symmetrical
Here is the final (for now :P) revision

The files for the watch band are posted here on Thingiverse

total project time: ~ 5hrs

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