I brought the prototype to the bike shop. Here it is shifting the hub for the first time:Īfter this things escalated quickly. Each of these took about 75 minutes to print at 15% fill (meaning they are 85% hollow and chintzy):īut finally, miraculously, I made the shifter work. Here's the pack of duds I printed on my way to making it work.
#123d design gear how to
I also had to figure out how to make the holes more durable against the crushing impact of the indexed shifting springs. What followed was a huge amount of trial and error to make the geometry shift the gears in precisely the right way. The flat bottom parts are called "rafts", easily removable supports that prevent the ABS plastic from curling off the build plate.Ī few days later I prototyped how the pieces (screws, springs, ball bearings) would fit together, and had an assembly that could move:
#123d design gear software
The MakerWare software that came with my printer turns this into an execution plan (akin to Logo) that you can check for errors. The CAD program exports an STL file (a mesh of triangles). The sound it makes is futuristic and haunting: Here's a video of that thing in operation. I chose MakerBot because it's well supported. Meanwhile, I bought a 3D printer, the MakerBot Replicator 2X. I had no idea how sophisticated the supply chain is for this stuff. The screws and springs you see in there are CAD models I downloaded off a supplier's website. I'd have to think hard about how the geometry moves and fits together, just like I simulate how a program will behave in my head, poking data in and out of memory.
What surprised me about CAD modeling is I'd enter the flow state just like I do when programming. I did some Alias back in school, so I'm not a total newbie, but look how horrible my first attempt at modeling the shifter was:Īfter a few days of experimentation with the CAD package I had a better design. The CAD software I decided to use was 123D Design from Autodesk (it's free!). On January 18th I set out to make my own shifter a reality. The question was: What would it take to create my own? There are two other compatible, aftermarket shifters out there, but I don't like their look either. But the standard shifters for it look like this monstrosity: It looks awesome and works great (better than my old 12 speed bike). The chain never moves off the chain rings. The geometry is totally different than what's out there. I wasn't interested in a typical derailleur shifter, but a custom shifter for the Shimano Nexus 8 internally geared hub used by Mission Bicycle*: I'd been considering an idea for the past few months: Design a new gear shifter for my bicycle. What's made me feel like a kid again is my 3D printer and the promise of rapid prototyping. It hasn't been the occasional strategy game that has a similar effect (Civilization, Sim City, Starcraft, etc). It's been a blast! But my time hasn't been spent programming. I haven't been able to sleep, staying up until 4am focused on making one more smidgeon of progress. I've been creating non-stop, obsessed with my latest experiments.
Programming made me so happy (and still does today).įor the past 30 days I've had that same feeling, something I haven't experienced since I was 13 years old.
I was inventing problems at the same time I was solving them. I'd dream about it and go right back in the morning. When I found a new programming problem I would work on it all night.
#123d design gear code
I was finally good enough at writing code to hack away like a madman. When I was 13 I became obsessed with programming.
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