Rocketry Hacks Number 1 -- Fin Jigs

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So I've been building rockets at HeatSync Labs for about a month now and have come to realize the true value in having a hackerspace. There are. Lot of parts to the process of building a rocket that are incredibly hard to do, or expensive or not worth the effort. But having a hackerspace on hand makes those things much more simple.

Take, for example, the fin can.

For a lot of the introductory kits, the fins are molded so that you have fillets to square your fins with. The high power kits, however, generally don't have this, and you have to carefully square and measure your fins and rail guides so that your rocket doesn't do stupid things.

However, with access to a CNC like a laser cutter, we can build jigs to make that stuff pathetically simple. :)

For my Arcas HV, I really wanted to make it a perfect model, so I did that, turning hours of measuring, in to a half hour of planning, Inkscaping and cutting and starting fires and the end result is a Thing on thingiverse.

The first draft of the fin jig

The first draft of the jig was Good Enough to get the fins squared, but did not solve a problem that is arguably as important: the rail guides that make sure the rocket gets off of the pad straight. This part is probably more important, in fact, because they guide the rocket at its most critical moment, when the fins don't yet have enough airflow to provide the rocket with a straight ascent -- if the rail guides aren't straight, the fins will never get the airflow needed and you'll have a ballistic rocket.

The version of the fin jig on Thingiverse has an added feature that I came up with while brainstorming some solutions to this with various folks around the lab. If we assume that the laser can cut straight lines (and if it can't, we have bigger issues than the rail guides), and that multiple cuts of the same design are identical, we can use them to square up our rail guides by laying the jigs out on a flat surface.

I'm going to be documenting more things that I come across in the next few months; soon I'll be diving in to the world of high G electronics in my quest to not spend hundreds of dollars on a logging altimeter.


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Ryan Rix is a hardcore freestyle vimmer, hacker, backend nerd and doer of cool things living in the Gray Bay Area, California.

Ryan is one of the storers of stories and infrastructure wonks at Storehouse, building the future of interactive storytelling and making sure the servers don't fall over in the process. He contributes to a bunch of Free Software projects, as well, including KDE and the Fedora Project.