Convertible Pencil Rocket (Parametric)
by CodeCreations, published
When I was a kid and bored in class, I used to pretend my pencil was a rocket launching from my desk. Now, don't get me wrong here -- I'm not trying to squelch the imagination of any little kids who dream of being astronauts some day; I'm just trying to help those pencils fly a little straighter so they actually stick into the ceiling like they're supposed to.
So what's this "convertible" business all about, you say? Well, that's the real beauty of this design: When the teacher comes walking by, you just set the dart -- er -- the pencil down on its fins and explain that it's a space-saving pencil stand. "Rocket fins? No, don't be silly Ms. Fields -- it's just a pencil tripod!"
This is NOT intended to turn a pencil into a weapon of any sort. That said, I bet this would probably make a great weapon of some sort.
The OpenSCAD file is parametric in case you need to tweak the sizes. I fiddled with it until it sliced nicely with 2-layer-thick fins (0.5mm nozzle), and that's how I saved it. I built it for the venerable Ticonderoga #2. Even though the hole is hexagonal for the pencil, the parameter specifies the in-diameter of the hexagon, so it should work just fine for round pencils, pens, or smooth rod, too.
(Yes, that's reindeer food in the background of the photo.)
This is a very quick print, and would make a great demo/give-away piece -- someone's bound to have a pencil handy at your demo!
Update 12/1/12: v1.1 You can now specify an angle for the fins so that the pencil might spin when it's thrown (untested). The new STL has this set at 5 degrees for a clockwise spin for right-handed throws.
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That would be tragic. It's a good point, so don't give this to anyone you think would use it irresponsibly. In my experience, the only time I've seen one of these upright is on my desk at work.
Im usually the opposite of a safety nazi but is that not reaaally dangerous?? imagine if a kid fell on it!
Thanks! Yeah, I originally wrote that module as I was just learning my way around OpenSCAD. I never got around to fixing it up, and so I just warmed up to it -- I've even started referring to it as "nutty" myself. lolÂ
The sqrt(3) bit works because the cos(30) is half the sqrt(3). The new radius is the old radius divided by cos(30), or the new diameter is the old diameter divided by sqrt(3).
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2) Slide onto pencil from tip. It should stop at the metal bit that holds the eraser on.
3) Don't get any crazy ideas.
4) If you did get a crazy idea, don't blame me. Oh - and be sure to tell me about it, too.
** Not responsible for lost pencils.
Featured Crazy Idea #1, courtesy of glen2: Make the fins bigger and able to slide along the length of the pencil. Put stoppers (like rubber bands) at each end of the pencil so the fins can't come off. Push the fins to the tip and hold the blunt end. Hurl pencil in an over arm throw, the fins should slide back giving a straight flight to the target tip first.
TOOL CHAIN AND PRINT SETTINGS:
For this I used slic3r 0.9.7, Marlin, and j-head 0.5mm with cheap 3mm "repraper" PLA filament (from China). I print onto glass covered with window tint with a thin coat of ABS juice. The printbed is heated to 90 for the first layer (measures about 80 with the IR thermometer), and 75 for additional layers. I used two perimeters, 10% honeycomb infill, and 0.4mm layer height. Hot end temperature depends on color, but is usually around 185.
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