this week we did composites. i decided i wanted to get a head start on my final project and start work on making my lightsaber's handle; i was hoping i'd be able to make it out of carbon fiber, because carbon fiber is badass and i want the most badass lightsaber. luckily, nadya just happened to have some spare carbon fiber lying around (i swear, the woman has literally everything you could ever want stashed away in some cranny of her small kingdom) and she was willing to part with enough for me to make my part.
for reference, here's what i'm thinking of making:

i'm making an interior (structural) shell and an exterior (decorative) one. the interior shell shows through the cutouts of the exterior; it's shaded in the above image and what i made this week. the idea was to make a ridged carbon fiber cyclinder. i wanted it to be hollow, but the thought of extracting a foam mold from a vacuum-sealed tube was daunting enough that i decided i could just scrape out a pocket of foam if need be. i plan on storing the electronics there, but should need more than enough space for a small circuit board, some wires, and a 9v battery. easy enough to carve out.

milling the foam

to mill my foam, i used the intelitek for no particular purpose other than it being less busy than the shopbot. this turned out to be something of a poor choice, since the intelitek is catastrophically slow. originally i had the step size set to 1/32"; after about three hours, my part was about a quarter of the way milled. i decided that this was not the answer and doubled the step size. the resolution change isn't terribly obvious, and certainly wasn't obvious enough to appear in the carbon fiber, but it did speed things up a lot. you can see the difference in the picture on the right.

prepping the composite

after my part had been milled (only seven hours later! use the shopbot, kids! but shoutout to james, who provided assistance, company, and moral support yet again.), it was time to make the composite. i had to cut a carbon fiber sheet--using proper protection, of course. i can't stress this enough. while carbon fiber isn't necessarily toxic, it can be harmful if inhaled and can cause a nasty rash if fibers get into your skin. gloves, long sleeves, and a respirator are absolutely imperative any time you're working with carbon fiber. (and don't get me started on fiberglass. that stuff can kill you.)
needless to say, i used proper protection. no carbon fiber rash for me!

after cutting a correctly-sized sheet of carbon fiber, i cut sheets of plastic wrap and batting for the bleeder/breather layers. i didn't want to bother trying to extract my mold from the composite so i left it untouched. i wanted to be careful with the sizing of my pieces--since i wanted to make a cylinder i was going to wrap the carbon fiber (and bleeder/breather) around my mold, then put it in the vacuum bag. turns out this plan only mostly worked, but i'll talk about that later.

making the composite: vacuum bagging

i used the epoxy resin to make my composite because it wasn't horribly toxic and would also work well with the carbon fiber. you don't want to mix too much epoxy; if you mix more than you use, it gets wasted, which is a shame. and you can use the epoxy pretty sparingly. my part didn't even use the smallest unit of mixed epoxy possible (one pump of one part, two pumps of the other part).
after i epoxied the carbon fiber sheet, i wrapped it as tightly as i could around the mold. i then wrapped that in saran wrap, then in bleeder/breather, and then (just to be sure) i put some tape around the bleeder/breather to keep it in place. unfortunately, the carbon fiber must have slipped sometime during this process, because i ended up with quite a bit of a seam on the part:

incidentally, the epoxy really does need 24 hours to dry. someone said four hours at one point. this is a blatant lie.

the last step was to get rid of the flashing. i was a bit worried about this, but it turns out that carbon fiber can be cut reasonably safely on a metal-cutting bandsaw if there's a vacuum really close to the blade to suck up dust immediately and if everyone involved wears respirators. this was a phenomenal fashion choice:

and that was it! the carbon fiber section of my lightsaber handle is done. i'm hoping i'll be able to work around the seam, because trying to bandsaw it off seems perilous and sanding carbon fiber is out of the question in the architecture shop. so, we'll see. i'm really pleased with how it came out, though--looks pretty damn awesome.

someday i will be ready for battle. for now, i have the most badass sushi roll ever.