machining

[a.k.a. dont kill yourself.]

so the big rule of using the lab machines: be safe.

some good pointers:
- know how to turn the machine off before you turn it on.
- dont push toward the tool
- dont reach into the tool
- always machine with somebody! friends are handy.
- do a dry run in the air first before dealing with materials
- use your ears; the machine should sound happy

so, hopefully by the end of this, we retain all our limbs and fingers, and everyone's alive.

a small list of available toys:
- spot welder
- ultrasonic welder (can connect + seal plastics, textiles)
- drill press (keep speed low, use key to tighten chuck, pedal control)
- radial saw (just for wood!)
- cordless drill (vrrrm vrrrrrmmmm)
- taps (for cutting in screw threads)
- die (make your own custom screws!)
- vertical bandsaw (hands on sides, curled grip, interchangable holding fixtures)
- horizontal bandsaw (adjust vise, speed, auto shutoff)
- scroll saw (for curvacious cuts)

fun with the nc mill... so there's scary sounds and lots of cryptic buttons, which means that john gets to happily help out with everything. easy to break or ram through stuff, so careful is the word. for our initial project we were constrained to three tools (1/4", 1/8", 1/16" bits) and about a 1/2" depth within the 3/8" die half. whee, featurecam!

using the leaf dfx that i did in corel (linked below), milled this with john's help. just a 2D shape, as a pocket created in featurecam. however, it came out quite prettily, with no real hurdles. i think we just needed to make the stem parts a tiny bit thicker to accomodate the bit sizes. perhaps another change for the future: add more runners so that the inner leaves get injected more evenly.

injection molding! so technically, one could flow plastic glass spheres, cut-up fibers (graphite, glass, natural), composites (fibers in binders, very strong and conductive), metal, and ceramic (powdered in plastic). apparently the swatch irony line was the first injection molded metal watches on the market. for us, we're just using pellets of ABS plastic that can be dyed using little color pellets. so here we are with the gorgeous results. the first couple we made only came in partially, with it just forming in two parts, the top-most leaf and the stem. blame it on the minimal runners. did a little better by decreasing the speed of injection and increasing the temperature a bit. by making it runnier and slower, it managed to fill in the internal gaps and create a leaf. yay! imagine hundreds of these, forming a botanical bonanza.

notes on the injector: fill the material pellets about 2/3 way in the hopper, and add dye pellets if necessary (they're found in baggies under the machine). first, PURGE: align the purge plate in base, make sure there's a 40-50 degree difference in temperature, and start hydraulics (big green button). the mantra: engage carriage, inject (squooze), extrude (fill the cylinder with material). to lower pressure, turn knob in back CCW. watch for the plastic to come teeming out the top and sides of mold when it's full. to automate, can use the timers to dispense the allotment of injected plastic. you turn the thingy on top to specify how much material to extrude each time.

the vacuum former is very fun and easy to use. the smaller envelope is about 12" x 12"; the larger is 24" x 24". use PET, and make sure to take off the protective sheets first! put whatever object you want to form around on the tray, and lower it to safety with the big lever. place the PET sheet in the hole, aligning the sides with the sandwiching gaskets. lower the top (you might need to jiggle the bottom tray to align properly) and hand-lock in place. turn on all the burners and let it cook. the PET is ready to form when it's hot enough; you can tell if the middle is sagging about an inch or so. [then comes the fun part...] you raise your object with the lever, and then push the big green VACUUM button and watch the plastic get sucked down around your thing. you can use the eraser next to the machine to smooth out corners and curves. when satisfied with the result, press the yellow RELEASE button and voila.



the best thing for this is making packaging, but i guess i liked to create something more, perhaps a more generic container. i liked these ceramic nesting bowls from crate and barrel, so i v-formed over them. one concern: figure out how to get your object out from the plastic after forming! i had a bear of a time trying to pry the largest bowl out. hints: before forming, spray objects with a touch of STONER (i.e. machining PAM spray, a touch of smoothing grease), or if it's still stuck, put a shot of the heat gun onto the plastic until it gives way. after forming, you can crop the PET using the scrollsaw (it makes an awful noise!) and use the sander to polish the edges (note: dont wear your black best, as the whitish specks get everywhere). anyway, the clear PET bowls look pretty cute, and make handy containers. also, since they fit the forms of the original bowls perfectly, i managed to augment my 3 nesting bowl set to a 6 bowl set. neat.

i originally had a vision of creating a 3D topographical terrain by vacuum forming in iteration over a series of growing hills. i'd make a model of three legos, say, and vacuum form. augment the structure a big, form another piece, and fit over. therefore, looking through the multiple transparent layers you could see each contour map corresponding to time, for example. this would have been supercool, but i didnt want to use up a lot of PET sheets for this week. perhaps for another time, i may be able to recreate my vision.