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blueChute case: Foilhat
Button Area
Our current case design (see project:H2 for a very early version) is pretty nice, but one issue is that the button caps are individually hand shaped and then superglued to the actuators of tiny surface mount switches. Not only is this a pain in the ass, but the buttons also frequently fall off in use, thus requiring the unit be returned to E Ink and fixed. So I wanted to try a sort of membrane switch type idea.

What I wanted was a die cut, backprinted piece of textured polycarbonate, like you would use for an overlay for the front panel of an equipment enclosure. There are lots of label printing companies that can make you a graphic overlay type part, and I especially wanted the embossed button areas. But in the end I used Maverick Label to prototype my idea since they are pretty affordable, offer online real time quotes, and fast prototype service. I did the design of the button area in Autocad and Illustrator and uploaded my files. About a week later, I had the parts.

They looked pretty good, though the printing was a bit marginal if you look too close. My friend JD says this is typical of the 'digital screen printing' resin print process used to make prototypes like this. Anyways, I got their 'Lexsaver' product, which has the printing done on a thin layer of PET, and then laminated to the back of a polycarb sheet, with adhesive on the back of the die cut parts as well.

I designed the case so the label sits in a milled out pocket on the front of the device, ideally sitting flush with the surface of the case. I will need to lasercut some plastic posts to stick to the bottom of the label to act as actuators for the SMT buttons inside.


Proof image from Maverick
Case Construction
The current case is built in a way that was convenient for me to prototype using the tools we have at E Ink, but it was annoying to outsource production. I had around 100 made by my friend Barrett at Nicobar Group in Shanghai which turned out very nice, but it was not easy since he needed to line up like 3 different shops to coordinate the build. I wanted the next case to be at once thinner and slicker, but also easier to send out to have made. So my new design is to have 2 sheets of CNC milled metal on either side of a lasercut acrylic core. The metal parts can be textured and finished separately, and then hopefully there won't need to be any finishing after assembly.

The front metal sheet is glued or laminated with sheet adhesive to the core, and the back is held on by 2-56 stainless flat head torx screws run into threaded laser cut holes in the core section. The label for the buttons in dropped into the pocket in the front piece. Both the front and back need pockets milled on the inside to accomodate the internal components. An acrylic window is incorporated in the back, for the radio antenna to sit under (it wouldn't work very well if you put it in what is essentially a metal box).

My first try is with clear anodized finish on front and back with label colors as shown. I also want to try clear anodized back with black anodized front and an inverse color label.

Handbuilt First Sample
For the sample shown in the pictures, I had the aluminum blanks lasercut at Laser Cutting Inc.. Then I lasercut the core on E Ink's cutter out of 2.8mm cast acrylic with 300LSE sheet adhesive laminated to one side, and tapped the holes with a 2-56 tap. Next, I milled out the blanks manually with the help of a rotary table on our bridgeport, then stuck the core to the front piece. Then I sanded the crap out of the whole case, to even up the edges of the three component parts, round over the edges and corners, and bring the whole thing to an even finish. I started with 60 grit and worked up to 320, followed up hand buffing using maroon and grey scotchbrite pads. Finally I sprayed it using a krylon matte clear finish, to simulate anodizing and keep fingerprints down. Looks pretty damn sweet!

Machine Shop Prototypes
I sent out for a couple quotes using my ghetto autocad files (I don't have solidworks or other 3d cad programs). One of the shops I got in touch with through my friend Ben had decent pricing and were pretty responsive so I ordered metal parts for 10 cases from them. We'll see how they turn out soon.

Design partially original and partially ripped off from other websites
by Holly Gates