This is the final version of the I-Hacked.com badge (art by surbo). This badge is modified slightly from the original design to house a bicolor LED (hevnsnt's awesome idea, not mine!) and to allow the battery tray to stay in place without any additional hardware (so it can be attached to other badges, etc.).
The battery tray also features a nice lip so the CR2025 wonâ€™t just fall out when you pull out the tray. This was done primarily to convince badge recipients that the battery only went in one way, as the bicolor LED was to remain an "undocumented feature". All badges had red/blue LEDs and started off red, but if you flipped the entire tray over and re-inserted it youâ€™d have a blue badge. As many of you probably know, blues and reds donâ€™t generally get along very wellâ€¦
This badge is constructed in a very similar fashion to the first prototype (http://www.thingiverse.com/thing:863), so use that as a basic guide. Iâ€™ll just cover the major changes here, but note that construction on this version is slightly more involved.
The middle bridging section on this badge has a couple protruding â€œnubsâ€ that grab on to the battery door when inserted. This means that the â€œarmsâ€ of this middle section that the nubs are on must be allowed to move. This is why thereâ€™s an etched out area on the middle bridging section in this version. This etched channel is meant to stop the acrylic glue from wicking up the entire arm and gluing it permanently in place. The etched side of the bridging section must face toward the surface youâ€™re gluing when attaching this piece to the back of the badge for this to work. You donâ€™t necessarily have to take the same precaution when attaching the top piece because you can easily see where the glue is wicking to and only glue the lower section. Acrylic isnâ€™t ideal for these kinds of snap together pieces, as itâ€™s relatively brittle, but the tags only needed to last a couple days.
Now to the matter of the getting the bicolor LED to work. Just having the correct lead touching the side of the battery was enough to get the prototype working, but to get the bicolor LED to work you need to have one lead of the LED rest on top of the battery and one rest below it. This will allow you to switch the polarity, and thus the color of the LED, by flipping the battery over. Unfortunately, a CR2025 cell is too thick to be used in this configuration so youâ€™ve got to create a shallow depression for one of the LED leads to lay in on the back piece by raster etching a bit of the plastic away. Make sure this depression is facing toward the inside of the badge when assembling! When inserting the LED, ensure that the lower LED lead is in this depression, and when inserting the battery, take care not to catch the leads on the edge of the battery and bend them up! As with the previous version, you can get the LED out after the badge is assembled, but itâ€™s much easier to try and get it right the first time. If youâ€™re not using a bicolor LED, just use the instructions from the previous version for, bending/inserting the LED.
Lastly, the lip added to the battery tray is something you can only do if youâ€™ve got direct access to a laser cutter. To form the lip, I raster etch the plastic away in multiple passes until I reach the depth I want (Iâ€™ve described this in a little more detail here (http://www.thingiverse.com/thing:773)). I use a pair of digital calipers to verify that Iâ€™ve got the depth I want before finally cutting out the pieces. I may revisit this project once our space gets a MakerBot up and running, as a lot of the parts for this project would probably be more easily constructed with a 3D printer and I could use some more ideal materials :)