Membership Card mechanicals

Support for the COSMAC 1802 Membership Card, see this Web page for details. Last updated Nov 19 2010. Edited by Herb Johnson, (c) Herb Johnson

Ways to drill out the Altoids can for the Membership Card front panel

Courtesy of cosmacelf Yahoo group discussions

0) Lee Hart's advice is:

I used the Front Panel board as a template. I taped it to the Altoids box cover, then drilled little holes where the switches, LEDs, and D-connector go. Use a drill bit a little smaller than the pad itself, so you don't drill out the plating in the PC board's plated-thru hole.

Then, I used a step drill (unibit) to enlarge the holes to fit the switches and LEDs. This kind of bit will drill clean holes in very thin material without leaving a burr.

Note that the LEDs have two holes (one for each lead), but no hole in the center. I just drilled both holes with a 1/8" bit so the holes overlapped, giving me one ragged hole in the center. The step drill then cleaned this up to produce perfect round holes in the center.

I cut the D-shaped center part of the D-connector hole with a "nibbler". This is a tool where you drill a roughly 5/16" hole that the tool fits into. It then "nibbles" little bits of metal sideways to get the desired shape. It works really well on thin metal like this. Radio Shack sells a nibbler at this WEb link.

1) fill Altoids can with water and freeze. Then drill using ice to support the can. Melt and drain ice. [Ray Sills]

Comment: Ice expands 4% over the same volume of liquid water, with tremendous force. it can break copper and iron pipes! I suggest you cut out a piece of wood (pin is easy to work with) to a rough fit, and tape or rubber-cement it inside the can instead. Lee Hart describes below, the use of styrofoam to support the pin sockets.

2) a Dremel tool with an abrasive cutoff wheel. this increased the tolerances a bit making the holes. [P. Todd Decker]

Alternative M/S container, more drilling

Courtesy of Mark Graybill, Nov 2010: I used a Whitney No. 5 Jr. hole punch on my Altoids tin. [But] in other instances where I have to drill thin sheet metal, I put a piece of wood on both top and bottom of any metal thinner than about 22 gauge. I usually put pilot holes in the top board, and take my time going through the metal. I don't use the drill bit as a punch, so it leaves a clean hole. Unibits work with this, too, if the top board is thin enough (I often have scrap veneer around), and as others have mentioned they leave a hole that doesn't need deburring, like a punched hole.

My Membership Card just won't fit in the Altoids tin without using a metal stretcher. I need about 1 mm of additional height....I've finally found a solution to the problem. I've decided to go to a larger tin. It's a Farrah's Harrowgate Toffee tin. It's about 3.5" square.

I'm taking advantage of the extra space to put the power source in the tin with the Membership Card, and I'm fixing it up with a sort of steampunk look. I did a mock up of the switch handles tonight and I'm happy with the results so far so I'll be pressing on with this.

The new can is not as much deeper than the Altoids tin as it appears in the photo. There is a lip about 3/16" of an inch tall around the bottom edge of the Toffee tin. So I don't have enough space to throw away willy-nilly, but there's definitely enough space to play around a bit, and put in some batteries.

Mark Graybill,

IC SOckets vs Pin Sockets

One Membership Card builder asked: "Has anyone had luck fitting everything into the Altoids can using ultra low profile sockets? Those individual pin sockets [as supplied] were just too tiny for me."

Lee Hart replied: "I built my first one with the ultra-low profile sockets. It fits in the Altoids box, but just barely.

"Then I found the socket pins. They actually lower the profile, making it easier to get it in the Altoids tin. But I agree; they are *tiny*! The first time I used these, I put the socket pins on the IC pins, then placed the IC+pins on the board, then soldered the pins.

"Since then, I found a slightly better way to deal with them. Put a piece of soft styrafoam on the table. Put the PC board on top of it. Push the socket pins into the holes on the board (and into the foam). Plug the IC chip into the socket pins. Now lift the board off the foam, and solder the socket pins to the board from the bottom. The IC is now "socketed", and can be removed if needed." - Lee Hart

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Herb Johnson
New Jersey, USA
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