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Archive for June 10th, 2010

Machinable Wax: First Cuts

This is a prototype for the case that will eventually hold a TinyTrak3 GPS-to-APRS encoder, along with a homebrew circuit board that combines the APRS data with voice from the helmet mic. The case slides into the back of our ICOM IC-Z1A and W-32A HTs, replacing the battery case.

It’s the most complex CNC machining I’ve done so far and I figured that was the perfect reason to carve up a block of machinable wax that’s been sitting on the shelf for far too long.

The exterior view shows why you use wax for the first pass… the ugly gash came from not retracting the end mill before the final G30, combined with trying to clamp a bendy shell in the vise. That was, of course, the final operation on that part!

Machinable wax case - exterior

Machinable wax case - exterior

The inside view shows the TinyTrak serial connector cutout (left half), as well as the shoulder to support the audio interface circuit board (right half). The two holes at the upper-right are 4-40 clearance for screws that serve as contacts for the HT’s battery connection and hold the board in place.

Machinable wax case - interior

Machinable wax case - interior

These survived far too many setups and takedowns as I figured out how to get all the cuts laid out and in what sequence to do everything. Now that I know a bit more about what to do, the plastic version should come out better; I’m sure I’ll also make better mistakes.

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