This post is work in progress.
Inspired by DL6YYM’s concentric design of the TP-III, I sought out to design a miniature concentric key using the same idea. The design would have to be small to accommodate the KH1’s form factor along with fitting inside the KH1 carry case. The design above was created around using parts I had around my shack.
I designed this in OnShape, a web based CAD application that I’ve been messing around with for the past year or so. There is a free version available to hobbyists like us! I enjoy 3D printing a lot. There is an extreme sense of accomplishment one can experience when you take something trapped in your brain, and make it a real life part. This project would be no exception.
One thing was certain, my design was going to need some way to integrate electronics. On the TP-III’s design, all parts were beautifully crafted aluminum. My 3D printed parts would be non-conductive and require a need for wires or cabling.
I decided to attempt to integrate a small gauge wire that would pass through the body of each CW paddle. You can see here in this image two small holes adjacent to the large disc magnet location. These tiny holes are the tail end of a channel that runs to the center of the paddle. The wire would then be held in place by a small M1 sized Brass Insert.
You can see here using this cross-section of the paddle that a small circular channel lives inside the key paddle to allow for the wire to pass. Initial tests had the entire channel located in the interior of the paddle.. except that making the 90 turn with magnet wire was difficult. I ended up exposing the channel so that you can manually feed the wire and thread it like a needle through both holes.
You can see here the small wire threaded through both the brass insert hole, and the opposite end hole. A round bearing will sit in the larger 8mm hole and is integral to the concentric design of the key.
Turning attention to the key body. You can see from this angle the opposing disc magnet placement… as well as 2 small set screws that will help the user adjust ‘travel’ for the key’s movement. I like a very small / tight travel, similar to my experience with the Bamatech TP-III. These set screws should allow us to mimic that action.
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