Learning a Couple Things from Constructing Dual-Lever Paddles from Relays

I wanted a set of paddles to bring with me while traveling for the holidays at the end of this year and the vintage Vibroplex Standard I've got in the apartment didn't seem like a good travel option. Thinking about what would be a decent starting point that would be more sophisticated (and, hopefully, consistent) than trying to use binder clips or improvised levers, I figured some SPDT relay contacts might not be too bad. Hence, the first attempt:

Fully assembled and cabled resulting key

The core for the switches is a pair of SPDT power relays stripped of their upper case and coil assembly, then superglued together with the NO contacts closest together. Critically, the relay contacts have to be centered on the internal copper frames (these are HF158). Then trim one side flatter to enable supergluing that to a scrap of plastic as the lightweight base. Best fit for levers? I went with an arbitrarily cut coffee stirrer that looked like it would work.

Lever attachment: needed stability, the correct height, and the correct spacing to line up with the moving contacts inside the relay.

Positioning was definitely a bit of a precision job to get the glue on the sticks without getting them out of position or the glue everywhere. A RAST connector shell and some tape got things close enough when set on top of a piece of aluminum stock. After that cured and I removed the contact-protecting tape, that was mostly done! Even without a keyer, I quickly noticed that there was a lot of over-travel in the contact. Of course, a power relay wants to cause some small wiping motion with each cycle to scrape the accumulating oxidation off the surfaces.

Completed view with levers and a fixed spacer between the inner contacts.

Fine and dandy for a non-adjustable set of paddles, right? Well, even with my weak keying skills (and too-short character knowledge list), I very quickly noticed that these would not do great at the 25 WPM character rate of CWA. Since these are simple levers, not only does the untuned contact gap result in lots of travel, the lever force amplification results in even more travel at the finger!

So, it served its purpose of being travel-worthy (if not exactly durable) dual lever paddle for my adventures for holiday travel. I vaguely got some practice in with it. Maybe once I can get some level of consistency out of the Vibroplex I'll consider putting this design (or at least a closely related successor) on the air. Hacks/improvements and a successor are in progress. . .