Rewanui (1940 NZR in 1:64)

[Lawrence Boul]

great minds - I have been working on servo drives for turnouts, on and off for some time. Arduinos offer the control, and can easily be interfaced with a CAN bus, which is the architecture I have elected to pursue for everything that is not loco control which remains DCC (I do have a couple of R/C but they are the exception and are not really intended for regular use - more an experiment).

CAN has many advantages, it is very tolerant of electrical noise, and can effectively work "plug and play" - for example, a lever frame can be plugged into the bus outdoors on a nice day, and indoors if the weather is inclement - though I guess you might not want the trains running in the rain. And lights, etc., can all be controlled by similar CAN compliant modules.

I saw an elegant solution for the servo cam drive a week or two back, I think it was one of the guys who are regular contributors to the Templot forum - rather than a cam, it used an eccentric and a small profile rolling element bearing. I didn't see or hear it operating, but it looked to be very well designed, with space to fit up to 4 microswitches I think. It's quite a bit bigger than your design, but that doesn't worry me as I am working in 7mm.

The beauty of a cam or eccentric drive is that the blades are pretty much locked with negligible power demand, backdrive is not possible. I guess that could also be a disadvantage, but generally I think not.

cheers
Simon

At the time I was hung up on something compact (and this is 16.5mm gauge). I also use servos for uncoupling so it simplified matters to use them for both. DCC - Ex is pretty much plug and play and the Rewanui control needs are relatively simple. No detection, signals, interlocking or anything of that nature.

CAD, 3D printing and cheap Chinese hardware does allow the creation of elegant solutions that in times past would have been impractical at home. Once upon a time you read about something and maybe built it with a few refinements. These days it's far more about gleaning the germ of an idea and building something tailored to need.

If this was a home layout the noise would be an issue for me, and I'd be looking for something silent or at least quiet. At a show audible confirmation is not a bad thing.