Crossover Control

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    Mike Pianta's solution for motorising the double crossover got me thinking:
    www.flickr.com/photos/scruffulous/albums/72157705092921234
    The problem with his solution is that it's lineair; to get from 'both straight' to 'both branching' you would have to slide the length of the key. So I thought, there must be a rotary way to do the same thing. Today I finally got around to playing with this idea and this is what I've got. It's not complete, I haven't done anything about RCX control, but the concept works.
    The curved slopes are what's pushing the actual points, rotating the axle is what moves the contraption through its 4 states.
    As pictured both sliders are pulled in by the elastic bands, so both points are straight. Turning the axle 90 degrees either way makes the dark grey cams push one of the sliders out to make that side branch. Turning the axle 180 degrees from its current position makes the light grey cams push both sliders out together.
    For RCX control I'm thinking knob-wheel + touch sensor or rotation sensor to make the motor turn the axle 90 degrees at a time but I'm not sure how to initialise it...
    My landscape and track sections use a combination of MILS and PennLug with the track 2 bricks above the baseplate. Annoyingly that's one plate too low to run the axle below the points to control both halves at the same time...

    Daddy Ogre, ThankTheLEGOMaker, and 5 other people added this photo to their favorites.

    1. UrbanErwin 2 months ago | reply

      Does the PF servo have enough power to move this?

    2. scruffulous 2 months ago | reply

      Oh, wow! Very clever.

    3. Duq 2 months ago | reply

      Probably, it's very light to turn. But the servo doesn't do 360 turns. The whole point was going to a rotary system so you don't have to run through many options; you're never more than a 180 degree turn away from the position you need.

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