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Blog- Ian Smith's 2mm Finescale Ramblings - Modbury - Trackwork 4 (Turnout Operation)

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Now that most of the trackwork has been installed on the first (Exeter end) baseboard, it is time to try it out!!!


Before I can though, a Turnout Operating Unit needed to be built. The first thing required is a method of connecting the Switch Rails to any under board gubbins. Obviously I had already thought all of this out up front, but I did need to open up the holes that I'd drilled to accommodate these fixings because I couldn't feed them down!! These first items were bent up from some 0.026" guitar string (ideal because being steel it is strong despite the small section, and also being nickel coated you can solder to it very easily).


Guitar String Switch Rail Connectors (these were the rejects, the ones used are identical but have slightly less horizontal wire to run underneath the stock rails). The little loopy bend fits around the foot of the Flat Bottomed Switch Rail, the tail being soldered along the Switch Rail towards the heel)


The actual TOU is constructed from 2 sizes of Plastruct square tubing (one sliding within the other). Brass attachments (rod drilled 0.4mm in the lathe) allow the capture of the previously fitted guitar string switch connectors with minimal slop, but little friction and no stress on the soldered joint between the switch rail and the connector.


Part for the TOU



Made up TOU (subsequently, a hole was drilled to accept the moving wire from the Memory Wire Turnout Actuator, and once fitted a small micro switch was attached to switch the crossing polarity)



What the TOU looks like from above the baseboard


For all of my turnouts and signals, I have decided to use Memory Wire actuators. These are built up on a piece of acrylic sheet (simply because I had some), and comprise a 5 volt regulator, a resistor in line with the actual memory wire, a pivot to allow transfer of the movement and a spring to return the wire to normal once the current is turned off.


Made up Memory Wire actuator (I actually had to modify this one switching the memory wire and return spring over as I'd forgotten that it would be upside down when fitted to the board - doh!



What it all looks like below baseboard


Below is a short video of the whole lot under test :






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