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I am installing Tortoise switch machines on my new layout which is a 3 rail o gauge atlas track.

My bench work is 1"3/8 thick including road bed.

They suggest going with a longer and thicker spring wire.

My question is how thick and how much longer?

Stainless or high carbon steel?

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Just make the spring wire a couple inches longer than what’s needed. It will be easier to install. Otherwise. Once the wire is in the throwbar hole. You need to hold it up against the underside of the benchwork to keep it in place as you fumble around with the screws. The older you get. It’s hard to get the wire through the hole in the throwbar from under the layout. I’ve even used doublesided tape to hold it up in place. Then used a spring clamp on the wire up above to make sure it stays up while you get the screws tightened. If you have a helper up above it’s a lot easier. Once your satisfied as to how it works and it’s fastened down for good. Trim the excess wire off above the bar with a pair of diagonal cutters

I agree with Bruce.   You do have options/wiggle room.  My bench work is 1 1/8th" including the roadbed.  The stock tortoise rods worked but Just barely.  I added a quarter inch using .026" and .029" piano wire.  Neither required enlarging the output arm hole ...although the .029" needed a decent push to get it in.  I went with the .026" as it is a bit more forgiving with light rolling stocks ability to move the points off the stock rail for non-derailing.

I use Brendan's technique of using hemostats with a slight modification to help center the throw correctly.  I first make sure that the switch is very loose.  I will send the throw wire up through the 1/2 inch hole and grab it with the first hemostat, then lift up on the switch slightly to guide it through the small hole in the throw bar and grab what goes through the second hemostat.  Remove the bottom hemostat and fasten down the switch.  I will then center the tortoise under the table and put in two screws loosely to hold in place to endure the throw bar moves correctly.  Then add the other two screws.

Also, I will solder the wires to the tortoise first so I do not have to solder upside down.  That is not fun.


I suggest using double pole double throw toggle switches with bi-color LEDs so you can create a map of your layout on your control panel and easily see which way the Tortoise switch machines are thrown. In the instruction sheet that comes with each Tortoise there is a great diagram on how to do this. This system has worked for me for the past 37 years. 22 gauge wire is perfect for the wiring.

I purchased the bicolor LEDs from Digi-Key. Their phone number at the time was (800)344-4539. The part description was LED T-1-3/4 UL BRT RED/GRN WH DIF and the part number was 160-1038-ND The manufacturer was listed as LTL-293SJW Thailand. I hope this helps. I just checked the Digi-Key website and the part is still available wit the same part number. Amazing, I bought them 37 years ago. They also offer LED 5mm black nylon panel holders. That part number is 67-1332-ND

Last edited by triplex

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