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…..........................................................…--- “Gravity-Switcher” ---

....--- Weight/Gravity Operated 3D Printed Switch Machine ---

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You can find all the files to 3D print this object and others on my thingiverse.com account ( HERE ).

This is a manually operated switch machine that sits under the turnout very similar to the 3D printed one that uses a servo ( HERE ). I've thought about it for some time and finally got around to designing it and trying it out over the last couple days. It uses weight and gravity primarily to move and hold the turnout's points from side to side. There is no need for rods and such going from it to the side of the layout to operate it. One only needs to run a line (fishing line should work) from the machine to the side of the layout. Simple eye hooks will probably suffice and the route doesn't need to be in a straight line from the side of the layout to the switch machine.

Now that I feel good about the concept working I'll work on a single pulley wheel that will be above the weight on one side and a knob and/or a lever assembly that will go at the end of the control line on the side of the layout.

Above are the two main 3D printed parts, the body and the control arm.

Equal weights are hung from both sides with a simple string. The one on the right will always pull the control rod down on that side since the lever arm to it is twice as long as the one to the weight on the left side.

If the weight is lifted on the right side by the line going to the side of the layout the weight on the left side pulls the control arm down on that side throwing the turnout's points to the other side of the turnout.

I installed the switch machine on the same test setup I use for the servo operated machine I made earlier this year ( HERE ). A mount is coming that will position a SPDT switch where when it is hit by the control arm it will change the frog polarity if that is needed.

With both weights hanging freely the machine throws the points to the right as shown above.

I tried some different weights and came to the conclusion that for the hand-laid turnout I was using 3 oz. on each side seemed to do a good job of holding the points in place very similar to how I setup a servo controlled turnout. One could try different weights for their situation.

I found a good source for 3 oz. and other size weights on the internet where if I bought 8 lbs. worth the cost per turnout would be about $1.50. Not a bad price for turnout control as if you have a printer or access to one these switch machines would come in at under $2.00 each.

With the 3 oz. weights I used when I pushed the throwbar with a finger it snapped right back into place. Adjust the weights for what you like.

To throw the points lift the weight on the right side. Here I'm doing it by hand but it could be done with a simple line to the side of the layout. Pretty low-tech.

I've posted a short video on YouTube ( HERE ).

Above a mounting location for a SPDT switch has been added to the bottom of the switch machine. Using it allows you to change the polarity of the frog as the points move. I've found these limit switches from a number of places and as low as $.50 each are less. Look for ones with the 9.5mm/.374” center to center distance between the screw holes.

I'll soon try and finish a single wheel pulley bracket and pulley wheel that will mount under the layout above the weight on the right side. The control line would go from the weight up and over the wheel and then to the side of the layout, hopefully, through simple eye hooks where it could be secured when the weight is pulled up to throw the points. Release it and the points are thrown back in the other direction.

Still to come:

1. Mount for SPDT switch for changing the polarity of the frog.

2. Fascia controls for lifting the weight. Probably two types, lever or pull.

3. 3D printed items to help when running the line in extreme, tight or 90 degree situations.

You can find the files to print this on my thingiverse.com account ( Soon ).

You can find all the files to 3D print this object and others on my thingiverse.com account ( HERE ).

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