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Switch Machine Here at Black Diamond Lines we build our own switch machines. This gives us flexibility that a purchased switch will not be able to provide. It also keeps the cost down. We will go through the construction and installation of a machine . |
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| The switch machines consist of the base, motor,
threaded rod, three (3) cherry switches, two (2) diodes, flat
head machine screws with nuts, 3/4" x 3/4" alum angle
1/16" thick, and a square piece of plastic with an eyelet
in it. Off the green wire are the diodes that direct power
to the motor
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| The base is plexiglass,
1/4" thick, 5" by 3". Plexiglass is easy
to work with, non-magnetic, but is pricey. Luckily
we were given a bunch of it.
Here the base has the motor siliconed to it and the threaded rod has been pressed onto the motor shaft. The end of the screw is supported by the alum angle. Before securing the motor the base, remember to put the plastic on the threaded rod. |
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| The movable piece is about 1.5" by 1.5". The hole is off center on the high side so that the bottom edge will just clear the base. If there is too much clearance, the part will rock back and forth during movement. This can cause a binding in the long run. |
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| Eyelet will be added to the movable plastic square. The throw lever that connects to the switch will pass through the hole. |
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| Threaded rod. We use a 10-32 bolt
about 3" long. The head is turned down to .125 (1/8") diameter.
A hole about .096 diameter is drilled into the other end
for a forced fit onto the motor shaft. One way to press
the rod onto the motor shaft is to use a drill press. Hold the screw on
the turned end and then
press it onto the motor shaft.
Be careful as the motor shaft is soft metal and will bend easily. |
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| Cherry Switch. These switches are used to direct current and stop the switch motor at the end of its travel. In the top picture you see three switches. The top cherry switch is used to direct power to the switch points to maintain the correct polarity. The bottom cherry switches stop the motor when the points are properly aligned. Along with two diodes, the switch motor will only go in one direction at a time. When the switch points reach have thrown, power is automatically cut off by the cherry switch to prevent the switch points from being damaged and prevent the motor from burning up. |
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How to wire the switch.
The cherry switch has three connectors on it. The connector on the side is connected to one of the diodes. The other end is connected to the green wire. This is the power wire from the control panel. The other diode attaches to the green wire and to the outside connector on the bottom of the other cherry switch. The black wire from the motor is connected to the left connector. A jumper wire is attached to the right connector on the bottom cherry switch. The right connector on the single cherry switch is not used.
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| On this end there are two cherry switches.
The outside connector has the diode connected
to it. The left connector on the bottom switch is not
used.
The top switch changes the polarity of the switch points. The blue and white wires pick up the power from the rails. The black is attached to the frog. Then as the switch throws the polarity changes as necessary to keep the trains moving. |
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| Wiring diagram. |
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| The switch is connected to the machine
by a 1/16" diameter rod. The rod is bent to fit into
the flat bar that the points are soldiered to. The rod
is bent over to form a kind of "U". It passes
through a tie into a liner tube. This protects the rod
and add support to it. Under the table the rod is bent
towards the switch and passes through the eyelet. The
switch needs to be mounted about three (3) inches from where
the throw rod passes through the track table. It also
will need to be mounted 90 degrees to the switch movement. This
way as the plastic part moves back and forth, the swinging of
the rod will move the switch points.
I hope this page will help you to save some money and create a layout you can enjoy for a long time. Black Diamond Lines |
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