Switchmaster turnout motors

[GM50 4164]

The N scale layout at my club uses servos for turning wires in tubes to throw turnouts.  Tam Valley has an extensive line of servo controllers, including add-on decoders for their boards.  See https://www.tamvalleydepot.com/

I am curious to see how the club went about turning rod with the servos for turnouts if you have any pictures of the process.

[GM50 4164]

After reading all this about what is needed to set up these motors, using servos seems a lot easier and less likely to cause trouble.  Setting the servos for pressure of the points on the rails is done with a plug-in electronic adjustment device that seems much simpler to operate than soldering a selection of resistors into power feeds. And the servos are readily available and relatively inexpensive. So, I am not seeing the attraction for these motors.

I chose to go the route of using servos for turnout movement. I mounted mine in aluminum U channel, then a piece of piano wire travels up through the 2" of pink foam to the handlaid turnouts. I throw the movement with a simple DPDT toggle switch. A servo tester is being used to control the travel of the servo.

[Maletrain]

I am curious to see how the club went about turning rod with the servos for turnouts if you have any pictures of the process.

I don’t have pictures, and the method used at the club is a cheapskate ad hoc approach to backfitting a bunch of already installed Atlas snap turnouts.
Mostly, the servos are mounted with screws to two ¾” square blocks of wood and then those pieces are hot glued to the bottom of the layout.  The servos are positioned so that the rotational center is directly below the brass tube that extends down through the layout.  A steel piano wire comes down through the tube and is bent 90° to parallel the servo arm above the arm, then bends down 90° to go through a hole in the servo arm.  Above the layout, the piano wire bends 90° to be horizontal low to the surface and runs perpendicular to the throwbar on the turnout, about the same distance as the arm length of the servo below the layout.  At the throwbar, the piano wire has a 90° bend downward to engage the hole in the bar.

Note that the directions of the two bends in the piano wire above and below the layout do not have to be in the same direction.  The upper direction is controlled by the location of the brass tube with respect to the throwbar hole.  The lower direction is optional, and can be adjusted to avoid structural things.  In some cases where physical obstructions exist, the servo is not directly under the tube and the piano wire runs to the arm as an extension of its direction from the servo center.  That has some lash, but there is enough slop that it works fine.

Before gluing the wood blocks with the servo attached, we use toothpicks to center the points midway in the turnout, then electrically center the servo, then orient the servo and block assembly to accept the bent wire with the servo rotation axis directly under the tube, gluing it in that position with the hot glue.  Screws would also work, but the servo is already removeable because it is attached to the wooden blocks with screws.
 
We then hook the servo cable to a Tam Valley “Octopus III” and use the Tam Valley push button servo aligner to adjust the throw of the turnout in both directions (after removing the toothpicks).  Once aligned, we set the Octo III for either momentary button or switch control and hook a servo style cable from the Octo to the panel switch.

An Octo III can control up to 8 servos, and allows panel LED light indications with the same cables.  Tam Valley also now makes a DCC auxiliary decoder device that plugs into the Octo in place of the cables to the panel (and then has inputs to that device for cables from the panel, too).

The turnouts at the club do not have electrically active frogs, so there is nothing there to deal with frog polarity.  For those that do, there are servo mounts that take auxiliary electrical switches, or you can use Tam Valley frog juicers independent of any turnout throw mechanism.

There are other Rube Goldberg mountings at the club to deal with physical obstructions, and servos can even be mounted on the upper surface under buildings and linked to the throwbars with long pieces of piano wire in a variety of configurations.

There are more elegant ways to use servos, but this works for us well enough.

[rodsup9000]

I am curious to see how the club went about turning rod with the servos for turnouts if you have any pictures of the process.

Here is how I do it on my layout
3D printed servo mount with limit switch for frog power routing



Drill 1/8" hole about 5/16th of a inch from hole in throwbar for tube



Make link out of .025 music wire




Servos mounted

[Sumner]

I use servos with a $2.00 controller that I add a second pot to.  The two pots they allow you to easily set the throw distance in both directions so that the points aren't overpowered ....

More about.....



... the whole setup here...

https://1fatgmc.com/RailRoad/Servo%20Control/Servo%20Control-Index.html

Sumner

[mike_lawyer]

I received a bunch of Switchmaster motors second hand, and it looks like they will fit the bill.  Question - does anyone know the size of the plastic spacer they recommend to use with screws to secure the motor to the table?  I am thinking maybe 1 - 1.5 inches might work.

[mmagliaro]

I used those Hankscraft motors (I think the early 90s was the last time).  Besides using a resistor to reduce
the current and torque, it also slows the motor down, which is not a bad thing.  But I didn't use them as a stall
motor that way.  I added two microswitches.   The actuating wire went through a hole in the shaft, one end of it bent and went up to the throwbar.  The opposite end of that wire was trapped between two microswitches, wired up so that when the motor
pushed the points one way, it could only run so far before the microswitch cut off power to the motor and it could only
be activated by the toggle (or pushbuttons) to run the other way.

All of this cuts off power to the motor so it doesn't keep "pushing", and if you set the limit switches right, and use a springy
connecting wire, it really avoids putting undue pressure on the points. 

All of this was quite a bit of work, and I don't think I'd do it if I had to control more than 2 or 3 turnouts this way.

[mark.hinds]

I received a bunch of Switchmaster motors second hand, and it looks like they will fit the bill.  Question - does anyone know the size of the plastic spacer they recommend to use with screws to secure the motor to the table?  I am thinking maybe 1 - 1.5 inches might work.

This is how I install mine.  They came with curved galvanized brackets (hardware store?), which are screwed into the plywood sub-roadbed from the bottom.  Note at the upper left, you can barely see two SPDT momentary switches, used to route power to the Shinohara double-slip frogs on the west yard ladder.  If I change to code 55 with hand-laid turnouts, I'd need to do this with every single turnout.  Ignore the light-colored wood rectangles, which are associated with embedded Micro-trains uncoupling magnets.

MH

[mike_lawyer]

I ordered some 1 inch plastic standoffs from Amazon today... I will report back on how well they work for installation.

[mike_lawyer]

Really enjoying using these Hankscraft motors for turnouts.  Using them with .025 gauge piano wire yields a strong throw but not too much force. 

I ordered 10 more motors to install, but they do not include throw arms.  I need to locate the brass throw bar, which is a brass wire approximately 3/32 in width with an eye at the end that is 90 degrees from the bar, as seen below.  Any idea what these are called and where I can find them?

[mike_lawyer]

Anyone have an idea what the brass actuator arm is, and where I can buy some more? 

[peteski]

Unless the company which made these sells the arm, it doesn't look like off-the-shelf item. You'll probably have to buy some brass rods then bend the loop yourself.

[Ed Kapuscinski]

They almost look like repurposed hangers.