This post describes the procedure and standards I use for installing
Tortoise switch machines on the main layout. This is the first of two related posts -- the next post will cover the switch wiring standards.
As I write this I have successfully installed 12 Tortoises on the layout, all driven by
Digitrax DS64s. The photos in this post were taken of the last two Tortoises I installed.
This process is not by any means fast. It takes me at least an hour per switch. I don't claim this is the best process, but it works, and it's the product of lots of learning, research, and trial-and-error.
Background: The TortoiseThe normal Tortoise installation position is shown in the picture below, which is copied from the Tortoise instruction sheet:
This photo is a bit hard to decipher because it is in black-and-white, but the components are all there. At the top you can see the switch (they use HO scale in this picture, but the same machine works for N and other scales too). The switch is on top of roadbed, which looks white in this picture, and that in turn is on top of a piece of plywood subroadbed. There is also a shaft drilled through the cork roadbed and plywood subroadbed. The Tortoise is attached underneath the plywood. A non-electrical metal wire, which I will call a "driving wire", links the Tortoise to the switch through the shaft. The driving wire goes through a “fulcrum”, or pivot point, which is piece of plastic with a small hole for the wire near the top of the Tortoise in this picture, then down to a screw near the bottom that holds the wire to the gears. When the gear shifts from one side to the other, the wire is moved and the switch above will move to the opposite side.
This is a simple but cool mechanism. Because of different scales and different thicknesses of subroadbed, the span of the “throw” at the top of the driving wire (that is, the distance the wire covers at the top when going from one side to the other) can be adjusted by moving the fulcrum up and down. The instructions also say that you can substitute a larger gauge wire if you like, and this can be useful in some situations.
Extending out of the bottom of the Tortoise in this picture is a circuit board for 8 electrical connections. The Tortoise is driven by a low DC voltage using the 1st and 8th connections. To “throw” the switch you simply reverse the polarity of the DC voltage being supplied, and that causes the gear to switch sides. Once the gear has gone all the way to one side the motor stalls. It can still receive power without causing problems, and depending on your situation you might want to keep the power constant to be sure the point rails are held against the side rails.
The other 6 connections on the circuit board are linked to two internal SPDT switches, which are switched whenever the main switch is thrown. The most common uses for these are to provide switched track power to the frog rails and to wire lighted indicators for a switch board. I will be using both of these functions, but this post only describes the frog wiring as I haven’t set up the light boards yet.
A sideways installation: conceptI chose not to install my Tortoises as described above, for two reasons. First, you’ll notice the Tortoise sticks out quite a ways under the layout – almost 4” when you consider the wiring attached to the circuit board. I simply won’t have that much available space under the upper deck, nor at certain parts of the lower deck (such as above the power cabinet). Furthermore, even where there is 4" of vertical space I prefer not to have the Tortoise taking up that much head room in the under-layout crawl area.
Second, on the lower deck of my layout there are many places where the thickness of the foam subroadbed plus the underlying plywood is as much as 2 ¾”. This means the driving wire has to be extra long, which is not by itself a problem. But it also means that the span of the “throw” of the end of the driving wire is huge, even if the fulcrum is moved to the absolute top of the Tortoise. Add in the fact that I’m in N scale, and what this means is that with a normal Tortoise installation the “throw” for the wire is 3x the distance needed to move the turnout (switch) from one side to the other. In practice this is still workable, as the wire is bendable. But the downside is the aesthetics. One of the key benefits of the Tortoise is that your switches move in slow motion, like the prototype. At a typical DC voltage the time it takes to move a switch from one side to the other is about 3 seconds. However, when the “throw” span is 3x the width needed to move the switch, what happens is that the switch is moved in 1/3rd the time, or about 1 second, and that means the appearance is way too fast.
Both of these are common problems and thus there are many proven solutions. The Circuitron people even sell special
sideways Tortoise mounting kit to address the first problem (but not the second). A while ago I ran across a link to this
model railroading news letter where on page 8 the author describes his procedure for sideways mounting. As I studied it I realized that not only was this cheaper than the official sideways mounting kit, it also had the added benefit of addressing the second problem (although that was not the author’s intent) because of the geometry of the two wires and fulcrums.
The procedure I use is copied from his, making adaptations only because I used different materials that were more readily available. After successfully testing this with one switch, I modified the remaining 13 Tortoises that I had on hand as shown in this picture:
My goal in the modification of the Tortoise is to prepare it for an installation that looks something like this, viewed from underneath the layout:
Note that both Tortoises in this picture are mounted sideways. The wire that drives the switch still runs through a vertical shaft in the plywood, but now there are two wires and two fulcrums.
The rest of this post describes how to set up this installation.
Preparing the Tortoise1) You are going to glue two pieces of styrene to each Tortoise. In preparation, you will file down Tortoise plastic “shell” slightly just to make sure there is a smooth surface to glue to. I first used a hobby file, but then went to a normal sized metal file as it was quicker. The first place you need to file is what will be the “top” of the Tortoise when it is installed – this is the side opposite the side with the gear. You probably have to take off the round sticker that the inspector put on it and then need to file down the “bump” down the middle where the two plastic pieces of shell were joined. Do so for the whole side. The second place you need to file is the side that is the “top” in a normal installation. Again, file down the bump in the middle.
2) For what will be the “top” of the Tortoise you will want to attach a piece of .030” styrene about 2 7/8” x 2 3/4”. This styrene will act as a mounting plate. As per the picture above, you see there is a plate of white styrene attached to the top of the Tortoise with glue, and the plate is screwed to the plywood to mount the Tortoise. I bought some large sheets of .030” styrene in bulk and cut them with a plastic cutter. Thicker styrene can also work – I would not recommend thinner. Once cut, I attach the styrene using common super glue, which dries very fast and holds strong.
3) You’ll need a second, smaller piece of styrene to act as the second fulcrum. In the picture above this is the piece of white styrene at the very left of the photo, attached to the Tortoise very near the plywood, and with the driving wire running through it. For this I used .040” styrene, cut to 1.5” x 1/2"”, and used super glue again to attach it to the Tortoise. It’s a good idea to drill the hole before attaching. I placed the hole in the center, lengthwise, and about 1/8" from the end (widthwise). The hole should be big enough for the wire, and after the hole is made you probably want to tilt the drill at an angle and move it in a circle to provide an angled cut so that the wire can tilt as the switch is thrown.
4) For driving wire some people recommend .025 piano wire. I use 18 gauge wire that I found at the local Michael's art supply store in the floral section. It's intended to serve as a stem for fake flowers, but it's very cheap, is available in bulk packages, is perfectly straight until you bend it, and can be cut easily. It's thicker and stiffer than the wire which comes with the Tortoise, which is an advantage, so I use it for both of the wires in each installation and save the stock wire for some unknown future use. The wire lengths should be cut to fit your installation, with some extra left over just in case.
If you use the thicker wire you'll need to drill larger holes in the Tortoise fulcrum and in the slot where the wire slides into the gear. I recommend buying a small hobbyist hand drill with an assortment of small bits -- you can use this for all kinds of model projects, and the hand drill is easier to control than a power drill. I choose a bit that is exactly the size needed for the 18 gauge wire.
For the gear slot, I use hobby pliers to hold the black plastic gear while drilling -- this prevents possibly damage by pressing too hard onto it. Ditto for when the screw is added. When that wire is in place add the green fulcrum, putting the wire through it.
5) Then you join the driving wires, one each for the styrene fulcrum you added and the green fulcrum that came with the Tortoise. There are many options here, but the easiest I found is to use a short (1/2" or so) length of chunk of retangular, tube styrene available at any decent model train shop (Evergreen Scale Models #259, .250 x .375"). I drill cross holes in each direction and put the wires through. While there may seem to be a lot of slack in this set up, in practice the first wire moves the second like clockwork.
6) For final touches, first add 4 holes to the edges of the mounting piece of styrene and pre-set 4 screws (I use #6, 5/8"). Then I add a label for the switch number. This shows a Tortoise where everything is ready for installation. Note it is upside down and the second driving wire isn't in the picture -- that will get added during installation:
Preparing the SwitchThere are three things you need to do to prepare the switch for Tortoise installation (or possibly 1 or 2, depending on your type of track). It is easier if you do these before you install the switch on the layout, but alas I'd already installed these switches, so I had to do these things after the fact.
First, here is an example of two Peco code 55 switches, installed in 2006 and still on the original AMI roadbed:
So here's the modifications that I make:
1) First, I connect a feeder wire to the frog rails. I described this issue with "Electrofrog" or "Live Frog" switches
last year. In my case, I had hoped that I could avoid having to make the extra effort to add a separate feeder wire the frog rails, but my experience operating the layout proved that in the absense of a separate feeder wire, the frogs frequently lose power due to dirt between the point and outside rails. You can correct this immediately by cleaning the rail contact points, but on a large layout you have to do this a lot during operating sessions, so it quickly becomes tedious.
Adding a frog wire retroactively to an installed Peco code 55 switch is a challenge, but doable. There is a connecting frog wire hidden underneath the switch. I found that I could access it from the outside rail of the straight route, between the 2nd and 3rd tie from the end. I used an eXacto knife to first cut out some roadbed, then cut the plastic under the rail, and then "dug" a bit into the under-rail plastic until I caught the wire on the end of the knife. I would then pull the wire out just enough for it to be visible. At that point I would strip about 1/2" of insulation off of a 22 gauge solid green wire, bend the end of the wire into a hook, and use it to "hook" the exposed frog wire. Once hooked I'd use small hobby pliers to clamp the wires together, then solder them, then drill a hole in the plywood for the green wire. The end result is a hidden feeder wire connecting to the frog rails on one end and sticking underneath the layout on the other end.
2) Peco switches have built in springs that force the switch to one side or the other. This is a nice feature in the absence of a separate switch machine. However, when using a slow-motion Tortoise the spring needs to be removed.
The spring is located right at the end of the point rails. You will see two metal tabs on the plastic part between the rails that spans two ties. Use and eXacto knife or similar to pry these up, then remove the plastic tab in the middle. Then push the metal tabs down so that you can remove the piece of metal that includes thow tabs. Finally, the spring itself is now visable. Pull it out with hobby pliers or a tweezer. You're done.
3) Finally, you need a hole for the driving wire that will link the switch to the Tortoise. I use the hand drill mentioned earlier. This hole should be in the large tie that drives the movement of the point rails, and I prefer putting the hole in the exact center of the tie between the rails, rather than, say, on the part of the tie on side of the rails. It just seems to work better that way.
First, I use a small drill bit to create a pilot hole, then a larger drill bit that is the exact size of the driving wire. Be very careful, as too much downward pressure can damage the switch.
4) One other thing you'll need is to drill the shaft through the subroadbed for the switch machine wire. I use a 3/8" bit, and am sure to clean the shaft of debris before installing the switch.
Here is a switch which has had all of the above steps completed, and even has a driving wire in the wire hole. At this point the switch machine below is not connected, so the wire has been slightly bent at the top to prevent it from falling through:
Installing the TortoiseWith the switch and Tortoise both prepared we are ready to connect everything up. Depending on the space available underneath this can require some real physical contortion to reach everything. To the degree possible try to provide adequate space and light. I use at least two cheap "clamp" worklights available at hardware stores. It's good to have two to provide lighting from different directions so that you avoid shadows.
1) Prepare the space.
Make sure there is a spot under the layout clear of wires and other obstacles. Here is an example of such a space:
On the left side of the picture you can see the bottom of the shaft for the driving wire, and the wire itself hanging down from the switch. Next to that hole is a white shelf support bar -- because of that we won't be able to install the Tortoise to the left of this shaft, we'll need to do it to the right of the shaft. On the right side of the picture you see the green feeder wire from the frog. In the middle of the picture is the red-and-black power bus. This is near the intended location of the Tortoise, but not in the way.
The Tortoise itself has to be positioned so that the movement of the switch wire is perpendicular to the switch itself.
2) Connect the Tortoise to the plywood.
Here's a picture showing this step completed:
This is a pretty simple step conceptually. Position the Tortoise such that the driving wire is through the styrene fulcrum (see left of picture) and that the fulcrum hole is at the center of the shaft. This gives the wire maximum movement potential -- if the hole is too near the sides of the shaft the you may find the switch doesn't move well. Also make sure the Tortoise is lengthwise positioned in the same direction of the switch itself -- this is to make sure that the wire movement is perpendicular to the switch. Then drill the 4 screws in and you are done.
In practice this is tricky. I usually put in the first two screws manually, at least part of the way, to make sure they go in straight and don't shift the location of the Tortoise. Then I use a power drill on slow speed setting with an extra long drill bit to keep the screws going in straight.
3) Connect the frog wire.
Here is a Tortoise with just the one frog wire attached, not yet soldered:
There are two options for adding wires to the Tortoise circuit board. One is to buy a 3rd party "slide on edge connector" which have wire clips on one side and a slot for the whole unit to slide on the tortoise circuit board on the other side. This is the smart way to do it, as it saves difficult soldering and allows for easy changes later.
So, since that is the smart way, naturally I do it the other way. Mostly out of trying to save money where I can. I solder the connections. Now, this is quite tricky but I've gotten so I do it quickly and reliably. And I figure that if I need to make changes later I can do so at the other, non-soldered, end of the wire.
After I have the Tortoise in place I think of the circuit board as having slots numbered 1-8 from left to right, from the point of view where you are sitting looking at the board directly (as in the above photo). In this case slots 1 and 8 will be used for the switch power from the DS64. I connect those wires last because it is easier to solder the inside slots first. Slots 5-7 will be used in the future for the switch board lights, so I don't talk about them in this post. Slots 2-4 are for powering the frog.
Slot 4 is the frog wire. This is the unswitched side of the connection, as shown in the internal Tortoise SPDT diagram below (taken from the Tortoise instructions):
I'll have more to say about the above diagram on the next step. For now, the point is that slot 4 is always for the green frog feeder wire.
Attaching and soldering is the same process for each wire. First, I strip about 3/8" of insulation from the end of the wire. The wire is then routed through the hole and, using hobby pliers, the wire is bent as shown in the picture above so that it forms a "U" shape and clamps onto the circuit board. You want to have only a small amount of wire extending above the board, and you want to make sure that there is no chance that any two wires above the board will touch each other. Below the board there is a thin, narrow strip metal for connectivity, so you want to run the wire along that metal strip.
Once in place, I use a soldering iron at 40W (the 20W setting doesn't work as well for this application). I place the flat end of the iron blade on one side of the wire and make sure it is touching the circuit board metal strip, then apply solder from the other side of the wire. The whole process takes only a few seconds -- as soon as the solder is applied I remove the solder source and the iron. The solder will tend to bind to the metal, not the insulation between the metal strips, if you are spartan with the solder there should be no shorts yet the connection should be solid.
4) Connect the track power wires
This picture shows the same Tortoise after the track power wires have been connected:
It's not clear from the picture, but the red track wire has gone to slot 2, the black to slot 3. The track wires are connected to one of the terminals on the power bus, as described in earlier posts on wiring standards.
The biggest challenge at this point is figuring out which track polarity goes to which of the two slots #2 and #3. There is no simple rule of thumb. It depends on the orientation of the switch itself and the orientation of the Tortoise. The only solution I found that works is a complicated procedure. I first look at the switch from above and mentally identify which rail is "red" and which is "black". Then I note whether we want the frog rails to be "black" or "red" when the switch is set to the "normal" or "straight" route. In that case the frog rails should be the same polarity as the outside rail from the diverging route.
Then I mentally note whether, in the "normal" position, the switch is set toward the wall or away from the wall. Thus, at that point I might be thinking "switch set toward wall, polarity black", for example.
Then I climb under the layout and position myself so I am looking at the Tortoise from the side of the circuit board. Let's say, from that point of view, that the "toward wall" position matches the left side of the Tortoise. So I will now say, "switch on left side, polarity black".
Now I look at the internal Tortoise SPDT diagram shown above in the previous step. At the bottom of that I have manually drawn in two boxes and a line connecting them. This represents the two possible positions of the switch. The box on the left is filled in, the box on the right is hollow. So what this says to me is that when the switch is on the left, the internal SPDT switches will be in the position shown in that diagram. When the switch is on the right, the internal SPDT switches will be in the opposite position.
And from this, I know that if "left side, polarity black", then if the switch is to the left slide, then slot 4 (frog) will connect to slot 3, so slot 3 should be the black wire.
Then after doing all that I repeat the mental exercise to confirm the result, then I attach and solder the wires.
After doing this for 11 Tortoises I've found it works every time. The only time I made an error in polarity was when I tried to short cut the process with a "rule of thumb", copying the wiring on a nearby Tortoise, but missing a detail so I made an error.
5) Connect the switch power wires
This picture shows the same Tortoise after the power wires were connected to slots 1 and 8:
One thing that might be confusing is that there are two pairs of white power wires -- one coming from above, and another extending below. The reason is that the Tortoise in this picture is one of a pair of Tortoises that drive a crossover. Crossover switches have the unique attribute that they should always switch together. That is, it makes sense only if both switches are set to "diverge" (so that a train can crossover between the dual tracks) or "straight" (so that trains can pass each other on the two tracks). So, in this case we wire the power for both Tortoises from the same DS64 switch slot, saving a switch slot and simplifying the control.
Therefore, the second set of white power wires are hanging down in this photo only temporarily. They will soon be connected to slots 1 and 8 on the paired Tortoise.
6) Connect the Tortoise driving wires
This photo is a repeat of the photo at the beginning of the post, and shows the paired Tortoises all set up:
You'll see that the driving wires are now connected using the piece of rectangular styrene tube. Back during the Tortoise preparation phase I drilled holes in the piece of tube so that perpendicular driving wires could go through both ends. Now the driving wires are routed through the holes.
It's worth remembering that the driving wire which goes to the switch will not be supported from above after this installation is complete. Therefore, in order to prevent it from sliding down and falling out, we need to support it from below, This is done by bending the bottom part of the wire around and using pliers to clamp it onto the rectangular styrene "connector".
7) Testing and tuning
Everything is in place but there is still quite a bit of testing left to do.
The first tests I run by powering up the DCC command station but not adding track power. The first test is simply to see if the DS64 actually drives the Tortoise using the switch address we thought we programed. Note that you may not see the switch actually move at this point (although it's better if you do), however, if you see the Tortoise switch gear move in response to the command then the test passes. If you have paired Tortoises, both must move, and their movement must be coordinated (so that both switches are either diverge or straight at all times). If this fails you need to check that the address is correct and then that the wiring is correct. (Or, if this is the first usage of that DS64, you need to verify that it is getting power and Loconet correctly.)
The second test is to make sure that the DS64 "thrown" and "closed" positions match that of the switch. If not the simple solution is to reverse the two wires that connect to the DS64. In fact, although it is possible to reason out in advance which switch power wire should go to which DS64 slot, in this case it's not worth the bother. I just connect the wires to the two DS64 slots randomly and half the time I end up having to undo and reverse them them -- a process that takes less than a minute. (Note: the reason I don't use the same process for the frog wires is that with frog wires we are dealing with soldered connections and the power test takes longer run.)
The third test is tuning the switch. Ideally as soon as the Tortoise gears starts moving the point rails will start to move from one closure rail to the other -- and get to the other closure rail just as the Tortoise completes the movement. You don't want the point rail to not reach the closure rail, obviously, but you also don't want it to get to the closure rail too soon either, mostly for aesthetics as noted earlier.
One adjustment is to move the green fulcrum on the Tortoise to increase or degress the span of the driving wire movement. The other adjustment is to slightly bend the wire if the switch is favoring one side or the other. This adjustment takes practice, and the first time you try it you may decide you need to start afresh with a new wire after too much bending. However, once you get familiar with the process this adjustment is usually completed and tested very quickly.
Once the switch itself has been tested for correct connections and movement you can remove the top of the driving wire that was sticking out the the switch hole. Thus the switch will end up looking like this:
Note that you can barely see the end of the metal wire in the middle of the switch tie. After adding scenic treatment this wire will be completely hidden.
The final test is the power to the frog. For this you turn the track power on. There are two tests. The first is to see if the polarity is correct. If not you'll probably know as soon as you turn the track on because the frog will short, as the point will be touching the wrong rail. However, just in case the short is masked by some dirt between the point and closure rails, also test with a voltmeter on an A/C setting.
The second test is to make sure the frog is getting power separately from the point-closure rail connection. That is, test to verify that the frog feeder and red/black track power wires you connected to the Tortoise are actually routing power. Using the voltmeter on the A/C setting, first test to see what normal track voltage is between two nearby rails. (For my layout, it's usually 12.6V or so, which is correct for Digitrax on the N scale setting.) Then put one lead on the frog, one lead on a nearby rail of opposite polarity, and manually move the switch so that neither point is touching a closure rail. The voltage should stay the same -- if not the frog feeder connection is either tenuous or non-existent. Throw the switch and repeat again, to verify this works with both polarities.
Now you are done. This post didn't cover the wiring standards or the programming standards for the DS64. I'll cover that in my next standards post.
