Visio wiring diagrams

So the past few days have been very busy both with work and with a home project. I have kept up with my promise to "do a little bit each day on the layout", but unfortunately this week the stress is on the word "little". I did make a tiny bit of progress on building more staging subroadbed, and have spent an hour or two with the nice package of DS64, Tortoises, and the LocoBuffer that arrived mid week. I'm starting to practice with these components so that I can understand their innerworkings, and when I do I'll post on that topic.

The other bit of progress was starting work on the staging Visio diagrams. Here are a couple of screenshots that show how these will look. First, this is the diagram of the lower tier of staging, near the loop:


Here is the "Key" section of the diagram, showing what the various symbols mean:


Hopefully this is self-explanatory to those who have read the wiring standards posts. It may also help to go back to a picture of this section of layout, before the bridges were put in, to see the track in situ and compare it to this diagram.

The purpose of the Visio is to help with maintenance and changes later on. Yes, the wiring follows standards and labeling conventions, but the Visio shows how it all hangs together. If you've ever tried to sort out complex wiring that you built months or years before without a diagram or labels, you'll understand how helpful such a diagram can be.

The Visio does take some time to set up, but once in place adding new track to the diagram isn't that time consuming. I find it best to write down the track data on a notepad when I'm working on the layout. Later, when I have access to a PC but not the layout, I can still "work" on the layout by transferring the notepad data to Visio.

Design influences: first layout

A little while ago I discussed the external influences that helped shape my plan for this N scale layout -- mostly from age 7-10. Extending on that theme, this is the first of a series of posts to talk about past layouts I've built, and the lessons learned from each.

I received my first train set as my 8th or 9th birthday present from my dad. It was a cheap Tyco starter set with just an oval, one engine, and 5 cars ... and I LOVED IT!!! Over the next few years I acquired some extra cars and track, but didn't think about a layout until I visited a friend of my dad's, who'd built a basic layout for his son. We were inspired, so my dad went to a train shop to do some research, and picked up this booklet:


This must have been the standard booklet for train shop newbies of the 60s and 70s. We knew nothing about layout design, so not surprisingly we settled on the sample plan in the book:


I was so excited. My dad would visit on weeknights (this was after the divorce) and we built a 4x8 table, put down plywood, and tacked down the track. No roadbed -- the book didn't include roadbed in the detailed instructions. Then we added ballast using the method in the book, which didn't turn out that well. I had to work for days to get the stray ballast off the rails. But still -- I had a layout!!! I bought a few cars, built a few structures, and a ran a lot of trains. While it never looked like anything that you'd see in a magazine I was happy with it and kept using it ... until we moved and the layout had to be disassembled.

So what did I learn here?

1. On paper there are 4 separate towns mentioned, but in the flesh the distance between them is tiny. Treating each siding as a separate town just did not look at all realistic. I didn't know it then, but Linn Westcott, the author of the book, was a prolific layout designer who had certain strong preferences that didn't fit my own, and in fact were counter to the general direction layout design has been going for the past 40-50 years. He did believe strongly in track plans with realistic schematics, which is a pretty universal preference now, but beyond that he didn't place much value on scenery or realistic setups. He was happy to have track going several times through the same scene, or have two towns on top of each other, or creating a "bowl of spaghetti" type of track plan.
   
   So, my first big lesson was that I wanted a layout to be somewhat realistic. The setting should be possible at least, if not entirely plausible.



2. In my post about external influences I mentioned love of passenger trains. So naturally, as this layout was being assembled I used my allowance to pick up a few passenger cars. I found that passenger cars look pretty ridiculous going around the tight curves (18" and 15" HO) on this layout. And further, that if you want any realism with passenger trains they have to go somewhere. With freight you can focus on the local switching, but passenger requires some distance. So, how can you get distance in a mere 32 square foot layout, realistically? As it turned out, I solved this with my third layout 15 years after this one was built.



3. This layout was in the basement of our small apartment building. No one bothered it, but it was a pain having to move all the rolling stock and buildings to and from our storage locker between sessions. Dust was also a major menace, even though we had a sheet that covered the layout when not in used. I'm sure both those factors reduced the time I spent with the layout.
   
   In subsequent layouts I've sometimes been forced into similar compromises, but when possible I avoid such situations.

After this layout was torn down I wouldn't start another one for almost 5 years, which will be covered in a future post.

Thinking about switch control on main layout

So, the decision I made a couple of days ago to go with Tortoise switch machines on the main layout sparked my thinking about the whole switch control issue. This isn't a new issue at all, but sometimes you need a spark to help you finally reach a decision.

I researched the docs at Digitrax, skimmed various web sites, and started an email discussion with Mike Gleaton at Charleston Digital Trains, who is my primary source for DCC paraphenalia due to his extensive helpfulness and responsiveness, not to mention his ultra-competitive prices.
Long story short, the solution seems to be the Digitrax DS64. Yes, I knew the DS64 could provide digital control of 4 switch machines (either slow motion or snap relay), but at $48 + shipping I was hoping for something cheaper. But here's what I learned are its advantages:

1. Meets requirement: It can use a non-track power source. This is important because otherwise a large number of stationary decoders can drain the track power, requiring boosters and potentially interfering with train operations. A single PS12 power supply ($8) can power 20 DS64s, possibly more.


2. Meets requirement: There are slots for additional input devices, such as a fascia board with switch controls. This is huge -- I thought I'd have to buy separate DCC devices to support this feature.


3. Meets requirement: The DS64 supports 8 routes. Now, I've known this since I first read about the DS64, but I didn't really think about it until now. You really do want routes for things like ladder switching, because otherwise instead of clicking one logical switch for the track you want to go to, you have to click all the switches in between. The idea of one-click switching is helpful both for manual switching boards and for simplifying dispatching for a large layout.
   
   But if you have a lot of switches you'll need lots of routes. For example, a single 5-track yard with switch ladders at both ends will require 10 routes -- two (one for yard entrance, one for yard exit) routes for each of 5 tracks. The biggest Digitrax command station, the DSC100, which I have, supports only 32 routes. Each DS64 adds 8 routes, twice as many as the number of switches it supports, and since the routes can include switches attached to any DS64, a layout full of DS64s gives you more routes than you can realistically use, even if you use the "virtual" route addresses that Digitrax suggests for special switch situations.


4. Meets requirement: It has sensors to provide feedback to the command station, the computer, and the fascia switch board indicating the position of the switch.


5. Very useful: The DS64 can be configured to turn power off to the Tortoises 16 seconds after the switch movement is finished. This isn't true for all layout situations, but I have found that when the Tortoise is powered off on my layout it still holds the switch points firmly against the rails, thus making continual powering of the Tortoise unnecessary. I hear that this is not always the case, but perhaps my use of thicker-than-standard gauge wire for the Tortoise makes the difference.


6. Possibly useful: The DS64 can control both snap-relay and slow-motion switch machines, but not both types from one DS64. This gives me the option later of using the same technology, the DS64, when I start adding DCC control to my staging switches.


7. Possibly useful: There are also features related to signaling, which I haven't explored. But this is a topic I want to tackle before I get too much farther along.

So, I've sent Charleston Digital Trains an order for a DS64, a PS12, and a LocoBuffer-USB for computer control. Once they arrive I'll start experimenting.

Upper Tier Bridge complete

So, track is in place, wired, cleaned, tuned and tested:


I changed the bridge curve slightly from what I'd planned to better align it with the track on the left. But it's still no tighter than 24" radius at the apex, which is plenty wide.

I haven't cut the rails yet to allow the bridge to be removed. I use a Xuron rail cutter (see figure 13 at the link) for rail cutting, but as good as that is for cutting rail before it is set in place, it makes a large gap if you are cutting in place rail. Better to use a thin saw for the purpose. I think I have one in my old HO equipment box -- if not I'll have to buy one. I'll target completing that task this week.

Otherwise there is a feeling of "downhill from here". It's been 10 weeks since I started dismantling the old staging, but now I've got the triple deck loop and the custom staging bridges in place. From this point I'll complete the upper tier nearest the wall and move forward until staging is complete. I will pre-wire the north end switches, but won't hook them up for remote control yet as they will be reachable by hand. All in all the rest of staging should be just about implementing a known solution -- no more big problems to solve along the way.

So, I've started thinking ahead to the problems post-staging. More on that in a future post.

Switch wiring milestone

Yeehaa! Ive finished all but one of that set of switches. I had to leave one undone due to running out of wire, but the one left is the easiest one to access. Even better, there were no more switch problems -- all the switch machines connected since the last post worked fine on the first try.

Here is what the temporary switch board looks like:


It's quick and dirty, but will suffice until I figure out a permanent solution. For each tier the switches are generally in a line, so I set up the board that way, with the left switch control being the "Straight" or "Normal" direction and right being the Diverging direction (as the label at the bottom indicates). The board itself was cut from a leftover piece of 3/4" plywood that had been used for paint testing, hence the interesting color.

The picture below shows the bridge area, sans bridge, with the switch wires visible. I bundled them together with tape but haven't fixed them in position yet pending the permanent switch control solution:


Except for the switch wiring everything is as it was a week ago. I did vacuum all around in preparation for finishing the bridge, which I will start today.

There are a couple lessons I've noted down from this week's experience:

1. Despite my intense budget consciousness, I've going to bow to the inevitable and accept that the best choice for switch power on the main layout will be the popular Tortoise. These are expensive relative to the snap-relay type of motor, but you can get them for $160 per 12 pack at Charleston Digital and the other price leaders, which reduces the pain somewhat. I reached this conclusion after working with the Atlas snap-relay switch machines. Yes, Peco and others make a better snap-relay than Atlas, but the whole concept just isn't as sound, in terms of reliable operation, as the slow-motion switch motor.
   
   Of course, once you accept that you have to use Tortoises for reliability there are a few other benefits that come with them. You get the SPST leads for powering the frog, you solve the problem of how to have the system remember the switch position, and you can use a cheaper decoder for switch control (such as the Digitrax DS44) than with the snap-relays.
   
   On the down side, the Tortoise eats up a lot of space under the layout, and that might be a problem under the upper deck. So, I'll keep looking for an alternative slow motion switch machine. However, the ones I've seen so far are more expensive than the Tortoise.
   
   As I get closer to working on the main layout I'll order some 12 packs of Tortoises and some decoders to go with them. I'll also revisit a past project: modifying the Tortoise so that it can power two switches at once. This cost-saving approach is useful in situations -- for example, a crossover -- where both switches will always change at the same time, so two switch motors aren't necessary.


2. The other big lesson from this week was the benefit of completing a part of the project end-to-end before moving on. In this case, I learned that I could have saved time by filing the switch rails and setting up the switch wiring before I installed each switch. But I didn't learn that until after I had the switches in place and found problems during testing.
   
   So, thinking ahead to how to apply this lesson on the main layout, I've decided to complete the scenic treatment on one section before I go back to laying new track. This is because I expect that once complete I'll learn some things that may change my track laying approach. The section I choose will probably be one that gets the least notice, so that mistakes won't be as obvious. Probably the north side of the peninsula, which not only can't be seen when you enter the room, but is also one of the least visually interesting segments of the layout.

Wiring Standards Part 5: Staging Switch Wiring

Staging uses Atlas code 80 switch machines, which have 3 output wires (red, green, black) of a very small gauge (28? possibly smaller?). The very small gauge is fine given that the machine is designed to accept only a short burst of current when the switch is thrown, and otherwise have no current running.

The wires that come attached to the switch machine are about 12" in length, so require extensions since the distance from switch-to-control panel is at least 3' and usually longer. For the wire extension I am using a "Rainbow" cable from Radio Shack, which is a ribbon of 4 solid 24 gauge wires in colors white, red, black and green. Connections from the ribbon to the switch machine wires are via clear 22-26 gauge butt connectors, also from Radio Shack, with the white wire left in place unused. The butt connectors are reasonably cheap ($2 for a pack of 24, which covers 8 switches) but the rainbow wire is $8 for a 20' roll, so I've got my eye out for alternatives.

Wires are labeled as other wires, with a labeling scheme of number-location, such as "4M" = 4th switch on the Middle tier. Numbering is generally sequential but that is not guaranteed. The wire number is currently the same as the switch number that will be used in operations schematics, but I reserve the possibility of changing the switch number for operations improvements without changing the wire number. Current locations are L (Lower tier), M, and U (Upper tier). The number-alpha format is designed so that switch machine wire labels don't get confused with the alpha-number format of track wires. However such confusion is unlikely anyway given that rainbow strips of wire are visibly very different than the red-and-black twisted pairs for track wire.

Switch wires are run under the subroadbed and bundled together with plastic cable ties to keep them tidy and reduce the possibility of pulling a switch wire out by mistake while reaching for something else.

Switch wires are run to the temporary control panel made up of Atlas switch controls. When the permanent switch control solution is designed some of this wiring may need revision, but at this point I think all that will be required is to disconnect the wires from the Atlas switch controls and connect them to the permanent device.

I'm Me-e-e-l-l-ting

I think I've figured out the Atlas switch machine problem.

As mentioned in the last post, the electric coil in these things gets very hot very fast. Just 3-4 switches in quick succession is enough to make the outside of the plastic case hot to the touch. A few more and the plastic case will start melting inside. Once that happens the plastic pieces that move inside can get jammed causing the machine to fail.

And of course, your natural response to having the switch machine fail is to run the switch a few more times to see what's happening. That's what I did with Switch 4M (middle tier, #4), thus making the machine so hot that the case is now irrecoverably deformed due to melting.

The solution is to have pauses between each time you flip the switch -- ideally of 10- seconds or so. This is NOT a problem for normal operations, but of course it's something you have to tell kids to avoid.

I now have all 5 connected switch machines working nicely, including one replacement. I also now have a solid intuitive understanding of the internals of these, which will probably be helpful down the road sometime. As I connect the rest of the machines I'll be watching closing for the same symptoms -- and if there aren't any I'll consider this problem solved.

Unfortunately, this problem did slow layout progress. I did nothing on the layout on Wednesday or Thursday. Granted, this week was very intense at work, giving me little time for hobbies. However, if my current task had been something mindless like wiring up more track I probably would have done some of that just as a mental break from work. But with the task being the solving of a difficult problem I just avoided tackling it until Friday night.

Oh well, I'll try to get the rest of the machines deployed and the bridge completed this weekend.

Stuck with Atlas switch machines

It's been a busy work week, which has slowed progress somewhat. But the real culprit has been the problematic switch machines.

I have set up a board with 16 switch controls, wired and joined together. That's 116 screws and 10 sections of wire needing insulation removal and joining to terminal screws. Not that I'm counting. I've connected 5 switch controls. That's 45 wire ends requiring removal of insulation, 30 wire ends to be connected into butt splices, 15 wire ends connected to screw terminals, and 10 labels to affix. Not that I'm counting. Only 8 more switches to go until I can return to the bridge and the upper level.

Unfortunately, I've run into some problems along the way. Remember that all of the Atlas switch machines were tested prior to setting on the layout. I'll need to be more careful in my testing next time. 2 of the 5 that I've connected so far don't work correctly. In both cases they consistently switch in one direction but not the other. I've taken apart and tried to diagnose, but haven't solved the problem yet.

In the past I've set problems like this aside and moved on. Usually that's been a mistake. I really should understand the problem and have a good sense of the innerworkings of the machines before I move forward deploying 50+ more of these, because I may find that the best corrective action is something preventative that I can do before deployment.

One really frustrating thing is that these things get so hot so fast. The instructions are clear about never holding the button down for more than a second, and I never do. However, when testing anything I'll typically repeat the operation for several iterations to see how it behaves -- but if you do that with the Atlas switch machine you can literally melt the plastic encasement, as I found with the 4th switch machine I connected.

So, when I get back to the layout tomorrow my sole task will be to figure out what's wrong with these two faultly machines.

Bridge work interrupted

Before laying the bridge track all that I'd planned to do was to vaccuum up the area and hand-clean the lower tracks one more time before putting the bridge back in place. But, once I started to do that I realized there were two projects, one small and one large, that needed completion before I put the bridge in place semi-permanently.

The small project involved putting scotch tape around the wire labels, some of which are already showing signs of non-stickiness. These labels have already proven helpful in tracing wiring for one reason or another, and I don't want them to fall off a year or so from now, forcing me to hand trace the wires to see where they go.

The big project is to connect/automate the remote switch machines. My practice to date has been to switch manually, with the idea of adding remote switching later. However, the upper tier bridge will block hand access to most of the switches underneath, so we'll need to have remote control of those switches now.

I have a vague idea that I'd like all layout switches to be remote controlled from 3 places: a computer, a DCC throttle, and a front panel. This is to provide maximum flexibility of operations. Doing some research it appears this is going to be quite a challenge, for reasons I'll explain in a later post. And expensive. And it's going to take some time to think this through before I'm ready to test out a proposed solution for remote switching.

So, for now I'm going to set up a temporary switch board for the south end of staging -- the north end will be able to follow the manual switching practice as those switches will still be accessible. The temporary switch board solution will combine stuff I'll have to do anyway, such as extending the wires to the switch machines, with stuff that is temporary but doesn't require buying anything I don't already have, such as using the "push button" switch controls that come with the Atlas code 80 switches.

I started this project Sunday. All switch machines were tested before installation, so I didn't expect any problems. So, naturally, I ran into a problem with the first switch machine, then proceeded to destroy it by pulling too hard on the wire while trying to fix the problem. Argh. Oh well, replacement switch machines are cheap and I'll probably need to keep 4 in stock (2 for left switch, 2 for right) as normal practice anyway. For now, I've simply grabbed a replacement machine from another switch.

I'd like to complete this Monday, but there are 12 machines to strip wire, add connectors, run and staple wire, add labels, test, adjust, etc. Maybe I can get a kid to help out with this ....

Design influences

We all have our railroad experiences, model and prototype, that influence our choices of what to model and how. A comprehensive listing of all such experiences would be too huge to list, but there are usually a small number of experiences that stand out among the others in terms of influence. In this post I'll describe my railroad experiences, and show how they explain why I've chosen the modeling themes that I have.

Like most model railroaders, love of trains is in my DNA. Before I could walk I was pulling myself up to look out the window of our apartment in north Chicago to watch El trains. As a toddler I would beg my mother to stay just a bit longer watching the huge Santa Fe exhibit at the Museum of Science and Industry. (I'm told I would stay still for over an hour transfixed at the layout.)

By far my biggest influence was between the ages of 7 and 10 when I lived in La Grange, Illinois, just 2 blocks from the Stone Avenue station on the Burlington route into Chicago. This three-track line is informally known as the "racetrack" for the intensity of railroad traffic that runs on it, which historically included high-speed passenger trains on tight schedules. The 3 years that I lived in LaGrange were especially interesting for railfanning as both the Burlington Northern merger and the founding of Amtrak happened then, increasing the variety of roadnames that ran on the tracks. I spent many hours photographing and drawing the trains I saw.

Then, sadly, my parents divorced. The only positive side effect of that was from a railfan perspective: as a result my sister and I rode the Burlington commuter train once per week to visit my father in Chicago. I loved going through the Cicero freight yard and seeing all the trackside industries along the route. But for me the best part was by far the approach to Union Station: first a trip around an impossibly tight curve, generating very louds squeals of protest from the trucks, then past the coach storage yards and through a seemingly endless field of double slip switches until finally the drama of arriving alongside the platform.

Then, in one of my best childhood memories, my sister and I were invited to ride with the engineer and fireman in the cab car (trains would back into Union Station on the Burlington line -- I suspect they still do today). We continued to ride with them over a period of 3 or 4 weeks. We saw how they performed their jobs and were even allowed to push the buttons to sand the track and blow the horn.

In subsequent years I've seen many railroads but always had a special affection for large Union Stations with complex trackage. I saw a lot of these during my years in Europe, of course, and each one left a lasting memory.

Now, I wasn't actively thinking about my Burlington commuter experience when I designed my current N scale layout. However, in retrospect everything I loved about that experience is a central feature of the present layout. The whole layout takes place in one city and features: a double track BNSF main line -- which was part of the original Burlington according to the fictional layout history; an active commuter Union Station with 8 tracks servicing trains from 4 directions; and an active city freight yard similar in function to what the Cicero yard was back then. There is even one Union Station approach that has a tight radius curve where I hope to duplicate the sound of the squealing wheels as the train slowly approaches the double-slip switches before the platforms.

I'll also note that the theme for my outdoor railway also is linked to personal experiences, but a different set of them. You see, during my teen years my mother and stepfather moved from the Chicago area to the western slope of Colorado, where we spent many weekends visiting ghost towns like Ophir and old mining towns like Silverton. We never rode the Durango tourist line (then the DRGW), but I sure was aware of it. Later, while living in California, I spent a lot of time reading about and visiting the sites of many of the old narrow gauge lines in the Sierras and along the coastal mountains. So, it's not a surprise that my outdoor line is based on an 1880s narrow gauge prototype.

Upper tier bridge (part 3)

The support piers on the other side of the bridge follow the same principle as described in the last post, but were easier to build because the bridge is only one-track wide at this point and the necessary joists are already in place. This photo shows the piers in place with C-clamps, a beam resting on top, and two levels used to verify that this end of the bridge is level with the other end.

It turns out that drill access to those piers was also problematic, and in fact I had to trim the leftmost pier to work around the middle tier subroadbed. I again used wood glue to hold the piers in place, this time snug against the adjacent piers, until the glue dried and I could put in the screws without C-clamps in the way.

In the next photo a quite a bit more has happened, and the bridge is starting to take shape:


In this photo the bridge beam on the right side is in place and the bridge itself has been positioned. Screws (#4, 1/2") have been added to the bridge floor to affix it to the beams. The end of the bridge on the right side has been trimmed to where the 1/2" plywood subroadbed will meet the lauan plywood, and the beam has had a notch cut in for where it will be supporting the 1/2" plywood.

In addition, the bridge "walls" have been attached to the edges of the bridge floor. These walls are 1 1/2" tall -- which is enough to add the lateral strength needed. They are attached with #4 1/2" screws, as was done with the middle tier bridge.

Unfortunately, the leftmost bolt is too close to the edge to allow a washer to be placed on it, now that the wall is in place. Minor oops -- I'll just trim some of the wall to make room.

One change not quite as visible is that the subroadbed for the upper tier entry track (adjacent to the back wall) is in place. I put this in when the bridge was removed. I was holding off on this task only because I wanted to verify that the subroadbed would not be in the way of the bridge.

In this next photo the bridge is ready for track:


The obvious changes from the last photo are that the blue roadbed is in place and the track path has been drawn with a marker -- the 30" radius curve I discussed in the first Upper Bridge post is the path used. Some changes from the previous photo are:

1. The roadbed and track have been laid for the upper tier entry track in the back. I did this now because it will be harder to access that area after the bridge is in place. You may also note that feeder wires are attached. If you look very closely you may also detect the upper tier auto reverse (AR) bus in yellow and blue, which has now been routed along the back of staging, where unfortunately it won't be very accessible after all three tiers are in place. I really hope I never need to get to this later. I did make sure that the places where the feeder wires attach to the bus are accessible.


2. The bridge has been leveled in all directions at all points. Interestingly, when the leveling was done at the nut/bolt/washer support piers I found that the pier tops were not level with each other, although I thought I'd leveled them by eye. It doesn't affect anything, except to show that leveling by eye doesn't cut it.


3. The last few inches on either side of the bridge have been separated from the main bridge by manual saw. These end sections will be permanently affixed to the support beams underneath, while the main bridge will be removable. The reason for doing this was to assure a very level transition from the bridge floor to these end sections.


4. Because the bridge is meant to be removed occasionally, not frequently, the bridge is attached with screws on the beams and of course the nuts on the middle piers. In order to access the screws the blue roadbed has had holes cut where the screws are.

The next post will cover the track placement (and will end the topic of this bridge). My intent is to use sectional track with railjoiners on each side. This will make the operation of replacing the bridge a little more challenging, but should greatly decrease the chance of derailments. Of course, if that approach doesn't work out I can remove and replace the track without changing the rest of the bridge.

Upper tier bridge (part 2)

So, here's the bolt/nut/washer support piers in place:


Construction is pretty straightforward. Use a 1/4" drill bit. It helps, once the bit is through the wood, to hold the drill in place and run it in reverse to clean out the hole. Then run a bolt through by hand a couple times to finish cleaning the hole.

Next, put the bridge floor onto the bolts:


There is a bit of a challenge aligning the drill holes exactly with the bolts. We (Daniel and I) accomplished this by first setting the bridge floor exactly in place, then using a hammer against a block of wood that was placed on the bridge floor directly over the rightmost bolt. The block of wood protected the top side of the bridge floor from dents, but the hammer (only one hit) caused the bolt to put minor indent in the bottom of the bridge floor. This indent was our guide for the 1/4" drill bit. Repeat 4 times, cleaning the hole each time, and voila!

We didn't set the levels of the support washers yet. Instead, I started on the supports for the loop end of the bridge. I cut and measured the pieces then started assembly. First, we need a cross joist. I reused a piece of 1/2" plywood from the first staging attempt. This works except plywood is susceptible to splitting, as this photo shows:


Fortunately, the split is minor so replacement was not needed. Next, I set up the bridge beams on top of the floor to figure out best placement. This is needed to calculate where the support tiers below should be placed:


Next, piers are cut based on the measurements taken in the photo above. Then the task is to get everything to hold together in place before attaching them permanently. This photo below shows the support tiers held in place with C-clamps. The beams are resting on top, unattached, and resting on top of them is a small piece of scrap lauan plywood (not the bridge floor, but the same material). In this photo everything is in an approximate position, prior to measuring and adjusting:


In the next step everything is in place and level in all directions:


Now to fix the support piers in place, starting with the support pier near the middle tier tracks (on the right). This is the standard procedure of drilling pilot holes then 1/4" dry wall screws. Access is difficult, so the drill holes are at an angle but still effective. Alas, there was a slight slippage down on the right side of the pier when I was drilling the right screw hole. Rather than redo it with another drill hole I added a single plastic shim under the right end of the joist, and by raising the joist on that side the pier tops were returned to level:


For the other support pier I found it impossible to position a drill for setting up a pilot hole given the crowded surroundings. However, the rest of the structure was, at this point, very rigid. So, I took the C-clamp off, applied wood glue between the pier and the lower joist, then re-clamped and re-leveled. A few hours later it was strong enough to take the clamp off and drill a pilot hole and a single screw.

The next post will pick up with the support on the other side of the bridge.

Upper tier bridge (part 1)

The upper tier bridge construction has gone well. I ended up using several new (for me) techiques but I think in the end it's worked out.

First, the planning. I held off on coming up with a final design until I could see how the rest of the staging layout turned out. This has the advantages that 1) you can see everything in 3-D when completing the design and 2) you can employ lessons learned while constructing the rest of the layout. But, it has the disadvantage that you may have unintentionally created difficult or impossible constraints while building the rest of the layout. I tried to avoid this by thinking through the likely upper tier bridge designs as I made progress on the other tiers, and by deferring any tasks that might impede the upper tier bridge construction as long as possible. In this instance, the process worked without the disadvantages.

The first step was to build cardboard cutouts of two possible routes for the upper tier bridge track to take, as shown in this photo:

The outer route utilized an 18" radius curve (my staging minimum for curves) and thus allowed for longer straight sections. I thought the longer straight sections might ease construction and also make hand access to the switches easier since it put the bridge back as far as possible from the aisleway. The other route was shorter utilizing a 30" radius curve to connect the two end points. This route was close to the original design and had a few advantages. First, the wider radius curve would tend to help operations: long trains on the upper tier will have to go around the 18" radius loop -- about 5/8 of a circle -- then reverse direction after a 7" straight section. This shouldn't be a problem, but a wider radius further improves the chances of smooth operation. Second, the 30" radius route only crossed one switch directly, although the other switches were behind it so access to them would be slightly impeded.

What to do, what to do? (as Dana Carvey once said on SNL). Neither was an ideal solution, as both would make switch maintenance a problem. And I'm sure switches will need maintenance, even if only once per year (assuming regular track cleaning runs with the track cleaning cars). So, eventually I concluded that no route was acceptable for a fixed position bridge. The only acceptable solution was to make the bridge removable for occasional maintenance. A lot more work up front, yes, but likely to save tons of time and frustration in the long run.

So, now that I have experience using 5.2mm lauan plywood for a bridge (the middle tier bridge), I concluded the most reliable, stable design for this curved bridge is as follows:

1. The bridge would have a triangular form, allowing for straight edges on the sides. Each side would have straight edge, similar to the middle tier bridge, but taller for the additional strength the larger bridge would require.


2. The bridge would extend over the end points to allow it to be fixed in, adding stability. Both endpoints would be supported by level blocks of wood, set on end (similar principle to the spline roadbed mentioned earlier).


3. The center of the bridge would be supported by nuts and washers attached to long bolts that are anchored to the center of the middle tier.


4. I'm not sure yet on how the track connections will be set up to allow for the bridge to be removable -- this is usually the trickest part of removable track due to the lack of rail joiners to keep the rails in line -- but there are a number of methods people have used for this so I'll figure this out later.

The first step in construction was to get another 4x2 section of lauan plywood. I have some sizable scraps left, but none was big enough to cut out the whole bridge in one piece. One 4x2 sheet is just $4.24 after tax -- very reasonable.

Once bought, I put the cardboard cutouts onto the plywood for use in drawing the lines for the bridge floor:


Once cutout the bridge floor is put in place on the layout for sizing and trimming (I intentionally allowed more space than needed along some edges to permit later adjustments):


Fortunately it fit nicely with little adjustment. Next step was to build the nut/bolt/washer supports for the middle of the bridge. These are the materials and tools used:


1/4" coarse thread bolts (12" length) and bulk packages of 1/4" coarse thread nuts and washers. The saw has a blade intended for metal cutting. The two bolts shown on the right side are what is left after the cutting has been complete. The picture should also have included a metal file, which is needed to get rid of the excess metal around where the bolt is cut. Ironically, once filed the cut side of the bolt is easier to fit a nut on than the non-cut side.

Here my 13 year old son, Daniel, is busily assembling the bolt support tiers:




Meanwhile, my 8 year old daughter, Emma, is helping out by cutting insulated rail joiners:


In the next post I'll show the results of what Daniel was assembling.

Why we test

I completed the middle tier track laying & wiring in the area next to staging then, as usual, tested it out. While this part of the project went smoothly there was one problem I found during the test that will probably save me a lot of time later on.

Here is a picture of the layout as of this morning:


What the test uncovered is that some of the #6 code 80 Atlas switches have a tendency to catch the wheel of a car taking the diverging route. The catch is at the end of the diverging closure rail (the inside rail) right where it meets the hinged part of the point rail. This became obvious with the Kato SD90/43MAC, which is fast becoming one of my favorite engines for finding latent track problems. I suspect that the long 3-axle trucks make this engine more susceptible to this type of issue.

There was one switch where it was very noticable, but once I watched for it the others all demonstrated the same problem at least a little bit. At no point did any derailments occur, but this is the sort of bumpy ride that leads to intermittent derailments.

The solutions was simply to file that edge of the rail. I did this on all the switches that are in place, and will include that as part of my switch-preparation routine, adding maybe a minute per switch. I also found, on one switch only, that the plastic frog and the plastic rail that adjoined the closure rail were just a bit too tight in the diverging route, causing a bump. Again, a quick bit of filing down solved this, and I inspected all other switches for this problem.

Otherwise, the track laying and wiring process was uneventful. On a minor note I found that a staple used to hold a pair of wires in place went in too hard and cut the insulation on both wires, causing a short. Easy repair with electric tape and a new staple. But that staple was located in an awkward spot and I must have had the gun lean too hard into the wood. I will take care to avoid this from now on.

Next task: The 3rd tier bridge. I'm in the measuring and planning process now and have decided to make it removable, which adds complexity up front but is probably essential for long term maintenance of the track underneath.

Wiring standards part 4: Auto Reverse and gapping

I was going to start this post with a description of Auto Reverse (AR) sections -- what they are and how they work. Then it occurred to me that someone else probably already had done that and, sure enough, you can find such a description at Wiring for DCC.

My layout will have 6 standard AR sections, 5 for the return track in each of the staging areas, and one for the wye at Union Station. There will also be one crossing with live frogs on the upper deck, and that requires a special application of an AR device. I'll address that topic in a later post, probably not until upper deck construction is underway.

Before getting to the wiring standards, there are a couple of AR section design standards to mention. First, all of the 6 standard AR sections will consist only of a single track, no switches or crossings. This not only simplifies installation, it also greatly reduces the possibility of accidentally triggering the AR device through electrical shorts (more on that later in this post). Second, standard AR sections will be at least one train length long -- some possibly fitting two or even three shorter trains in a pinch. In general you want AR sections to be at least as long as your longest train. This is pretty obvious if you think of every car as potentially carrying electrical current in the wheels. It's true most freight cars have plastic wheels, but many have metal wheels, and all it takes is one wheel to bridge an insulating gap and cause a short.

The AR wiring standards will be:

1. Each standard AR section gets its own power bus. Terminals won't be needed, instead feeders will be connected directly to the bus.


2. AR devices will reside in the power cabinet, making them easy to track with the other power devices and easy to debug problems.


3. The AR bus wires will be colored blue and yellow to distinguish them from the other layout wires. It doesn't matter which rail gets which color, so by convention I make the rail that is closest to the nearest wall for most of the AR section yellow. No reason, just because.


4. The wire for each AR bus is 16 gauge stranded. 14 gauge would be overkill because a) the length of the AR buses top out at 20' and b) the amperage draw will be much smaller than for the power district buses. 16 gauge stranded wire is available reasonably cheaply at Home Depot in multiple colors. The blue/yellow bus wires will be twisted to keep them together. They are labeled with "AR" and the name of each section, such as "AR-Upper Tier".


5. AR feeder wires are 22 gauge like the other feeder wires, are black, and like the other feeders are soldered to every other rail joint. Each feeder is directly connected to the appropriate AR bus wire. This is done by stripping a 1/2" off the bus wire insulation and the end of the feeder wire insulation, wrapping the exposed feeder wire around the bus wire, soldering, covering with electrical tape and then scotch tape, as electrical tape doesn't stick well. The electrical tape isn't really needed except that it might prevent oddball shorts in strange situations.

The photo below shows part of an AR section with the associated wiring:



The track nearest the camera is the return track for the lower tier. Below the track you can see the twisted blue/yellow AR bus wires, and at the left you can see an attached label with the name "AR - Lower Tier". On the right you can see two black feeder wires connecting the rails to the bus. You'll note that there is electrical tape around the connections, and scotch tape on top of that.

Part of the AR wiring standards remain undecided. First, I'm not sure what AR device I'll use. I have one Digitrax AR-1 on the layout now, which provides a simple AR function for one AR section, and it works like a champ. There are a few complaints about this on the internet forums, but mine has worked perfectly out of the box without need for adjustment. It may be that most of those who have trouble are using larger scales, or older locomotives. N scale may help in that I'm using lower voltage (the Digitrax DCS100 command station has an N scale setting) than HO, or that N scale locomotives draw less current.

On the other hand, I might have just been lucky with my one AR-1. But, I am currently leaning toward sticking with the AR-1 until/unless troubles arise. However, I hear good things about DCC Specialties' PSX, which replaced the similar Tony's Trains products, so they may be worth the small extra outlay in costs.

One product I recommend *not* using for auto reversing is Digitrax' PM42. I bought this because it was advertised as a low cost way to have 4 AR sections. That is technically true -- if you have a separate 12-18V AC power supply lying around doing nothing. And if you have a DT300 or DT400 command throttle to program it. And on top of that you'll need to do a nest of soldered wiring for the inputs and outputs. But the final kicker was that after I'd spent a couple of hours soldering everything and getting it all in place I found out that one of the 4 sections was faulty. ARGH. Yes, Digitrax support is excellent and they would quickly replace it, but that would have meant unsoldering everything, filing a support ticket, printing it out, and going to the post office to mail it. I've decided to accept the bad section and let the other 3 get used for power management.

The other pending decision is whether to connect the AR sections directly to the power booster or route it though a power district, and if so which one (maybe put all ARs in one power district). Logically you'd probably want ARs under a power district so that they don't short the whole layout. Except that there are frequent discussions on the forums about conflicts between an AR device and a PM circuit breaker. Fortunately, as all these devices will be in the same cabinet I can defer the decision, and once made it can be changed easily.

Finally, AR sections, like power districts and "live" switch frogs, require insulated gaps. You can either cut a gap in a rail and optionally fill it in or you can use an insulated rail joiner. I prefer the latter, and as a standard use the Peco insulated joiner even for Atlas track. It's smaller, hence less obtrusive, but it does a much better job of holding the rail in place. It can be disguised well as part of track scenicing. A situation may come up where the rail joiner is not practical, such as where the joint is on a tight curve, but until then insulated joiners are the standard.

Track cleaning car revived

Got the CMX Track Cleaning car working again.

"Track Cleaning" is another one of those internet forum debate topics. Everyone has to do it, there are lots of products and solutions out there, and there are a few people who post extraordinary claims such as "I just put a drop of flubber oil on the track once every 10 years and never worry about dirty track again". But the reality seems to be that there is no perfect solution, so you keep trying stuff until you find what works for you.

I won't go over every thing I've tried, however in the end I've always returned to cleaning by hand with rubbing alcohol and a paper towel. Alas, that doesn't work for out of reach track, and it's also a slow process. Furthermore, experience is that it's easier to keep clean track clean proactively than to reactively address dirty track. So I figured that it is best if I start a regular habit of automated track cleaning for this new staging area now, before it gets dirty. And that means finding a cleaning car that works.

The CMX solution looks pretty good, actually, and it seemed to work well today. I bought this car a couple years ago, but ran into a problem. The CMX has some very detailed instructions. One thing they talk about is using either very strong solvents which are good for very dirty track, but dangerous, or milder solvents which are good if the track is already pretty clean. The list of mild solvents included Fantastik and Formula 409. Well, as far as I can tell whatever 409 they were thinking of was a different 409 than the one I got -- which is possible since manufacturers often use the same product name for lots of similar things. In any event, I simply used the wrong solvent. Too sudsy, it got gunk on everything. The CMX car was a mess and the track needed manual cleaning.

So, I set the CMX aside and tried the Atlas cleaning car I got at the same time. I, alas, opened it to find it was for DC only. But, I found someone on the internet who was selling imported DCC board decoders for the car. I bought one, but it didn't work. Possibly because the instructions were a Google Japanese translation. At that point I gave up, picked up the paper towels and rubbing alcohol again, and put the two cleaning cars in boxes that went into my "project stack".

Today I opened the CMX project box, used water, an old toothbrush, and a scrubbing pad to clean everything off. Put all the pieces back together and tested that the car ran okay. Then re-read the instructions and used 70% rubbing alcohol (hey, it's not strong but it is a solvent I know and trust). I fiddled with the valve to get the drip rate correct and ran it around the track a few times. The only thing is I don't really know how well that solvent cleans -- but if I find dirt accumulating I'll use something stronger.

Oh, and my Kato F7 had trouble pulling the car. The CMX car is heavy and of course has a lot of drag on the track. The 6-axle SD90/43MAC did much better. It's worth noting that the CMX instructions (which are really written for their HO version) mention that with dirty track you may need two engines to push the cleaning car.

Mid tier bridge complete

The mid tier bridge is now in place, track is down and wired, and testing was completed this morning, as shown in this photo:


The SD90/43MAC engine being tested in this photo has not been converted to DCC yet (a little more than half of my 50+ locos have had decoders installed). The power back being used for testing on the right is a DC power pack. I bought 2 of these packs for about $25 each in 2002 when I first got into N scale and thought I'd try DC cab control.

Now I use DCC on the layout, but the DC power packs are still useful. Being modern packs they function a lot better than the old DC power packs I'd been hauling around previously (and have since given away). In addition, you want at least one DC power pack to test new locomotives before installing a DCC decoder. And the other power pack is useful for powering accessories like lighting or switch motors/machines, unless you want to control switches with DCC.

The yellow and green wires you see running from the power pack to the track are alligator clip wires that you can get in a bundle at an electronics store. These are, IMHO, pretty much a must-have for model railroader as they are so darn useful.

Finally, some discussion about the middle tier bridge. This is a useful bridge technique if you have the need to span a long distance with minimal clearance over the level below. This is, of course, appropriate only in an off-layout area where you aren't trying to model a real bridge. The base of the bridge is thin lauan plywood that is strong enough to hold comfortably the weight of the heaviest train, and has good properties with regard to gluing and retaining screws. The width should be enough for the train and some space on either side for finger access. Too wide, however, may cause the floor to bow inwards. The sides can be made out of any stiff material that attaches easily to the floor -- typically the floor material can be used for the sides, as I've done. the sides should be cut so that the bottom will be a straight edge, because that will define the roadbed level for the bridge. The top-to-bottom width of the sides needs to be sufficient to provide enough strength to hold the trains and prevent sagging.

Support for the bridge comes primarily from the plywood at either end of the bridge. To keep the surface level a notch is cut in the 1/2" plywood so that the last inch or so of the bridge floor rests on the plywood. You can see the notch area in the picture below. In order to fix the bridge in place I first verified all was level (two thin plastic shims helped here) then used Elmer's Wood Glue, which creates a very strong bond with two pieces of wood.

This photo shows the underside of the bridge and the notch area where the right side of the bridge will rest:


When constructing the bridge I was anticipating having to use the wood glue to attach the sides to the floor, but it turned out that the wood held #4 1/2" screws very well -- these are the smallest wood screws you can get in bulk at my Home Depot.

The only real challenge was holding the side and floor in place for the drill hole and the screw. For that I found these very useful:



A small table vise, and an example of the large and small C-Clamps I use. I don't suggest these are the best available. Rather, they are what I've acquired over the years. The red-handled clamps were bought to assist with my German layout almost two decades ago. If I were buying new now I'd go to Micro-Mark, where they have a lot of very slick looking clamp and vise tools.

The next step will be to revive the CMX Track Cleaning car. At each stage so far I've cleaned tracks using the tried-and-true method of isopropyl alcohol (70%) and a paper towel, with a Bright Boy eraser only to get rid of stuff like glue drops. Once clean though, the best thing to do is to keep it clean with regular runs with a track cleaning car. So, I'm going to start that process now before the staging loops get dirty again.

Lower tier section complete

Minor milestone reached. As the picture below shows, the trackwork for the lower tier of the current section of staging is complete:


All the track shown has been wired and tested with a variety of locomotives (SD90MAC Kato, 2-8-0 Athearn, F3 Kato, SW1200 MicroTrains) that have proven in the past to be particularly sensitive to track problems. Of course, all testing has been with DC -- I should run some DCC over the switches to verify there are no shorts, but I don't expect any as these switches did not have shorting problems with the previous staging setup -- other problems, yes, but not shorting.

(Aside: DCC runs at a consistently higher voltage and amperage than DC, so DCC has built-in, fast-acting circuit breakers to protect the DCC and locomotive equipment in the case of shorts. One side effect of this is that momentary shorts which occur on switches aren't noticed on DC systems but can shut down a DCC system. This is why some more newly-designed switches have been labeled "DCC friendly", meaning less susceptible to shorting. For whatever reason I haven't experienced this problem running DCC on my layout.)

Two notes about the above construction:

1. The ideal order of construction on the staging area is upper tier (farthest from layout edge), middle tier, then lower tier. I will be following that order after I get past this section. However, at this juncture I should get the track down and tested on one tier before I construct the tier above it due to the planned bridges. Once a bridge is in place it will make access to the area underneath more difficult.
   
2. The biggest concern of mine vis-a-vis reliable operation in the staging area is the Atlas code 80 #6 switches. By using #6 switches, instead of the smaller and more standard #4s, the likelihood of reliable operation should go up because the switch curves are less sharp and abrupt, thus less stress is placed on the moving trains.
   
   Even so, on the first staging attempt I experienced fairly frequent derailments with these switches. By luck, I recently bought a stack of 1980s Model Railroader issues very cheap from the back of an antique store and discovered an article from 1985 on making your Atlas N scale switches bulletproof. The article was about the #4 switches (for all I know they didn't have #6 switches then), but I followed it closely and got many good pointers. One thing I learned is that Atlas has improved their switches many times over the years. A number of problems the author mentioned in design aren't present anymore. Still, he provided a good methodology for testing both the switches and the switch machines, and some instructions for improving reliablity. These boiled down mostly to filing the tips of the points and of the frog if the switches showed signs of catching the wheels. This was a useful article and I now run every new switch through this standard set of tests and adjustments before putting it on the layout.
   
   Yet, the article didn't address the two biggest concerns I had going in. The first, from what I could diagnose from the first staging attempt, was that the top of the rails were uneven when the switches were connected in a ladder. This is apparently because when I glued the switches to the roadbed I used pins to hold them down, as I normally did for all track back then. But the switches have smaller pin holes in the ties than the flex track does, so this caused the pins to push the ends of the switches down harder into the roadbed while leaving center of the switches not so deep in the roadbed -- in effect causing the switches, when viewed from the side, to to have a convex shape. Put them next to each other and the rails went down-up-down-joint-down-up-down-repeat, and no wonder derailments were common as model trains don't do vertical curves well. This time around I'm still gluing the switches on the roadbed (of course being careful not to glue the area near the moving points and throwbar) but using flat weights to hold the whole switch in place, not pins. So far this has successfully kept the rails level from switch to switch and, at least up until now, elminated the derailments.
   
   There is one other problem that concerns me, although it's not yet caused operational issues that I can detect. The straight rails on the switch aren't really straight, but instead tend to bow slightly in the direction opposite the diverging route. This is so slight that it won't be a problem for an isolated switch, as the adjoining flex track can make up for the slight curve. However, in a switch ladder this causes the train to go through a slight left-to-right movement while going down the straight tracks on the ladder. So far this is just something to watch, but I do wish Atlas would fix their #6 switch manufacturing to correct this curve. Alas, I bought all the code 80 switches I thought I'd need for this layout a couple years ago, so even if Atlas does correct it I'm stuck with what I have.

My final comment is that these posts are now almost current with the state of the railroad construction. The above picture is from yesterday. I did get a little bit done on on the layout today, and I hope to post on that tomorrow.

Wiring standards part 3: feeder wires and track

In the last wiring post I covered the power bus terminals and feeders leading from the terminals. Now I'll cover the standards for connecting feeders to the track.

The first question is: how many feeder wires do you need per length of track? When you buy a starter train set with an oval of track you get one pair of feeders for the whole oval. But if you try to do that with a larger layout you'll probably run into trouble for two reasons:

1. Voltage drop, as mentioned before. The resistance of nickle silver rail is much greater than that of copper wire, so over a short distance of rail the voltage will drop enough to slow your trains.
2. Rail joiner problems. Rail joiners are designed to hold two rails in place and to pass electricity between the rails. However, over time some joiners will loosen or get dirty and eventually provide an imperfect connection. This will lead to even greater resistance (see point 1) or loss of connectivity altogether.

Now, this doesn't mean that every layout without power buses experiences rail joiner problems or large voltage drops. There are real life examples of layouts with long stretches of track where power is passed only by rail joiner and things seem to work well. However, in my experience every layout that relies on rail joiners for electrical connections has evenually experienced power drops. And this is why the power bus method is so widely recommended.

So, you may ask, we need to add feeders to the rails every few feet, but exactly how many feet apart? This is a matter of frequent debate on the model railroading internet forums. At one extreme are those who argue that rail joiners can never be trusted and thus each rail must get its own feeder. Not quite as extreme are those who argue feeders should be 3' apart, but don't require a feeder per rail in instances (like switch ladders) where many separate rails are used in a 3' span. At the other extreme are those who argue that spans of 10' or more are okay between feeders.

After reading what everyone said and thinking about my own experiences I tend to agree with those who don't see rail joiners as a long-term solution to connectivity, but I also don't see it necessary to space feeders every 3'. So, I decided to connect the feeders at every other rail joint. That is, feeders are attached at the rail joint, so every rail has a feeder, but there is only one feeder per two rails. This saves time and resources.

Alas, no solution is without controversy. By soldering the wire to the rail joint I am also soldering the rail joints, which is another big debate topic on the forums. Some argue that joint soldering causes problems because the metal rails will expand and contract with temperature changes. Soldering inhibits expansion, thus on hot days the rails will eventually bend out of gauge somewhere as a result. Others respond that they've never had this problem despite soldering their rail joints, and I'm in that camp. I solder all curved flex track joints and half of the straight ones, and in 2.5 years I've had no problems. I suspect there are as many as three reasons I've been so lucky:

1. The temperature variation in my room is not extreme -- from 60F to 85F at the limits. Even on our hottest days the room doesn't exceed 85F, and if it ever does there is a room A/C that is available, albeit almost never used. I suspect people who see problems often see greater temperature swings.
2. This is a very dry area, without great swings in humidity. Humidity doesn't affect the metal rails, but it can affect the roadbed and subroadbed depending on the material used. I have heard from many sources that Homasote -- a popular roadbed especially amongst those who hand-lay track -- is especially susceptible to contraction/expansion with humidity changes. It may be that the expansion/contraction problems some people are seeing have more to do with the roadbed than the track.
3. N scale may be less susceptible than HO and larger scales. I'm not married to this idea, as the rail sizes between the two gauges aren't that far apart (my code 80 in staging is not that different than code 83, which is the most common for large HO layouts). On the other hand, the track width for N is just over half of HO, and that might make a difference. However, for whatever reason I've noticed that it's rare for an N-scaler on an internet forum to complain about soldered joints causing track bendage due to expansion.

So, to make a short story long, I connect feeders to every other rail joint. Here's an example from the current staging construction:


As I keep mentioning, in staging looks don't matter. In fact, I personally like to have all the behind-the-scenes construction and wiring details visually evident in staging because visitors often find that stuff just as interesting as they find the sceniced portion of the layout. So, in staging I solder the feeder wires to the outside of the rail joint, thus avoiding potential problems with the wheel flanges hitting the wire on the inside of the rail. I'll describe the detailed procedures for soldering wire to rail, both for staging and the main layout, in more detail in a future post.

So, this post concludes the standards used on this layout to get power to the track under most circumstances. There are, however, a couple of exceptions yet to discuss. One is auto-reverse sections, and the other is track wiring for switches with "live" frogs. My next wiring post will cover auto reverse. I'll hold off on the discussion of switches with "live" frogs until I get back to construction on the main layout, as this doesn't apply to the Atlas code 80 switches used in staging.

Some adjustments and problem solving

Construction doesn't always go exactly as planned, especially when you are trying new techniques. This picture shows two adjustments that I had to make to solve of the problems I've encountered so far:



On the right side of the photo you see a red-handled C-Clamp in place. It's holding that section of plywood in place while the Elmer's Wood Glue dries. You see, I mismeasured the curve angle when I cut that subroadbed, and although I re-checked it, I thought I'd left enough extra width as a precaution so I didn't check to closely. Fortunately, the open space next to the subroad bed is unoccupied so the fix is as easy as adding a small bit of plywood. Because I want the two pieces of plywood to be the same level, and because of the difficulties with using screws to attach a narrow piece of plywood into the side of another piece of plywood, a strong wood glue is the preferred solution.

In the center of the photo is a bit more challenging of a problem. A short length, about 15" of curved 1/2" plywood has been put in place to serve as subroadbed for the middle tier return track. The wood had to be this short because the subroadbed on either side of it is 5.2mm lauan in due to clearance requirements underneath. Alas, the short length means only two support piers are available, and two is simply not enough to force the plywood into a level shape. I've found you need at least 3 piers, no greater than 12" apart.

So, the subroadbed was bowed up on both ends. The solution was to find a piece of 1 1/2" wide plywood with one very straight edge (I had some left over from the first staging effort), and attach it to the under side lengthwise against that straight edge. It's a slightly delicate operation as this type of wood is prone to splitting. I used 5/8" #6 screws, pilot holes, and of course C-clamps to line everything up. The end result, though, is indeed level and even.

One can avoid such problems with a subroadbed technique known as Spline Roadbed, an example of which is at the link. It requires extra effort in construction but done right it assures very even surfaces. Advocates also point out that it can be used to create natural spiral easements (transitions from straight a.k.a. tangent track to curved track).

However, in addition to the extra time and cost involved with creating spline subroadbed, most spline methods require extra vertical clearance (however, the specific spline method shown at the link above definitely minimizes this disadvantage).

For now I seem to be able to create level plywood subroadbed through careful construction, and in terms of spiral easements I use another technique that gets good results (to be described later). However, spline roadbed is a good method to be aware of, and I may decide to apply it to some situations later in the layout.

Roadbed, track, wire and switches(!) in main staging

Steady progress. Much of the reason the staging loops went so slow was that there was a lot of repetition:

1. Measure/test latest construction
2. Move staging loop section to side desk, make adjustment (or redo construction)
3. Move back to corner desk, measure and test again.
4. Repeat 2.
5. Repeat 3.

Plus I really had to get the staging loops right the first time because once locked in place they will be very hard to modify.

Now I'm able to do stuff right on the benchwork, and to do large sections at once. Below are two photos, this first one is from January 26 (two days after the previous layout photo):

The above photos shows the subroadbed for the lower two tiers is in place (after measuring and adjusting to make sure it was level), the lower level roadbed is in place, track has been laid for the lower tier return track (nearest to the layout edge) and guidlines have been drawn for the other track.

This photo was taken 5 days later on January 31:

Now, I'll admit that at first glance it doesn't look like much has changed. But look more closely and you'll see that many tasks were completed:

1. The most obvious is in the center of the photo, where switches and track have been laid for the lower tier, and at the time of the photo more track was being glued down. I prefer to weigh the track down during gluing, instead of pining it down, except where curvature requires pins. This is because pins have a tendency to cause the track to be unlevel when they are pushed in too far, especially near short track pieces like switches and rerailers.
2. Blue roadbed has been put in place on the middle tier. You can't see it from here, but this required some adjustments in the area of transition from the lauan plywood loop to the 1/2" plywood to make sure all was level.
3. The support piers for the upper level entry track, near the wall, are now all in place. I waited to do this until I had the mid level subroadbed set in place, because I wanted to verify everything would fit before adding the rest of the piers.
4. The power bus and two terminals are in place. There is one terminal in the lower left of the photo. The other is attached to the joist near where the lower level roadbed splits to form the loop. There are also two feeder wires in place (K1 and K2) and lower level track that is set in place has been tested.
5. The blue/yellow pair of Auto Reverse (AR) wires is now attached along the front edge of the layout, and extends all the way to where the power cabinet will be (not in photo). This is for the lower tier return track AR section.

So, of course you know what happened the first time I tested an engine on the lower level track -- I found a problem on the lower level staging loop.

The AR blue/yellow wire is 16 gauge, as I'll describe in an upcoming wiring post. On the loop I chose to attach it directly to the rail as a measure of simplicity, but I probably should have transitioned to 22 gauge wire just in case. It turns out that on the wire connection for the outside rail of the lower tier the wire sticks up just enough to cause the snowplow of a Kato SD90MAC (the longest diesel actively in service on railroads today) to bump the wire and get stuck. Now, of course I tested this when I first built it, but I used a Kato SD70MAC (just slightly shorter) as well as a variety of other locomotive. Turns out that the slight difference in size is just enough.

I'm debating what to do. You see, it only affects this one locomotive type (I've retested with all the others), and only when the locomotive is facing forward going in one direction -- the opposite of the direction of this one-way track. I will fix it, as it bugs me. But I have time to think it through first, as this wire connection is -- and I know Murphy is laughing -- in the exact worst place for maintenance access on the staging loop.

Wiring standards part 2: Terminals and Feeders

The first wiring post covered power cabinets, power districts, and power buses. Now that we've got power to the underside of the layout in the form of the bus, we now need to get it from the bus to the track. The wires that connect the track to the bus are called feeder wires or just feeders.

Later in this post I'll discuss the standards I use for attaching feeder wires to the track, but the first question I want to address is how to attach the feeders to the power bus. There are two basic approaches:

1. Directly connect each feeder wire to the bus wire of the same color (i.e. same polarity). This makes sense for layout areas where track is sparce, such as a single track main line on a shelf. In such cases there aren't a lot of feeder wires so a short, direct feeder connection is best.



2. Connect all local feeder wires to a terminal that is attached to the power bus. This makes sense where track density is high. The staging area on this layout is an example of just about as much track as you can squeeze into a given area. In this case you simplify the wiring by connecting feeders to several central terminals.

There are other published wiring methods, but these appear to be the most commonly used. On this layout I use the terminal method predominantly, and the direct connect method in places where track is sparce.

An example of a terminal used on this layout is shown in the photo below. This picture illustrates the various wiring standards in practice:



There are many things to note in this photo. First, the terminal strip itself is an 8-slot barrier strip that I buy at Radio Shack for about $3 each -- cheaper than I've seen elsewhere. I don't say this is the best choice for this application, but it's the best I've found available and the price is good.

Second, note the power bus. This is the pair of 14 gauge wires near the top of the photo, one red and one black, that each weave through 4 of the slots on the terminal strip. It's a bit of work to strip that much 14 gauge wire and snake it through 4 terminals, which is the one drawback of this method. If you use this method be sure to use solid, not stranded wire for the power bus as it's much harder to do the same thing with stranded wire.

Note also that on the left of the terminal strip you'll see a label on the power bus wires -- "PD-1". This means "power district 1", per the standards discussed in the first wiring post.

Third, under the terminal you can see a label "1-J". This means power district 1, terminal J. By convention, terminals on a power district are named A, B, C, etc., with A being closest to the power source, B next closest, and so on. This convention is not a guarantee, as future layout revisions may result in, for example, a new terminal "P" inserted between terminals "C" and "D".
Fourth, you'll see smaller red and black wires connected to the wiring screws on the bottom side of the terminal. These are feeder wires. In general the feeder wires are on the side of the terminal that is most accessible given the location of the terminal.

Feeder wire conventions are as follows:

1. Wire is 22 gauge, red for attaching to the red power bus, black for black. 22 gauge is large enough to carry the power the short distance to the track, and small enough to easily work with when attaching to a rail. I prefer solid wire but I use stranded when solid is not available. I avoid buying "hobby" wire because it is incredibly expensive, instead buying the large spools from Radio Shack. Unfortunately you can't specify color when you order, and it is important to have an equal amount of each color, so instead of ordering in advance I just pick up a few extra spools when they have some in stock.


2. Feeder wire pairs are twisted in order to keep them together for easy tracking (feeder wire distances are so short that you don't have to worry about impedance).


3. The twisted pairs are stapled to the layout wood to hold them in place with a T20 (narrow) or T50 (wide) stapler, depending on the specific situation. I am careful to use long staples (1/2" or more) to avoid the staple damaging the wire itself.
   
4. Each wire pair has a name. For example, 1-J-3 means power district 1, terminal J, wire pair #3. The track location to which a feeder wire pair is attached is noted on a Visio diagram along with the name of the wire pair. (I'll post a sample of the Visio diagrams sometime in the future.)


5. Wire pairs are labeled with their name, usually dropping the power district as that is obvious by the location of the wire. So a typical label might be "J3". There should be at least two labels per wire -- one near the terminal and one near the track.


6. By convention, feeder wires are attached to one of the 4 terminal screws for their wire color according to the following pattern: From left to right, wire 1 goes to the leftmost screw, wire 2 to the next, 3, 4, then wire 5 back to the left most and so on.


7. I try to keep to a limit of 12 feeder pairs per terminal, which equals 3 feeder wires per terminal screw. If more are needed then another terminal should be added. This means that the screws, from left to right, would have the following wire numbers: 1-5-9; 2-6-10; 3-7-11; 4-8-12.

The next wiring post will discuss attaching feeders to track.