Track Repair and Turntable Polarity Test

In my excitement after securing the turntable motor last night, I turned the module over and knocked it against my knee (I tend to work on the floor). Normally that wouldn’t have been an issue, except my knee struck the excess rail that extends beyond the module surface, where the fascia will eventually lengthen the module a bit.

That made for a big mess. The rails popped right off the ties and bent upward, severing forty or fifty plastic “rail spikes.” There was nothing I could do except replace that length of track. Here’s the damage:

So tonight I pulled out the soldering iron and desoldered the feeders. Then I pulled the track up to the first turnout and laid a new length of Flex-Track in its place. After gluing it down, putting some weights on, and soldering the feeders on, it looks like new.

After that repair I needed to do something a little more exciting, so I temporarily wired the turntable up.

I was afraid the locomotives would get hung up on the gap between the approach track and the turntable deck rails, and I was also afraid that the polarity of the tracks wouldn’t switch when rotating the deck.

For those who are unfamiliar with Peco’s turntable, I may need to explain this “polarity” piece a bit. The reason I opted for Peco’s turntable instead of another plug-and-play turntable is because it has a genius system for switching the polarity of the rails whenever the deck makes a full rotation.

This system depends on two separate brass collars beneath the turntable deck. Two spring-loaded brass plungers move across the collars when the deck rotates. Each plunger conducts electricity up to one of the two rails, and after both rails pass over the gaps between the collars, the polarity reverses (i.e. the positive rail passes over the negative collar and vice-versa). If this didn’t occur the layout would short out every time the deck made a full rotation.

Another benefit of the polarity changing is that a locomotive moving forward onto the deck can be turned 360 degrees and continue to move forward off the deck. It doesn’t matter that it just came from that direction; with the reverse in polarity, the locomotive still registers as moving forward.

Good news all around: the locomotives can get on and off the deck with no extra effort, and the polarity changes as it ought to.

Here’s a video of the turntable in action. Pretty soon, my hands won’t be needed except to push a button on the DCC controller. Next up, I hope to begin working on the software and hardware that will allow me to do just that. On that note, my brother-in-law sent me some documents and instructions earlier today, so I have some reading to do.

Turntable IV

Well, it isn’t pretty, but after a whole lot of head-scratching and futzing, I now have the stepper motor attached to the turntable, and am able to rotate the turntable deck with minimal friction.

As you can see here, the biggest initial obstacle was the mass of wires and switch motors. To clear them, I had to extend the mounting beam a foot longer than expected. Once in place, I drilled the hole for the motor, then sanded it out a bit.

Yep, pretty much like that. At this stage I could tell there would be some friction issues to deal with between the deck and the well. Both components are plastic, and the slightest lean in the pivot mechanism sends one side of the deck screeching to a halt against the wall or floor of the well. I sanded some of the well, then I filed down the underside of the deck ends. That helped a little, but I could tell I’d need to place some shims under one end of the mounting beam.

Before I got into fine-tuning, I wanted to make sure everything was situated and solid. I attached the motor to the mounting beam with a couple of machine screws.

I then used CA glue to fix the iron axle inside the deck. Now the deck can be dropped in and pulled out at will by loosening or tightening two small inset hex bolts on the shaft coupler.

After putting a couple of shims between the baseboard and the mounting beam (to reduce a lean which caused one side of the deck to dip down while the other lifted), the deck could be moved slowly and without much friction.

Turntable III


Remember last year when I asked Peco about the DCC turntable motor that was slated for release in 2016, and they told me it would be released later in 2017? Well, it wasn’t released in 2017. When I asked them about it more recently they told me they were having some technical difficulties with the indexing, but assured me that it was slated for release in 2018. They thanked me for my patience.

I do have patience, but I’ve come to realize that I don’t have much faith in Peco’s ability to manufacture a motor that will work well. Judging by the prototype, there will be modifications necessary to mount the motor directly to the underside of the turntable. Also, the motor probably has a gearbox, which probably has plastic gears, and that means it will not be very accurate (especially an earlier model, while the kinks are being worked out).

So, I reached out to my brother-in-law and told him what I needed to do, and asked him to guide me through the hardware and software setup of an Arduino-based, DCC-interfaced turntable motor. He knows far more than I do about circuitry and programming–it’s what he does for a living.

After a few days he gave me a shopping list:

  • Arduino Uno
  • Adafruit Motor Shield
  • Iowa Scaled Engineering DCC Shield

To power the Arduino, I sourced a power cable from the electronic graveyard at my office. The motor shield stacks right on the Arduino and drives the motor via jumper wires. The DCC shield (which is slated to arrive next week) will translate commands from the DCC controller to the Arduino, which will then tell the motor shield what to do.

I got the Arduino and motor shield today:

As you can see, I also got a stepper motor, a 4mm to 5mm flexible motor shaft coupler, and a 4mm steel rod.

Figuring out a mounting system for these mechanical components will be my primary goal for the next few days while I wait for further guidance from my brother-in-law. The mechanism may look something like this:


So, although it doesn’t seem like it, there’s quite a bit of activity happening underneath LSR, and if all goes as planned, I will have an indexed, programmable turntable soon.

Turnouts V

Yes. I finally finished installing all six SMAIL switch machines and remote mechanisms. One was a little fidgety, so I had to reposition the mechanism a bit to increase the “push” of the cable, but after fifteen minutes of honing the tension it works as well as the rest.

I tried taking pictures of the process (again) but after the first three steps or so they become so intensive that I cannot spare a hand. Sorry about that.

Here’s all six machines:

I played around with the layout for an hour and a half tonight; it’s already tons of fun, and I’m not even switching wagons yet. Once the turntable is active, this module will provide many hours of enjoyment.

Here’s a video of the 0-6-0 Bellwether moving over all turnouts.

Turnouts IV

I finally got around to installing two more SMAIL machines. Once again, I have no documentation of the process; I think I’d need someone taking photos as I go because the work is too fidgety to be dealing with a camera. But here’s the finished product, anyway:

What a mess, right? See, if I had any track-wiring experience, I’d have used about half as many feeders, but I’d have made them four times as long, and I’d only have installed a single set of bus wires down the center of the layout. That would have given me more space to work with, and all that crowding that you see would have been spread out.

Because some of my feeders are immediately beneath the turnouts, there wasn’t enough room to have the switch machines swing a certain way, so I had to turn them around and run the cables in a long arc to the SMAIL motors. In the image above, only the uppermost turnout has a straight cable.

All of the turnouts work perfectly, although I will probably use some electrical staples to help keep them in place.

Turnouts III

On LSR, there are a lot of steps and pieces involved in throwing a single switch!

First I bent six piano wires like so:

Then I cut six lengths of brass tubing like so:

I drilled a 1/16″ hole two ties away from each throw bar, like so:

And then I inserted a length of brass tubing into each hole until it was level with the tops of the ties:

And a bit of fussing on the underside. The feeder wires almost thwarted three or four switches, because they are so close. Almost.

With a pair of pliers, a pencil, and some wizardry, I bent each piano wire again after measuring each turnout from the hole in the throw bar to the center of the brass tube.

Then I inserted the piano wire so the long end extended through the brass tube to the bottom of the layout, and the short end was dropped into the hole in the throw bar:

After checking to make sure that each turnout moved freely, I flipped the module and bent each length of wire at a right angle:

Toggling this wire back and forth from under the layout throws the switch. The remote mounts will be affixed to these wires, and the SMAILs will be attached by wire and tubing.

I think I’m at the halfway point now with the turnouts. For fun, I connected a SMAIL to the terminal block and programmed it into the PowerCab. It moves exactly as I expected. Hopefully by the end of this coming weekend, I will be able to switch my turnouts by pressing a few buttons.

Wiring IV and First Run

I finished wiring all of the track except for the turntable. There are a few things I would do differently next time, but overall I am pleased with how it looks and functions, and it seems pretty bulletproof.

On the topside, my turnouts are still without the SMAIL switching machines (which will be installed and wired up soon), so the points on the turnouts aren’t very reliable. If I don’t hold the points in place tightly, trains running close to them will falter or stop completely.

It works well enough with a pencil in hand, so despite the lack of switch machines and without regard to my fledgling abilities with the PowerCab controller, here’s footage of the first run of the Bellwether.

The thump at the end of the video was my cat, Pisces, who batted the out-of-frame Bellwether off the tracks. This is why I will usually be operating the layout at shoulder-level, atop the bookcase which started this whole blog.

Here’s a photo of the perpetrator:

Wiring III

Bus wires going in. “Quick splice” connectors are key here; initially I thought I’d have to strip and splice, which would have taken days of soldering and shrink-tubing. Each connector takes maybe a minute or so to pry open, place the wires, plunge the metal clip, then snap the top down.

I ran out of connectors though, so can’t finish it all today…

I also connected the wires to a terminal strip at the “open” end of the module. This will make it easier to connect a second module later on.

Wiring II

I spent the better part of today cutting, stripping, and crimping wires, then (making a mockery of) soldering the feeders to the track.

Once the feeders were all in place, I started running the bus wires down the layout, but I didn’t get too far yet. Perhaps this weekend I will finish connecting all feeders to the busses, and then the Bellwether will be able to traverse every inch of the layout except the turntable and beyond.