Sankei Buildings

  

There seems to be very little available to help construct a z-scale city/townscape. Rokuhan, the Japanese z-scale manufacturer has a limited range of small buildings, and Faller, a German model maker, produces a number of buildings but mostly in European and older style.

I finally found a small Japanese manufacturer called Sankei which produces laser-cut papercraft models of a fairly wide variety of Japanese buildings and many in the required 1/220 scale. Here’s an example of a generic-looking commercial building being put together:

As supplied

All the pieces ready to go

Part way

Almost there

  • The instructions are written in Japanese, but illustrated really well so no Japanese language skills are needed.
  • A sharp craft knife is needed to separate the parts from the provided sheets – look for the tiny attachment points and slice them cleanly.
  • You’ll need glue to assemble the parts, they don’t snap together. I used just the tiniest bit of PVA – it dries slowly enough to allow re-positioning if needed, but quickly enough that the model soon takes shape.
  • Look out for symbols printed on the parts, they’ll tell you when it’s important to get a piece the right way round.
  • You can buy them on Amazon here, but if you’re buying more than one or two go to HobbyLink Japan and collect together a few under the same postage.

The Sankei buildings look great (especially considering the low-cost compared to other plastic model kits), have a surprising amount of detail for such a small size, and a fairly fun and relaxing to put together. Recommended!

Interestingly, after building a few of these, I’m beginning to feel that building similar things from scratch might be possible, with a decent quality card stock. If I’m feeling adventurous I might try this in the future…

Light sensors – logic and testing

  

The logic to control a locomotive is a simple state machine, summarised here – a train starts in “SPEED_UP” state, and moves through the list when certain conditions are met:

SPEED_UP – Accelerate. Move to CRUISING when the top speed is reached.

CRUISING – Maintain top speed. Move to ENTERING_STATION when a sensor is hit.

ENTERING_STATION – Slow down. Move to STOPPING when a different sensor is hit.

STOPPING – Slow down quickly. Move to STOPPED when speed reaches zero.

STOPPED – Wait. When waited for a few seconds, move to LEAVING_STATION.

LEAVING STATION – Speed up and maintain a slow speed. Return to SPEED_UP when no sensors are hit (ie, we’re clear of the station)

And after uploading code to the Arduino to reflect this, the end results is this:

Light sensors – installation and wiring

  

After testing and choosing light sensors, I started wiring everything up.

Small holes drilled through the board to accommodate the sensor:

5mm hole and light sensor in place

Had to remove one sleeper, but the end result is fairly unobtrusive

And various wiring completed:

Next up, it’ll be time to write some control logic and test everything so far…

Light sensors – selection

  

I’ve occasionally seen automated train stopping systems on model railways where the train rolls in at full speed to a station, and suddenly stops when it trips a sensor. I think we can do better given the drive-by-wire system I propose – two sensors, one at each end of a station should give enough information to the microcontroller about where the train is to allow a gently slowing approach, and a slow departure until clear of the station.

So I know I need lights sensors to detect the presence of a train approaching a station and reaching the end of a station. It’ll be important that the sensor can react quickly in low lighting conditions, and it should be easy to interface this with the Arduino.

After a bit of googling, I came up with a few alternatives:

TEMT6000

SFH 203 Photo-diode

NSL-19M51 LDR

FC-51 Proximity Sensor

AMS302 Photo-transistor

 

 

 

 

 

 

 

 

 

 

Each was tested by attaching to an Arduino like this:

Note that these testing notes are incredibly unscientific.

Results:

TEMT6000 – Responds to changes in light quickly, but detects no changes in near-darkness.

FC-51 – Interesting unit which combines an IR LED and IR Sensor, but difficult to calibrate, and weirdly the underside of my test train doesn’t reflect IR light.

AMS302 – Responds quickly, and has heaps of range at the near-pitch-dark end of the scale

NSL-19M51 LDR – Responds to changes slowly, and not particularly sensitive.

SFH 203 Photo-diode – Similar charactistics to the AMS302 – responds quickly with good sensitivity

So it’s between the two similar-looking photo-diodes. The AMS302 perhaps performs slightly better, and has a flat top which should make it easier to conceal under the track-bed. We have a winner!

Next I’ll be installing the light sensors and testing a simple control program.

 

Control systems

  

There are two main methods of controlling a model train layout – analog control (typically a simple controller with a direction switch and a throttle which controls the power to the tracks), and DCC, a digital control system which sends signals to individual locomotives. but still uses a throttle-type control as the user interface.

I want to do something a bit different – as this layout is mostly intended for continuous running rather than yard movements, throttle control of individual trains isn’t really needed. Also, many z-scale locos are too small fit the decoder chips required to run a DCC system.

So I’ll create a drive-by-wire system using a micro-controller to regulate the power to the tracks and a simplified control system based on toggle switches to change train behaviour. The Arduino (link to site) is inexpensive, small and easy to work with, with an add-on called the MotorShield which is capable of powering two train tracks independently. Arduinos and their addons are designed to stack vertically, but I’m combining them here with a ribbon cable to allow flush mounting on the underside of my layout board.

Arduino and MotorShieldV3

Trees

  

I planned for one side of the layout to be forest – dense trees evoking the foothills of Mt Fuji in autumn. Not sure how close I’ll get, but I started by ordering some 1/220 scale model trees.

Close-up of the newly placed trees

Still lots of ground to cover with forest

View of the whole layout so far

Each tree is attached individually by making a small hole, filling with hot glue and inserting the tree trunk. I’ve added some static grass tufts to try to make it look a lot more forest-like, but I think there’s still a long way to go.

Products used in this post:

Ground Cover

  

I got some Javis ground cover and applied with PVA glue. Here are some pictures of the ground starting to take shape…

Bagged Javis Scenics

Application is simple – just brush on PVA glue, sprinkle the ground cover, hoover the excess once dry.

Layout starting to take shape

Products used in this post:

Ballasting

  

Ballast refers to the rocks that make up the ground under real-life railway tracks.

Real-world ballast (Image from WikiMedia)

To recreate this in z-scale, I purchased some light-grey model railway ballast – I think it’s just coloured sand, for anyone wanting to save a bit of money here.

There are an awful lot of descriptions online describing how to apply it – the process I used was a bit like this:

  • Pour a small amount of ballast along the length of the track
  • Using a small paintbrush, carefully push the ballast in to place and away from the rail ties.
  • Carry on for what feels like forever gradually brushing the grains in to place

And then it’s time to glue it in to place:

  • Using a small dropper bottle containing a 50:50 water:PVA mix, gently soak the positioned ballast
  • Wait 24 hours
  • Scrape all the excess and errant grains of ballast that got stuck to the track

Waiting for the glue to dry

Before cleaning up the mess

Overview of all the ballasting – still some clean-up to do here:

Products used in this post:

Hills

  
I think I want the layout to depict a variety of areas – a town and a bit of countryside with hills. In larger gauges, most layouts seem to use either papier mache or large blocks of foam to model hills and cliffs.
For the modest sizes involved here, I figure I’ll avoid some of the mess involved with cutting blocks of foam or playing with plaster and use a stack of 3mm foam board sheets. 10 sheets stacked will give sufficient elevation for the high points of the layout. About 30mm clearance is needed to comfortably fit most z-scale locos, although they won’t be able to run carrying large cargo containers – luckily I’m not planning to do that.
A skim coat of basic decorators caulk evens out the steps, and then the whole thing can be glued to the baseboard.

Stack of 3mm foam boards coated in white decorators caulk

Once all the hills were relatively smooth and in-place, it’s time to lay out the track again. At this point, all the foam ballast is added, and the track is pinned in to place using tiny nails.

First test of all track laid with the hills in place

At this point I also added the first bridge (in this case, a Rokuhan girder bridge), and used more PVA to make sure it doesn’t move.

Notch cut out of the cliff-face to allow the bridge to sit firmly in place.

Products used in this post:

Track Test

  
With the board made, it’s finally time to test that the track fits. Here’s the layout loosly laid on the board. Everything just about fits, and it looks like the inclines needed will be no more than 3% grade – pretty steep, but the best I could do in such a small layout.

First track test

Real rail tracks are laid on ballast – to begin to mimic this, I’ve used 2mm craft foam, carefully cut to shape with a craft knife. The result looks something like this:

Roughly laid foam to form form the bulk of the ballast

The plan is to cover this with coloured sand to give the appearance of scale rocks.