A Modular Layout for "O" scale trams Part 2

Both end modules have been framed and the curved edging has been fitted. The track has been laid on one of the boards and I will take a break in construction for awhile while I test all the trams on the 12" radius curve. I don't expect they will all work first off as I think I will need to do some fiddling with the wiring that joins the trucks together. There is a hugh swing with "O" scale on a 12" radius curve and consequently a lot of movement is required in the wiring. So far I haven't been able to find a wire that has the sort of flexibility that suits me because my models are very light weight. The answer may be added weight or more flexible wiring or both.


The 12" radius curve is what I would call a minimum radius curve with no room for error. To ensure accuracy I made a 32mm track gauge which was also a trammel along with a second 32mm gauge from flat aluminium strip. The photo above shows the gauges in use along with a couple of pieces of steel bar which roughly hold the rail in place ahead of the soldering. The 60" curve was eye balled and the 18" radius curve was laid out with a cardboard template. The rails, it took 6 lengths for this one module, were all pre-curved around various size tins so they were very close to their final curvature.

The next photo shows an overall view with all the track down. The lighter tear drop section in the middle will be cut out now that the track is laid so that the curved back scene can be fitted. The darker colour on the rest of the layout is the sealer to waterproof and protect the wood so I can apply the plaster road later without any problems. There is 9' of track on here so I intend to break the track up electrically into two equal length sections in case I have a need for it later. It will be pretty hard to do when the track is embedded into the roadway.


I wanted to see what a tram would look like on the 12" curve and the last photo shows a Brisbane drop centre doing just that. This view will be lost when the central back scene is in place as a tram on the loop will only be able to be viewed from outside the circle.

I need to drill the holes for the span poles next and locate them in some way so I can still find them after the plaster has been applied. This are is fairly tight area and once the central back scene is in place I wont be able to drill the holes for the inner poles as they will be only millimetres from the back scene so they have to be done now. The back scene will protrude above the baseboard the width of a piece of A4 paper. Coloured photos of a Brisbane street scene in landscape format will be glued to the back scene. Hence the need for a couple of millimetres gap to the inner span poles.

Now off to spend awhile testing and fine tuning my trams.

A Modular Layout for "O" scale trams Part 1

I have decided to start building a modular layout to run my trams on. I have always been fond of the dog bone style for exhibitions as all of the trams running are visible for all the time which is better for viewer interest. Initially it will be only a continuous loop with no point work but 3 or 4 trams will be able to tail chase each other using fairly simple automatics. Later more complex track work can be built on additional modules if I feel so inclined.

I decided that the straight sections would be 450mm deep as this gives me a reasonable width roadway and two footpaths as well. The rear scenery will be on a separate bolt on section so that the scenery can be changed without affecting the track and overhead. I wanted the front to be flat so I ended up deciding on a distorted tear drop shape for the balloon loops.

This is where track design software comes in handy. I use XTrkCad and a few hours experimenting with different ideas resulted in the track plan below. The overall size is 3' 6" x 2'6" The return loop radius is 12" and the upper entry curve is 18" with the lower entry curve being 60" The baseboards follow the curvature of the track and end up 1'6" wide where they will join onto the straight sections. The track centres are 3 1/2" where they leave the board. Pushing cardboard cut outs of Brisbane trams back and forth over this point shows no problem with overhang and no problem hitting a tram on the other track.


The last photo shows the baseboards having just been cut out with a jigsaw. The two pieces of board were screwed together and cut at the same time. I must remember to flip one of the boards over before attaching the pine under frame otherwise I will have two right hand ends. The inner tear drop shape will be cut out after the track is laid and a curved back scene will be fitted. But at the moment it is still required to provide the centre point for laying the track. The five odd shaped slits are where the timber frame passes underneath. The frame would get in the way of the jigsaw so I felt it was better to clear those areas now. They may be hard to see because the pencil is fairly light but the radial pine frames, that will be at right angles to the track, are positioned to provide support for the span poles.

Now I have to cut all the timber for the framing and the strips to form the curved edge around the module and glue them into place. Then I can think about the best part. Laying track.

A early version Drop Centre in "O" scale part 7

This will be the last post in this thread as this model is finished and it will be time to move on to other projects now. I am very pleased to have won the "Best Scratch Built Loco" award at this year's Brisbane Model Train Show with this model. So to celebrate here is another photo of the finished model followed by a photo of the inscription on the trophy.




There is one thing I still have to do to this model. The 3 pole Mabuchi motors I'm using are very variable in performance. I have run into the problem of their wide speed variation from motor to motor before. I suspect this is from poor quality control during the manufacture of the permanent magnets. With the two trucks set up on my test track, one truck ran at close to twice the speed of the other one which is one of the biggest variations I have seen in a long time. The direction didn't matter. I have a good supply of these motors and one day I will have to swap motors in and out until I get a pair that run at about the same speed.

At the moment the tram runs smoothly with the faster truck trailing and tends to surge slightly the other way around. One day!!