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Discussion Starter · #1 ·
I have recently got back into modelling after taking a break for a few years, and am experimenting with the use of linear motor propulsion for model rail and road. This little micro-layout is my first attempt at the rail side.

The Monbulk Creek trestle bridge is a popular viewing spot on Puffing Billy, a busy 2'6" gauge tourist railway on the outskirts of Melbourne, Australia. This 37"x15" micro-layout covers the bridge and its immediate vicinity. The layout is almost complete, lacking only trees and proper backscene.

The layout uses a linear motor drive system, my own re-implementation of a product by IDL Motors (www.teenytrains.com). The track is made up of small printed circuit boards with three strings of interleaved electromagnet coils printed on them. When these are powered in a suitable repeating sequence, they act much like a conveyor belt and drag along anything with magnets. The bare circuit boards are covered with a paper image of the track, generated in Anyrail. While the track plan is just a simple oval, the back straight has an automatic queuing system so that only one train at a time is running through the scenic section.

The chosen scale is 1:350, or 2.2mm gauge (!). I had originally intended to model this in T (1:450), but ran into length problems with the carriages due to magnet-spacing issues. 24mm turns out to be the minimum workable carriage length, and with those short narrow-gauge coaches... All structures and trains are 3D printed on a FlashForge CreatorPro. The trains are typical of normal non-holiday traffic on the line, with a long train hauled by an articulated Garratt, a medium length train hauled by a 2-6-2, and a fire patrol trolley.

Video #1: a track inspection run prior to line opening:
https://youtu.be/jsAcQBRm3oA

Video #2: early track testing and train experiments:
https://youtu.be/w3ZlAIuZqGU

There will be a final comprehensive video in a month or so, after the trees have a chance to grow (aka slow airmail from China).

And finally some pics in its current, treeless state:
 

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Holy <BLEEP> ... this is AMAZING! A bit insane, I suspect ... but AMAZING!

I wouldn't have thought such micro scale were possible as a home-build, but you've certainly proven me wrong, Martin.

Incredibly well done! I look forward to the "growing" trees to come!

TJ
 

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An incredibly old railway modeled using hi tech! That's what's great about the hobby! Thanks for sharing your ingenuity!
 

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Discussion Starter · #6 ·
A bit insane, I suspect ...
I play with model trains - of course I am insane. Aren't we all?

--------

I hadn't planned on doing another video until the layout was complete, but was talked into it. This one shows the trains doing what trains do, albeit only in train-set mode...

 

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Discussion Starter · #9 ·
Is the train made up of individual engines and vehicles?
Each vehicle is self-propelled, with several magnets underneath that interact with the coils in the track. They do have what I think of as couplers, but they are really just alignment pins to keep everything moving in line. Without them, each coach swings from side to side on its own, which just doesn't look right.

The more magnets per vehicle, the more traction, and the more widely spread, the better the steering. Each magnet is equivalent to an axle with really sloppy, coarse-scale wheels. So depending on the magnet arrangements, they behave very much like similar fixed wheelbase and bogie stock. Those coaches effectively have a single 8-wheel bogie, and are steered much like a semi-trailer on the road (i.e. an Aussie road train). If the coaches were longer, I could arrange the magnets into bogies which would be much more self-stable, and largely do away with the need for "couplers". Which has implications for shunting in the future.

Having each vehicle self-powered, so to speak, means I can run unlimited length trains, and they happily negotiate grades of 1 in 10 (10%). What they don't like is any sort of camber or sideways tilt.
 

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Discussion Starter · #10 ·
The Ebay trees have arrived, so are being rebuilt into Gum trees and installed on the layout. About half of them are now in place, with another couple of dozen gums to go. Then it will be the tree ferns, Europeans and undergrowth. The trunks and branches are a bit over-thick, but this is more noticeable on the photos than in real life. While some of the trees seem huge, none of them are more than middling-tall for Eucalypts. Even in this scale, we still have to use sub-scale trees!
 

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I guess I better stop complaining about the challenges when building something in n scale.

That is well done......cheers
 

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This is absolute genius! Insanity, too, of course ... but pure genius!

In watching the new video, I love the speed (very realistic), and the way that all of the cars wobble back and forth a bit, much like real train cars.

Very much looking forward to seeing the next with-landscaping video.

And ... what nut-job prunes such tiny trees?!?!? ;) (I say that affectionately, of course!)

TJ
 

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Discussion Starter · #13 ·
I've traditionally been an N-gauger, and working in the smaller scales really isn't all that different. It is about the same amount of detail per square inch, just applied a bit differently. Plus you can get by with much cruder models. However, I will say that my next few layouts are going to be largely treeless!

I'll do a full video when the beast is finished, which hopefully shouldn't be long now.

The low speed was intentional. The wobbles, not so much. And of course I'm crazy - I play with model trains! But perhaps I'd better not mention my tentative experiments with a 1:10000 scale model (that's 6" to the mile). It's on the list. :)
 

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Martin, can you put the trains-and-coin photo into better perspective for us? What's the diameter of that coin? And/or, how long is the loco and the cars, roughly? Did you say about 24 mm, or just shy of one inch?

Thanks!

TJ
 

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Discussion Starter · #16 ·
Martin, can you put the trains-and-coin photo into better perspective for us? What's the diameter of that coin? And/or, how long is the loco and the cars, roughly? Did you say about 24 mm, or just shy of one inch?

Thanks!

TJ
The diameter of the coin is 28.65mm.
The carriages are 23mm long x 6mm wide x 7mm high.
The NAs (2-6-2T) are 24mm long x 6mm wide x 8mm high.
The NG (2-6-0+0-6-2) is 43mm long x 6mm wide x 9mm high.

The key limiting number here is the carriage length - 24mm is the minimum value for "length + gap" for any vehicle with two neighbours, due to the number of magnets required for propulsion and stability, and the minimum spacing to the next vehicle's magnets. For future standard-gauge models, I will be looking at using 1:450 and even 1:600 scales. And looking at using decals rather than paper overlays.
 

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And looking at using decals rather than paper overlays.
Thanks for the dimensional info, Martin.

Re: decals ...

You're already 3D printing. Any chance you have access to a color 3D printer? Not too common (yet), but we're getting there.

Cheers,

TJ
 

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Discussion Starter · #18 ·
Thanks for the dimensional info, Martin.

Re: decals ...

You're already 3D printing. Any chance you have access to a color 3D printer? Not too common (yet), but we're getting there.

Cheers,

TJ
I don't really see much of an advantage for printing this sort of stuff in full colour, since limited resolution and feature size are the main problems I have to deal with. For example, I can manage to make rough indentations for entire doors or windows, but not to precise size or with any kind of detail. Switching to a resin printer or using a service like Shapeways would improve that, but they each bring their own brand-new set of problems.

Using decals should let me improve on the simple paper strips I am using for detail work right now, since that approach isn't good enough for the trains I want on my next project.

This CAD image of one of my Puffing Billy locos is right at the limits of what I can currently print, and as you can see it is really just a collection of very simple shapes. Even with that, a small decal would let me do a much better door/window/cab-side area.
 

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Thanks for the 3D-printing info/feedback, Martin ... I see your points!

And ... the finished layout looks SUPERB!!!

TJ
 
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