GardenRailway

Edit:29 janv. 2017, Cre:30 juin 2015

Monorail

A monorail model, garden train scale, freely inspired from the Schwebebahn of Wuppertal, Germany.

1rst photos

Introduction

This is something that I was willing to develop from some time now. Garden train scale monorail are very rare and there is nothing available on the commercial market. However, I find them quite appealing and think they could add a nice touch to a garden railway.
Waiting a 3D printer to come, I have developped this monorail model with all mechanical parts 3D printed. I prefer suspended monorail and have taken inspiration from Schwebebahn as the simplest mechanism available.
The key point was the motor bogie. I have developed own motor casing with internals from an old LGB motor bogie Stainz "1"

The cars are not a model of the Schwebebahn, as I have used 'off the shelf' bodies (from Newqida) without side doors. I added enginer cabin, balcony and floor structure. I like the idea of open balcony in the style of train and tramways of the end of 19th century.

The monorail model is not yet finished but first car is mostly done and motor bogie is working and tested.

Specifications :

Scale : LGB so approximately 1/22.5. The standard cars are a bit too wide for a monorail.
Banking +/- 20° and +/-15° if power rail (Schwebebahn:+/- 15°)
Motorisation: LGB motor, with 3D printed casing.
Rail: tube 8mm diameter
Wheels diameter : 44mm at rail axis
The beam could either be a wood lath or a PVC pipe diam 32 (for outdoor use). I do not recommend terrace polyethylene plank as the thermal expansion is too large.
Minimum turning radius with the shown geometry: 600mm (which allow 1/4 bend of 1m length). With that radius, rail diameter shall be reduced to 7mm in curves.
Power supply : battery or power double rail.
It might be possible to use the LGB tramway bodies nearly 'as is'. A modern looking monorail can be done with the LGB/Toytrain ICE set.
Car adaptations are made with plastic cards and profiles (styrene/ABS/PVC), so adapted car bodies shall be in plastic that you could glue, and it is difficult to adapt LGB bodies which are in an UV resistant plastic very difficult to glue. I have used chinese Newqida bodies.
I have developped printed parts for a switch, not yet tested, and different railway hangers, which open possibilities for bridges and other structures.
As the real shwebebahn, the car is slightly offset sideways (this is a parameter in OpenSCAD) to counterbalance the bogie weight. Counterweight seems not needed.
Motor bogie is installed at the back of the leading car to increase traction with the battery weight (if any) which will be installed in the central car (as end cars have bolted roofs).

Power supply

Monorail could be electrically supplied by batteries or by a power rail. I am using a 'N' gauge track as double power rail. The running rail is not used for power supply as it is in aluminium and in PVC on curves. Outdoor Installation may need a motorised rotating brush for power rail cleaning (to be installed in the front of the leading bogie), with similar cinematic as the current collector arm. My feeling is that power rail is good for indoor use and battery operation better for outdoor.
I have developed a power supply rail and current collecting system based on 'N' track.
Instead of what is shown on photos, you need a spring on each side of the current arm system.
The last photo show how the track template is used to adjust the position of the track on the wood beam support.

Outdoor use may be simpler with battery operated train and radio.

Modelling

All parts are designed with OpenSCAD, which is a 3D modelling language. It does have serious limitations, but with practice and a clear 3D view in your head, the design could be relatively fast. Only for people experienced in programming. This does allow largely parametric design.
OpenSCAD does not replace a good CAD program, but there is no CAD program available for amateurs which have convinced me. FreeCAD does have capabilities but its ergonomy is not good. Sketchup is quite easy to use but not well adapted for 3D printing. There are capable CAD programs cloud based for 3D printing, but I have lot of doubts about the perennity of cloud based software.
Unfortunately, there is no way to export OpenSCAD model with full colors. If you want to use the model in another program, You shall export part after part and reassemble the puzzle. No fun, but this is a drawback of OpenSCAD.
Total printing time will depends from your machine speed capabilities and the finition quality you wish and that will go from 15 hours to 50 hours for the monorail. You shall add some time for the way beam supports if you decide to print them.

There are options in OpenSCAD for the beam choice, but you need minimum knowledge of this program to change options.
Default parts are for a rectangular beam.

Construction and assembly

There are a whole bunch of parts to be printed. For outdoor use, the painting will protect it from UV. Motor casing shall be done in heat resistant plastic (hence, NOT with PLA). You could use PETG, ABS or Polyamid (Nylon).

The bogies were among my very first printed parts and I have done many tests, so they have not the best finish. You could get a much better finition, but you shall go slower than me. Also, a good cleaning shall be done before painting.
Non brittle material shall be used for parts with extended gussets, as the half of the bogie which support the car. Wheels may be better done in PLA for better surface finish and more precision with the holes.

Motor bogie was tested at 13.8V without load during 2h. It is thermally stable and does not goes to high temperature. The real load will be low compared to the usual service of a garden train so I do not expect huge thermal increase. Free wheels are running on ball bearings (623).

Cars

Cars are NewQida (China) car bodies bought new on Ebay at Zenner shop (Germany).
If I had better searched on ebay, I could have bought identical complete cars for less
than what I payed the bodies. Search phrase on ebay.com:
"New G Scale Garden Passenger Coach Carriage Compatible 45MM" seller "1234-click"
or a complete set of 3 cars for 100£ (w/ shipping) on ebay Uk, seller "ecreastcoastrotor"

The cabin, balcony and roof are made in plasticard, styrene or ABS.
Roofs were not available, so they are also built with plastic card. The ABS roof (1mm) was difficult to heat bent, so I recommend to use thinner card (0.6~0.8 mm).
Extra windows are made with slim CD case (which are thinner than ordinary CD case).
I glued low cost U plastic profiles 12x12 under the base to simulate chassis and make a support
for the driver cabin and balcony. Driver cabin and balcony were built from scratch in plastic card.
Central car is a full body cut to 4 windows and the end is rebuilt with plastic card.
It may be less work to buy and modify a complete wagon notably because there is already a roof.
Using genuine LGB parts is delicate as it is very difficult to glue on the
plastic used by LGB (ASA). It could be anyway of interest to use 90953 cars (ICE) to build
a 'modern' looking Monorail if the early XXth century style is not for your taste.

Motor bogie

LGB motor bogies are heavy, bulky and due to their shape, motor shall be above the wheel axis. I have developed a new compact casing for the motor, which is installed below the wheel axis. The original motor is extracted of 'Stainz' "1" locomotive bought on ebay, which was destroyed during shipping due to poor packing. I think the best source for bogies is the Playmobil bogies, but I have to buy one to see the differences with the Stainz bogie. However Playmobil bogies have only one geared axle instead of two for the LGB, so the traction will be divided by half. First tests shows that may be unsufficient.
The casing may need adaptation depending your motor source as most LGB bogies differ on details. This parts need support and need some cleaning work after printing. Dimensions were well accurate, but I had to add a few clearance for ease of motor installation.
The motor bogie wheels have a groove for rubber O-ring to improve traction. Install them after painting if you don't want to spoil them.
The motor wheels are for axles with end flats. It seems that new LGB bogies have a different system, so wheels shall be adapted.
Don't forget to grease with a plastic compatible grease and beware to not lost the shaft end balls.

Freewheel bogie

Wheels are running freely on ball bearings 623 (10x3x4)
Wheels are now designed with more elegant open frame and shaft support is monobloc.

Central car hinges

The central car is suspended to the front and back cars.
Having two hinges make the banking angle identical for all cars.

Rail

The rail is an aluminium tube of 8mm external diameter.
In curves, it is replaced by a plastic rod of 7mm.
The rail supports are screwed to the tube with 3mm wood screws. You need to predrill the aluminium tube first

Future developments

I have developed an on-vehicle switch, but is a bit complex (it needs one RC servo per bogie, and you shall have two motor bogies to have traction during the switching), so I won't build it now. If someone is courageous enough !

Files - NOW AVAILABLE (Nov. 2016)-

Design is now available on GitHub

  • OpenSCAD parametric model, adapted for new customizer.
  • Printed parts, STL
  • Schemas/Photos

Links

Schwebebahn

Other monorails models

(c) Pierre ROUZEAU
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Page mise à jour le 29/01/2017 18:15