READ THIS BEFORE PRINTING! This thing is marked as work in progress, but I think it's important also to clarify that this is a side project that is more a display piece. It's designed in scale size which means it's really big, and my track has a lot tighter track radius than full scale so this locomotive has trouble navigating turnouts. This is mainly because of the size of the wheels, and even though I tried to put a lot of weight in it, it still cannot go through the turnouts. If you really want to print and run this locomotive on my track design, you can try with smaller diameter wheels. Otherwise I recommend going for the Hectorrail 141 instead or the Z70, they work a lot better on the track.

Update! Arduino-code now added. It's a very simple code that uses an arduino Pro Micro board, an IR remote kit and a servo.

Link to IR-kit: https://www.banggood.com/Infrared-IR-Receiver-Module-Wireless-Remote-Control-Kit-For-Arduino-p-914005.html
Link to Arduino-board: https://www.sparkfun.com/products/12640
There are many similar boards so you might need to change board in the Arduino build environment. Check the code for outputs, the connections are very simple. The signal wire from the servo can be directly connected to the motor-pin on the arduino. Same for the IR-kit, no extra components needed. Only the LED's require resistors, value depending on your supply voltage and the chosen LED's. If you don't know what resistance to use, connect a potentiometer and a multimeter in series with the LED and adjust the potentiometer until you get around 10-20mA, which would be on the safe side for most Arduino board (check your boards maximum current on the I/O's!).

The electronics is powered by a 4-cell NiMh battery pack in the prototype, check the servo and your arduino board for maximum voltage if you want to use higher voltage, like 2 cells lipo.

Time for a new locomotive! This time the very common here in Sweden, the RC6. Used by SJ (short in Swedish for "government railways"). It is developed to be compatible with the OS-Railway project: http://www.thingiverse.com/thing:2146361

SCALE 1:45

Few things still on the to-do-list:

• window frames for side windows
• cover for roof top box. My idea for this box is to have a hatch and buttons/switches underneath, if nothing else just the power switch. Right now I need to pull the roof of to connect the battery.
• installing the IR remote receiver in a good place, right now it's just loose.
• Trying to print a little bit smaller wheels, these big ones has a tendency to derail in the switches despite bogies, maybe it would also help to make them thinner, but there is some serious weight in this locomotive so too thin wheels would not cope if you just place it on the table and not on tracs.
• 2-axle drive. Right now only one axle is powered by the gears in the exact same way as the Z70 locomotive, with the exception that this one doesn't have room for a servo, it needs a 16mm motor with gearbox. This is due to the fact that this locmotive has bogies that both turn and tilt. Of course it's possible to engineer the drive mechanism differently, and I encourage anyone to do that if you desire a different type of drive! This was the quickest way for me to get it running. My idea right now to make it dual axle drive is to put 2 belt wheels and a rubber band between, much simpler than having more axles and bevel gears.
• Scale stuff under the "belly". There is supposed to be some tanks, boxes and stuff under the middle of the chassis, between the bogies.
• car coupler. This version do not yet have a car coupler.

General description
This locomotive is really big, but not that hard to print. It is a fairly accurate replica of the RC6 locomotive and the size in O-scale meant that it's longer than the build plate of most FDM printers. This is why the chassis and body is divided into 3 parts.

The parts can be glued together using super glue (cyano acrylate). I prefer the gel-type as it's not as fluid as the regular one, it works really well. Melt glue works good but it hardens so quickly so it's really tough to glue these big parts together using that.

The bearing houses can be used with the same size ball bearings I've used for the cars and the Z70, 6mm OD, 3mm ID and 2,5mm thickness. However, in a test I did I found that PLA has very low friction so a set of PLA dummy bearings worked really well, so don't be set back if you don't have ball bearings, print the PLA bearings at least for a start.

This locomotive is developed to function with this railway even in curves and tilting angles, thus the bogies can both rotate and tilt. However, it really needs a low center of gravity as it has a tendency to fall of sharp curves if it goes too fast. An idea I have is to place an integrated battery compartment into the middle chassis part. This would lower the CG and make it more stable. But on a flat track it runs really smooth and well in the current version.

Electronics
The main controller is an Arduino Micro Pro together with a standard Hitec servo circuit board extracted from an old servo, but used with a high-end DC-motor with gearbox. I will post a link here to a suitable motor soon, so check back for that!

The Arduino controlls headlights on both sides, red tail lights and extra lights, in total 6 light channels. It is controlled by an IR remote kit.
Link to the IR-remote kit: http://www.gearbest.com/transmitters-receivers-module/pp_227122.html?currency=SEK&vip=1041013&gclid=CNP7pK7TwNMCFUeZGwodTHcImQ
Arduino micro pro: https://www.aliexpress.com/store/product/Free-Shipping-New-Pro-Micro-for-arduino-ATmega32U4-5V-16MHz-Module-with-2-row-pin-header/318950_1348800135.html
As stated above, source code and schematics will be published soon.