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RC6 Locomotive for OS-Railway - fully 3D-printable railway system!

by Depronized, published

RC6 Locomotive for OS-Railway - fully 3D-printable railway system! by Depronized Apr 25, 2017

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Fusion 360

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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 "goverment railways"). It is developed to be compatible with the OS-Railway project: http://www.thingiverse.com/thing:2146361

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.

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.

Print Settings

Printer Brand:



Prusa Mk2










Printing of the parts is pretty straight forward. The prototype in the pictures has been printed with PLA.

The only support-critical parts are the front and rear "cabins", which required both support from the build plate and part for the windows.

All the parts in the pictures were printed using the standard Prusa i3 mk2 and all color changes were done by changing filament, not by dual nozzles.

A resolution of 0,2mm is generally enogh in my view, but I leave that to your taste. The most critical parts are the power assembly for the roof which needs to be printed at 0,1 or smaller to turn out good enough. Don't use a brim here because it's very hard to get off the brim from such small components without damaging them. Also make sure your build plate is very clean for the power rig stuff. I clean my Prusas bed with acetone.

Depending on the settings of your printer, many parts will need a bit of work, like the holes which I needed to use a drill because the holes turned out too narrow. I don't want to change this in the CAD as you might have your printer better calibrated than mine. But if you think the screws are too hard to turn, use a drill to carve out a bit of the holes before assembling and it will work.

Needed hardware
The bogies are assembled using M3 hex screws. I will add more details here soon, but if you want to get started printing do so and measure. Most times I try to leave room for long screws so it's possible to use whatever you have laying around instead of forcing you to buy screws in exact lengths.

M2x16 is what I've used as I purchased a bag full. I used countersunk M2x16 that I have cut off to suitable lengths where needed. This is far easier than ordering lots of different lengths so if you plan on ordering, order a bag full of this dimension and you'll have enough for the whole build. The only place where M3 is used is the bogies.


The locomotive in the picture has had no post-print processing other than removing support marks. No sanding, acetone smoothing or other process has been used. This also means that if you print with higher resolution and use a post-processing you can achieve far better surface quality than the prototype shown in the pictures.

glue the 3 body parts together, and the 3 chassis parts together but don't glue them all together after, it's good to mount the body onto the chassis using the screws so you have a way to do maintenance or changes later.

Most parts are straight forward to mount, most using M2 screws that I simply cut off in length if needed.

The roof top power assembly uses thin piano wire <0,8mm in the joints. You can probably fit legs from components such as LED's if you don't have piano wire.

The windows are easiest assembled by gluing the window frames onto a clear plastic and cutting around them. The windows can then be glued to the body using gel CA or other glue of your choice. I printed many versions of the frames in different scaling until I got a good fit, maybe you need a different scaling, if so, print the window frames from the ZIP-file and adjust the scale according to your needs. The window frame assembly file has a scale of 96%.

Don't hesitate to ask questions in the comments if something is unclear!

How I Designed This

Designed using Fusion 360

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When you think to upgrade the loco with arduino's code and link to accessories that you are mentioned in the article?

Hi, that's a backburner I know. :) I'm working on getting a tram finished here, so haven't really payed any attention to the RC6 lately, but the best incentive for getting the last bit done is if someone wants the stuff. :D Are you printing one right now? I'll try to make a rough connection diagram and upload the code during the week, code is kind of rough but it's a start and you can improve on it.

Now the Arduino code is added! :)

Comments deleted.

I would like to 3D print your STL files but unfortunately they don't fit inside my small RepRap compatible 3D printer when using Cura. The printing size is only 160x160x160mm. Therefore I ask you if you could split your STL files in smaller pieces and upload them. I am interested in O scale but some other model railroaders may be interested in G scale.Thanks for understanding. Greetings from Helsingfors.

Hi, you can follow this tutorial to make the parts fit your print bed: https://www.youtube.com/watch?v=6n1h3DmMbZc

Aug 18, 2017 - Modified Aug 18, 2017
amazonas - in reply to Depronized

Is there no other way? I don't want to download a 95MB installation file, which is Autodesk property.
I installed this MessyMixer and tried to split in two parts the original "assembly_body_middle.stl", which has the filesize of 32MB.
Surprisingly I get first repeatedly a warning message "...mesh manifold too complex" or something like that and the the resulting STL files have the size of +80MB each (+160MB in total). Sorry, but for simple shapes I expect a simple light-weight solution.
BTW, out of curiosity I tried to split other STL files with MessyMixer and it works fine, even if it generates far too many meshes. So, my conclusion is that the original STL file should be geometrically well defined and saved in a rather small filesize. When I inspect all STL files for this Sveedish Rc-6 locomotive, the most problematic file to split is "assembly_body_middle.stl". Any workaround solution?

It is a very complex model due to the surface, it's even basically too much for my computer to handle in the CAD-program as well. (Fusion 360). So when working on the assembly I have to select that part as invisible, otherwise everything takes forever to do. Because of this, and that I barely have time for any CAD-work these days with small kids at home and full time work, I will not do any special modifications to the original CAD-work. Sorry, maybe you can find someone with a large enough print bed that can print these parts for you?

Thanks for the quick reply. I understand, family and job first, the hobby comes second.
Probably Fusion360 cannot handle repetitive surface details, I have never tested.
I will re-design twice the body (one version with smooth surface for the ex-JZ-441 and another with embossed/engraved surface for the SJ Rc-6) by using OpenSCAD, very easy. Thanks again for sharing your nice locomotive with the community.

Thanks for understanding, and it's not a Fusion-problem, it's the dinosaur hardware I'm running it on. :) Don't hesitate if you like to upload your modified parts as a derivate, might be more people wanting that version.

I wonder if this could be scaled down to, say, H0, which should be roughly half the size. Inside looks to have enough space for the electronics and motor, but I don't know about other delicate parts. I tried printing couple test tracks at 37.5% - TT 12mm gauge, in both 0.2mm and 0.1mm. It's OK but feeling too flimsy with simple scale down. I believe with some uneven scaling sacrifice it could be done. I guess for small child it's better to have larger and sturdier toy anyway :)


Yes this is designed with regards of structural integrity to work in the O-scale, but keep in mind that this is with PLA so if you print with a stronger material then maybe the track joints will be strong enough. I guess it's the beauty of 3D-printing after all, just go ahead and test. :) I have not tested, but if you do it would be nice to see the results! :) Generally I would presume that for H0 scale the SLA style printers are more suitable to get good enough details.

Jun 3, 2017 - Modified Jun 3, 2017

Hej Olle.
Tack för du delar med dig av ditt fantastiska arbete med Rc maskinen.
Jag har själv börjat rita på en Rc, men nu slipper jag det, Tack för det Olle.
Jag bygger och kör i nollan själv och har riktiga hjul och riktig räls.
Så det blev genast problem med boggierna, hjulen passar inte.
Just nu går min Profi3D maker för fullt med Rc chassit (8 timmar)
Himmla kul att studera din konstruktion.
Återkommer när jag printat ut lite mer.
Mvh // Gert Persson, Malmö

Tack! Ja jag kanske borde vara tydligare i dessa uppladdningar att detta inte är kompatibelt med kommersiell O-skaleanläggning. Jag håller själv inte på med någon annan järnvägshobby än det jag 3D-printat så jag har inget att testa med (och prio för mig är att tågen och de 3D-printade spåren ska fungera ihop). Däremot finns det ju en del spelrum för hjulen så du kan ju alternativt rita nya hjul, men du kanske redan hittat en lösning? Ja lägg gärna upp bilder på det när du skrivit ut!

Jun 6, 2017 - Modified Jun 6, 2017
McDOZ - in reply to Depronized

Nu är det mesta printat, endast strömavtagarna kvar.
En fantastiskt fin konstruktion. Jag häpnar av din ingeniörskonst, Fem stjärnor från mig!
Jobbar du med SolidWorks? Jag själv har fastnat för Inventor 2016.
Men mina konstruktioner bleknar jämfört med dina, suck.
Har dock lite frågor. Skala 0 i Sverige o Tyskland är 1:45, 1:43 i UK och 1:48 i USA.
Rc:ns hjuldiameter är 1300 mm = 28.8 mm i Nollan räknat på hjulringen, inte hjulflänsen.
Skall beställa dito hjul ifrån Slaters i UK så att man ser de blanka skivorna från skivbromsarna.
Får nog modifiera boggierna då för att passa de större hjulen.
Plogarnas två hål? hur har du tänkt där? Har limmat ihop de två delarna men parena möts inte på mitten?
Jag använder Simplify3D slicer program och där ser det väldigt konstigt ut när jag försöker printa fönsterramarna?
Dom hänger inte ihop i dom första lagren, några syns bara till hälften.
Har testat många olika inställningar men problemet kvarstår.
Skall printa en modell till och då köra ABS istället. Kanske jag provar att printa en i skala 1 - 1:32 också.
Hytterna blev otroligt fina (8 timmar), värst var att rensa dom från supportmaterial.
Jag återkommer // [email protected]

Tack! Jag använder Fusion 360 och improviserar mestadels, jag testar mig fram tills resultatet är någorlunda som jag vill. Jag hade gjort denna i princip klar när jag inte tyckte formen stämde överens, efter noga granskning såg jag att det var att fönstren lutar en smula inåt, men den lilla vinkeln gjorde enormt stor skillnad på utseendet så det var bara att rita om hytterna hehe..

Apropå skala, jag har 1:45 som riktmärke, men det är som sagt enbart ett riktmärke. När det gäller hjulen så visste jag att de i skala-storlek skulle vara omöjliga att köra i mina växlar så jag skalande ner dem från början. Nu visade det sig att de fortfarande är för stora, får se hur jag ska tackla det.

Plogarna var från början tänkta att skruvas fast på 2 ställen, men jag tänkte att jag först skulle testa med ett hål för att se hur vinkeln blev, sedan blev det inte av att rita infästningen för det andra, jag upptäckte också att det var rätt praktiskt att plogen kan vikas in om man kolliderar med något istället för att den spricker.

Angående fönsterramarna, jag har inte Simplify3D så jag kan inte felsöka det, jag kör med Slic3r mestadels men ibland även Cura. Det hela kan bero på att ramarna är vinklade på modellen och jag var tvungen att försöka vrida dom plant först, sedan exportera till STL för att de ska gå att lägga dikt mot byggplattan. Kan vara att vinkeln inte är exakt. Ska titta på det vid tillfälle, men du kan ju testa med Cura eller Slic3r så länge. Fönsterramarna var det svåraste på hela modellen, fick skala om dom flera gånger, mecka med vinklar etc för att de skulle bli bra.

Tack för dina snabba svar.
Har printat Z70 också i bara farten, och den är lika fin som Rc6.
Hela karossen i ett stycke, men det blev himla bra när väl supportmaterialet var avlägsnat.
Nu väntar jag på Smooth-On preparat ifrån USA som slätar ut årsringarna på printet.
Sen lackering och vädring. Motorlösningen går jag och grunnar på.
Fusion 360 verkar lite enklare än storebror Inventor. Inte mycket restrains problem enligt YouTube klipp.
300$ i månaden om man inte kan få en student licenc som varar i 3 år.
Återkommer med lite bilder när jag fått på lite färg.
// Gert

Haj igen Olle!
Var har du köpt 2x16 mm skruv, hittar inte så små skruv i Malmö.
Fönsterramarna får jag inte rätt på.
Kan man tänka sig att jag köper ett set av dig?
Jag kan Swisha pengar till dig.
Du kan maila mig direkt på admin [AT] railworks punkt se
// [email protected]

jag svarade i ett privat meddelande här istället, om du inte ser det.

Riktigt grymt jobbat, Ska skriva ut denna till min gamle far som är både lokförare samt lokentusiast. Han kör RC6'or på daglig basis o blev helt av sig när jag berättade om din modell. Du har inte fler lok som används i svensk drift på gång?

Hej! tack! Ja RC6'an har man ju sett nästan dagligen ända sedan barnsben så därför låg den ju varmt om hjärtat. :) För mig är tågintresset främst tekniskt, dvs jag har inte koll på olika tåg/lok-modeller eller så, jag har väl mer kan man säga ett generellt modellbygge-intresse med fokus på fungerande modeller och när jag köpte printern och såg att barnen var intresserade av Brio-tågbanan så fick jag den här idén. Jag har ett pågående projekt att bygga tvärbanans A35, men ligger lite på is just nu då jag måste designa om transmissionen, men jag ska bygga klart den någon gång. Problemet med tågen generellt är att de blir så förbaskat stora i O-skalan. Det är knappt så att RC6'an klarar av att ta sig runt min bana med tanke på de tighta radierna, så spårvagn är nog egentligen mer lämpligt.

This model is absolutely fantastic! Good job.


Designing models like these takes a lot of time, and I already have a project roadmap that will keep me busy the rest of the year for sure, I'm working on a tram right now. A bus is unfortunately outside this scope, but I would advice you to ask in any 3D-printing facebook group, best for you is if you find someone that wants to design it for them selves as well.