Building instructions

Forum about the OS-Railway project available on Thingiverse. Here you can ask questions, look at building pictures, share ideas, pictures and STL's.
florint
Posts: 12
Joined: Sat Oct 10, 2020 6:56 am

Re: Building instructions

Postby florint » Wed Oct 28, 2020 2:52 am

Status report: I was able to assemble the front bogie and it works nicely. However the back one is a nightmare. I even printed it twice thinking that I had some tolerance problems with my first print.

I didn't even attempt the upper part of the bogie, only the lower part. The problem is that the mechanism is very hard to turn (although there are only two junctions) so I gave up and just left the wheel axles disconnected from the central shaft.

I couldn't figure out how the bogie connects to the main chassis. Is that M2x14 countersunk suppose to go through the chassis too?

I would like to give up on this back bogie and simply print another copy of the front one but I don't know how to attach it. Will I attach it the same way as the front one?

Florin

admin
Site Admin
Posts: 409
Joined: Thu Jan 11, 2018 7:46 pm

Re: Building instructions

Postby admin » Wed Oct 28, 2020 7:32 pm

Hi, the boogies are connected differently to the chassis. I thought this was obvious from the pictures. The reason they are connected differently is that I found that in turns where there is also an incline, the bogies will tilt and loos traction, or even derail. So with this locomotive I wanted to counter that so I made the motorized bogie "float" using a ball joint, to make it always touch the track with all of its four wheels.
explode.JPG
explode.JPG (51.51 KiB) Viewed 2042 times
Regarding the boogie, can you post some pictures? In some of my previous designs I used holes the exact size as the shafts and those required drilling, but on this one there are no holes that should squeeze the shafts. If the mechanics is very hard to turn, it has to be some part that jamming so you need to eliminate which one it is. Try removing one of the wheel axles and see if it's still hard to turn, if it is, remove the other wheel axle and see if just the center connection axle is also hard to turn, if so you have some issue there with the gears probably, touching somewhere. You could add thin nylon bushings. Also make sure the ball bearings there can turn easily.

Just out of curiosity, I accidentally put the wheel axles in the wrong way once withe their gears on the same side which means they turn against each other! No wonder the train would not move! :D I had quite a laugh when I found out what i'd done!
with all the ball bearings in place, no gears scratching the walls it should turn fine. You could sand the flat surfaces of the gears a bit because there is often uneven spots from the printing process that can make them go rough against other parts.

I'm actually just about to start recording some instruction videos here, I'm going to try to do an assembly video of this one as soon as possible!

florint
Posts: 12
Joined: Sat Oct 10, 2020 6:56 am

Re: Building instructions

Postby florint » Sat Oct 31, 2020 1:41 am

I see. So the rear bogie is supposed to "hang off" the main chassis through the ball joint? I wasn't sure if the long screw marked "M2x12 countersunk" that goes through the ball joint piece was supposed to also go through the chassis. I guess I should have realized that it is not, otherwise you wouldn't have specified "countersunk"... This makes sense now.

I think I have a problem with my printer, my filament or both :-) I broke the ball joint piece while trying to force it inside the matching socket in the chassis. I suspect the socket is smaller. I'll try to reprint the ball joint piece using PETG which is more flexible 🤞

F.

kevintieman
Posts: 6
Joined: Tue Jan 05, 2021 10:55 am

Re: Building instructions

Postby kevintieman » Tue Jan 05, 2021 10:59 am

Hi, Thanks for publishing this project! This is the single most awesome thing to 3d print and enjoy with my kid :-D.

Question: is it possible to use the motorized bogie from the EMD GP38 for other locomotives? I really like the gearbox and brushless motors (I already have the correct brushless motor size and esc from an old rc plane). Currently I'm still waiting for the ballbearings but it seems to work well already with the printed ones.

admin
Site Admin
Posts: 409
Joined: Thu Jan 11, 2018 7:46 pm

Re: Building instructions

Postby admin » Tue Jan 05, 2021 7:09 pm

Thanks! :) No it's not possible at the moment, there are major differences, primarily in the mounting so the chassis need to be modified in order for this to work. But if you haven't noticed yet, I have published another project based in this motorized bogie:
https://www.thingiverse.com/thing:4710367
I haven't printed it though so cannot guarantee that it works!

kevintieman
Posts: 6
Joined: Tue Jan 05, 2021 10:55 am

Re: Building instructions

Postby kevintieman » Wed Jan 06, 2021 10:15 am

That looks really awesome! I'm definitely giving this a try once I get the EMD GP38 running properly.

I want to experiment with the train stopping at a station, slowing down before corners etc using rfid tags. I ordered a reader and a bunch of tags to experiment with. The idea is to lay rfid tags on the track that the train will read, all tags have an ID so the train will know where it is. Currently I'm looking at the 13,56 mHz variant, as that has a range of 3 to 5 cm which should be more than enough looking at the ground clearance of the locomotive. This idea is not new and already used in commercial applications for model trains (https://www.traintraxx.com/).

I'm also printing the servo controlled turnout which I will hook up to a esp32, communication will go through MQTT (inspired by the other post by aligator, as well the argument it's excellent for IOT).

That is, if this all works out of course :D

kevintieman
Posts: 6
Joined: Tue Jan 05, 2021 10:55 am

Re: Building instructions

Postby kevintieman » Thu Jan 14, 2021 9:47 am

Btw, I checked the new train design. The chassis is accepted by the Cura slicer, however it reports that the body shell is not manifold (I at least managed to separate the shells using Meshmixer with a plane cut). My Meshmixer or Fusion360 skills are not good enough to fix this. Definitely looking to improve on my skills though.

admin
Site Admin
Posts: 409
Joined: Thu Jan 11, 2018 7:46 pm

Re: Building instructions

Postby admin » Fri Jan 15, 2021 6:15 am

RFID-tags is a really good idea! if you could program it so that the decision of what to do is taken by the remote and not the on-board ESP32 I think would be an advantage so that the layout and configuration could be set up from the remote. I'm working on a new remote using also ESP32 (TTGO).

Regarding broken shell, yes I know that Fusion 360 doesn't always get it right! I try to export them from Prusa Slicer (which can repair most of them) but apparently I haven't done that here. Thanks for letting me know, I'll check that.

kevintieman
Posts: 6
Joined: Tue Jan 05, 2021 10:55 am

Re: Building instructions

Postby kevintieman » Tue Jan 26, 2021 9:39 pm

I was initially planning to let the train do the decision making, but it would make sense to have a central system do that. It's easier to program the layout from the comfort of your laptop/desktop though. You can then use the controller to control speed and start/stop. I'm still waiting on parts though and development will be slow because my second son is still in the baby phase at the moment :-). My 2 year old is already enjoying the train and learned how to control it with the onboard servo tester while I wait for the esp32's :lol:

admin
Site Admin
Posts: 409
Joined: Thu Jan 11, 2018 7:46 pm

Re: Building instructions

Postby admin » Wed Jan 27, 2021 8:39 pm

Sounds awesome! :) my son was actually around 2 years old when I started designing this system!


Who is online

Users browsing this forum: No registered users and 1 guest