Rail Trucks

I have two Bachmann On30 Rail Trucks that I got through eBay.  They were advertised as having operational problems but didn't mention them missing windshields and visors.  Fortunately Bachmann still has these available as part of their cab body kit ($20.39) so I ordered two of those.  I also ordered two "Cab and Driver" packages ($11.33) for the snow plow and driver.  I didn't realize at the time that this package also included a windshield and visor so I guess I'll have spare parts for a future project.

My plan for the Rail Trucks is to make the necessary repairs to get them running and then convert them to RF control with battery power and sound.  One truck has broken gears and the other has an electrical short.  On both trucks I'm replacing the gears with NorthWest Short Line (click here) metal gears and replacing all the wiring on both.  For the electronics I'll be using components from Stanton S-cab (click here) and Soundtraxx (click here).

When I first sat down to work on this project I knew right away that I'd need a way to conceal the electronics.  The Rail Trucks come from Bachmann with a short stake bed and a small plastic box in the bed to hide a DCC decoder.  My plans include a 1" speaker, a TSU 2200 decoder bundled with an RF receiver, a battery controller board and two 1000 mAh Ni-Cad batteries.  I needed a bigger box.

I Googled "Galloping Goose" for pictures of the rail trucks that had been used by the Rio Grande Southern (RGS) railroad during the first half of the 20th century.  They had at least one that Bachmann copied for their flat bed rail truck but most of the RGS Geese had long enclosed boxes in place of the open bed and were used for LCL (less-than-carload) freight.  Some of these were later converted for passengers.  I found one Goose model that had a freight box but it was still too long.  I did like the style of it though and used that as an inspiration for my own design.

I sat down at my computer using TinkerCAD to work up what I needed and printed it out on my Anycubic Photon SLA 3D printer.  I've worked with a filament printer for the past two years so I was familiar with the design software but this was my first project on a resin style 3D printer.  With a filament printer this cargo box would have to be done in 5 separate pieces, 4 sides and the top, to improve the details.  I wanted to see what I could get away with on the resin printer so I attempted to print the whole box in one shot.  My first try showed some distortion, warping, in the walls so I flipped it over in TinkerCAD and printed it upside down.  The second try came out great, just as I had planned it.  I went back to TinkerCAD and drew up a "ghost" box using the interior dimensions so I could work out how to arrange the electronics.  I made boxes with exact dimensions of the boards, batteries and speaker and placed them in the "ghost" box.  The picture below is a screenshot from TinkerCAD.  I slid one of the 800 mAh batteries back to show the placement of the other components.

By planning my use of space in the CAD program I realized if I widened the box just a bit it would have room for a pair of 1000 mAh batteries instead of the 800 mAh ones I first planned to use.  This is probably overkill for a rail truck but both sizes of batteries cost the same.  I'll probably be able to run these trucks for a week without a re-charge.  Cool!  Because I had designed the walls of the cargo box extra thick for printing I was able to find the additional interior width without actually making the box any wider on the outside.  In the picture above you can see the speaker and it's baffle box are placed in the forward half of the truck so it'll fire down through holes drilled in the bed.  I placed the BPSv4 near the top because it has two reed switches (on, off) that can be controlled with a magnetic wand.  The decoder / RF receiver has an antenna at one end that should work fine with the plastic cargo box.

While using TinkerCAD I added 0.032" holes for ladders and door handles.  I'm thinking about adding a "roof rack" so I included holes for that too.  Using the CAD program for this works well because you can get perfect alignment whereas drilling them by hand they'd be all over the place.

Using the filament printer I would send my CAD generated designs as .stl files to be processed for printing by Cura, a "slicer" program that I found to be intimidating because of it's 100's of controls.  I found that Cura wouldn't work with my Photon resin printer so I downloaded Chitubox, another slicer program, which I was pleased to find only had 16 controls.  I'm really impressed with the easy and intuitive controls of the resin printer and the prints are finished much quicker than with the filament printer, at least half the time.  Best of all, the quality of the print is light years ahead with smooth surfaces, super detail and very little "post-processing" cleanup such as sanding and filing.  Filament prints required a lot of cleanup.  The downsides to the resin printer are that it requires using gloves when coming in contact with the uncured resin (which is slightly caustic) and parts need to be cleaned with isopropyl alcohol (I use an ultrasonic cleaner) and then cured in direct sunlight or under a UV lamp.  I use paper towels to soak up excess resin right after a print and place the part in the cleaner for 10 minutes.  Once that's done I put the part under a UV lamp in my curing box for 45 minutes.  Under the sun it can take about 2 hours.  I'll usually start printing another part while I'm going through the cleanup/curing process.  This box took 3 hours 48 minutes to print which included 903 layers, each one .050 mm thick.

I'll update here as I make further progress.

8/14/21 - I've been in contact with Neil Stanton about what parts would work best for this application.  The batteries I originally wanted are not available right now.  After discussing it with him I decided the rail truck didn't really need all that battery power so I'm going with a single 800 mAh instead.  Since one of the rail trucks already had a decoder he quoted me a price for just the RF reciever and a BPS with an 800 battery.  Good deal.  Placed my order today.  I'll order the electronics for the other truck when my oil well comes in.