For the last several days I've been printing like a mad lad for an upcoming large product, but there was some filament at the end of my first 1kg roll that needed to be used up. Rather than waste it or save a bunch of scrap filament, I decided to test out some new part files designed on Fusion 360.  Honestly, I'm quite happy with the results of this testing!

I wanted to test the feasibility of making rolling stock and other model equipment by breaking down the model into assemblies that can be glued together like a kit. It took a couple of tries, but on the third go everything finally went together smoothly.  The model is a 28ft narrow gauge box car in O scale and here are the results of the 3D printer:

Side view of the model with 3D printed sheathing.

3/4 view of 3D printed sheathing.

Side view of 3D printed frame.

3/4 view of 3D printed frame.

Bottom view of 3D printed car frame.

The assembly consists of two kinds of parts, a frame, and sheathing. The frame pieces interlock in the corners and are quite strong once the glue dries. I like having the option of not using sheathing if wood or styrene sheet would work better.  I do like how the 3D printed sheathing came out.  Everything was printed on my Ender 3 V2 and nothing required any kind of support. The part files consist of:

• Floor frame
• Side frame
• End frame
• Roof frame
• Floor deck
• Side sheathing
• End sheathing
• Roof sheathing

There are still parts I need to design which will make a more complete car.  These include:

1. Freight trucks
2. Truck bolsters
3. Roof walkway
4. Door assembly
5.  Queenpost bolsters/beams

Small detail parts are probably best if they are made of metal rather than being printed.  Grab irons, queenposts, brake gear, door latches, etc... would be more durable if they were made of white metal or brass.

My assembly process to get this far has been to first print the frame pieces.  Depending on the scale and size of the printer, this should take one or two print sessions.  The sheathing is then printed, also in one or two batches. I glued together the ends, sides, and roof frame and at the same time glued the deck onto the car floor frame. Once both assemblies were dry, I glued the car body to the car floor.  Once the frame was dry, the sheathing pieces were added.  I stopped at this point because I want this model to be a prototype and demonstration of how the pieces fit together.

I'm happy with the result because it is a square freight car that didn't take too long to put together on a work bench.  None of the pieces required support structures or special printing techniques, they just printed right onto the bed. Using the weight of the individual parts in grams, a model should only cost about $3.00 in PLA filament.  That includes the parts I have yet to completely design, so that figure is an estimation. Wheels, couplers, detail parts, paint, decals, and weathering would add to the cost, but ideally this would be about $15-20 per car.  The biggest benefit that I can see here is that now there's an option to make rolling stock and equipment from unique prototypes, or have something that looks different from what major manufacturers sells.

If anyone is interested, I'll be happy to share the files. I don't know how to post them up here though, so I'll have to look into that.