Comparing 3d Printed Freight Cars Against Kits of the Past
March 18, 2018
Our Hart gondolas are special because they represent models that haven’t been done accurately in HO. When I talk about the Hart gondolas, like to highlight how the models represent freight cars that haven’t been done accurately in the past. There’s no resin kits, no brass cars. However, we did have two cars in the past: the craftsman kits from Silver Streak in the 1960’s, and Train Miniature’s plastic shake-the-box kit from the 1970’s. Both are good for their time, but we can do a lot better in the 2010’s.
How much better? Let’s compare the Dry Creek Models Hart gondola against the Silver Streak and Train Miniature kits. I picked up both at a train show recently.
[ Silver Streak ]
Let’s first look at the Silver Streak kit. For the time, this is a neat kit. It has the underframe trusses from the real car, side-mounted brake cylinder, and matches the SP cars with eight posts on each side.
The kit also lacks the car sill at floor level on the real cars, instead showing siding going all the way down to the bottom edge of the car.
Just like the modernized SP cars, the Silver Streak Car has grab irons on each end supported by a short vertical piece of wood. It’s also missing all the door hardware; the real cars had castings at the bottom of each post, but that’s a pretty tiny detail to include. The modeler who built this kit didn’t quite get the partitions at the correct location - they should line up with the outer post.
The model’s a little coarse with 6x6 strip wood serving for the top rail and for the posts, but it’s a fair tradeoff for intermediate modelers building their first car. It’s nice to see the board detail on the inside faces of each side. It’s also a bit oversize, with the sides measuring almost five feet high compared to three on the real car.
[ Train Miniature ]
Here’s the Train Miniature car. Again, it looks like it got inspired by the Southern Pacific cars that would have been seen in the 1930’s and 1940’s… or they just copied the Silver Streak car. The car has the correct eight spaces between posts. The grab irons don’t match the real car. More importantly, the trusses are pushed out to be even with the sides - definitely not how the real car was built. Like the Silver Streak car, Train-Miniature left out the car floor visible on the sides. Again, the car sides are taller than
[ Dry Creek Models ]
And finally, here’s the Dry Creek model. I pulled out one of my “original” cars just to highlight the detail. 3d printing gives us a lot of advantages, including the ability to throw in all that detail for the door hinges , the door latch mechanisms on the posts, and the various bolts all over the model. The truss is lighter than the Silver Streak car, we can see the car side frame and floor.
[ Top down ]
Here’s all three from the top: Silver Streak on the left, the Train Miniature, then Dry Creek’s 3d printed model. The Silver Streak car did correctly model the sloping hopper. It’s not perfect; this kit shows the hopper as incorrectly extending up along the bulkheads on each end. But I’m pleased to see they included the supports that ran through the hopper, even if they’re incorrect. There’s no detail on the doors, but then that’s a pretty tiny detail.
The Train Miniature kit’s hopper is hidden by the load, but that brake cylinder and brake gear in each end is completely wrong for the car, and misses the fact that those partitions were meant to be removable so the car could be used as a typical gondola.
And finally, for the Dry Creek models version. We see the braces running through the hopper (with the notch to hold the 4x10 that supports the doors when closed. We see the end bulkheads definitely look removable. On the far end of the car, you also might see the hinged apron that allowed running a plow through all the cars - a detail that wouldn’t be needed on either of the other modernized cars, but does highlight how 3d printing lets us throw all that sort of detail on the car.
[ Bottom ]
Finally, here’s the underside of each car - Silver Streak on the left, Dry Creek in the middle, Train-Miniature on the right. This photo highlights how the other two cars are a bit oversized compared with the actual cars, and the needs of manufacturing made details like the trusses much more clunky than on our 3d printed model. Both Silver Streak and Train Miniature made some parts oversized (like the trusses) and also placed the trusses differently to make the car easier to manufacture. Both also had to lose some of the interesting detail: braces for the trusses, side sills, etc. in order to make an economical and easy to build kit.
All in all, the Silver Streak and Train Miniature kits are fine for both their time and for what they’re intended for. They had to design parts to be manufacturable (Train-Miniature moving the trusses out), needed oversized parts for easier assembly, dropped details to keep part counts low or permit injection molding, and did the best they could from photos.
The Dry Creek model, instead, gets to benefit from being 30 years in the future. I had access to the SP blueprints which the earlier manufacturers may not have had. 3d printing meant I could make parts closer to scale, and could easily add details that would have been impossible with injection molding. 3d printing also allowed me to refine the models, and quickly make variants: doors up vs. doors down, or the modernized cars without the side dump doors. If I found some railroad back east had a similar car but with a minor tweak, I could make that too. If I was injection molding, I would have had one shot at making the molds, and would have focused on making only the kit that would be most popular.