I always wanted to have some NMBS B Cargo freight cars to transport steel on my model railroad. If you have ever been in Belgium, you may already saw those passing by at a station. These freight cars are pretty common and go by the name shimmns.

Several model railroad manufacturers already developed H0 models of these cars. However, I wanted to have a challenge and design one myself :muscle:!

Design

I use Autodesk’s Fusion 360 as my design software because I’m familiar with the design process it uses and the free license for hobby and academic purposes. However, the software is closed-source and locks you into the Autodesk ecosystem. I tried FreeCAD in the past, but I haven’t been able to get the same results with it as with Fusion 360.

It’s impossible to design the freight car in one piece. You make mistakes on the way and want to redesign some parts later on. Because of this, I design each part separately.

Each part of the freight car is designed separately.

Once I designed several parts, I create an assembly. An assembly is a design file where you import several parts and assemble those together. Moreover, you can design your parts in such way that they are 3D printing friendly while you can check in the assembly if they still fit together :smiley:.

An assembly of my NMBS B Cargo Shimmns freight car.

Designing and testing such cars takes weeks or months to get them right :open_mouth:. Although, once they are finished, you can be very proud of your achievement :smile:.

3D printing

I print my model railroad designs with a 3D printer. I have a Velleman K8400 at my disposal where I upgraded the bed to a heated one and an E3Dv6 extruder.

The Shimmns freight car consists of dozen of 3D printed parts. Not only the chassis is 3D printed, but also buffers and other smaller parts. These smaller parts sometimes require custom support which is removed after printing.

3D printed parts of my Shimmns freight car. Smaller parts such as buffers have their own custom support which is removed afterwards.

They say: “Three times a charm”, that’s the same for my prints most of the time. It takes several iterations to get your design and prints right. You have to take tolerance and other factors into account, while the model still have to be functional. However, you always learn something from a failed print which you can avoid when designing your next model!

Assemble time!

The best part is of course the assembling! It’s always a great feeling when you assembly your design and it just fit :smiley:.

The freight car’s canvas skeleton is first assembled. The skeleton is used to support the blue canvas of the freight car. It consists of several ribs which are separately printed and assembled as one skeleton.

Assembling the skeleton to support the blue canvas of the freight car.

The canvas is created from tissues and thinned wood glue with water (50/50).

  1. The tissue is flatted with the paint roller. The paint roller makes sure that tissue is soaked with the wood glue mix
  2. The tissue is placed over the skeleton and tighted by hand.
  3. Let it dry for a whole day. The tissue will become hard because of the glue, perfectly for painting!
Creating a canvas from a tissue with a wood glue mix.

I painted the whole model with a cheap paint spray can. It’s important to first paint the PLA plastic of the model with a primer. Afterwards, 2 layers of the final colour is sufficient to paint your model.

Painting the model with a cheap paint spray can.

Details are important when building a scale model. I created a mold to create the handle and other parts of the model. The mold is 3D printed and allows me to reproduce these smaller parts of each model in the same.

Handles and other smaller parts are created using a 3D printed mold.

Last but not least, the decals are added to the model as a final touch! It’s a precision work, but they make a big difference for a model.

Decals and final details are added.