Completing the Dummy Chassis for a Bachmann EMD DDA40X

The test print for the Bachmann EMD DDA40X has arrived so in this post I will show you how it worked out and what we did with it.

This print was made from Shapeways’ White Strong & Flexible material (WS&F) and this was the first time I’d used it.  The finish was a little rough out of the box but the overall definition was good, as shown below.

DDA40X Dummy Chassis 1

It is, as the name suggests, strong and it holds its shape perfectly.  Given that the chassis  will be mostly covered up the roughness is not a concern, although it could easily be smoothed with a quick wipe with sand paper.

The chassis has been designed to work with the fuel tank which comes with the DDA40X. The fuel tank clips onto the chassis using the same fixing lugs that are on Bachmann’s power chassis.  Below is an image of the tank clipped onto the chassis; what it doesn’t show is that the lip on the chassis that fits inside the tank is little bit too big and needed to be filed down.  This has been fixed in the 3D model.

DDA40X Dummy Chassis 2

Bob, who does the painting and assembling, wanted to add power to the model as the DCC circuit board was still in the shell which also controls the top and tail lights and the flashing light on top.  Because this is a test print, and because I haven’t drawn the correct ones yet, we are using dummy trucks designed for an EMD DD35 model.  These work with 4 Fox Vally 36″ metal wheel sets (FVM3611) each.

The trucks are printed in the Shapeways FUD material as they are highly detailed.  Bob sprayed them with a base gray and then added power pickups using thin copper strip.  The strips where soldered to the ends of bolts to be used instead of the bolster pins as pictured below.

DDA40X Dummy Trucks 2

DDA40X Dummy Trucks 1

The strips pick up power from all axles on each truck.  The washer was added to the first photo above because the chassis sat a little too low and rubbed on the side of the trucks.  An extra down stand has now been added to the chassis 3D model to accommodate this.

The shell needed a little modification as well.  Power wires have been added to the circuit board with washers so they can be connected to the bolts which attach the trucks.

DD40AX Shell 2

The central corridor has also been completed.  Because the Bachmann chassis fills the whole shell, Bachmann did not add the side walls to the corridor, but when the shell is fitted to my dummy chassis there would be a big void viewable through the doorway.  Bob used plastic strips to complete the corridor.  He painted the inside of the walls black and the corridor Armor yellow to match the shell.

DD40AX Shell 3

With all the parts assembled it became apparent that the overall model was too light so Bob added some extra weight inside the fuel tank as pictured below.

DD40AX Shell 4

Here is the model on the track powered up. It runs freely and is perfect for a second unit or mid train helper.

DD40AX Dummy 2

As this was the first time using the WS&F material I’m keen to try it on another project. It is rougher than the FUD and has a little less definition, but its strength and cost effectiveness will lend itself to projects which, if made using the FUD, would be unrealistically overpriced. Obviously body shells etc that require the detail will have to be done in FUD but with 3D printing any range of parts for the layout can be produced, and new materials are always being made available so watch this space!

Once I have drawn up the DDA40X dummy trucks I will make the kit available through my Shapeways site.