Over the last few weeks I have been working on the 3D model for the Baldwin DT6-6-2000 center cab locomotive and it is now ready for a test print.  In this post I wanted to share with you some of the details I have included in this new model.

If you missed the first part of this model design you can find it here.  I finished the first part with the image below which showed an overall view of the shell at the then current stage.

Since then I have finished all the little details and fixed several of the issues that were not working.  The biggest issue was the size, or to be more precise, the length.  Although the 3D model has been accurately drawn, this shell has been designed to fit onto a powered chassis taken from an Atlas C-628 with the trucks rotated, as I illustrated in the first post.  The issue arose when the trucks were rotated they were not located in the same position as the DT6-6-2000’s trucks and they clashed with the bulkheads at either end.  To resolve this I have added 100mm at each end, which doesn’t sound a lot and in fact, in N scale, it works out to be an extra 1.25mm overall, but having tried to keep it as accurate as possible, suddenly adding 100mm made it look odd.  To hide this I dispersed the 100mm throughout the model by moving door sets up by 10mm etc and I don’t think you’ll be able to tell.  I also had to add about 60mm to the height because of the chassis being slightly taller but once again I don’t think it will be noticeable in N scale.

To make sure this would fit the power chassis snugly I also modeled it in along with all of its lumps, bumps and fixing points so these could be replicated in my 3D printed shell.  Below is an image showing the chassis fitted into the 3D model with half the shell removed.

I also modeled in the power chassis trucks without their side frames.  This is because I need to provide new side frames as the C-628 frames are not right for this model.  A fellow modeler has also produced side frames for this locomotive in cast resin and when this kit goes up for sale I will include a link to his website for anybody who would prefer to use those.

My truck side frames for this kit, pictured below, are designed to fit directly onto the power chassis trucks using the same fixing lugs.  The side frames also clamp the power pickup strips to the wheel tips so getting the size of the side frames right is very important; if they are loose the locomotive will have bad power pickup or even worse, will simply fall apart. If they are too tight the wheels may not turn easily and this will overstress the motor.

Another issue I ran into was that the C-628 trucks are not only taller but also have a lot more going on.  Consequently, when I put my frames over the power chassis trucks you can see way too much.  To resolve this I had to increase the height of the frames by 60mm and blank off some of the clear spaces. However, as pictured below, I don’t think they look too overworked, and on the plus side it adds strength to the print.

The other major detail I have added is the cab interior and engineer.  Just about all of the ready to run locomotives I have ever purchased don’t have engineers or crew in the cabs and given the capabilities of 3D printing it seems silly to leave them out.  The real DT6-6-2000 has a cab which stretches across the whole locomotive, and as there is an engine in each nose section, you can see through to the other side.  However with this model when you look into the cab from the side all you will be able to see is the C-628 metal chassis, so I have designed a cab section with a blanking wall that is a separate part.  As well as hiding the metal chassis this allows you to paint the inside of the cab and the engineer before fixing it into the shell.  I have provided a cab section with an engineer for both sides allowing either one of the engineers to be removed as required.

The cab and controls look a little basic but remember this is for an N scale locomotive and they will only be visible through the windows, a bit like the image below.

And if the cab was illuminated with a nice yellow light from above this would look great!

The windows have a recess on the inside of the cab to make it easy to fit a small rectangle of clear plastic as glazing; I will provide a template in the instructions for cutting these to the right size. I have also included details such as the air horns, body lifting brackets and steps on the shell as shown below.

Behind the headlights I have included a cutaway so after drilling through the headlight an LED can easily be pushed in from behind.

The handrails are all separate parts and I have added holes in the shell which match up to lugs in the handrails, which makes them easier to install.  If you want to make your own handrails out of a thinner material, such as brass wire, the holes are designed to be in the right places so they can be used as guides.

And here is the finished 3D model

The test print has now been ordered and in a later post I will show you how it came out.