Cotton Belt EV Caboose 41

The previous post covered the other "test" caboose I built when I began developing the concept of a 3D printed modular caboose kit. The prototype for this model was the inspiration for the whole caboose project. Like some standard cupola cabooses of Norfolk & Western and Great Northern, Cotton Belt's extended vision cabooses had the cupola side windows placed at the corners. Although it is possible to modify an Atlas caboose to represent this unique variation, I decided instead to try my hand at 3D printing a replacement cupola.

With the memory of kitbashes of a Frisco extended vision caboose:

...and one of Mopac's distinctive extended vision cabooses fresh in my mind:

...it wasn't long before I decided to print a new roof, ends and sides to save myself the trouble of cutting up the Atlas model. And so began - innocently enough - what has become a quest to be able to model nearly any version of the International Car Company's extended vision caboose.

Since the process was described in the previous post, I will let the photos do the talking here for the most part.

This was the first cupola I designed for this caboose. It has an opaque, white appearance that is the result of washing it in isopropyl alcohol to remove the waxy residue that's part of the printing process. Unfortunately, the alcohol also had the effect of distorting and shrinking the part. I also discovered that the alcohol made the part brittle at the same time I discovered the shrinkage. When I tried to fit the cupola to the modified Atlas body it split the cuopla. I printed another version of this cupola design and that's what you see on the model. 

After experiencing an alignment issue between the cupola and the printed body (which occurred because I didn't include any keys or tabs so the interior would remain clean for detailing), I revised the early higher cupola design to eliminate the sidewall extensions originally designed for the Atlas body and incorporated the additional body height into the sides. This design change means the higher cupola cannot be easily modeled using the Atlas caboose without modifying the body to include the side extensions, but it really isn't a difficult problem to solve for the motivated modeler. I couldn't see why my design needed to suffer to accomodate the Atlas body when I had no intention of using it for future builds. This change was carried out through all affected models in my product line. If you look closely, you can see the area underneath the cupola where I had to use Bondo to fill in the misaligned areas between the cupola side extensions and the sides.

I painted this model with a brown paint mixture I tried to match to an Athearn Genesis caboose. I started with Model Master Rust and mixed in some burnt umber and burnt sienna until I was satisfied/gave up. The orange ends were much easier: they are Model Master Go Mango. The window frames were painted the same as on the Santa Fe caboose. 

Just as with the Santa Fe model, I'm happy with this one. I would like to see the printing process get a little better and cheaper, but in the end I got much more than I had hoped for when I originally dreamed up the idea of printing rather than kitbashing this model's cupola. 

Highball! 

Santa Fe EV Caboose 999700

This caboose was built using an Atlas HO scale extended vision caboose as a starting point and with 3D printed sides, ends, roof, cupola, underbody and roof details. I painted it with Model Master enamel paints and lettered it with Microscale decals. The prototype was distinctive for being the only extended vision caboose to wear the color scheme of the proposed Southern Pacific Santa Fe Railroad known as Kodachrome or Shouldn't Paint So Fast.

Here are the 3D printed parts:

These photos show the body assembled, a process which is pretty simple. I began by aligning the correct end to the correct side applying "tack weld" dots of CA adhesive (super glue) from the inside of the body, then running a bead of glue along the inside of the joint once the fit is satisfactory. I repeated the process with the remaining end and side, then assembled the two L-shaped assemblies into a four-sided box. Finally, I aligned the roof parts to the opening for the cupola and secured them in place.

On this model and the Cotton Belt model no starter holes or grab iron ends are present, so all the wire parts were added using makeshift paper templates. I'm sorry to say it looks like it. But the good news is I revised all the models after assembling the two basic bodies so that each one is equipped with starter holes and grab iron ends appropriate to each prototype. In fact, I would say I learned a lot with these two models so that no others using this design would be so primitive. 

At this point I decided to replace the Atlas steps and crossover platform with Moloco parts and styrene sheet. Although the Atlas steps are pretty close to the Santa Fe prototype other than the number of steps, there is a clear difference between the Atlas part and earlier cabooses such as the Cotton Belt prototype that is the subject of the other build I was working on in tandem with this one. Since I would have to do the work anyway I decided to do it for both models. At this time I had primed the model with Model Master primer, which makes it much easier to work with and photograph than the unpainted translucent model.

The average end user of 3D printing services such as Shapeways is able to produce some really nice parts at this time, but to purposely leave out any mention of the weaknesses of this process as it is today would be dishonest. In the interest of full disclosure, take a look at the "ridges" in the roof running lengthwise in the photo below. Although I think I have a pretty good idea what causes this effect and how to avoid it, it sometimes still shows up. I was able to sand the ends of the roof and the tops of the embossed areas to try to minimize the appearance of the ridges but it's not completely effective. 

Finally, here is the model painted and decaled. I used Model Master Chrysler Engine Red, Insignia Yellow for the body and Light Ghost Gray for the aluminum window frames, followed by a drybrush of aluminium over the gray and black for the window gaskets. The trucks are painted with a mixture of black, burnt umber and gray.

It still needs light weathering and final details but that will have to come a little later. I have too many more of these projects to finish, not to mention the CAD for additional projects. It's not a perfect model by any means, nor was it an inexpensive one, but I think it is a good representation of the prototype, one that's not easy to obtain in HO scale.

Highball!