Grand Trunk Railway 3D Printed Caboose - Part 2

I'm now the proud (?) owner of an Anycubic Photon Mono X 3D printer... Why I say proud with some irony is because these little beast requires a lot of care to operate, but they yield great results for what they are.

Over the last few days, I refined my original 3D model following advices and examples by Dave Bedard, another Canadian 3D modeller doing a great job with CPR prototypes. I want to thanks him because I was able to better understand how supports work and can enhance the work. Following his example, I broke the model in several parts to ensure better quality prints. Going full monolithic is a recipe for disaster and breaking it doing into a simple but efficient kit is a much better option.

So far, I've completed the upper structure and printed a first test. I can see a few places that can be improved, including grabiron brackets and fitting tolerance between parts. Also, it became quite apparent that modelling some parts true to scale simple means they can hardly be seen. They will need to be slightly scaled up to provide more visual interest. This is a compromise I can live with because what's the deal about details that are barely visible?

The next big step will be completing the 4 bars archbar trucks and breaking the underframe into printable parts. No idea when it will be done, but I hope soon.

Grand Trunk Railway 3D Printed Caboose

I've been working on various 3D printing projects since earlier this year. Most of them are geared toward models I need for our layout but that can't be found in kit or RTR versions. However, a few are only whimsical projects of my own because I fancy the prototype to some extent.

About three weeks ago, I stumbled upon a set of CDS Lettering Grand Trunk Railway caboose dry transfers and purchased them on the spot... $4.00, you can't go wrong. It prompted me to start looking again at pictures of typical Grand Trunk Railway cabooses of the early 20th century. They always caught my eye because of their lovely Bombay-style cupola roof. But the most interesting thing is this specific caboose was quite similar to a very common model of an old time 3-windows caboose once offered by MDC/Roundhouse and now produced by Athearn.

A typical GTR caboose (credit: unknown)

Then I thought, why not design a 3D printed conversion mini-kit... which I started designing right on the spot. Lots of compromises had to be done, but thanks to Clare Gilbert, Roger Chrysler, Steve Lucas and Brian Westhouse, I soon had enough pictures and information to move forward. A friend printed a few tests which showed it was a promising idea. A day later, the artwork for decals was ready too, with custom drawn fonts.

However, it became quickly apparent bashing the Roundhouse caboose would take a lot of time and not look that prototypical. Printing a kit can be costly when you take into account all the related cost, but resin isn't where most of the expenses are. Why not simply make a complete caboose kit like Dave Bedard does on Facebook? For almost the same cost, you can have an accurate model and not just a stand in.

And now I'm at the crossroad. You can't design models if you don't have a printer. You need to test the design, try different orientation and supports to get optimal results. You must also build the kit to find out the issues. This can't be done by relying on others' printer. Thus I decided to acquire a 3D printer. Over the last few months, 3D printing as started to take a more prevalent place in my modelling. Projects that were pipe dreams are now possible. It is no longer required to be hostage of the dwindling detail parts market that is dying off. I often wanted to convert a few of my old steamers in better rendition of Grand Trunk and Intercolonial locomotives. Need a headlight, a dome? No problem. I've been experimenting with this media for 7 years now and it had finally reached the level of quality I wanted.

The Grand Trunk caboose kit joins my growing catalog of models, namely the CN Transcona-built 65ft woodchip car, the CN NSC-built woodchip car and the CN 65ft gondola. I have still to figure out how I will produce and market these models, but I have already a few options out there.

The State of My Various 3D Print Projects

 As you know, I've been pursuing a few 3D printing projects including two CN woodchip cars, a CN 65ft gondola and a GTR Bombay-style cupola caboose conversion kit.

During the last few weeks, I was able to iron out most design flaws out of my initial 3D models and I'm getting prints of the level of quality I wanted, i.e, almost no sanding, fine details and ease of assembly. However, I'm not a master a this trade and the most tricky part in the process is adding 3D supports to your models so they print correctly. A mistake in that department and serious deformations can occur. Don't ask me why, just look at the failed shells in my garbage bin and you will understand.

In that regard, looking a various online 3D printing resources was useful, however, very little videos or tutorials are geared toward railway modellers. Most are in the wargaming hobby, meaning deformations are at least more tolerable because they work with organic shapes. Unfortunately for us, our prototypes are mainly boxes and if something isn't 100% square it shows off quite a bit and ruins the look whatever the quality of the print.

So I'm trying to figure out how to design the best supports for my prints. Until this serious (and last issue) is finally addressed, I hope to be able to move forward toward production or distributing STL files for those interested. At this point, the GTR caboose conversion kit is my priority because it is smaller and can serve as a good base to sort out printing issues.

While I don't hope to make a living out of these projects nor want to start a business at any cost (lack of time and interest), I wish these models can be available to other modellers as soon as I can.

CN 65ft Gondola series 156000 - More Improvements

Design is an iterative process. I could have use the printed shells as is, but I prefer to refine the design a little bit so it can fit my needs and others much better.

The car ends were reworked a little bit to look better and be easier to produce. A few prototype pictures also shown I didn't use the right brakewheel housing, so this issue was addressed. I tried molding the brake rod directly on the model like an old blue box era car, but it didn't look great. It will be easier and more realistic to simply insert a small L-shaped wire.

The space between structural members was also a little bit too tight for a Kadee #242 coupler pocket and I adjusted it to fit perfectly. 3D print is great when you can keep preparation work at a minimum. I also alter the coupler height to conform to NMRA standards using a Kadee coupler gauge.

The next big change came later when I tried to fit weight on the underframe. My initial thought was to fill the space between the members with steel shots. However, after testing how much weight could be added, it was clear it was a far cry from basic NMRA recommended practices. The cars should at least weight 5.5 oz each once completed. Right now, the shell with trucks, couples and metal wheels is about 2.5 oz. I need 3 oz more and it was clear that could only be achieve with lead.

I have a box full of Select Xtras lead wheel weights part #FSL03 laying around. A quick test shown me they would fit perfectly between the main underframe members and be completely invisible... excepts for a caveat: the intermediate members would need to be removed. Given underframe details are less important in my eyes than a great looking gondola interior, it didn't take me long to remove the extra members from the 3D mode. It is certainly less accurate, but at least it doesn't impact the brake rigging, which is much more important because it can be  seen under certain circumstances. On the positive note, an entire wheel weight stripe can be used per car, adding exactly 3 oz as required.

CN 65ft Gondola series 156000 - Learning From Your Mistakes

Through my limited interaction with 3D printing over the last few years, I've come to realize this technology wasn't a panacea to all the ills of modelling, but rather a tool. And like any tool, it comes with a set of possibilities and another of limitation. It's all about mastering the skill if you want to succeed, and to be honest, I'm not there yet. However, I have started using a friend's 3D printer and having to set the printing parameters, model orientation and add supports is quite a steep learning. It's something I wanted to avoid at all cost, but at some point, you do it yourself or nothing will ever happen, just like kitbashing.

New large capacity printers can do 65ft cars easily

Another game changer is how printing volumes have increased with new generation printers like Elegoo Saturn and Anycubic Photon Mono S. We've reached the point it's possible to print very long freight cars without requiring to break them into small parts. In my eyes, this is a big improvement. As uou have probably read when I assembled the woodchip cars, using 3D printed panels wasn't great.

When I started modelling in 3D I did what most people do: I read the printing material limitation then foolishly tried to cram as much details I could, if possible using scale measurement, in a vain quest for ultimate prototypicalness. Unfortunately, I also hit a wall. Perfectly at scale details aren't always printing well, but worst, sometimes they print well but they cast so little shadow you barely see them. As crazy as it may sound, prototypical doesn't translate as realistic. Like art, you need to exaggerate a little bit some features to make them stand out and play their role. Knowing what must be "improved" isn't always easy, but at some point, after a few print, you start to understand that some hills aren't worth dying on. A good example are open cars like gondolas. You've got to choose what you can live with: a detailed undeframe or a permanent load because weight in resin models is a major issue.

On a positive note, I've found out I can now print excellent one-part models, including very fine and realistic ladders, brake chains, hooks and other intricate details. Funnily enough, it's like an Athearn blue box car with a few extra bits. And I won't fool you, it was my goal since these models are basically replacing Walthers 65ft gondola and will be used in operation. Nevertheless, they can be easily improved and detailed.

Print failure due to inadequate supports

Visible layers due to inadequate supports (vibration)

At this point, I'm experimenting with supports. A print need supports and they are key components for a quality and smooth print. However, they can leave pock marks and you want to reduce them or locate them where they won't be noticeable.

Lots on support marks on the floor isn't great

On my third gondola print, the supports were located inside the car as it was printed upside down. The reason is simple, the underframe details are supported by the floor as the car is printed. It ensures a very neat print, but I'm not a fan of patching support marks with putty on the car floor. I have a few options, use less supports, which would probably be advisable and maybe, try printing the car upside so the supports are on the underframe. It would make support removal easier and most pock marks wouldn't need to be repaired because they would be virtually invisible or buried under steel shots providing weight to the car.

A last mistake was the trucks. Taking inspiration from trucks made in Delrin by manufacturers, I designed my own Barber S-2 70-ton trucks. I then proceeded to print several pairs, which is much more economical than ordering them.

Unfortunately, while looking great, the bolsters were fragile and prone to snapping when installing wheels. A sturdier design with a solid bolster was implemented, making the resin strong enough to sustain normal abuse. It was a simple fix, but it proves your parts must survive the layout if you want the model to be a success and not a shelf queen.

Top: original bolster, bottom: improved design