The Ups & Downs Of 3D Printing Tanktainers

I’ve been a bit quiet about my 3D printed models recently; although I’ve made some progress I’ve also run into some problems which have really slowed me down.

So I thought I’d run through some of the steps I went through when trying to finish the models I’ve discussed in previous posts, some of the problems I experienced while doing that and what I’ll be doing next…

Overall I’ve been very happy with how the three printed tanktainers I’ve produced so far have printed but to finish the models I still needed to:

  • Clean the models to remove any residual support wax.
  • Paint the parts.
  • Create and add decals.
  • Assemble the models.
  • Create and add etched details such as walkways.

I didn’t necessarily complete the steps in that order though, so here’s how it actually happened…

Creating The Decals

I’d been itching to have a go at creating the artwork for one of these models since I started this project so I decided to start with the bromine tank. Why? Two main reasons, firstly, from the pictures I found online, most bromine tanks don’t carry any logos that I’d need to seek permission to use if I wanted to sell the models/decals in the future and secondly, bromine is so dangerous that bromine tanks are usually absolutely covered in ADR placards and warnings so they look really dangerous and cool!

I created the graphics for the decals in Inkscape which is an open-source, vector graphics equivalent of Adobe Illustrator. It was quite a steep learning curve but once you’ve got your head around layers, configuring snap-grids and using lines, curves, text and changing their properties it’s not too difficult to produce nice artwork. There are also a couple of good how-to guides on creating decal artwork that I used during the process but the key things to remember are to only use vector-graphics, that it’s best to put each colour used on a separate layer, make sure you only use RGB colours and remember to convert any text used to curves.

I was able to accurately scale the text and signs used on the tanks using prototype photographs and dimensions that I already had from building the CAD files for the models and I managed to find and resize some open source vector graphics of the various ADR placards used on the tanks which saved me the challenge of having to draw those from scratch.

Here’s a sample of the finished decals:

When the artwork was complete I sent it off to be printed by a company called Railtec. They produce very high-quality decals but they are very popular so unfortunately it may be some time before I receive the printed decals back.

Creating The Etches

I knew when I started this project that I didn’t want to try and 3D print details like ladders, walkways and placard holders; I think doing so looks clumsy and crude because 3D printers can’t print tiny details at scale thicknesses (yet) and it adds extra ‘bits’ that just get in the way or snap-off when you’re trying to clean, smooth and paint the models.

I’d actually started to plan the various parts that I would recreate with etched metal while putting together the CAD for the models as you need to think about incorporating tabs to support items like walkways before you create the etches or print the model.

As with the decals I created the vector-graphics for the etches using Inkscape.

There are a couple of extra design criteria to think about when creating etches (such as whether to use full etch or front/back half-etch, minimum hole sizes restrictions and minimum part thickness restrictions) so I spent some time reading the design guides produced by a variety of etching companies to make sure I fully understand the fundamentals and limitations before I started creating the artwork.

Here’s the end result of all that digital work:

This is the smallest sheet size you can have etched. As you can see you can fit quite a few copies of an individual etch or lots of different etches for different models when you work in N scale.

I’d planned to have the etches printed by a company called PPD, they get good reviews and produce excellent documentation. My artwork was accepted first time without needing any modification which is testament to PPD user documentation.

Unfortunately even though the quote they gave me wasn’t expensive I’ve had to hold-off on getting them produced due to lack of money.

Financial Problems

So, the really first problem I ran into was financial. I was already concerned that although my models compared favourably to any existing off-the-shelf items, they were quite expensive to print and decals/etches added further cost. I had initially been hopeful that I might be able to sell a few prints to help fund the costs of getting decals and etches produced but it wasn’t happening despite my best efforts at self-publicity. I didn’t have a job while all this was going on so I was getting worried about sinking too much into the project. Instead I thought I should focus on getting the models painted, assembled and photographed, perhaps I’d have more funds by the time they were finished and I’d be able to generate a bit more interest. So I pushed on with cleaning and painting the 3D prints…

Cleaning the Models

The first thing you have to do before painting a model printed in Shapeways Fine Detail Plastic is remove any remaining traces of the support wax that is used to support the model while it prints. Leaving wax in place could prevent paint sticking to the model plus if there is a particularly bad build-up it can and does look unsightly. However, despite trying a combination of manual removal with a tools, washing the model in cleaners such as acetone and a strong degreaser I still wasn’t sure I’d been able to remove all the wax from the models, particularly wax in some of the hard to reach areas.

I pressed on and smoothed any areas with visible print-lines. Overall the curved surfaces of the bromine tank and the end caps of the all the models had printed brilliantly, there were also no visible print lines after a little smoothing.

Unfortunately, the tank on the model I’ve been referring to as Tanktainer Type One wasn’t so smooth, complicated somewhat by the fact that the bands around the tank were vulnerable to damage so restricted sanding.

Here’s a comparison of the surface of Tanktainer Type One on the left and Tanktainer Type Three on the right:

In these pictures there doesn’t appear to be a massive difference but there is. I now wonder if the thickness of the tank walls could have been a factor in the quality of the exterior surface. The wall of Tanktainer Type Three on the right is thicker than Tanktainer Type One on the left?

Getting slightly frustrated and running the risk of damaging the models with over-zealous cleaning my curiosity got the better of me so I pushed on and decided to paint.

Painting & Assembly

As I don’t have access to an airbrush I use high-quality artists brushes and enamels to paint my models. Properly thinned with white spirit I find enamels go on much better than thinned acrylics and they also dry more slowly allowing you a chance to blend paint applied at different times more easily (imagine painting around a cylinder and working your way back to your first strokes).

After a couple of thin coats everything was looking pretty good and all the parts still went together as intended.

Painting did flag up a couple of areas where some of the details could do with being made more robust. Surprisingly this wasn’t due to paint build-up but because some of the detail had been created right on the limit of Shapeways 3D printing ability and a coat of paint highlighted every rough spot.

At this point, I’d only really been looking at the models under a magnifier or with the naked-eye and when I got the digital camera out to take some pictures my heart sunk. Everything looked rough! I felt deflated, even though the human eye can’t see it, the camera was picking up every tiny imperfection and mistake.

Time To Reassess & Next Steps

So I decided to step away for a while and reassess what I was doing. Not only do things usually look better when you come back to them after a break (which they did) but I had to reassess why I was doing this: was I trying to start a business or just make some models?

I think I was hoping I’d be able to start a little side-business but I’m being more realistic about that now. I am producing these for me and if anyone is interested in buying then that’s a bonus.

I’ve also taken some time to think about whether there is another way to produce these models (resin casting or injection-moulding) but I don’t believe it would be possible without simplifying the models and/or investing a significant amount of money.

So for now, I’m going to slow down and focus on one model at a time. I still enjoy producing the CAD files so there is no reason why I shouldn’t carry on building a library of CAD models. 3D printing costs may come down and there is a chance another high-resolution 3D printing service will enter the market and lower costs.

I haven’t yet got the money to 3D print the kit versions of the models I’ve already produced but that looks set to change soon and I hope that may solve some of the issues I’ve run into with cost and tank surface quality.

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