Hit the Bricks

1/19/2018

Brick texture samplesAs you may have read about already, the first building kit that I made was SK001. It is modeled after a building built from bricks. Since I had no idea how bricks at 1:160 scale (n scale) would turn out on my 3D printer, I decided that before I started to design the building, I would focus on creating a brick pattern that would look good from my printer. I wanted to create an actual brick texture rather than a flat brick simulation. It's 3D printing for pete's sake! It's gotta be 3D!

I first established my requirements:

  1. The mortar lines between the bricks will be large enough to capture watered down paint during the weathering process.
  2. The bricks need to be large enough to be practically seen by the eye but small enough to be realistic in N scale.
  3. It has to be a repeatable pattern that can be used in future models.

Next, I did a quick search on Google for a standard brick size in the U.S. This would be a good place from which to start modeling my bricks. The dimensions that I found were a depth of 3 1/2 in, a height of 2 1/4 in, and a length of 8 in. According to the Woodland Scenics Model Scaler app on my smart phone, this converts to a depth of .508mm, a height of .357mm, and a length of 1.27mm in N scale. The average mortar thickness between each brick is 10mm which converts to .0625mm. That's pretty tiny! It's SO tiny that it wouldn't be practical to go with strict scaling measurement because the human eye standing at least 4 feet away wouldn't be able to see these details.

It was time to make some functional alterations to would allow the bricks to be more visible to the human eye. This means that I'd have to sacrifice the prototypical scaling measurements. I decided that it was worth it in order to make them look good. The depth would remain at between .5mm - .7mm. That is deep enough to capture paint to create the mortar lines. The thickness of the mortar lines would be 1mm. This would be easier to see than half a millimeter! The brick height would be about 1.5-2mm and the length would be 3-4mm. Proportionally, this would look pretty good.

Armed with my measurements, it was time to go to my CAD (Computer Aided Design) program on my computer and make some digital brick models. I created a slab that was 20mm x 10mm x 2mm. I then created some long thin slabs using the dimensions above to create a grid. I lowered the grid onto the top of the 20mm x 10mm x 2mm slab so that they sunk into the slab by about .5mm. I then subtracted this grid so that it would cut out the mortar lines. Presto! I had my brick wall sample!

Now it was time to take it to the 3D printer! Would it turn out the way it looked in the CAD? Would the material expand slightly when cooled altering the dimensions? Would there be a little extra "play" when the printer created the patterns, again altering the dimensions? As you can see from the photo, it took some trial and error to understand how the printer would behave. This required several revisits to CAD to make some compensations in the design. On one sample, the mortar was thicker than the bricks. That wouldn't work! I also experimented with staggered vs straight brick patterns. I have filed those away for future kits.

Once I had a brick pattern that would work, I went back to the CAD tool and designed SK001 with the brick pattern applied to the wall surfaces. I was also able to use them for SK003 and SK006.

All in all, it was a great learning experience. I learned a lot about how to use my CAD software and I was able to create several satisfactory brick patterns that I could use for other kits in the future. Time well spent!

-Rafe