Features and Specifications
- Dimensions: 80 x 30 in (6'8" x 2'6"), 200 x 76 cm
- Scale: ~1:390,000
- Projection: Mercator
- Four stain colors — there are 25 of each color and no adjacent counties share the same color
- All counties are labeled with their name in 3/8" vertical text
- The outer banks are not shown (too thin) but all 100 counties are represented (no counties are exclusive to the banks)
- The counties are cut out of 1/2" birch plywood and glued to another single piece of 1/2" plywood
- The counties are spaced with a 1/8" gap
My friend does some work for ShopBot Tools in nearby Durham, NC. He recently let me borrow a HandiBot CNC tool.
One of the first things I did with it was cut out a small etching of North Carolina and its 100 counties…
It wasn’t long before I thought about cutting out the individual counties and piecing them together like a puzzle. The HandiBot has a 6 x 8 inch cutting area, so it seemed like if the largest counties filled that area I’d have a sizable (but manageable) map on my hands. (Full disclosure: I didn’t even calculate how big the map would be before I started making it. I just figured out how to scale the map so the HandiBot could manage even the largest county.) I did a test run of 10 counties with some thin wood…
My next thought was that it’d be nice to label the counties. In the end I labeled them with their names, but I had also considered putting one or more of: population, year established, county seat, etc. but it would’ve been too busy, especially for the smaller counties.
For the text I used a simple online tool that lets you fill out a form to generate G-Code for any given text. I wrote a Python script to automatically fill out this form for all the text I needed. http://microtechstelladata.com/TextToNCcode.aspx
Here are some early labeled counties…
For most counties, the text is placed at the centroid of the county. But I had to manually tweak the position for many counties. And for a few, I had to rotate the text.
After I figured out all the details, I entered full production mode to cut out all 100 counties.
I used a 90 degree v-bit to cut the text and etch a bevel around the perimeter. Then a 1/8" ball nose bit was used to cut out the counties. I marked the HandiBot placement with pencil so I could do several cuts, change the bit, and then do the second pass.
After I finished cutting all 100 counties, there were obvious variances in the wood grain, so I ended up redoing a lot of the counties.
Here’s what the map looked like after recutting many of the counties…
I was loving it already. I hated the idea of staining — so much work! But I knew it needed to be done.
I had the idea to use multiple stain colors. The four color theorem states that any 2-D plane can be colored with only four colors in such a way that no neighboring shapes share the same color. So I wrote some code to generate such a coloring for the 100 counties.
The first results from the staining were very pleasing!
The stained pieces looked great, but through the whole process of staining I wasn’t quite sure what to expect when assembling the entire map.
Once I started assembling it, I’m sure I had a giant grin on my face because it looked awesome…
I also applied a semi-gloss clear coat, which didn’t turn out as nicely as I had hoped — I ended up with some bubbles hardening in it but they aren’t really noticeable unless you look for them.
Now I needed some way to mount this thing on the wall. I ended up doing a huge tiling job with the HandiBot… I penciled in a grid on a 4 x 8 foot piece of plywood and cutting 44 individual 6 x 8 inch tiles to create a single piece that I could glue all the counties onto…
I stained the backing board too so the raw wood color wouldn’t show through the gaps between the counties. I also engraved some text on the back of it.
I then learned that wood glue doesn’t work so well on stained wood. And it wasn’t really practical to clamp all of the counties. So I just sanded both sides really well and applied pressure for several seconds. It turned out fine — the glue doesn’t need to be super strong here.
Luckily, the final product is big enough to be impressive but small enough that one person can move it around. I would guess it weighs around 50 pounds. Here I am holding the completed product…
All in all, it took me 2–3 weeks to do this. I’m excited to work on more CNC projects!