93 lines
4.2 KiB
Markdown
93 lines
4.2 KiB
Markdown
+++
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title = "A Very Digital Artifact"
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slug = "a-very-digital-artifact"
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date = "2022-11-11"
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[taxonomies]
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tags = ["3dprinting", "CAD", "GIS", "CNC", "art", "sundries", "proclamation"]
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+++
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![A plywood slab carved with CNC into a topographic representation of California][main_image]
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# A birthday wish
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Last summer, I wanted to get my wife something nice for her birthday. For many years, she had
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expressed an occasional and casual desire for a topographic carving of the state of California,
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where we live, and I thought it might be something I could figure out how to get her. In the end,
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after many dozens of hours of work, five weeks, and several hundred dollars paid to a professional
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CNC machine shop, I had the artifact shown in the picture above. This is the story of its creation.
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# First steps
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Before you ask, I did not do a ton of research before embarking on this. As I write this, about six
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months later, it only now occurred to me to do a basic search for an actual physical thing I could
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buy, and luckily it seems that CNC-carved wooden relief maps of the whole state are not trivially
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easy to come by, so, *phew!*
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No, my first step was to see if there were any shops in the area that could carve something out of
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nice plywood, about a week before the intended recipient's birthday. I found one that was less than
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ten minutes away, and filled out their web contact form. They had a field for material, and I said,
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"some nice plywood between 0.75 and 1.0 inches thick or similar" (I didn't know exactly what was
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available and wanted to give broad acceptable parameters), and under "project description", I wrote,
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> A relief map of California, carved from wood. Height exaggerated enough
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to visibly discern the Santa Monica mountains. I can provide an STL file if needed.
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For some [incorrect] reason that I only later examined, I just sort of assumed that the shop would
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have a library of shapes available for instantiating into whatever material medium you might
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need. But just in case, I included that hedge about being able to provide an STL file. Needless to
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say, that was a bluff.
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![the programmer's creed: we do these things not because they are easy, but because we thought they
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were going to be easy -- from twitter user @unoservix, 2016-08-05][programmers_creed]
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*<center><sup><sub>me, every time</sub></sup></center>*
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Also needless to say, my bluff was called almost immediately, and I had the following exchange with the
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shop:
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> *CNC Shop*: STL can work but I can’t manipulate it, which could save some money. If possible can it
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>be exported to an .igs or .iges or .stp format?
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>
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> *Me*: Yeah, STP should be no problem. Can you give a rough estimate of the cost for 1x2-foot relief carving?
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>
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> *Shop*: Without seeing the drawings, I can’t give even a close price but in the past they range from
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>a few hundred dollars to several thousand dollars.
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>
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> *Me*: That's totally fair! I'll get you some files in a few days.
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As you can see, I leaned even harder into the bluff; my next communication with the shop was nearly
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four weeks later. But that's getting ahead of things.
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# Meshes and solid bodies
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First off, let's talk about file formats and how to represent shapes with a
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computer.[^math-computers] I said I could provide an *STL
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file*. [STL](https://en.wikipedia.org/wiki/STL_(file_format)) is a pretty bare-bones format that
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describes the outside surface of a shape as a set of many, many triangles, each of which is described
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by three 3D points. This format is popular with 3D printers, which is how I became familiar with
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it.
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This type of representation is easy to create and read, but it's not great for manipulation.
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# Public data
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## From space?
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## Thanks, California state!
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## In Australia, it's pronounced "g'dal"
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## Give it a good smear
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# Test prints
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# Final cut
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# Thanks
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[main_image]: PXL_20220723_214758454.jpg "A plywood slab carved with CNC into a topographic representation of California"
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[programmers_creed]: programmers_creed.jpg "jfk overlaid with the programmer's creed: we do these things not because they are easy, but because we thought they were going to be easy"
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[^math-computers]: I'm pretty sure this is more "represent shapes with math" than with a computer, but
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the computer is just helping us do the math and it's more relatable.
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