Physical

Casting a freeway interchange

Art, Atoms

If you live in LA, you probably are familiar with huge freeway interchanges. It’s an impressive network of forming a big knot that somehow channels various streams in all the possible ways. It has huge curves sweeping above and below the main wide arteries. Anyway, they are cool. My favorite is where the 110 and 105 interchange and I’ve been mulling over making a cement casting of it for a while now. It starts with grabbing 3D data from the interwebs and turning it into a functional model.

Once the data is prepped, I prepare it for 3D printing. I want the final piece to be 26 inches wide which is wider than any printer I could get my hands on so I break it up in tiles and run some tests.

  • cut out a tile and make a negative shape
  • positive and negative tests

Next step is to figure out the process of making the mold. There two options but the first step for each is the same: glue the tiles back together (there will be 16 of them) and use bondo, sand paper to smooth out all the irregularities, and spray paint some urethane to smooth over the result. The question is: should I make the urethane mold directly from the positive 3D prints, or should I create a positive plaster intermediate I can tweak and further polish, and make a mold out of that? If I go with the plaster, I worry that the brittle nature of the plaster and the rigidity of PLA filament will cause the small details to break as I release the plaster image from the 3D print. If I pour the mold directly on the 3D print, I worry that the tell tale 3D print lines will be captured by the mold and that I will not have had the chance to polish it with the control a plaster intermediate would give.

So, next step is to test both approaches on my two test prints, and also test printing a tile with PETG filament which I hear is more flexible. If you have any recommendations, I’m all ears…

Building an Ultra Large Format Camera, Part 1

Art, Atoms

The basic elements of a camera

One of the cool things about a camera is that at its core, it’s very simple. All you need is a lens that focuses light and a surface that this light gets focused on. The process of bending light with lenses to focus on a surface was first explored during the Renaissance with the camera obscura. It wasn’t until the 19th century that people figured out how to keep a record of how much light hit a particular area of that surface. Anyway, to make a camera, all you really need is a lens and a surface for the light to hit, and to create an image from a camera, you either need to trace the image you see projected on the surface or you need some kind of coating on the surface that reacts to light.

lens_ring

Is that a large lens in your pocket?

After giving me a taste of 4×5 tintypes, my buddy at Tintypebooth showed me some large old lenses from photographic systems used in spy planes that he had bought on ebay. These things are serious! They are very heavy and the glass is super thick; there is just something massive about them, and when you hold one and feel its weight, you can’t help but be awed by their image making potential and you get possessed by an urge to unlock that potential. He pitched the idea of building a ultra large format camera with one of them, a little “Kodak Aero-Ektar 24” 610mm” number, weighing in at just over 10 lbs and sporting a few scratches I like to think were caused by the strafing of some of the Luftwaffe’s last Messerschmitts.

Let’s decode those numbers, shall we? The 24” is the size of the image plane and 610mm (also 24”) is the focal length.Based on my previous post about lenses, it means that at its shortest, this camera will be a little over two feet long. At four feet of distance between the lens and the plane, the image on the focal plane will be the same size as the subject in focus four feet from the lens, and six feet will create an image bigger than reality. The film holder will need to accommodate plates that will be 24 inches on one side. I may need a bigger car…

camera_build

I need a plan

Patience is a virtue I’ve always been in somewhat limited supply of. We have this killer lens… What’s the fastest and cheapest way we can get a picture out of it? Sure, we can design a fancy camera with a lot of bells and whistles but it would take a long time and cost a pretty penny. For now, I just need a bare bones proof of concept prototype. I’ll focus on the basic pieces and see if I can build it myself. I’ll build the back out of oak and do all the struts and supports using aluminum channels. The animated image above is a Maya model I built to scale that shows how all the pieces need to fit together. It doesn’t look too difficult, does it? One thing not shown in the animation is that the back that will hold the plate will be interchangeable with another back that will have the ground glass necessary to focus. The process will be as follows: first you will use the ground glass back to focus, slide it out, and then slide in the film back to load your camera.

film_back

Baby got back

Kim Kardashian’s got nothing on this bad boy! I built this 24″x20″ film back over the past couple weeks. I’m not a great builder and my Home Depot tools are a bit wobbly so I wouldn’t call it fine craftsmanship but it will hopefully do the trick. Oh, and did I forget to mention it’s not exactly square? Yeah… Let’s just say it’s square enough. It’s made from 1″x2″ and 1/4″x2″ red oak lumber which I routed to get the insets. It will make a great example when we eventually hire a finish carpenter for the next fancy version of the camera. Here are some pictures of the various pieces it’s made of (you can also see that I like to wear my slippers when I take pictures of my handy work).


More to come…

Here are the steps that come next and will be documented in a hopefully not too distant future.

  • I already bought the aluminum extrusions that are necessary to build the film back support, the lens plate holder, and the rails. I will need to learn how to properly drill in aluminum and figure out how to connect all the pieces. (anyone in Venice with a drill press?)
  • I will built the lens plate, mount the lens on the plate, and mount the plate on the rails.
  • Last will be creating the bellows. Not too sure how that will work but what the hell! We’ve got a few ideas. I’m sure we’ll figure something out.

See? It’s basically like it’s done already…