Camera Design: Update 7, “The Plate Tray”

Template Sketch

Plate Tray Sketch

Life has calmed down a bit and now it’s time to get back into building this camera. Title changed to Camera Design since it’s no longer a challenge for the most part. My next logical step is to start working on the plate holder. Get that designed and then I can work with getting those pieces attached.

When I designed the holder I started with the quarter plate, so I might as well start milling that first.

The plate tray is what the plate will sit on while in the holder. It’s purpose is to hold the plate steady for the photo while minimizing the area where the two touch. Because sometimes you can accidentally cut a plate a mm or two smaller or larger than exact Quarter Plate size, I wanted to make sure there was room for error. The holder door will eventually swing from the back and apply pressure to the quarter plate making sure it won’t come out of the tray or slide around and damage the corners of the collodion any more than necessary.

Template Cut

Tray Cut

The material this will be cut out of will be black plexiglass, a little smaller than 1/8″ in thickness. I’ll cut the corners to a little less than half of that and make sure they can still take the pressure of the back door without cracking. Because this is a black plexiglass the corners of the plates will be completely unexposed. Some people like this, some don’t. If you want those corners to expose a bit, you can always get this made in clear plexiglass or cut the corners completely out and string wire across each gap for stability.

Here’s the cut with the inside piece and protective backing paper still attached. As I’ve mentioned many times before it’s not a good idea to just cut your parts out, you’ve got to build bridges so that the pieces cut won’t just go flying.. The machine mills the recessed (pocket) corners first, then the middle piece and finally the outside. I have cut the bridges at this point but you can still see them on the inner piece.

Template Test

Tray Complete

And lastly, the finished tray with a quarter plate I use for testing inserted. The edges are smooth but need finer sanding in some places. The pockets fit perfectly, they’re a little large but that’s good as this plate here is perfectly a quarter plate (3.25×4.25″ size). I’m going to clean up the pockets and hit them with a torch to give them a smooth surface. Need to make them as easy to clean as possible.

As for the design, I’ve never seen bowed insides before but came up with that while thinking about oyster shells. Oyster Shelling is when liquid from a previous plate transfers to your emulsion surface and causes problems. By bowing out the insides I’m protecting my edges from touching the tray. The less chance of contamination the better!

Next up in the design is a plate holding sandwich, with this part at the center. On one side I need to interface a wooden door that will close and apply pressure (leaf spring most likely) to the back of the plate so that it won’t slide around. On the other side I need another piece of wood that will not only allow the holder to interface with the camera with an air tight seal, but also take a dark slide to keep the plate unexposed during transport.

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