Archive for February, 2008

Film Holders – Progress

Thursday, February 21st, 2008

It has taken me a while to sort out the dimensions of the film holders, and actually begin building them, but I am making progress. I assumed the film holders would be the most challenging to build, and they have been.

I started with the plan of only making a few holders. My thought was that because the camera will be so large, I won’t be taking it into the remote wilderness, so having a limited set of film holders will cut down on weight, and clutter. To change film in the field, like with any sheet film camera, I can black out a hotel room, or bathroom etc, or make a huge changing bag to use in a car. I also, concluded, that since this was just the first phase of the build process that they might not come out right, so my intention was to just get a couple working holders for tests and initial trials of the camera. If I decide I need more later, I can remake them, with the added experience, that, hopefully, I will have at that point.

My plan was to start making 5 double sided holders, with the idea that I might only get 3 working holders out of it. I figure 3 holders would be the minimum I needed to conduct tests and shoot my first photos. My assumption about only getting 3 out of the 5 is proving to be right. Film holders are incredibly difficult to build because of the 1/64th inch precision that is needed.

After milling the cherry down to size, I started on the task of cutting the 1/16th inch slots for the slides and septum. I opted to use a slot cutter in a shaper table. The alternative was to mill the slots, but that would have taken me into a whole other world, that I wasn’t prepared to enter. I figured the slot cutter would get me as close as I needed.

The slot cutter approach has proved to be challenging, yet I believe workable with practice and experience (neither of which I had when I started). I took me a day to really get a hang of it, and once I did, I was able to produce the results I needed. In the end, though, I lost 2 sets of rails, due to mistakes, so I am down to the 3 I had been planning for, and I think I am past the most demanding part of their assembly. The slot cutter is touchy on starts and stops and uneven pressure. Plus because I was cutting down the length of the pre-cut rails, any little wobble caused the slot to widen beyond 1/16 inch. I learned that if I cut the sizes down to their rough lengths, they are much easier to handle on the shaper, which is the opposite of other tools like the table saw.

The one major adjustment I had to make in the middle of the slot cutting was that the cutter only went to a 3/8th inch depth instead of the half inch I was told it would. The loss of that 1/8th inch could come back to haunt me, but for now I am going ahead with my recalculations. The new depths are basically scaled to what the tools could provide. The whole process required a lot of advice, and ingenuity in the cutter setup, so a thanks goes out to the shop master, Steve, who showed me what I need to know.

So from here on out, pretty much the rest of the camera will consist of cutting lengths, rabbets, tenon and mortises, plus the box joints for the rear standard; no more 1/16th inch slots, thank goodness. Oh, yeah, and the Aluminum parts; I still haven’t figured that one out yet. Hopefully these tasks will prove much quicker, and more forgiving, but I am not counting on it.

roughrails.jpg

The shutter

Thursday, February 7th, 2008

As I mentioned, in the lens post, I also got a shutter for my beast off that auction site. It’s a 50′s era Ilexpo, Packard shutter. It was a lucky find, because it is one of the few shutter designs that would work with my monster lens, and has a built in mounting system. This particular type of Packard shutter isn’t quite as common as the other newer ones. Packard shutters are still built and the company is still around, but the shutters aren’t built in to an systems anymore, so you have to figure out how to do it yourself if you want a new one, which are quite expensive by the way. For the size I need, it would have been up around $500 for a new shutter. Too much is going into this camera as it is, so I am stoked that I found this.

The shutter is a bit worn, but once I took it apart and figure out how it worked ( a simple yet ingenious design) all I had to do was remove one limiting screw to get the full range of motion back. At some point, I might want to remake one of the brass parts to compensate for the wearing, but as it is now it should work pretty well, and with a little Teflon grease it will probably be smother than it ever has been.

The shutter mount has a pretty standard lens plate setup, so that I can remove the lens on its own plate without having to remove the shutter. This is hugely better than most of the home brew mounting systems I have run across. This gives me the option to use more lenses, if I ever find more, or can afford the restored ones that are sold in boutiques out there.

I am starting to really grove on the idea of using a 100 year old lens with a 50 year old shutter on a home built camera using both traditional materials, and modern building techniques.

As for the camera build; I am starting to move out of the planning stage. I think I have a lot of the problems sorted out at least in theory, so I am beginning to work on the parts I know I have sorted out, like the film holders. I have already purchase my cherry wood, and planed it down. There really isn’t any such thing as rift cut, or quarter sawn cherry anymore, at least not at local lumber shops. Apparently the Chinese furniture factories have been buying up everything, so unless I want to spend 10x the $ and wait for months to track down what I want, I am going to have to settle for what I can find. This isn’t as bad as it sounds though, because if I buy big enough boards I can cut out the best parts for those pieces that need to be milled to 1/64 of an inch tolerances.

I also ordered and received, in a day, my garolite, A.K.A. Phenolic plastic, and 1/8th inch aircraft grade, corrosion resistant aluminum sheeting ( I also got some 0.001 stainless for a pinhole “lens”. another project I want to tackle at some point) from McMaster.com. They ship super fast and their rates are quite low. I think I will buy my exotic raw materials from them from now on.

The materials I chose are a bit on the steep side, but getting them from McMaster made it doable. Phenolic plastic is very rigid and quite strong, plus light opaque. It makes the ideal dark slide, and septum for the holders. With this plastic I can do with 1/16 material that probably would require 1/8th in other materials, and at a much lighter weight. The aluminum, if I can find a good laser cutter, or learn to mill it, is way high on the material grade-sheet, but it is so strong that once I anodize it, it will provide that super strength, and light weight in the critical areas of the camera that will need it with its huge stresses. With a 5lb ( I weighed it finally) lens I will need all the strength I can muster out of my materials without making it so heavy that I won’t want to use it. PLus I am learning that stresses don’t scale up linearly as you might figure. Going from 8×10 to 12×20 doesn’t multiply the stress by 2 or 3 as you might guess, but maybe up to 10xs more. Everything has to be overbuilt, but with the same tolerances. ITs just like me to take on the hardest type of project on my first attempt. I wouldn’t have it any other way though. If I am going through all the trouble, I might as well make it big and bad ass right?

All in all, I am making progress, and I can see the camera taking shape in my mind, but I can also see I am going to be in for a lot of work, and a LOT of trouble shooting. I am very glad my schedule has lightened up a bit for the next few months, cause I am going to be in the shop a lot.

packardshutter.jpg


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