Time for a little more work on Mitchell 46

On Mitchell Standards and some early GCs, you could order an option that had a series of gear boxes that would do automatic fade-in/fade-out over a selected number of frames. Mitchell 46 at one time had this option, but the kind folks who tried to reflex it ripped out most of it and disposed of the parts. I had a few days between other projects to try and put this feature back together. The fade-dissolve feature is made up of several components. The first group of components is a simple sliding gear box that adjusts the speed at which the variable shutter will open or close. The output shaft from this gearbox travels through the back of the camera casting and interfaces with the variable shutter control on the back of the camera.

The variable shutter control on early Mitchell Standards is operated by a fairly complex rack and pinion design. The rack operates the gear that is connected to the variable shutter shaft, and the two pinions move the rack to either the shutter open or shutter closed positions. To complicate matters even further, there is a brake assembly as well as a flywheel that is attached to the main focal plane shutter that was intended to stop the camera when the end of the face-in or fade-out cycle was completed. This brake is operated by a spring-loaded trip rod that the rack gear triggers at the end of its travel to set the brake. Ultimately, camera operators found this system to be unreliable and over-complicated, and Mitchell eventually replaced the whole system with a simpler, more reliable shutter control mechanism.

Mitchell 46 was built with this original version, so I am trying to restore it. With the limited time I had to work with Mitchell 46 this week, I began by repairing the sliding gear box, making a few parts, and stealing a few parts from partial sliding gear boxes in my parts inventory. I was able to get everything working, except for the outer control knob and link shaft that is found on the top of the camera. This part of the repair will have to wait for another day. I next moved on to installing the brake, caliper, and trip rod assemblies and the variable shutter control module. I got as far as disassembling the variable shutter control module and got the parts in the ultrasonic cleaner. Then time ran out as I was putting everything back together for testing, so that will also be a project for another day.

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