Monday, May 4, 2015

Cipher Solver - Opus 1 Repairs

Cipher work on Opus 1 began today! Here's the tracking document:

With this many valves needing replacement, the question was to make a new windchest or renovate the existing windchest?

The windchest was designed for the older style Petersen valves. However, the older Petersens and the new Petersens have different screw points. Also, the new Petersens have a claw that is supposed to grip into wood. Because we have an acrylic top, this claw can’t dig in to the material and therefore it prevents the valve from sitting flat on the acrylic. The solution we came up with during initial construction was to make an adapter plate. These adapter plates relocated the screw hole, lifted up the valve so the claw did not impact the surface, and sealed the old screw hole.

We decided to replace three entire rows of the old Petersens with new Petersens. We decided this for two reasons. Almost all the ciphers were on old Petersens that had pads that were much larger than the hole. The ideal pad size in only 0.25 of an inch larger than the hole. This creates higher effective pressure on the valve, which helps to prevent leaks. This strategy required taking out the old Petersens, making adapter plates for these valves, putting in the adapter plates, then putting in the new Petersens. 

During initial research, it was misunderstood that the pad size needed to be at least 0.25 larger than the hole. It seemed like the larger the pad the better, however this did not turn out to be the case. The margin needs to be as close to an eighth of an inch all around in order to have the best seal.

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