Cumulative testing, round 4

With the partial stack back on the bench, let’s review where we are, and confirm where we should be. At this point, the pneumatics were all tested on their decks, so we know they should be tight. The secondary valve chest has also already been tested, so that we know the chest is tight both when the valves are on, and when they are off.

While regulating the stack to the piano, the activation of notes may have shown any weaknesses in the secondary valves or pneumatics. If yes, fix them first. In other words, it is a good idea to continue the idea of “cumulative” testing by ensuring that the secondary chest and decks work well in concert, together, with no leaks heard either when the valves are on, or off.

Now let’s add the primary chest into the mix (assuming you have a double valve style stack), and run the tests again. The primary chest has the bleeds inside, so if there was an issue with sluggishness of returning secondary valves when testing repetition, this should be corrected and repetition should now be lightning fast. That is to say, the valves and pneumatics need to repeat as it is humanly possible, and then some; 10 reps per second is a good starting point. Any other problems relating to the interaction of the primary and secondary chest should manifest by now. For example, I discovered at this stage that two of my valves were weak (one was completely stopped, in fact), by troubleshooting the source of the problem I discovered that I had put too much sealant in two channels of the L board, so I had to rectify that problem before continuing.

With the suction attached, actuate each note in turn again, watching for rapidity and evenness of response. Listen for any leaks, and get visual confirmation if possible by calibrating suction loss with a vacuum gauge.

If the three main elements of the assembled stack (primaries, secondaries and decks) are performing well together: congratulations! It’s time to proceed to the last stages of the rebuilding.

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