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Restoration of the ex-Irvin's Marenghi

7 Violin and baritone chests

I put these two chests together because they are very similar in construction. They were worked on in my home workshop while I waited for decent dry weather, when the glue would actually dry. The violin chest carries five ranks of pipes, and the baritone, two 2. Both chests are fitted with their original Marenghi lever actions, which had to be retained at all costs, for historical reasons, despite being very "wrong" in pneumatic action terms. The wind pressure inside tries to open the primary exhaust valves instead of holding them closed, with a very real risk of ciphering. This makes for extremely fiddly and accurate adjustment. The lever springs need to be strong enough to hold the valves shut against the wind pressure from within, but not so strong the puffs cannot open them sufficiently to close the internal valves. This is essential to allow the internal pneumatic motors to "exhaust" correctly and pull-down the pallets. However, these actions remain susceptible to ciphers if dust or grit gets onto the valve surface, preventing complete closure. It may not be enough to make a note sound, but is very likely to prevent a note stopping once started. Proof of correct setting-up can only be realised once mounted into the organ and on their correct wind-supply from the main chest.

The internal pneumatics were re-leathered, all valves renewed, and all springs re-made in phosphor-bronze. The chests were thoroughly cleaned inside and out and given a coat of shellac. Then they were re-fitted with hardware, and thoroughly tested on the wind, working the levers by hand. However, testing with their primary puff-boards would have to wait until later, when more adjustment then would be inevitable.

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