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Orchestrelle, Chapter 23.1
Rebuilding the Æolian Orchestrelle
58-Note Player Reed Organ, 1912 Model "W"
by Richard Vance
Copyright (C) 2002 by Richard Z. Vance
rev. A, 11 December 2002

Chapter 23.1 Reworking the Vox Humana Rotating Shutter

    The rotating shutter vox humana (called "Tremolo" in the Orchestrelle) was found in very bad condition.  Normally the blades of most voxes are made of stout red German pressboard.  But these were made out of Bristol board, colored red.  Perhaps the Great War made genuine pressboard hard to get.  This cardboard was dried out and very brittle, and most of the shutter blades were broken partly off, and the remainder crumbled at a touch.  Even the turbine blades, normally protected inside the turbine shell, were bent, cracked, or had come unglued from the hub, and scraped the inside of the turbine shell.  Everything had to be replaced.

    However, getting the remnants of cardboard out of the grooves in the shaft and hub, remains a tedious task.  The only way I have found, is to soak the wooden parts to soften the old cardboard and glue.   The the remnants must be scraped out, a bit at a time, with the edge of a saw blade.

    I could not fine a reasonably priced source of red pressboard of the required thick gage.  So I cut some rough blanks from a large pressboard artist's portfolio wallet, and stuck two of them together with contact cement, to get the proper thickness.  No doubt I will go straight to hell for using contact cement in an 'ethical' restoration.  But any kind of water based adhesive will curl up the card, making any sort of flat result impossible.  It worked.

    Unlike in most American reed organs, the ends of the blades were considerably mitered, in order to clear the large Helmholz resonator array of the Orchestral flute rank.   The system was temporarily assembled and installed, and a cardboard template was made.  By trial-and-error, the template was cut such that the blade would clear both the vox support frame, and the resonator.

    Using the template, the blade shape was laid out on the cardboard blanks.  The blanks were rough cut close to the line with scissors, to make final cutting of the card easier.

    Both blades must be the same shape and size, to keep the rotor in balance.  So both blades were cut out together, using straightedges firmly clamped to the cutting board, along the layout lines.  Then the blades were glued into the grooves in the shaft.

    At assembly, it was found that the pins in the ends of the shaft had worked loose, and the ends of the shaft threatened to split, producing wobble in the action.  It was necessary to drill out the pin holes and bush the new holes with 3/32" ID brass tubing.  The old pins were fixed into these tubes with Locktite.  Then the shaft was drilled in two places at each end, and long #4 screws were driven through, to firmly clamp the new pins and tubes in place, and defeat any tendency of the shaft to split.

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