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Orchestrelle, Chapter 18.1
Rebuilding the Æolian Orchestrelle
58-Note Player Reed Organ, 1912 Model "W"
by Richard Vance
Copyright (C) 2001 by Richard Z. Vance
rev. A, 8 February 2001

Chapter 18.1 - The Secondary Valves; Introduction

    In earlier models of Orchestrelles, these valves, which vent all the playing pouches in the ranks, were directly actuated by the pressure pulses from either the key touchbox or the tracker bar.  When the 116-note organs were introduced, it apparently was found necessary to add primary valves to amplify the signals from the tiny punchings in the 12/inch 116-note roll.  For production uniformity, this double valve system was soon also applied to 58-note instruments, and the old single valve system was abandoned across the board.  Sometime in the past, someone had contemplated converting this organ back to single action, eliminating the primary and actuating the secondary directly from the manual valves.  (The player part was abandoned.)  This might have worked, but the effort was apparently never completed, and the secondary valve system came to me all taken apart, and with crude "mends" applied in an effort to keep the organ working without a full rebuild.

    Most people can skip this part.  For some reason that I can not figure out, perhaps to gain maintenance access from the rear, part of the lower edge of the back board had been hacked away.  Fro each of the six backplane panels, there should be four spring loaded screws holding the secondary valve system tight to the backplanes.  But with the lower part of the back board missing, the two center backplane connections were left with only two screws each, so I had to make a new backboard. So I went to Cindy and Ken Greenlee's Woodcrafters Supply (nice people, I could not have done this project without them) and selected the nicest piece of 1/2" maple they had.  Using the remnant of the old board as a drilling template, I replicate the old board, boring the 1/2" holes from both sides to avoid any splitting of the surface around the holes.

    To prevent any end grain leakage, the holes were liberally gooped with Zinsser's BIN pigmented shellac primer, a material very like the shellac and white pigment filler that Aeolian used to seal channels.  After the BIN is painted into the holes, the surfaces are wiped clean with a paper towel.  One of the advantages of BIN is that, unlike plain shellac, hot glue will stick to it, so any remnant left on the gasketed surfaces does no harm.  Then the exposed edges of the board were masked and shellacked to match the original.

    Another clever design trick of Aeolian was the way the secondary (as well as all the six rank boards above it)  was gasketed to the backplanes.  They originally used very thick white gusset sheepskin, almost 3/32" thick, to allow for any dimensional variation between the panels.  Around each hole in the backplanes (all 406 of them) they glued a thick cardboard washer with a 1/4" rim, sealed with a coat of shellac.  This concentrated the joint closing force in a small area around every hole, insuring a tight seal.  Every one of these holes, except for those associated with the minority of the notes that are being played at any one time, is under pressure, and small leaks here would add up to a big loss of wind.  Such thick sheepskin is hard to get, so I chose Leather Supply House thick elk skin as a substitute.  A pattern for the holes was made in Visio; attached to the strips of elk with Spray Mount, and punched for all the many holes.

    The gasket strips were glued on the back side of the board.  The original gasket strips were glued on after the whole secondary was assembled and tested, so there were no holes to gain access to the #6 flat head screws that fasten the back board to the valve frame.  But for me, it was easier tom punch these holes too; they are not in the critical areas of the leather around the wind passages.

    The gaskets on the side of the board facing the valve frame, as well as all the other gaskets in the secondary, were made of very thin vellum skiver.  Leather Supply House item "CS1 Splits - Hairsheep Sueded both sides" is an ideal replacement for this.  But this leather is so thin, stretchy and flexible, that a different technique is required to punch out such complex gaskets without distortion.  The skin is adhered to a piece of Masonite with Spray Mount, and the Visio patterns are stuck on the leather with a light coat of Spray Mount, partly "killed" with talcum powder.  Then the punchings are made right on the Masonite, and the strips are cut apart with a snap knife and straightedge.

    First the thick back gasket is glued on.  The holes are covered with masking tape so that any glue that runs through from gluing the front gaskets will not spread out onto the sealing areas.

    Then the front gaskets are glued on, along with another 1/2" piece that seals the wind chamber at the top of the assembly.  Since the split hide is not big enough to make these gaskets in one piece, one must be very careful when trimming the ends of the segments and pushing them together, to leave no gaps.  Still another advantage of hot glue; while it is still hot, stretchy leather can be slid along the surface to make perfect butt joints.

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