Rebuilding Harmoniums in Swiss Music Boxes

To begin with the lumber used in the construction of the bellows unit and baseboards is generally of very poor quality, containing knots and other defects. Because of the moisture content in the wood, screws and other fasteners rust (sometimes almost completely), rotting the holes in which they are placed. Other than craft or marblized paper on outer surfaces, no sealers such as shellac were ever used, Over the passing years, as the wood dries out, these defects, being only covered over with craft paper, begin to open up. Glue joints become brittle and break. Besides the ravages of time, there are the ravages of attempted repairs which can cause greater difficulties.

Proper restoration of the bellows unit is very critical as the pumping motion is very slow. The force which the clockworks applies is also minimal. The leather used in covering is very thin, (cabretta) and the ribbing must be equally thin but rigid. Covering and ribbing procedures are done as close to the original method as possible.

There are two basic types of bellows units for the harmonium. Figure 1. is the most common. These are composed of pine slats not more than 5/16ths thick. These boards are often cracked or warped. All lumber used in replacement parts is well seasoned yellow pine, completely clear and defect free. When ever possible, we try to keep as much of the original structure intact. Please keep in mind that in most cases all pieces should be replaced.

The unit represented by Fig. 2 is somewhat more difficult to restore. Hinging of the duplex pumping bellows and the design of the reservoir make recovering labor intensive. What is the most difficult however is the fabrication of the main body of the bellows unit (shaded in black). This requires an elaborate setup on a surface wood planer in which the new part must be placed at an angle against the grain....a very dangerous procedure.


The Reed chest, Fig. 3, with its laminations and intricate cells and channels, is particularly vulnerable to the elements. As Fig. 3 shows, the chest is composed of three laminations, two outer layers of maple or cherrywood, and a tapered core of yellow pine. The trackers and pallet rest on the top layer while the reeds are fastened to the bottom. The core has rectangular holes, (see cutaway) with a piece of veneer dividing them lengthwise into two cells. The reeds* (two for each pallet hole) are fastened to the bottom layer. These layers usually begin to delaminate around the outer edges, causing the top layer to split in the vicinity of the pallet holes. A suitable repair on the reed chest is nearly impossible for three reasons:

1. Laminations need to be fully separated to determine of there are any breaks between the cells in the core.
2. Any attempts to do a "quick fix" can damage the core further. Many of the units I've seen have evidence of previous attempts at repair.
3. Due to the different shrinkage and expansion rates of hard and softwoods, many of the pieces may no longer line up.

Fabricating the outer layers is straightforward. Creating the tapered core requires a risky setup similar to the part in Fig. 2 but somewhat less dangerous. The tapered core is very thin and is sent through the planer with the grain perpendicular to the blades. Often it takes more than one attempt. When this process is complete, the cells must be very carefully cut by hand and the dividers dovetailed in. The core is very delicate at this stage and any mishandling can quickly nullify the previous hours of labor.

When the reed chest is fully assembled and fastened to the new bellows unit, the tracker arms are cleaned, new pallets are fabricated, worn or fatigued springs replaced. The new wood surfaces are properly sealed, thus ensuring a longer life than its previous incarnation.

Restoring these splendid music boxes mechanisms demands the most professional meticulous care and the harmonium, though the more humble part of the instrument is deserving of the same.