Harmonium Repair

Indian Harmonium Repair and Maintenance
By Brian Godden
All photographs, illustrations, diagrams, and repair explanations are from works in progress, and are 
COPYRIGHT PROTECTED © Brian Godden 1/1/2005.
Any reproduction in any media without permission is strictly forbidden
Harmonium Basics and Problems

Dont’s  1: Do not leave the instrument in the trunk of your car or outside.  Do not ever leave the instrument in sunlight. 2: Don’t allow children to hit the keys or over-pump the bellows 3: Don’t allow anyone to tamper with the springs, action regulating screws,  or reeds. 4: Don’t turn the damper or drone knobs, as this will cause air leakage.

Do’s 1: Keep the instrument in a cool (never below freezing) and dry location. Use a cover or box for storage. 2.  Use the harmonium regularly, move all stops and play all keys. This will stop the mechanism from jamming and reduce reed corrosion. 3: Before you start to play, pump the external bellows to fill the internal   bellows until some pressure builds up.

Harmonium models
Click for schematic diagrams of the stick and pallet models  Basic Model
and the  Scale Changer/Coupler Model 

The basic model has two banks of reeds, with a single or double fold bellows. They are a small 3 octave console style, or a fold-up suitcase version. They are usually made from cheaper timbers, and the finish is relatively rough. They use the Solid Key Mechanism, as seen below.
The next level is the console or fold-up suitcase models with 2 banks of reeds, 3 1/4 octaves, with a 7 fold bellows. These are made from rosewood or teak. They use the Stick and Pallet Mechanism, as seen below.
Next are  models with 3 banks of reeds and 3 3/4 octave ketboard, including some models with the addition of a coupler,, or a scale changer, or both. These can be console or fold-up. They are made from the finest quality woods and materials. They use the Stick, lever, and Pallet Mechanism as seen below. There are many other styles of harmoniums which are variations of the above 3 basic models.

Common Problems With Harmoniums

Sticking keys

The most common problem with harmoniums is sticky keys. The way to fix this depends on the type of action in your harmonium (see the diagrams below and identify the type of action you have).

The Solid Key : With the expansion and contraction of the wooden sound board, the guide pins and hinge pins can be moved out of vertical position. These pins need to be realigned into vertical alignment. This will center the action and stop the key from binding.

The Stick and Pallet : This type has no vertical pins to give problems; the guide pin and pivot rail are usually the culprits. The key has to be carefully removed from the pivot rail. Then the friction areas need to be lightly sanded and a little fine chalk applied (do not use blackboard chalk as it has anti-squeak wax in it–sidewalk chalk is ok).

The Stick, Lever, and Pallet: The pivot rail fix is similar to the Stick and Pallet, however there are more parts involved, including the coupler sticks which run diagonally underneath the keys, and the lever pins. The coupler sticks have vertical pins that can cause the sticking. To access the coupler sticks and the lever pins requires a complete disassembly of the keyboard, scale changer, and coupler. This is a job for professional repair person.

Sometimes there can be other causes for sticking, such as: twisting of the wooden shafts which can cause the key tops (the plastic area where your fingers touch) to bind against their neighbors, and swelling of the woods in damp weather. To free-up these keys sand them along the sides.

Buzzing Reeds and Tuning

Harmonium and Shruti Box Reed Sets

Buzzing Reeds
Buzzing or rattling reeds are usually caused by the soundboard shrinking, which closes the gap between the reed block and the reed tongue. This can be remedied by releasing the mounting screws, loosening the reed from the sound board, then re-tightening the screws. If this doesn’t fix the problem, a new reed may be necessary.

In some instances buzzing can be as simple as a loose reed. If this is the case, it can be remedied by tightening the mounting screws. Sometimes these mounting screw holes are stripped and need to be filled with a tooth pick dipped in glue. After the glue is dry, the toothpick must be carefully chiseled off level with the sound board, and then a 1/16″ pilot hole drilled, and the reed remounted.

Sometimes buzzing or false tones can be caused by dirt stuck in the between the tongue and the reed block. A metal scraping, or a wood scrap is the common culprit. These can be removed by gently lifting the reed tongue with the butter knife or a razor blade; the offending particle will come right out. Be very careful not to deform the reed.

Harmonium Tuning
Harmoniums are tuned to the western equal temperament scale. ( which means that each note is equally out of tune by a very small degree) Tuning harmonium reeds is a very exacting procedure, and I do not recommend that it be attempted by the untrained. However there are many folks who understand the precise nature of tempered tuning, and want to learn how to do their own tuning work, and for them I will detail the procedure.

The Tuning Tools.

The tools above are an engraving triangle pointed chisel, and a butter knife with a curved and thinned blade. The butter knife has been thinned to a razor blade thickness so it slide under the reed tongue without distorting the reed. The butter knife is used to support the reed while the scraping process is done with the engraving tool. I make my own tools, but a simple razor blade and an Exacto knife can work quite well. Reeds can be 4″ long and as small as 1/2″. Great care is needed with the small reeds.

Tuning the reeds
When raising the pitch of a reed, you have to scrape minute amounts of material from the tip (the first quarter of the reed). When flattening the pitch, you have to scrape the back area of the reed (the fourth quarter of the vibrating section of the reed) near the rivets . This must be done in a very uniform and even manner or the reed will lose its balance and produce an impure sound.

The quality of the tuning process depends on the correct air pressure being maintained throughout the full range of octaves. By pumping less on the small reeds and more on the bass reeds you can arrive at a pitch balance. If you don’t balance the pumping, the reeds will not entrain (synchronize pitch) properly. When a reed vibrates under higher pressure, it will play a lower tone than with lower pressures. The bass reeds can move as much as a quarter note between high and low pressures. This is a matter of sensitivity, experience, and intuition .

The basic tuning principle for Equal Temperament, is to make the fourths wide, and the fifths narrow (at middle C, they should beat against each other at around one beat a second; at one octave above middle C, 2 beats a second; at one octave below middle C, 1/2 a beat a second).

To begin you will need to isolate one set of reeds, by closing all the other stops except the one related to the selected bank of reeds. Do not start with the bass set, as they drift too much as the pressure in the bellows varies. You set the temperament by tuning a sequence of fourths from middle C up: middle C – F – B flat – E flat – A flat – D flat – G flat. Then a tune a sequence of fifths: middle C – G – D – A – E – B – G flat (all within the first octave starting from middle “C”). If you arrive at the same G flat, then your tempering is correct. Once the selected set of reeds are tuned, you can open the other stops and tune the bass and treble reeds to the tuned set. Once all banks of reeds in the center octave are tuned, you tune all octaves up and down from the center octave. Mastering tempered tuning usually that takes an apprenticeship or a piano technicians course, so be patient.

In some harmoniums there is air bleed between chambers, due to warped timber or leaky seals. Then you will need to place strips of paper under the tips of the offending reed banks, in order to get a single reed to sound. If the harmonium has air escaping from the bellows, or the outer seals around the air chambers, then it can’t be properly tuned until the leaks are fixed.

WARNING – Over tuning the reeds will cause them to loose their clarity and volume.

Electronic chromatic tuners for guitar such as those made by Korg or Boss can be helpful. They cost around $100.00. They require a 2 second sample of a steady pitch to read correctly,  and a harmonium reed is not steady enough to give an accurate reading. For setting an acurate temperament, they are not good enough. Your ear is more accurate.  For general touch-up tunings, they both work well.

The Equal Temperament frequencies for the U.S.A. standard 12 note octave ~ “A” 440Hz,
and the Equal Temperament frequencies for *Indian Standard 12 note octave ~ “A” 445hz
(*Indian harmoniums vary between A 435, to A 450. most often between 5 to 10 cents sharp. India is so diverse that no true standard really exists)

Once again, I advise the novice not to try harmonium tuning, as it requires great skill, understanding of the tempered scale, and the hands of a skilled craftsman. I take no responsibility for reeds destroyed by using this process.

Air Leaks

Common causes ~ Followed by the repair techniques.
Air can leak from many areas of a harmomium, here are the main ones:
1: The external bellows.
2: The intake vent on the back of the external bellows.
3: The internal bellows.
4: The leather seal between the reed case and the main air chamber.
5: Warping of the reed case or the main air chamber.
6: Keys and damper alignment on the soundboard.
7: Cracks in the sound board.

The following is an outline of repair procedures for the above 7 problems. It would be impractical and confusing to detail every possibility, so I will be brief.

The first thing to do is to close all the stops and pump the bellows until the internal bellows is full, and see if and where the air is escaping. You can use smoke from a lit stick of incense to check the external bellows and the intake vent. You can use smoke to test the dampers and sound board area.

1: The repair for the external bellows may require the seams and folds be re-leathered. We use fine quality glove leather under 1/16 in thickness, and contact cement. The panels of the bellows are made from card board and can be worn through by fingernails of the pumping hand. New cardboard panels are not usually necessary, and a complete rebuild of the bellows is too time consuming and costly to be practical. So patching with leather is usually the answer. Sometimes the seams where the bellows attaches to the backboard need to be resealed. I use a small spatula to get contact cement between bellows and the backboard wherever it is loose. Sometimes we have dry and brittle areas on the hinges or on the attachment to the backboard. We can fit an extra strips of glove leather on the outside of these areas without dismantling the bellows. The leather has to be thin enough to allow the bellows to close properly.

2: The intake vent has a flat leather flap valve which may need to be replaced. This is a delicate job. The valve is behind a metal or wooden plate held on with 10 or so wood screws on the back of the external bellows. Carefully remove this plate without damaging the leather seal around the perimeter. The valve is a piece of goat skin “split” (rough on both sides). it is a heavier gauge than the glove leather. It must be flat. It needs to be glued with contact cement on the upper edge only, and be exactly the right size for the vent hole.

3: The internal bellows repair, means you have to remove all the stops and dampers, remove the 4 screws that attach the main air chamber to the walls of the outer case, and lift out the main air chamber out – complete with the inner bellows and pressure springs. Then you can examine the bellows for leaks. If the seams are split then you will have to re-leather them, using the same glove leather as used on the outer bellows.

4: The leather gasket which creates the seal between the upper reed case and the lower air chamber can become hard and compacted. It will then not make a perfect seal. This can be replaced with strips of goat skin leather splits. (fluffy on both sides) it should be as thick as 3/32″ and no thinner than 1/16″. Each strip of leather should be glued down with a small single bead of contact cement, carefully laid down the center of each rail and partition of the air chamber. Do not cover the whole rail surface with glue, because the edges have to remain fluffy and loose, and too much glue will cause the leather to lose its compressibility.

5: When an instrument is built it begins the process of drying and shrinking. As this happens some warping can occur. The reed case and the air chamber can warp or twist. If this is the case then the reed case and the air chamber will have to be removed form the instrument. They will have to be planed flat, and re-leathered with 3/32″ goat skin splits. Veneer shims will have to be fitted to the support rails to make up for the loss of material during the planing procedure. realigned and remounted. This is a delicate procedure, and should only be attempted by skilled craftsmen.

6: As the new harmoniums drying process proceeds, all the wooden parts continue to shrink. The outside length of a harmonium may shrink by as much as 1/4″ before reaching its final size. The better quality harmoniums are made from better woods, with less shrinkage and warping characteristics. The keys, dampers, and their hinge rail, may shrink at a different rate to the sound board. The key shaft may twist or bend, and consequently the dampers may not line up correctly with the reed vent holes. The leather pads on the dampers may become compacted and dry and need to be replaced with new fluffy leather pads with felt backing. Damper pads need to be glued in the center of the damper pallet with the edges unglued. Twisting and bending of the keys can be repaired by careful filing and sanding, and in the worst case, by replacement of the warped shafts. Because of the many different makers of harmoniums, it falls to the repairer to make his own replacement parts.

7: The sound board is usually a solid piece of spruce or rose wood. The rose wood soundboard has over 100 reed vent holes cut through it. This, along with shrinage, can cause the soundboard to crack along the grain direction, which is parallel to the front of the instrument. The spruce soundboards grain runs front to back, parallel to the reeds, and that is the direction of the spruce cracking path. If these cracks happen, it means that the keys, scale changer, and coupler mechanism must be removed. it requires that the cracks be cleaned out with a thin junior hacksaw blade. The cracks are filled with pieces of hardwood veneer cut to size and smeared with a little wood glue. After the glue is dry, a wood chisel is used to level the veneer and remove glue traces. A vacuum cleaner should be used to make sure no scraps have dropped into the reed vents. Then the re-assembly can be done. This is a tedious process, and care must be taken not to dribble glue through the sound board onto the reeds underneath.

These repairs are complicated but not impossible. Be careful and patient. I take no responsibility for damage caused by anyone using these techniques.

Good luck,

Brian Godden