Grand Regulation – part XXVIII


Step no 42: Check Damper Guide Rail, Ease or Rebush

All of the felts in a piano eventually ear out with age or use. One of the more overlooked areas of wear is in the damper guide rail. Perhaps the reason the guide rail, and for that matter, the entire damper system, is overlooked is because technicians hate to work on the dampers. Granted, the work is tedious, frustrating, and often a source of complaint from the pianist when it is not functioning correctly. However, the solution is to learn how to regulate the dampers, not to avoid it!
New pianos are much easier to work on since the felts are (or at least should be) in good shape. Before attempting to regulate the dampers, the first thing to check is the damper guide rail. One by one raise each damper head with your hand. Gently rotate it inside the hole and check to see if the damper wire has proper clearance. If it does not, then the hole will have to be eased. If it is too loose, then the felt must be replaced. Let us assume the worst and talk first about rebushing the damper guide rail.
Preferably this should be done in a shop, although it doesn’t have to be if you know how to do the job. Remove and store safely the action to the piano. Build a holder for the damper head / wires. I use a piece of firring strip 1” x 2” x 60”.  Blocks 3” x 3” x 1” are glued on to the ends of the fir strip. Holes are drilled about 1/2” apart, just large enough to fit the damper wires, but not so large as to let the dampers fall out if the fir strip is lifted upside down. Each hole is numbered and felt is glued onto the bottom of the 3” x 3” blocks.
Position the holder directly in back of the damper guide rail, letting it rest on the case, soundboard, strings, or whatever. Loosen all of the screws on the damper wire blocks. Carefully, making sure that the wires do not get bent out of shape, remove each damper head/wire from the wire block, pulling it through the guide rail and inserting it into the proper numbered hole in the damper wire holder. This is most easily done by starting at damper number one and working up. Spread the strings on each side of the screws for the damper guide rail, and remove the screws and rail. Either mark the screws for the holes, or else screw them back into their holes.
If the guide bushings were press fitted into the holes, removal of the felt will be easy. Where they were glued, take the damper guide rail to a drill press and punch the old bushings out. Make sure the holes are cleaned. Before the new felt is installed, I like to sand and refinish the guide rail to make it look as good as I can. Only the highest grade bushing cloth should be used to rebush the guide rail. Often this grade of cloth is not available domestically. Buy it in large sheets. Tear a strip from this sheet to the proper width to fit the guide hole. When the felt is inserted into the hole, the torn ends of the cloth will tend to mesh together at the seam.
Cut the cloth into 6” strips and taper one end so that it can be started into the hole. Insert the cloth through the guide rail hole from the top down. That is to say, the excess cloth will protrude from the counter-sunk side of the hole. Put a drop of glue onto the cloth on the counter-sink, and cut off the excess. I realize that not everyone likes to glue their damper guide rail bushings in. The only comment I can make is that those people must not have had the experience of pushing a damper bushing out the bottom of the hole while trying to ease a tight bushing! Use hide glue for this job. Reinstall the rail and dampers reversing the process used to remove them. Again, be careful not to bend the damper wires. When the wires are being inserted back into the wire blocks, they should move freely through the brass screw holder. This is a must when regulating the damper lift from the tray and key. If the wire does not pass freely into the hole, take a small drill bit (one smaller than the hole) and using the shank of the bit, not the cutting end, rotate the bit inside of the wire block screw hole, These brass inserts are just press-fitted and sometimes get turned a little when the screw is tightened against the damper wire. The drill bit will reposition this brass insert to allow the wire to move freely inside the hole.
Regulating the damper wires will be covered in the next two steps on the checklist. Now let us talk about what to do if a damper wire is sluggish and needs to be “eased.” To help find such ,tight bushings, one quick way is to raise and lower all of the dampers using the: sustain pedal. Any sluggish dampers will return slowly. Don’t come to conclusions yet, though, as sluggish dampers can be caused by things other than the damper guide rail. Also, although the dampers do return fast enough using the sustain pedal, they may still have excess friction at the guide hole.
Remove the action, and …
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