Grand Regulation – part XXIX

Combined Steps no43 check damper lift from key (1/2 dip)
& no44 check damper lift from lifter rail 
The regulation of the damper levers involves checking for evenness of the levers for proper sostenuto tab adjustment, how high the levers are for proper damper lift from the keys, and how evenly the levers lift from the lifter rail. Since these three aspects are inseparable, steps no 43 & 44 are combined for this discussion.
The time to worry about how well the sostenuto system will work is when the damper levers are regulated to obtain proper lii from the keys and lifter rail. The first principle to remember is that the levers must be perfectly level in the rest position. This will give a straight line for the sostenuto tabs, which is vital for the sostenuto system to function properly. Once the tabs are level, it is simple to adjust the sostenuto knife.
Never, never adjust the height of a single damper lever to correct for improper damper lift from the key or from the lifter rail unless the offending lever is not level with the others. Individual adjustment of damper lift from the key or from the rail is made by altering the thickness of the lifter felts. If the piano being regulated is brand new or at least new enough that the lifter felts are not worn, then proceed to adjusting the evenness of the damper levers. If the piano is older, especially if the instrument is being rebuilt, replace the key lifter felts and the damper rail felt.  Failure to replace worn lifter felt will surely result in lost time and big headaches.
The only way to replace the damper rail felt is to remove all of the damper wires (see last post’s discussion) and also remove the damper rail itself. Replacement felt should be of similar thickness and of sufficient density, like understring felt. While the lifter tray is out, lube the pivot bearings and return spring. Reinstall the lifter tray and damper wires. As was explained in step no42 in the last post, the damper wires must ride freely through the brass inserts in the damper levers. If the hole of the brass insert has been aligned and the wires still do not pass freely, reduce the size of the damper wire by light filing.
To regulate the height of the damper levers while maintaining a perfectly level line, I have a homemade aluminium square 1” x 1” x 46”. At each end of this square are holes large enough to let a threaded rod pass through. The rods are screwed into a wooden base. Nuts and washers are placed above and below where the rods pass through the square. This jig can then be placed inside the piano on the keybed directly underneath all of the damper levers. The piano action can also be placed where it normally goes, this jig not interfering since it is back under the levers!
Sample damper wires are screwed tight to their levers, making sure that the levers are too low in height from where they should be. These sample wires are at the extreme ends as well as selected places through the middle of the action. The nuts on the threaded rods are then screwed up or down to raise all of the damper levers higher or drop them lower as needed. The proper height for the lifter rail is found by installing the action and checking the damper lift from the keys. Usually this is adjusted so that the lifter felts on the back of the keys engages the damper levers at 1/2 the key dip. This specification can be changed a little up or down to make the action feel a lithe heavier or lighter as desired. Just remember that the point of engagement must be soon enough to lift the dampers high enough to clear the strings. Also remember that altering the way the action feels by adjusting the point of damper lift from the keys is ineffective hen the pianist plays with the sustainpedal down!
When the correct damper lever height is found, remove the action and tightenall of the damper wire screws so that the dampers are seated on the strings ml the bottom of the levers just touch the aluminium squares. If the damper heads move while tightening the wires, take a pair of pliers and twist the wires so that the damper heads are aligned to the strings. The screws should be quite tight. You do not want the heads to be loose enough to be able to get out of alignment after a few months of playing.
At this point, all of the damper levers should be perfectly level at the bottom, and all of the sostenuto tabs in a straight line. The point of damper lift from the individual keys and from the lifter rail can now be checked. The procedure for correcting too early or too late is the same whether it be for the lift at the keys or at the rail. If the felt needs to be thicker, shim with paper underneath. If the felt is too thick, simply remove a layer or two with a sharp knife (best for key lifter felts) or use a hot blade and scorch the felt (best for the rail). On some pianos altering the thickness of the felt is unnecessary.
Many European style actions have spoons which can be bent slightly up or down to regulate the lift from the keys. These and other actions also have capstans or let-off type buttons to regulate the individual lift from the lifter rail. If the above procedure is followed, that is, making sure that the level of the levers is correct first, then adjusting each key for lift and each damper for lift, the painful experiences of regulating the dampers will be diminished. That is not to say of course that there won’t be problems with some pianos.
Pianos which have split lifter trays are among the worst offenders. The procedure here is …

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