Grand Regulation – part XVI


34) The Drop 

The modern grand action compared to the old type of action that was used for instance in the square grands show one great difference. Absent in the square grand mechanism is the repetition lever and the auxiliary features  which go with it. Namely the drop screw, the repetition lever support spring, and the repetition lever height adjustment screw. The purpose of installing the repetition lever was to gain more positive and faster ability to repeat notes.
The technician who regulates this old style action has an easier job than if he were regulating a modern action, for there are fewer adjustments to make. This is especially true when regulating the escapement. He would only need to regulate the let-off screw. If he were regulating a modern “double escapement” action, he would have to regulate both the let-off and the drop.
Picture how the modern action works in the escapement process. At rest, the hammer is supported at the knuckle mostly by the balancier. As the key is depressed and the whippen rises, the balancier compresses slightly and lets the jack carry the hammer upwards. Somewhere near the time that the hammer approaches the string, the jack tender engages at the let-off button. Eventually the jack trips out fully from under the knuckle. Likewise, the drop screw must be withholding the upward rise of the balancier as the jack trips or else the balancier would take over the thrust of the hammer and cause it to “block” upon the string. Hence the name “double escapement” action.
Most technicians have experienced “blocking” hammers, especially if it is the let-off that is faulty. Not only will the hammer “block” upon the string, but as long as the key is depressed, the hammer will stay at the string, completely dampening the sound. In the event that the drop screw is too high, the hammer will only momentarily “block” upon the string. Because the balancier is supported by a spring, the hammer will rebound from the string and the knuckle will cause the balancier to compress. In this case, some dampening has occurred, but the string will continue to speak.
Almost as critical to the performance of the action would be the maladjustment of the escapement too low. Where the drop is set correctly but the let-off is too far from the string, a loss of power and control would be evident. Removing the jack from its duty too early results in the thrust of the hammer being turned over to the balancier for the remainder of the distance. Just how far from the string the hammer lets-off too early and how strong the repetition spring is would determine how great the power loss.
In the case where the let-off is the correct distance from the string but the drop is too far, a very slight power loss could be evident. More important would be the lack of “surefootedness” as I call it that the pianist would feel. When the drop screw engages the balancier too early, again the balantier compresses, robbing some energy from the hammer’s thrust (however so small the amount, it does exist). The greater the amount that the hammer drops, the more the pianist will feel it as he plays.
He won’t be able to explain just what it is, rather the fact that something does not feel correct as he plays. I should probably explain that during normal playing, the hammer never really “drops”. A technician must depress the key slowly in order to see this. What I am talking about when I say drop is actually the point of escapement for the balancier. Under ideal conditions “double escapement” of our modern piano should be felt as one occurance by the pianist. At the same instant that the jack tender is engaged by the let-off button, so should the balancier be engaged by the bottom of the drop screw. Providing that the let-off is the correct distance, this escapement happening at the same time would give the correct amount of drop. 
Two points of resistance rather than one will be felt by the pianist, if the escapements do not occur together. A sensitive pianist will surely complain about this. Unfortunately, we do not always regulate the ideal piano. Sometimes the drop must be regulated so that the points of escapement do not occur together. The rule of thumb is for the drop to be about 1/2 the let-off distance. If the letoff is at 1/8” from the string, then the hammer should drop to about 3/16” from the string. I hasten to add that in fine regulation, the actual distances are second in importance to the way the action feels.
A technician who expects to perform concert level regulation must develop a touch almost as sensitive as the concert artist’s. How can a technician do really fine regulating or voicing, if he can not play the piano? A craftsman who has a sensitive touch and a knowledge of how the piano is suppose to play can easily run his fingers up and down the keyboard and tell without pulling the action out whether the escapement is properly regulated. There is a certain feeling which is hard to describe when the action is in proper regulation.
The dynamic range is the widest and the control is the finest when the let-off is as close as is permissible. The already mentioned “surefootedness” is only possible when the drop is correct. And, most important of all, there is the heavenly exquisite touch when all of the keys play uniformly. Often I have heard pianists say that they would rather play on an action that is uniformly out of regulation that to play on one where some notes are correct and others are not.
I have mentioned my feelings about how well a technician must play the piano in order to do fine regulating and voicing to other technicians. Some agree, some don’t. Isn’t it interesting how the customers of those technicians who do not play end up calling me when the first technician couldn’t solve a problem? Time and again, I have sat down to a piano that I have never seen nor heard before, and taking a few minutes to play it, I have correctly identified not only the complaints that the customer had, but also the solutions!
The list of problems that can be identified in this manner is almost endless. Obviously, tuning and voicing should be included along with faulty escapement, faulty repetition, incorrect aftertouch, flat knuckles, worn key bushings, improper damper lift and seating, too tight action centres, too high damper stop rail, too strong repetition springs, etc. The real art of regulating a grand action is to know by feel how the action is working.
A good habit to develop while tuning pianos is to try to determine what needs fixing on the instrument. Besides sharpening your troubleshooting skills, you will impress the customer with your knowledge and run a good chance of picking up additional work. All too common is the “tuner” who does nothing except tune the piano unless the customer makes a complaint. A true “craftsman” should be able to tell his customer what ails the piano, rather than relying on the owner to complain to him! Our discussion on step number 34 The Drop will continue in the next post.
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