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.

Grand Regulation - part XV

33) Let-off (continued)

For those technicians who find it difficult to set the let-off in the piano by watching the space between the top of the hammer compared to the thickness of the corresponding string, there is another method. Find someone in your area who sells magnetic signs such as those found on the sides of cars or trucks. The magnetic backing for these signs comes in 1/8” and 1/16” thicknesses, which are perfect for use as let-off gauges.

Purchase at least two strips of this material, one of each thickness, about one inch wide by around twelve inches long. The one inch width is sufficient to place the strips against the under sides of the strings without having to worry a lot about whether the strips will cover the hammer strike line. The twelve inch length is variable with the piano. The lengths should be no longer than the sections between the plate struts or else the strips will be too long to adhere. The larger the piano, the more sections are created by the struts, and the smaller the widths are of these sections. You may want to carry an assortment of lengths of this magnetic material.

To use, remove the action and set it aside. Take something such as a felt wedge and block up the sustaining pedal to left the dampers away from the strings. Otherwise, if there are bichord or trichord damper wedges in the area where the magnetic strips are to go, they will prevent the strips from adhering. Position the strips against the undersides of the strings, being careful to place them directly at the hammer strike line. Reinstall the action and check to see if the strips are positioned correctly. If not, carefully reposition the strip with a small tool.

Now comes the easy part. Seat yourself at a comfortable height so that you can see and work on the let-off rail. There is no need to see what is happening at the string level. Depress the keys one at a time and adjust the corresponding let-off button until a very slight resistance is felt as the hammer lets-off against the magnetic strip. When regulating in this manner it is important to remember to continuously depress the key and feel how the hammer lets-off.

Try to get each key regulated so that exactly the same amount of resistance is felt at the point of let-off. Use the 1/8” thickness for the tenor and low treble sections, the 1/16” thickness for the top treble. After all are adjusted, remove the magnetic strips and check the point of let-off visually. This step must not be overlooked! Invariably there are slight corrections which must be made. Despite the fact that the resistance which was felt was uniform, the actual point of let-off will vary a little.

There are both pros and cons to regulating in this manner. The pros are that it is by far easier and faster to set the let-off with a magnetic strip, especially if the regulation was way off from where it should be. However, the cons are important. Obviously, these magnetic strips will not adhere to the bass strings, so approximately 1/4 to 1/3 of the let-off must still be set by eye! As was mentioned above, those which can be set with the strips must be double checked by eye for accuracy. Most importantly, the best let-off is one that is tapered uniformly from note 1 all the way up to note 88. The magnetic strips do not give a tapered let-off. Instead, they give a noticable break where the change was made between the 1/8” thickness strip to the 1/16”.

Despite these drawbacks, I still like to use these magnetic strips. When the let-off is way out of the ballpark as it often is, I find it far easier and faster to use the strips to get the let-off close and then refine it by eye than for me to completely adjust the let-off by eye. I believe it impossible to perfectly regulate the let-off in a uniformly tapered line the first time through no matter what method is used. Therefore, being somewhat reluctant to work harder than I have to, using these magnetic strips gives me a known setting for the let-off according to the thickness of strip used, and from this I can easily achieve what I want. There are two exceptions to the rule. One is where the let-off is nearly correct as on a fairly new piano. For such instances I simply regulate by eye. The other exception is when I have help available. Using another person relieves the strain of constantly looking above at the point of let-off and then bending down to turn the let-off screws. While I depress the keys and watch the hammer let-off, my assistant (usually my wife) turns the let-off button up or down at my instruction.

One piece of helpful advice when watching the point of let-off in the top treble sections is to use an old mirror. Normally the plate obstructs the view to directly see the hammer let-off. By using a mirror set at about a 45 degree angle to the strings, the hammer can be seen to rise against the string from the side and clearly show how far the hammer is letting-off.

Before ending our discussion on step#33 of the 50-point checklist, I would like to caution technicians on a few things. Be sure that the let-off rail screws are securely tightened. It takes only a slight movement of that rail to cause the hammers to block upon the strings. Secondly, if the let-off button felt has been worn, replace it! It is very frustrating to try to regulate the let-off when this felt is worn. You all know what I mean. You turn the let-off screw 3/4 of a turn without getting the hammer to let-off close enough. Then with a slight additional turn of the screw the hammer now blocks! You back the screw off a little and it goes back to being too far. Gradually you ease the screw to the right until the let-off is correct. You know darn well that the jack tender is riding half-in, half-out of the old groove in the button felt.

How stable is this kind of regulation? How long before the felt wears again and causes the hammer to block? How much time does it take to replace this felt? I doubt that it takes me a whole hour to remove the old felt and glue on new ones, and the time spent is almost made up in the ease of regulating with new button felt!

Finally, pursuing this worn felt problem a little further, do not assume that even a new piano is in perfect regulation. I have frequently found new pianos where the hammers were blocking, or almost blocking. There seems to be two main reasons for this problem. One is pure negligence on the manufacturer’s part. The action was regulated on a bench at the factory and the strings of the piano did not match the height of the let-off rack. If the strings were a little lower than the let-off rack, the hammers will block because the let-off is too high. The other, somewhat more subtle reason, is that the let-off button felt was not of sufficient quality for the job. It compacted too easily and after a little playing the let-off became too high. If the let-off were quite close before this felt compacted, it will cause a blocking hammer.

I realized a long time ago that no matter how old or new a piano is, or how prestigious the manufacturer, the piano invariably needs some refinement of the regulation. After a while a pattern even starts developing. Name me a manufacturer and show me a new piano from that factory and I’ll tell you what points to look at that probably need refining. One piano always need work on the action centres and voicing. Another always has tight centre holes on the keys and too little aftertouch. A third usually has problems with the bichord bass dampers. And so on. A good craftsman who knows his art can pretty well know in advance what a certain piano will need before he sees it for the first time.  

Grand Regulation – part XIV

33) Let-off (continued) 

Previously discussed were the regulation steps that affect the point of let-off, namely the jack alignment to the knuckle and the raising or lowering of the whippen either through altering the key height or by turning the capstan. The amount that these changes would affect the point of let-off is marginal. It is far more important to realize that regulating the let-off affects other steps more than the other steps affect it.

The two steps which are affected by regulating the let-off are dip and drop. Remember that in this discussion dip includes aftertouch. Looking first at how let-off affects drop, let us define drop as the amount of downward movement that the hammer has after the point of let-off. Keep in mind that the regulator has to move the key downward very slowly in order to see this drop of the hammer. During normal playing, this drop as such would not be visible, as the hammer would just rebound from the string into check.

If a graph were drawn to show the movements of the hammer versus the slow, downward movement of the key by the technician, the amount of drop and how it is affected by the let-off becomes clear. In all of the graphs shown, the key dip is set to a specific measurement  which will not be changed. In figure 1 the hammer travels upwards from the point of rest and lets-off (marked “A”) at 1/8” from the string. The hammer then drops away from the string let’s say another 1/8” (marked “B”), and then rises back up yet another 1/8” (marked “C”). This last upward movement of the hammer coincides with a small downward movement of the key which we will define as aftertouch. 

Figure 2 illustrates what happens when the hammer lets-off closer to the string, all of the other regulation steps staying unaltered. The point of let-off has changed to 1/16” from the string, the drop increases to about 3/16”, and the aftertouch decreases to about 1/2” of what it was in figure 1. The aftertouch decreases because it took more key dip to raise the hammer to a higher point of let-off, and it took a fraction more dip for the hammer to drop the farther distance compared to figure 1. The pianist will complain that the piano now “plays hard” since there is insufficient aftertouch. The action also feels a bit sloppy because of the excessive drop. He might even notice that when playing very lightly the hammers have a tendency to “bubble”.

Figure 3 tells what changes happen when the let-off is too far from the string. Here the point of let-off is 3/16” from the string. The drop now decreases to about 1/16” and the aftertouch increases to about 1-1/2 times as much as in Figure 1. The aftertouch increases here for the same  reasons why it decreased in Figure 2. It took less dip to raise the hammer to the point of let-off, and less dip for the hammer to drop the smaller distance. In this case the pianist will complain that the keys feel spongy, as there is too much aftertouch. I doubt that he would complain of too little drop, as he would not normally be able to feel it. The complaint may be heard of slower repetition.

As can be seen from these graphs, a change in the point of let-off can really affect another regulation step. I will explain now why it is important to know that almost nothing affects let-off while let-off definitely affects drop and especially the aftertouch portion of the key dip. Remember the circle of five steps? By adding let-off and drop to this circle all seven main steps of section IV The Touch portion of our 50 point checklist are shown in their relationships to each other. 

If it were your job to regulate an old action that had just had new hammers / shanks / flanges installed, where would you start regulating on this circle? Let us assume that some years previous this action had been regulated to compensate for the wear which had then taken place. It is reasonable to expect that the capstans, let-off buttons, and drop screws had all been tuned up. Now with new hammers and knuckles these screws would be too high. The hammer line is too high as well as uneven. Because the escapement is set too high most of the hammers block upon the strings, or with the action out of the piano, the hammers “bubble” on top of the jacks.

The repetition springs are also weak from hours of playing. You could start regulating by setting the hammer line back down to about the correct blow distance, but you cannot even begin to set it perfect since the repetition springs are weak. The springs cannot be strengthened yet since the backchecks are out of regulation. The backchecks cannot be set because the escapement is so high the hammers will not go into check, but rather “bubble” on top of the jacks. The dip could  be set with a dip block, but correct aftertouch could not be proved out. So, what do you do?

I would suggest that in such circumstances, once the key height has been established, the place to begin is with the escapement. Yes, that is right! Let-off and drop can, indeed sometimes must, be set first. It has already been stated that changes in the capstan and jack alignment minutely affect the point of let-off. The only step which affects drop is let-off. So by regulating the let-off and drop first and then continuing through this circle of seven steps a very accurate regulation can be made almost the first time through. I realize that if you are used to regulating the backchecks last that this method may seem a little strange. However, it is the only way out of the maze.

When turning the let-off screw, check to make sure that the drop screw is down far enough in order to see the hammer let-off. Otherwise the hammer will continue to rise right past the point of let-off if the drop screw is up too high. Since regulating the let-off must always be done in the piano, double check your work previously completed. As the hammer is seen to rise against the string, recheck the hammer to string alignment. When looking under the pinblock. Inside the action as you turn the let-off screw, recheck the jack tender to let-off button alignment. After a while rechecking your work in this manner becomes second nature.

If you are wondering what special tool is used to set the let-off with the action inside the piano, take a Mason & Hamlin screw stringer tuning lever (still available through all supply houses) and grind the tip so that it fits well between the let-off screw and the let-off rail (see figure 4). This is of course the tool used on regulating screws as found for example on Steinways. On pianos with let-off dowels, use a special tool made to fit the hole in the dowel. Yamaha for example sells a tool made to fit the holes in their dowels. A regular capstan tool will not work unless the tip is ground down to make it smaller in diameter. I once purchased a ratchet-type Mason & Hamlin let-off tool which was supposed to make it easier to set the let-off screw where you wanted it without having to keep taking the normal tool off the regulating screw. I tried this new invention, but quickly went back to the original tool, as it is faster for me to use. 

To be continued.