Last discussed in the 50-point guide to grand regulation were the two main methods to regulate. One is called the Blow Priority method, the other is the Dip Priority. To determine whether a given procedure is Dip or Blow Priority, just look to see which of the two is regulated first in the order of steps listed. Once the dip or blow has been adjusted, all of the other action regulations are then set based upon this first measurement.

To explain this further, there are seven main steps in section IV, The Touch portion of the 50-point checklist These seven are: 1) Blow, 2) Dip, 3) Let-off, 4) Drop, 5) Backcheck distance, 6) Repetition strength, and 9) Jack Height to the balancier. Again, as in the past, the dip includes  the correct aftertouch measurement. Let us take the example of a Blow Priority system first. If the repetition spring is strong enough to support the hammer first adjust the jack height in order to insure that as the blow is set that the hammers will always return to the same setting. Step two then would be to set the predetermined blow distance. Depending upon how worn the whippen felt is, how flattened the knuckle has become, and how much the hammer has been filed the capstan will need to be raised further to compensate for greater wear in order to achieve the desired blow distance.
Raising or lowering the capstan affects directly or indirectly all of the remaining steps. Raising the capstan raises the whippen assembly, which causes the jack tender to become closer to the let-off button, and the balancier to become closer to the bottom of the drop screw. Once the let-off and drop are correctly set, changing the capstan will necessitate readjusting the let-off and drop. If the correct after-touch is to be achieved, the dip measurement is predetermined by the blow and let-off distances selected. The amount of dip will affect the backcheck angle. And, as we all should know, we set the repetition spring strength based upon the hammer’s release from the backcheck. So out of the seven main steps in section IV TheTouch, changing the capstan will affect one way or another all seven steps: To eliminate any unnecessary doubling back to reregulate a step already performed, set the blow distance right in the first place, and all of the other six steps will come out correct the first time through.
Remember the “circle of five steps” as explained in the first article of our series on grand regulation? If not, please look again at our first post. This illustration helps to show how each step affects the others.
Adding the let-off and drop in between the blow and the dip completes the circle with all seven steps. Of these seven, only two can be places of compromise to compensate for action wear. The let-off, drop, backcheck distance, repetition spring strength, and jack height can only be regulated to specific tolerances or distances, with very little room for variation. Only the dip and blow can compensate for action wear. The Dip and Blow Priority methods are the means of setting one of these variables in the beginning, making any compromises needed with the other variable latter.
One school of thought amongst piano technicians is that the dip is not a variable. In other words, there is a specific measurement that the key is supposed to go down, that measurement being standard throughout the world, and no variation from that measurement (usually 3/8”) is acceptable. This of course leaves only the blow distance as a means of compromise as the action wears. I believe this school of thought to be a little narrow minded. There are times when the dip should be altered a little. When I say a little, I mean within + or – .036” at the maximum. Next week, we will discuss just how “‘standard” this measurement is.
We have already discussed what the main areas of wear are: 1) the compacting of the whippen cushion felt from the force of the capstan against it, 2) the flattening of the knuckle from the force of the whippen, and 3) the wearing of the hammer felt as it becomes grooved and out of shape from hitting the string. As these forces take their till the amount of after-touch, which is mainly a safety factor for this purpose, decreases to the point of being non existent. Once the action has worn to this point, if a technician has not yet made adjustments to compensate for wear, the piano becomes very hard to play. The pianist will complain that the keys feel like they are ‘bottoming out’. Raising the capstans to bring the blow distance back to the original measurement will help restore aftertouch. Keep in mind that we are only discussing here the wear that takes place in the upper part of the action mechanism.  I assume that any settling of the keys at the balance rail will have been corrected and restored back to the original level.
What do you do then, if after raising the capstans the amount of aftertouch is still insufficient? Many times this is the case. Aftertouch can be.obtained by either: 1) raising the capstans more, reducing the blow distance even more, and thereby reducing the amount of power available to excite the string, or 2) increase the key dip, leaving the blow distance to what it originally was. Increasing the dip, of course, decreases the speed of repetition. Torn between a loss of power or a loss of repetition, what do you do? This will not be discussed at this time. However, the choice should be made depending upon the pianist’s preference and the circumstances under which the piano is being played. At this time we will go on to discuss the Dip Priority method of regulation, and then make some comparisons between the two methods. In a few months ahead, we will discuss power and repetition when regulating the worn action.
In the Dip Priority method, the dip is set first with a key dip block to exactly what you want the white key dip to be. Forget about the black keys for now. As step two, again assuming that the repetition springs are strong enough to support the hammers, set the jack height. Steps three, four, and five will have to be adjusted slightly to get the correct results for aftertouch. Step three is blow, four is let-off, and five is drop, If after setting the drop the aftertouch is either too shallow or too deep, raise or lower the hammer line (blow) until the correct aftertouch is obtained. Once the blow is altered, the let-off and drop must be readjusted, too. Next, set the dip on the black keys. Later I will explain in detail how to do this. Finally set the backcheck distance and then the repetition spring strength.
Now we can compare the two methods. Some doubling back may occur in steps 3 to 5 in the Dip Priority method, whereas no doubling back was needed in the Blow Priority method. This is minor and will cause little time to be wasted, if sample keys are tested in each section before regulating the whole piano. The major difference as I see it, is that in the Blow Priority methods the aftertouch is set after the blow and let-off, there by obtaining a uniform amount of aftertouch on every key, regardless of any discrepancies in the action parts. However, in the Dip Priority method the aftertouch can vary with each key as a result of these same discrepancies in the action parts. Of course this variance in aftertouch is easily corrected by adding or removing punchings, but then this means more doubling back for the Dip Priority method. Besides, as I understand the school of thought, the dip should be set exactly the same for every white key by means of the key dip block. What is wanted is uniform key dip. Some artists insist upon a piano which has uniform key dip, others insist upon one with uniform aftertouch. In short, the Blow Priority method results in uniform aftertouch, the Dip Priority method in uniform key dip. There is a distinct difference between the two. Next month we will discuss the two decisions that have to be made before the process of regulation can begin.  

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