Grand Regulation In Detail - Setting The Hammer Blow - part 12

We left off talking about the two factors that create the striking point for a hammer. Assuming that the hammer glue joint is 90 degrees on the shank, which it must be, these two factors are: 1) The distance from the hammershank centre pin to the centre of the hammer molding, and 2) The position of the hole in the hammer molding, more commonly called the hammer bore distance. In measuring factor number one, the measurement is always taken from the centre of the centre pin, to eliminate any error because of larger centre pins.

Looking at the diagram, this distance for factor number one is labeled (L). In this particular instance, (L) = 5 1/8“, which is a common measurement. (L) determines the type of arc that the hammer will take on its upward movement towards the string. The distance that the hammer travels in this arc is labeled (S). (S) is correctly termed the hammer travel distance. Note that this is different from (6) the hammer blow distance. These two words should not be used interchangeably.

As the hammer is moved in or out on the shank, this distance (S) changes. Minute alterations of (L) by the technician as he glues on a set of new hammers is acceptable in order to achieve the correct striking point. However, keep in mind that the piano was designed with a specific distance for (S). The work that the knuckle does in raising the hammer is in a ratio which is dependent upon (L) and the placement of the knuckle. The closer that these two placements are to what was designed, the better the action will perform.

Of greater importance than factor no1 is factor no2, the hammer bore distance. I regularly find good make grand pianos where the bore distance is wrong from the factory! When manufacturer installs the hammers, he should measure the distance (A) on the diagram. This is the distance between the bottom of the string and the centre of the centre pin on the hammershank. Unfortunately, many pianos are manufactured without regard to this measurement. (A) does fluctuate a little from what the piano was designed to be, mostly because of differences in the thicknesses of the plate castings. Sometimes the string height varies because of improperly installed agraffes, or in the case of a rebuilt piano, the string heights will vary because the plate was lowered in order to achieve proper downbearings.

When rebuilding, always wait until the new strings are installed before sending off for new hammers. Never buy stock hammers. Insist that the hammers be bored to match the piano. Either send to the hammer duplicator the measurements for (A) for each section of the action, or else bore your own. Anyone who has regulated many actions will have noticed that the string heights vary not only between similar pianos of the same make and model, but will also vary between the different sections of one instrument. Ever wonder why the hammer rest rail never fits the bass hammershanks like it does the tenor? One cause can be improper hammer boring. Why? Most grands are made with the hammers bored at a stock distance, to supposedly fit all of the pianos made of that model(s). No interest is paid to what (A) is, or whether (A) is the same for each given section of the action.

Why is this so important? 

 

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Grand Regulation In Detail - part 11

32) The Blow

Step no12 was adjusting the key height and leveling all 88 keys. Last month we discussed step no31, regulating the jack height. These are the only steps that directly affect the blow distance, or hammer line. Indirectly the repetition springs will also affect the hammer line if the springs are weak. However, we had to make sure the springs were strong enough to support the hammers before the jack height was set. Therefore, we should now be ready to set the hammer blow distance.

Once set, there should be no need in doubling back to readjust this distance. Remember that before all of the jack heights were set, a number of sample keys were regulated for jack height, blow, let-off, drop, and then the regulation was proven to be correct with proper after-touch. I always use the end keys in each section as my samples. First, this allows for any irregularities in the string height going from section to section. Second, it gives me a hammer at the end of each section which has been set to the correct blow distance. Doing step no32 The Blow then becomes a simple matter of drawing a line between the tops of these two end hammers and setting the remaining hammers in each section level to this line.

This, of course, is accomplished by raising or lowering the capstans. If the hammers do not return consistently back to the same height when a test blow is given to the keys, check for weak repetition springs, too much lost motion in the jack height, tight hammershank flange centres, or tight key bushings. Any time that the capstan is changed, it is a good rule to give the key a test blow to see where the hammer will settle in its height. During this test, watch the rebound of the hammer as it comes up off the hammer rest rail/felt. All 88 hammers should rebound with the same freedom. If they do not, stop and check for nonuniformity in the centres, as this will make the action play unevenly no matter how well the action was regulated.

When all of the hammers in each section have been made level to the samples, install the action back into the piano and play each note vigorously. At no time should any one hammer be higher or lower than its neighbours in a section. Any unevenness should be corrected. Incidentally, the practice of raising one hammer to give the proper after- touch to that one key is wrong. In order to have perfect evenness of touch, uniformity of tone (i.e. power), and a uniform repetition, all hammers must be the same distance from the strings. More will be said on this subject at a later time.

In selecting the proper blow distance, look at the tangent relationship between the jack and the knuckle. Ideally, the knuckle should be glued on at 90° to the hammershank, and the jack should be in a straight line with the knuckle core. This would give the ideal of a jack at 90° to the hammershank. The shank should be about a shanks height off the rest felt. If it is a great deal more above the rest felt, make sure that this angle between the jack and shank is checked. An angle of more than 90° will result in a loss of power. What we want is the maximum acceleration of the hammer without destroying this tangent relationship. As has been mentioned before, altering the blow distance or altering the key dip are the only two steps which can be changed to compensate for action wear. Never set the blow distance without also considering the dip. If it is unacceptable to change the dip, and if this tangent relationship of the jack to shank has to be compromised, perhaps you should think in terms of installing a new set of hammers/shanks/flanges.

 

In the past, I have stated that ...

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Grand Regulation In Detail - Jack Adjustment - part 10

I pointed out in the past that we really do not set the jack height, as the jack is not variable in its height. Rather, we set the height of the repetition lever relative to the top of the jack. However, I have always called this regulation setting the jack height, and I intend to continue to do so. The specification in regulating is to have just a fraction of space between the top of the jack and the bottom of the knuckle with the whippen at rest. This can be compared to setting the lost motion in a vertical piano. However, in a grand the amount of space needed is even less than in the vertical.

Before taking the action completely out of the piano to adjust all keys for the jack height, I like to set sample keys for blow, let-off and drop, as well as jack height. Doing this first and proving these sample keys with aftertouch insures that after all of the steps in Section IV are regulated, the piano will play properly.

In order for the jack height regulation to be stable, the repetition springs must be strong enough to support the hammers. We have all seen hammers that do not return to the same height after each time they are played. This can be caused by either too much lost motion between the top of the jack and the knuckle, or by repetition springs that are too weak.

Assuming that the repetition springs are strong enough, the culprit is the jack height. As well as causing an uneven hammer line, too much lost motion also causes a loss of power. On the other hand, too little space will not allow the jack to return under the knuckle as fast as it should (or not at all) and hence cause faulty repetition. Some technicians set this measurement by feeling the top of the jack versus the side of the balancier window where the jack sits. The specs call for a 0.2mm (or a paper’s thickness) space that the jack should be below the window.

This is fine if the piano being regulated is brand new or if the knuckles have just been replaced. Under these conditions, the surface of the knuckle is very even across the face where the jack contacts it. If the knuckle is not new, chances are that the leather has begun to get grooved in the middle from the force of the jack hitting it. To obtain the proper space between the jack and a grooved knuckle will require that less than a 0.2mm measurement be used. In some cases the top of the jack may have to be even with or higher then the balancier window. With a grooved knuckle, there is only one way to regulate. That is by using a process called “winking the jack”.

With the whippen at rest, gently slip your finger in between the top of the jack tender and the bottom of the let off bottom. Slowly depress the jack tender as if it were going through the process of let-off. Be careful not to push down on the whippen while tripping the jack. Depending upon the type of action you are working upon, you may see the hammer “wink” or not! By “wink” I mean that the hammer will fall slightly lower than its neighbours. Sufficent space must be allowed for the hammer to fall, so the hammer rest rail must be set a shanks diameter below the hammershank at rest. If the action has hammershank rest felt instead of a rest rail, either raise the shank or remove some of the rest felt.

For some unknown reason, some makes always give a perfect little “wink” for this test, but others are not as reliable. Therefore, ...

 

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Grand Regulation In Detail – Regulation where the piano is - part 9

Whenever the subject of grand action regulating comes up, the thoughts always turn to benches, key levelers, and let-off racks. As others gloat about how they designed their own bench tops to try to duplicate the piano’s keybed, I usually wander off shaking my head asking myself, why so much bother when they could just use the piano itself? I agree that many of the procedures in the 50-point checklist must be done in the shop. These include such repairs as rebushing keys, refelting the keyframe, replacing keytops, etc.

However, many of the steps that may be done in the shop can also be done at the piano, or at least in the customer’s home. These would include such things as reshaping hammers, repairing action centres, polishing capstans, cleaning knuckles, etc. If the piano is not already in the shop for rebuilding, I much prefer to work right in the customer’s home. I have no need for an elaborate bench top, let-off racks, or Jarvas type key levelers! As a bench, I use the keybed of the piano, or if need be, my lap or the piano’s lid (padded of course with a moving pad). Instead of a let-off rack, I use the strings themselves (far easier and more accurate). In place of a key leveler I use a small straightedge about 15” long which I carry in my case. 

 

Also in my case is a good supply of punchings and other repair items so that I can arrive at a home to tune the piano, and end up staying there all day, reshaping hammers, doing action repairs, and a complete action regulation. I don’t work out of a large van either. In fact, many days I work out of a motorcycle! With experience I know what to bring to be prepared for the day’s troubles. In most cases, the customer would rather that I work on the piano in her home. She can watch what I am doing, the piano is not out of commission any longer than need be, and if any unexpected repairs crop up, l can consult with the owner while at the piano. It is certainly easier on me since I often work many miles from home, and it is awfully hard to carry a grand action home on my motorcycle. 

 

These reasons for working at the piano are secondary. Of real importance is the reduced time to complete the work (which means more money) and greater accuracy. Let us make a comparison of two equally fast working technicians, one who regulates at the piano, the other who carts the action back to the shop. Let’s pick a ten-year-old piano which has had normal usage. All that is needed are the usual minor adjustments to the action as a result of a little wear and settling in of the action parts, reshaping and voicing of the hammers, and tuning.

The first technician, who regulates at the piano, immediately proceeds to reshape the hammers. This can be done by turning the action around in the piano with the hammers facing the technician, or else putting the action on top of the piano. He then takes apart the action, removes the keys, reinstalls the action without the keys, and cleans everything prepatory to bedding the keyframe. After bedding he aligns all of the action parts, using thestrings ofthe piano as his guide. Next, he regulates the action mechanism in the piano, and lastly tunes and voices it. Approximate time: one working day.

The second technician, who is going to regulate the action at his shop, takes ...

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Grand Regulation In Detail - Part 8

In part VII of the series on grand regulation we discussed the two methods of regulation for grands, the Dip and Blow Priority. Now that we know the differences between these two methods, two decisions must be made before Section IV ‘The Touch’ can be begun. The first decision is what procedure to use to accomplish the regulation process. The other decision, depending upon which Priority method was chosen, is to determine the correct measurement for the dip or blow. Once these two decisions have been made, the remainder is a piece of cake. Without these two decisions, regulation becomes a long, hard task with lots of wasted time.

Let us look at some of the many grand regulation procedures that are available to choose from. This list is by no means all inclusive, and just because a certain procedure has been omitted from this list does not infer anything about its relative merits and value to us. 

 

The five procedures listed on the left are Dip Priority, the five on the right are Blow Priority. In viewing this chart you will notice that some procedures have more steps than others. But pay more attention to the order in which these steps are listed. For instance, in procedure no10 the whippens are aligned to the knuckles as step number three. But in step number seven the hammers are aligned to the strings, making realignment of the whippens necessary. Other procedures listed have similar mistakes. I would certainly modify the order of some of these procedures to eliminate such needless doubling back. 

 

If you were to regulate an action, which of these procedures would you choose? Should you select the one that is from the factory manual for the brand of piano being worked upon? If so, then each time you regulated a different brand of piano you would use a different procedure! Needless to say, this is awkward. Or should you select a procedure written by your favourite author to use on all brands of pianos? Chances are that your author’s procedure is different from what the manufacturer calls for, and may not be as detailed as the factory manual. As an example, some pianos have an auxiliary whippen spring. If you did not know this, and the procedure you were using doesn’t mention it, you would probably overlook it. Well then, should you select the procedure that is the most detailed? I don’t believe so. Just because it has 125 steps doesn’t mean that it is better than one with 50 steps!

How do you decide upon a procedure? Obviously, you want the one which is easiest and fastest for you. People differ in their abilities and knowledge. What works best for one technician may be awkward for another. I suggest that everyone make up their own procedure to suit their own needs. In creating your own, remember that the order of steps must be logical so that the minimum of doubling back occurs.

As a help here, consult the Grand Regulation Chart which appeared in the 2nd post of this series on grand regulation. Naturally, you will want to include those steps such as reshaping hammers and rebushing keys that are normally done when regulating an action. Every step should be in a convenient order to go along with how you regulate. Do you bench regulate or do you regulate at the piano, or a little of each? In that case, you have to create your own procedure. 

 

Now that the procedure has been decided upon, next is to decide what measurement to use for the ...

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