Regulation of a Grand Piano Part 2.

2. The 'lost motion' between the moving of the key and the hammer's beginning to move should be adjusted out using the pilot screw beneath the felt pad of the whippen foot. When at rest, the hammer shank should be about 2 mm above the hammer rest felt and the nose of the hammerhead is 47 mm from the strings. Some compromise will be required here, though, if both measurements cannot be achieved, favour the 47 mm hammer blow - try to get as close to this as possible.  

3. With the action in the piano, set the let-off point of a few sample keys to about 3 mm from the strings. The let-off point is the point at which, after the set-off, the hammer comes to rest on the repetition lever. (Often the set-off is so low that the let-off cannot be set. If this is the case, raise the set-off high enough to allow the let-off to come into play). I set sample keys every 5 notes - a major third and the notes in between. Holding 2 sample keys down, line up the let-off points for the 3 in-between notes.

4.Next job the set-off - this can be done on the work bench. The Set-Off is the point at which, when slowly depressing the key the hammer falls away from the string. This is the famous escapement taking place. Holding a key down (the hammer resting at the let-off point) set the neighbouring hammer's set-off point to about 1 mm above the let-off point. repeat across the keyboard.   

5. Regulating the check-off. This is where you simply play a note and hold the key down - the hammer comes to rest (having been caught by the back-check). The distance from the string cannot be fixed as a general rule. The crucial point is that the repetion lever is 'charged' and ready lift the hammer when the key - and therefore the back-check - is released. To achieve this the check-off point must be lower than the let-off point.

6. Regulating the repletion springs. When the key is held down after striking the string, the hammerhead is held by the back check. When the key is released slowly, the hammer should gently lift up to 6 or 7 mm. When the spring is too weak, the hammer falls away from the strings. Too strong and the hammer kicks up. The spring should be adjusted so that the hammer lifts gently. Sometimes the springs have to be bent in order to strengthen of weaken them, but sometimes there is a simple screw adjustment. This adjustment has to be made for all 88 notes! 

7. Regulating the dampers. This is perhaps the most demanding of stages in the regulation process. Some pianos have easy adjustment features but mostly, you have to set each damper to begin lifting from the string when the hammer is about half way up to the string. At the same time every damper should lift together when the pedal is operated. This is a trial and error issue and you keep going until you get it right.

Back to PART 1

© Steve Burden

   

Regulation of a Grand Piano Part 1.

Regulating a grand piano is not as simple as just taking accurate measurements and making slight adjustments. Many years ago I telephoned an Action Manufacturer to order some action parts and during the conversation I asked if there was a 'regulating manual' for their actions. I thought there must be some written instructions but the response was an emphatic: "No!" 

So we in the piano trade are left to make as much sense of regulating a piano as we can! Experience is important but having a keen sense of what works well and being dissatisfied with ignoring obvious problems is crucial if we wish to find success. There are good books which will explain what happen during the stroke of the key but not even these will help when correcting some of the many possible problems. Regulating work, even on new pianos, is not as simple as we might hope. 

Fortunately, there are principles which, when understood, form a structured approach to get the job done. The following is my own method for regulating - it is not the only way, but I have found it to work well on most pianos.

Please note: while regulating pianos, some improvisation is required to get the best out of any given piano.

Most actions work well if the depth of touch is 10.5 mm. and the hammer blow 47mm. 

1. First job is to level the keys and set the depth of touch - best done with the upper part of the action separated from the keyboard. With a set of lead key weights, place the weights on the front end of the white keys (front of the ivory key tops so the the keys are resting on the front-touch baises) and level the keys so that across the keyboard they appear perfectly in line. Any adjustments are made using paper or card washers under the front-touch-baise.

Then, for a few sample keys, attach the weights to the back check and measure the depth of touch at the front of the key (as compared to the keys with the weights still sitting on the front - I set sample keys every 5 or so white keys). Touch depth should be 10.5 mm.

This done, gradually transfer the weights to the back checks and level each of the white keys to be in line with the sample keys. This takes care of the white keys.

For the sharps: with the lead weights still clipped to the back checks, ensure that the top surface of the sharps, when resting on their individual front-touch biases are about 1 mm above the top surface of the white keys. Again, set a few sample sharp-keys ensure sharps are level and then proceed across the keyboard. 

Then, with a few sample sharps, attach weights to their back checks and set the height of the front end of the sharps to be 12 mm above the top surface of the white keys (These white keys must also still have the weights on the back end of the key). Using sample keys as a guide, continue to level all the sharp keys across the keyboard.

The upper part of the action is now screwed back onto the keyframe.

PART 2

© Steve Burden