Friday, 24 October 2014

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

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