Regulation ..

Simply, regulation is the mechanical adjstment of the action and pedals.

Items of felt and two leather items have been highlighted in red. As you can see, the entire mechanism rests on mostly felt and a bit of leather. Varying amounts of wear occur from playing. The amount of wear depends on how the piano is played. Wear is not even. Regulation accounts for this wear.

Grand Action Model

I think both views help demonstrate the relationship.

Gand Action Model Actual Photo

The entire action is relying on woven felt for friction control, noise reduction and smooth play. As the action is played, the felt wears and the tolerances deteriorate. Not all adjustments wear at the same rate.

It is said that there are approximately 36 individual adjustments for each key. At the time of Initial design, Manufacture or or rebuilding, this may be true.

For the average person, anywhere from one to ten adjustments per key may be likely. This can take anywhere from half an hour to several hours depending on what is needed.

Needs are based on players requirements. The needs of a young beginner are different from those of an advanced or professinal player.

If you are having your piano tuned, this is the best time to ask questions regarding regulation. A piano tuning is a very close inspection of every note in the piano.