Piano Regulation for Pianists ~ by Rich Van Slooten – A440 Precision Piano Tuning


I am often asked to give a short explanation of the elements of piano regulation – especially to pianists with little detailed knowledge of a pianos’ inner working.  Since regulation steps and procedures can be very technical and detailed, I will attempt to keep this explanation as simple as possible.

  • Regulation involves the proper setting, adjustment, and calibration of piano action component parts so that when a pianist plays (depresses) a particular key, its corresponding hammer will strike its unique set of strings in such a manner as to produce a tone quality ranging from ppp to FFF, depending upon the velocity of key stick movement.

There are approximately three major elements of a piano action: (1) the Key Stick which is essentially a lever arm; (2) the Whippen which contains a pivot arm (jack) to engage the hammer knuckle and lift the hammer towards the strings; (3) the Hammer/flange/knuckle assembly which converts the key stick movement into angular hammer motion capable of striking the strings with enough force (hammer mass) x (velocity) to excite the strings and produce a tone quality transferred from the strings to the bridge and onto the sound board.

The above three elements Key Stick, Whippen and Hammer – linked together, form a lever arm arrangement  designed to convert a small displacement of the finger tip on the key (approx. .4 in.) into a large movement of hammer travel (approx 1.8 in.), with sufficient velocity to produce a wide range of dynamic sound.  The mechanical advantage of the lever arm arrangement is referred to as the Action Ratio, i.e., the ratio of total hammer travel distance to the downward displacement (dip) of the key stick – commonly referred to as leverage.

  • The essence of piano regulation is to make sure the action ratio is properly set per optimum design and performance specifications for your particular instrument.

Often this involves adjustments of only a few thousands of an inch within the lever mechanism.  What can cause a piano action ratio to change? Normal wear, changing weather and changing component dimensions.   Periodic adjustments are frequently necessary to compensate for normal wear.  Normal piano playing will eventually wear groves into pressed wool hammer heads.  Felt key and action center bushings will wear or compress;  wood action parts will warp, twist or change dimensions when subjected to changing humidity conditions.  Excessive key stick friction – hard playing or unresponsive keys are commonly linked to poor regulation.

  • The most pronounced wear will occur in the mid-range of the piano, typically over a three octave range centered around middle C, where the majority of the piano playing takes place.

There are anywhere from 20-40 steps in regulating either upright or grand pianos.  Typically a major regulation can take anywhere from 8-40 hours, and in some cases even longer.  The cost of simple to complex regulation will range typically from $300 to $2000 or more depending on the level of detail, wear and replacement parts required.  More expensive regulations usually involve some type of action rebuild or refurbishment.  However, once a piano has been properly regulated, minor adjustments for wear or humidity effects can usually be made during subsequent piano tunings.

The primary steps in action regulation are as follows:

(1)   Determine whether major component parts can be refurbished and reused.

(2)   Do hammers need reshaping or replacement?  Reshape if possible.

(3)   Verify integrity of knuckles, back-checks and damper felt

(4)   Bed the key-frame or action brackets; check setting of action glides

(5)   Determine the optimum action ratio for key dip to achieve hammer travel

(6)   Coarse set key dip & level all keys both sharps and naturals

(7)   Space keys and check for proper key bushing dimensions

(8)   Lubricate key-bushings with micro TFE or equivalent Prolube lubricant

(9)   Space and travel hammers to strings

(10)           Align back-checks

(11)           Check and align jack spacing

(12)           Perform rough regulation of repetition springs/levers

(13)           Regulate jacks to knuckles

(14)           Set repetition lever height

(15)           Regulate capstans

(16)           Set hammer let-off

(17)           Perform coarse regulation of hammer drop

(18)           Regulate key dip w/key-dip block

(19)           Regulate back checks

(20)           Recheck repetition springs/lever height

(21)           Refine regulation by going back over steps 10 – 20

(22)           Regulate trap-work pedals to action lever arms

(23)           Regulate dampers to key stick travel

(24)           Regulate dampers to sustain pedal travel

(25)           Regulate sostenuto pedal

(26)           Regulate una corda pedal

(27)           Recheck slow release of dampers onto vibrating strings to ensure even dampening.

Note:  Fine regulation of a piano involves essentially the same steps, however, they are repeated over and over (sequentially) to achieve the optimum settings for even and responsive piano playing and note repetition.   Elimination of excessive key friction is also a major goal of fine regulation.

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