Improving Upright Dynamics & Repetition

[Newton Hunt]

I cannot imagine why you think it a bit much to from from the bottom of
the world to the top.  I would love to make the trip in reverse!

Make certain all action, bracket and let-off rail screws are tight.

Let-off should be a scant 1/8" or about 3mm in the bass to 2mm in the
top treble.  Any closer and you wil get some blocking during soft
playing.

Sharps should be leveled at 12mm above the naturals at the front end of
the sharp, the white keys should be assesed for dip at the very front of
the key, not over the pin as some would have it.

Use a micrometer to measure the thickness of your dip block at the front
of the block and perpendicular to the bottom surface of the block.  Sand
to get the same measurement at bother corners.  Write the measurement on
the block and use the same procedurefor all the blocks you own.  You
should have three or four, each different than the others.

Determine best relationshep of dip to hammer travel in each section and
average the results.  Dip should be about .390 inches or 10mm and blow
distance sould start at 1 7/8" or 48mm and should be decreased a mm ata
time until you reach 1 3/4" or about 45mm.  Safety factor, or the
distance the key travels after the jack loses contact with the butt,
should be no more than .050" or 1.27mm.  Dip con be increased to 11.5 mm
or .410".  Outside the .410" and 48mm and the 10mm and 45mm ranges you
will loose performance.  With a jproperly set up action the 10mm and
48mm shouold work best.

Capstans should be regulated so that the jack just brushes the butt when
returning to rest position with the hammer at rest position.  CLoser
than that can cause missed repeats and further than that robs the action
of power.

Damper springs should be no stronger than needed to mute the strings. 
Spoons should be regulated so the damper lever is engaged when the
hammer is half way to thge strings.

Butt springs should be even.  Butt springs have very little leverage,
but they are very important for repitition.

Pinning, especially in the butt flanges and jack flanges should be even
and low in friction.  These pins should have about 4 to 6 grams in the
butt flange measured from the far edge of the flange from the pin and
the jacks should have 2 to 3 grams measured at the top of the jack.

Backchecks should be regulated to 15mm (5/8"), but no closer than 12mm
on a light blow.

The bridle wires and the soft pedal should be regulated so that when the
soft pedal is depressed the hammers should move about 40% of the
distance to the strings and the straps become taut but not allow the
keys to lower.

Some better pianos have a liberty rail, a thin rail that is positioned
so that the jack cannot go more than a fraction further than the key
moves it.  Other pianos have nothing, some have a felt on the inside of
the back stop to stop the jack and others have a felt glued to the back
of the let-off rail.  Let-off rails can be moved front or back to
provide faster jack return.  Forcing the jack against a stop is counter
productive.

Consider that in most uprights the mass of the action and key is much
lower than on a grand.  The average of the up and down weight (without
dampers) should be in the 35 to 38 gram range.  Less than 35 grams
effects repitition adversely and more than 40 is dangerous to players
hands.  Installing very small weights in the front of the wippen is one
possibility to increase repitition without seriously effecting overall
touch weight, but measurements must be taken before willynilly
installing weights.  Advancing in small increements is critical,
understanding the pianist's needs is critical as well.

An action is a series of levers.  The designer fashioned the action to
perform best at certain adjustments, both at installation and during
regulation.  The designers specifications may well be unknown, but the
hammer shank should just barely not reach parallel to the strings.  If
this is off then new hammers or moving the action may be in order. 
There are other specifications that must be met, like the main action
rail should be vertical to the floor when installed and it's height
relative to the keys which can be changed, but with great tripidation
until the exact jproblem is known.

IF you have a specific action problem or a problematic customer give us
a shout and we will he happy to help.

	Newton
	nhunt@jagat.com
	New Jersey, USA