Help on repairs!!

[Newton Hunt]

Let's look at this from a slightly different perspective.

Make certain all screws, front and back have been tightened.

We need to think of an action in terms of function and not so much in
terms of it's misfunction.  Isolating the problem almost always
suggests the solution to a problem.

First consider the piano action to be an integration of the following
major systems; key, wippen, hammer and damper.

Isolate each section and test separately to help isolate any problem.

Disengage the key from the rest of the piano and check the following:
	The key is a simple lever so:
		Free movement up and down.
		Bushings, check for hang up, smooth operation front and center.
		Bottom hole, not too enlarged to allow tilt and hang.
		Capstan for burrs
		Sides for rubbing another key.
		Clean and lubricate key pins.
		Check level, alignment, dip and pin alignments.
		Improper contact with other action parts.
		Gross misalignment of capstan and other action parts.
	Key weights.
		Check actual up and down weights and calculate friction and balance
weight.
		Balance weight should be over 32 and friction under 12.
		Consider placing additional weights into keys.
	
Isolate the wippen from the other components and check the following:
	Sticker and abstract for:
		Wear of sticker felt (depression or missing material);
		Binding of key connections.
		Friction in pinning.
		Misalignment of parts.
		Inappropriate contact with other parts (backchecks and bridle
straps, keys).
		Parts that can become disengaged. (Wood nuts jumping out of key
socket)
	Rocker (main wippen part)
		Condition of rocker felt.
		Wippen flange pinning (too tight = friction, too loose = misaligned
parts)
		Jack flange glue joint for looseness.
	Other wippen parts.
		Jack pinning.
		Jack spring condition.
		Tightness and alignment of backcheck and bridle wires.
		Damper spoon for roughness.
		Backcheck tightness
		Bridle strap condition.

	Check the let-off rail for screw and hanger tightness, alignment
front to back.
	Check the liberty rail (if it has one) to determine if the jack is
being forced against it.
	Liberty rail and/or let-off rail should allow a small movement of
jack forward when 
	the key is fully depressed.

Push the hammer rest rail as far forward as possible and release it so
it falls back into position and watch the follow of the hammers.  Do
this quickly and slowly.  Any lagging hammers have tight pinning. 
Check hammers for too loose pinning.
		
Check the condition of the hammer springs and their seats.

Isolate the hammer section and check the following:
	All glue joints.
	Check condition of ALL felts.
	Pinning, too loose or too tight.
	Bridle strap for condition and determine if it hangs up on backcheck
or let-off rail.
	Check the condition of the butt leather (or felt)
	If felt then capstan has to be adjusted to allow the jack to move out
and under entirely
	unimpeded when moved by finger pressure.  (Felt wears so much faster
than buckskin).
	Check condition of backstop leather (or felt) for effective
engagement with backcheck.
	Misalignment of all parts.

Isolate the damper section and check:
	Free movement back and forth (with and without the spring)
	Condition of spring and spring seat.
	Check the condition of the damper lever felt for excess wear from
lift rod and wippen spoon.
	Check for rubbing with neighbor felts.
	Check the felts aligned with strings.
	Check that the lift rod swings freely but the bushings are not
excessively free.
	Check that the hooks are aligned in the same plain.
	
Action Parts:
	Check the action brackets (tighten screws), the hammer rail hangers,
main action rail.
	Check action support bolts and upper bolts and nuts.
	Check condition of center keybed support (underneath keybed)
	Check condition of pedals.
	Check condition and alignment of all case parts.
	Check and tighten all plate bolts and screws.

Finally check that the hammer shanks are just short of being perfectly
vertical when hammer is against the string.  If they go past vertical
then there will be repetition problem.

This form of analysis works for any kind of machine, grand pianos,
computers, software, cars or anything else you are working upon.

Think in terms of functions as being chains, one link leading to the
next link.

I may well have left out something along the way but careful
examination of the parts and thinking of their interactions will lead
you to the cause of the problem. 

AX-Mozilla-Status: 0009tated, is it's own solution.

		Newton Hunt
		New Jersey