broken hammer shank

[Vanderhoofven]

Dear Friends,

I am in a quandary.  I have a customer, retired music professor, with two
Steinway grands in his living room.  He is a very high caliber pianist, and
practices about 4 hours a day.  Last tuning, I broke a hammer shank on his
newly (3 or 4 years ago) rebuilt B, note C#4.  I glued the shank back
together, then called Steinway, but couldn't get a hammershank to replace
it unless I was buying a complete set.  I called the rebuilder, and he sent
me two different Steinway shanks and flanges.  I also called Renner, who
also sent me two hammer shanks and flanges.  Unfortunately, none of these
shanks and flanges is exactly like the shanks and flanges installed 4 years
ago.
 
My customer is concerned about how the differences between the hammer
shanks will affect the touch of his piano.

Here are the differences.  

Current shank and flange             
1. shank tapers to round shape       
2. drop screw is at an angle    
3. knuckle is smaller
4. flange height - .398 in
5. flange width - .52 in
6. shank width - .468 in
7. shank height - .255 in
8. distance from flange center pin to rosewood of knuckle - .16 mm
9. distance from center of flange screw hole to center of drop screw - 20 mm
10. smaller knuckle

Replacement shank and flanges
1. shanks taper to octagon shape
2. drop screws are straight up and down
3. knuckle is larger
4. flange height - .349 in
5. flange width - .473 in
6. shank width - .468 in
7. shank height - .236 in
8. distance from flange center pin to rosewood of knuckle - .16 mm
9. distance from center of flange screw hole to center of drop screw - 20 mm
10. larger knuckle


Which of the differences listed above will affect the touchweight and feel
of the action?  How will they affect the action?  Are there other
measurements you need in order to solve the puzzle?

I am just learning about action geometry and touchweight and do not yet
understand how these differences between hammer shanks and flanges may
change the feel and touchweight of the action.  Understandably, my customer
is not completely happy with the way I have handled the situation, but I do
not know where to obtain a shank and flange that completely matches the
ones currently on his piano.  Until we find a match, the decision has been
made to leave the original in place.

I would appreciate any help or suggestions!  I would also like to forward
responses to my customer, unless you think it is not prudent to do so.

Sincerely,
David
Missouri Southern State College
Cottey College

David A. Vanderhoofven, RPT
Joplin, Missouri, USA        
e-mail:  dkvander@clandjop.com

web page:  http://www.clandjop.com/~dkvander/
#pianotech page:  http://www.clandjop.com/~dkvander/ircpiano.html