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Eric, I'm sorry I misunderstood you to say that the string heights were =
lowered. As far as inducing warping, it is more to get the middle =
mounting blocks level or slightly raised in the senter to match the =
string heights. The straightness or lack of it may be involved only in =
the torque of screwing down the feet to the blocks but I suppose some =
radical could bend the thing. BTW have you ever encountered the front =
mounting higher than the back? Yes, it has happened from the factory. =
Chris Solliday
----- Original Message -----=20
From: Wolfley, Eric (wolfleel)=20
To: 'College and University Technicians'=20
Sent: Thursday, July 21, 2005 1:55 PM
Subject: RE: [CAUT] Steinway stack height
Chris,
My string heights are in the 7 1/2" range for the most part (a little =
higher in the middle) and the hammerflange centers are at 5 =BE" so the =
real problem is getting the 1 =BE" blow distance without peeling the =
bumper felt off to within 1/8" of the wood. I've dealt with a couple of =
actions where I would like to raise the rear of the stack up to avoid =
the "dreaded repetition lock-up" but have glued extra felt on the =
bumpers for the sake of expediency. Do they ever actually induce warping =
in the stack at the factory to match the curvature of the string =
heights? I've never had a stack that rocked on a flat bench or noticed =
one that was flexed into a curve on the keyframe.
Eric
Eric Wolfley, RPT
Supervising Piano Technician
College-Conservatory of Music
University of Cincinnati
-----Original Message-----
From: Chris Solliday [mailto:solliday@ptd.net]=20
Sent: Wednesday, July 20, 2005 12:52 PM
To: College and University Technicians
Subject: Re: [CAUT] Steinway stack height
Eric, the real relationship in this is of course from the string to =
the center heights. If 7 1/2" is the string height, correspondingly =
the hammer center height should be 5 3/4" which is a difference of 1 =
3/4" ( a familiar number), so consequently shouldn't the hammer center =
height be 5 1/2" if the string height is 7 1/4" ? Is this what Mike Mohr =
means by "the action height is unique..." and "Maintaining the =
relationship between... ?" Just a slight caution regarding lowering the =
stack height only in the back, it can result in the dreaded "repetition =
lock-up." But with your shanks so close to the cushions it's probably =
not a problem. I think Pianotek sells different size rest felts so you =
can maintain a good relationship to the shank. As for the straightedge =
thing it doesn't mean that you should just stand there forever checking =
it continuously, however great a relief from our regular duites this may =
be, but rather just when setting the two center mounting blocks and =
maintaining a slight curve (or not) to match the string heights. =
Although it certainly would be a good way to measure warping if you knew =
where it had originally been set. Accurate string height measurements =
are really key, especially with Steinways, for this kind of work. Chris
----- Original Message -----=20
From: Wolfley, Eric (wolfleel)=20
To: 'College and University Technicians'=20
Sent: Thursday, July 21, 2005 11:29 AM
Subject: RE: [CAUT] Steinway stack height
Thanks Chris and all that replied. I'll thumbtack the specs to the =
wall so I won't misplace them. I did contact Kent Webb and the current =
spread specification is 4 13/32" which translates to 4.40625"
The piano in question is indeed of 1968 vintage (Mr. Purdy) and was =
originally Teflon with the big fiber knuckles. I isolated the problem to =
two sources: The rear of the stack was 1/16" too high (3 5/16").easy =
enough, I carefully planed the shoes down. The shank bumpers on the new =
wippens I want to use (Tokiwa miracle wipps) are 1/8" higher than the =
original. We save a lot of old parts here.it was good to have some =
samples to check. This piano had a new soundboard installed a few years =
ago (before I started here) and obviously the string heights are lower =
now than its original incarnation.=20
In Chris's post below I can't exactly visualize what they are =
talking about when they say "continually check for straightness with the =
straightedge on top of the hammershank flanges". My only guess is that =
if the mounting blocks aren't all on the same plane the hammer rail =
could warp down or up where a stack bracket is screwed down but it seems =
like it would have to be really bad for this to happen.
Eric Wolfley, RPT
Supervising Piano Technician
College-Conservatory of Music
University of Cincinnati
-----Original Message-----
From: Chris Solliday [mailto:solliday@ptd.net]=20
Sent: Monday, July 18, 2005 5:07 PM
To: College and University Technicians
Subject: Re: [CAUT] Steinway stack height
"B" at note 62 in NYC hammer flange 5 3/4"
rep flange 3 1/4" based on string height of 7 1/2" you didn't =
say if pre 84 or post or the new incarnation but the spread pre 84 was =
4.381" and post 84 was 4.395" This may have changed on the latest and =
greatest and for that I suggest you call Kent Webb or email him. I =
think it is important to note that according to Mike Mohr's =
Forefinishing Notes, which I consider a reliable source, "Set Action =
Frame Height" says "IMPORTANT NOTE: the action stack height, as =
determined by the thickness of the mounting blocks. This action height =
is unique for each instrument, and is the result of the individual =
string height for a piano. String height variables are the result of the =
plate fitting and belly operations... String heights change from bass to =
treble usually in an arched or crowned manner. These numbers for note # =
62 represent an average. Maintaining the relationship between the stack =
height and the string height ensures: A) the proper BLOW distance at the =
same time the hammershank is properly off the cushion. and B) the proper =
HAMMER ROTATION is needed to minimize overstriking or shallow striking =
conditon. NOTE; if string height is lower or higher than above, keep the =
relationship the same..." (and later after shimming or planing the bass =
and treble mounting blocks) "continually check for straightness with the =
straightedge on top of the hammershank flanges." I know you only asked =
for numbers, but what the heck, I felt like sharing. BTW I'm sure you =
remember that we discovered when shimming or planning it is best to =
rotate the stack on the hammer flange pin axis which means adjusting the =
front foot differently than the back foot. Of course there are even =
greater subtleties to this process but then you did just ask for the =
numbers. Stay well, Chris Solliday =20
----- Original Message -----=20
From: Wolfley, Eric (wolfleel)=20
To: 'caut@ptg.org'=20
Sent: Tuesday, July 19, 2005 9:53 AM
Subject: [CAUT] Steinway stack height
Hi All,
I'm sure somebody out there knows the specs for the distance from =
the keybed to hammerflange center and keybed to wippen center for a =
Steinway B. I have these written down somewhere but can't find them and =
I don't trust my memory. I'm correcting a problematic action and believe =
the stack to be too high since to get the proper blow distance the shank =
cushions have been reduced to nubs. The bore distance of the hammers is =
correct and the string heights are in the normal range.
Thanks!
Eric Wolfley, RPT
Supervising Piano Technician
College-Conservatory of Music
University of Cincinnati
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