[CAUT] Steinway stack height

[Chris Solliday]

This is a multi-part message in MIME format.

---------------------- multipart/alternative attachment
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



---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/caut.php/attachments/8c/5d/34/49/attachment.htm

---------------------- multipart/alternative attachment--