Scruffing -was - Over-Strike vs Under-Strike

[Marcel Carey]

I think there has to be some kink of balance. I remember old uprights
with cedar shanks in the treble section. When I replaced some of these
broken shanks with maple ones, the tone would get ugly. Mind you these
hammers were tapered a lot and were very light, but there must be a
reason why the cedar shanks produced such a good tone compared with
maple ones.

There is so much that happens when the hammer hit the strings that we
don't know. It's a very complex system and we only can try different
things, but going to just a more rigid shank might not solve all our
problems.

Marcel Carey, RPT
Sherbrooke, QC

> -----Message d'origine-----
> De : pianotech-bounces at ptg.org 
> [mailto:pianotech-bounces at ptg.org] De la part de ed440 at mindspring.com
> Envoyé : 26 novembre 2006 21:39
> À : Pianotech List
> Objet : Re: Scruffing -was - Over-Strike vs Under-Strike
> 
> 
> I believe Kawai experimented with carbon fiber shanks and 
> decided to stay with wood.  I don't know why.  (Don Mannino's 
> class on the millenium action has the finest high speed 
> movies of a piano action I've seen.) For an experiment you 
> could probably just glue two shanks together and see if it 
> made a difference. Ed Sutton
> 
> -----Original Message-----
> >From: carlteplitski <koko99 at shaw.ca>
> >Sent: Nov 26, 2006 9:00 PM
> >To: ed440 at mindspring.com, Pianotech List <pianotech at ptg.org>
> >Subject: Re: Scruffing -was - Over-Strike vs Under-Strike
> >
> >
> >What a great subject.   Have read all or most of the 
> opinions thus far.  
> >Am thinking that  whoever asked
> >if it was possible to tune out the flex has come close to 
> the answer for 
> >" me."   If a stiffer shank were used,
> >and the strike point, or " sweet spot " of the hammer was 
> able to make
> >contact, flex should be mininized.
> >The incorrect flex robs the impact  position of power and 
> direction , 
> >because square contact
> >is compromized.  Assumming that the correct geometry has 
> been satisfied 
> >, by putting all the working parts
> >in their proper position before action takes place, then the 
> quiet or 
> >violent movement of the key will determine
> >if the hammer must flex or not.    I don't think an  action 
> can be built 
> >to be able to satisfy " ALL "  the  possible 
> >weights which can be applied at any time by an individual . 
> . Power is 
> >realized by square contact, at any speed.
> >A glancing blow isn;t as powerful as one straight on.  
> >
> >Carl / Winnipeg
> >
> >
> >>What does scruffing do to the sound?
> >>If the hammer did not scruff, would the piano sound different?
> >>How hard do you have to play to have significant scruffing 
> in a vertical?
> >>Is it more significant in a particular range?
> >>Ed Sutton
> >>
> >>-----Original Message-----
> >>  
> >>
> >>>From: Frank Emerson <pianoguru at earthlink.net>
> >>>Sent: Nov 25, 2006 1:00 AM
> >>>To: Pianotech List <pianotech at ptg.org>
> >>>Subject: Re: Scruffing -was - Over-Strike vs Under-Strike
> >>>
> >>>It's been a while since I have seen the slow-motion photographic 
> >>>study, but to the best of my recollection, the shank 
> flexing due to impact with the strings seems to overpower 
> other considerations.  Uprights could certainly benefit from 
> more substantial shanks.  I said that my drawing was 
> exaggerated, but not by much.  It is amazing how an upright 
> hammer flops around before coming to rest.
> >>>
> >>>Frank Emerson
> >>>pianoguru at earthlink.net
> >>>
> >>>
> >>>----- Original Message -----
> >>>From: Steve Fujan 
> >>>To: Pianotech List
> >>>Sent: 11/25/2006 12:02:22 AM 
> >>>Subject: Re: Scruffing -was - Over-Strike vs Under-Strike
> >>>
> >>>
> >>>Wow Frank, great sketch!
> >>>
> >>>Hmm......
> >>>So, if the shank flex causes upward scruff, and the offset axis 
> >>>causes downward scruff, then could they be "tuned' to cancel each 
> >>>other out?
> >>>
> >>>Intuitively, it seems like scruffing and flex are both power and 
> >>>clarity robbers.  Could super stiff shanks help minimize both?
> >>>
> >>>Steve Fujan
> >>>
> >>>
> >>>
> >>>
> >>>On 11/24/06, Frank Emerson < pianoguru at earthlink.net> wrote:
> >>>How can scruffing occur unless the hammer shank flexes?  
> It does flex, and it does scruff, but always upward.  As the 
> flagpoling of the shank reverses, the hammer begins to scruff 
> downward just as it is rebounding from the string.  The 
> proximity of the axis of rotation to the string is less 
> significant than the length of the hammer bore from the 
> strike point.    This can be seen in slow-motion photograph 
> of action movement.  It is amazing how much an upright shank 
> flexes.  You would think it would break before flexing as 
> much as it actually does.  A grand shank flexes also, but not 
> nearly so much.  The drawing below is simplistic and 
> exaggerated, but illustrates the point. 
> >>>Frank Emerson
> >>>pianoguru at earthlink.net
> >>>
> >>>
> >>>----- Original Message -----
> >>>From: Steve Fujan 
> >>>To: joegarrett at earthlink.net;Pianotech List
> >>>Sent: 11/24/2006 12:47:45 PM 
> >>>Subject: Re: Over-Strike vs Under-Strike 
> >>>
> >>>
> >>>Shifting slightly to the concept of scruffing...    The 
> hammer contact will always "scruff" towards the hammer pivot 
> axis (unless the pivot axis could somehow lie in the plane of 
> the string).   The closer the pivot axis is to the string, 
> the less "scruffing" will occur. 
> >>>Steve Fujan
> >>>
> >>>
> >>>On 11/24/06, Joseph Garrett < joegarrett at earthlink.net> wrote:
> >>>Upon reading the follow-ups of Jons query, I'd like to 
> wonder which is
> >>>which. I've always considered "Over-Strike" as the 
> Downward angle of the 
> >>>hammer, which would put the hammer Beyond Perpendicular. 
> ??? Am I correct 
> >>>on that? If so, then, "Under-Strike" would be, where the 
> hammer does not
> >>>achieve Perpendicular, on contact?? The "Over-Strike" 
> hammer, (on an 
> >>>Upright), would "scruff", (for lack of a better word), 
> downward, at impact. 
> >>>The "Under-Stike" hammer would therefore "scruff" upwards.
> >>>Do I have all of this backwards? Confused minds need to 
> know what the 
> >>>consensus is.<G>
> >>>
> >>>
> >>>Joseph Garrett, R.P.T.
> >>>Captain, Tool Police
> >>>Squares R I
> >>>    
> >>>
> >>
> >>
> >>  
> >>
> >
> 
>