Counter bearing treatment

[Ron Overs]

Hi list,

Newton Hunt wrote regarding overall piano design; 

>There are variations, all kinds of them, which I prefer to bore my
>hammers to so I can get the best performance from the action.  So, in
>answer to your questions, the hammer shank should not go past
>horizontal because there will be a loss of energy in returning past
>horizontal again and because the hammer may well be overstriking.  The
>hammer should strike the string when it is perfectly perpendicular to
>the string for best energy transfer.  . . . . . 

Absolutely. However for many pianos, allowing the
hammer shanks to travel past horizontal can marginally improve
poor action geometry. Many actions have excessive friction between the 
jack and knuckle, primarily I suspect, as a result of installing larger 
knuckles on an actions which were originally designed with smaller 
knuckles.

> . . . . .   Now we are talking about action ratios
>which are far more informative than just a key to blow ratio.  I once
>had an Old Weber where the bass string height differed by 5/8" from
>one end to the other.  I asked to have the hammers bored to compensate . . .  
>When hung they looked a little odd but the
>action regulated to a gnats aspiration and felt so "good"!  So don't
>assume that one measurement is sufficient, you need one from each
>section end.

Agreed. Our hammer installation involves measuring (key bed to string,
minus the key bed to hammer centre pin distance) for the first, last and
two intermediate notes of each string section.  Furthermore, all hammer 
shanks
should travel through the same arc of rotation to make possible a fine 
and even
regulation. All shanks should sit at the same angle when at rest.
Any variation (caused by incorrect or 'nominal' hammer boring distances)
will result in action geometry variation between string sections.

>S&S Hamburg assembles an action and carefully places it into a
>case.  S&S NY places a key frame into a case then adjust the stack to
>fit the string locations then drop a line from wippen to key top to
>locate the capstan line.  The first will give a consistent strike
>ratio the second practice allows the ratio to change and effect action
>performance. 

I suspected this from measuring many Steinway actions. We've moved
the capstan position and altered the wippen heel height on several S&S 
disasters
to improve the geometry.
I find it incredible that a factory with such experience should choose to 
ignore
a most basic action performance parameter - the key/hammer ratio.

>Capstan location has the most profound effect on action
>leverage, ratios and performance than any other element
>whatsoever...period.  What that means is that relocating capstans will
>solve more problems than spread action, hammer weights, key weights,
>or knuckle location.  All these can solve problems but if the capstans
>are mislocated then the others won't have sufficient effect to bring
>the action into "compliance".

Well said!

While on the subject of actions and action geometry; we have just
completed the design of a new grand piano action. The first new
grand piano (a Samick 225, assembled by us) with the new action
will be on display at the Australasian Piano Tuners and Technicians
Convention in Sydney, July 2000. (Website - www.aptta.org.au)
The new action has very low friction with higher up weights.
While I understand that some technicians have expressed
reservations about low friction actions, our prototype has been
well received. If you would like to know more about the new
Overs action, email us and we will let you know when further
information is released.

Ron E. Overs
Overs Pianos

Email: ron@overspianos.com.au
Website: www.overspianos.com.au