hammer change - shaping

[antares@euronet.nl]

On donderdag, mei 8, 2003, at 22:01 Europe/Amsterdam, Isaac OLEG wrote:

> Hello Andre,
>
> The instruments in the conservatory are shaped every year a little.
>
> I've heard of a shaping method with a small wood plank and filing
> paper 80 grit on it , that is supposed to be the standard method used
> at Yamaha France, and that allow to "uncap" the top of the hammers
> very fast (even the bass hammers). No finishing with finer grit, a
> friend is supposed to show me that trick someday, did you see that
> method ?

Sure Isaac,

'Hand filing' is the old method and still in use by many technicians in 
many factories.
Using # 80 is a very fast method and very dangerous. I prefer 3M #40 as 
it has more of a polishing quality but still has 'teeth'.
In that case you 'do something' to the surface of the crown and 
underneath the crown without really taking off whole chunks of meat.


> Indeed filing hammers in the piano mean being in a very uncomfortable
> position, and if the marks are deep a lot of work is due after filing.
> Is not it better to give the hammers new power before filing them ,
> then we probably can shave less felt, as we work on a tensioned
> material. then final top voicing is remaining only.

Nah... If it is a healthy hammer, it has enough power in the cushion 
area and in the 'basement' or the battery. The problem with grooved 
hammers is that  a. the crown is damaged with grooves and broken fibers 
and b. the top of the hammer has hardened a lot during the previous 
time of 'banging'.
Filing away the grooves is not such a problem but the real problem lies 
in symmetry.
If we file the crown, the pear shaped hammer becomes an apple.
A STW hammer has per definition a diamond shape and at worst a pear 
shape.
If we just file the crown the hammer will become indeed a pear and when 
the grooves have become very deep the shape of the hammers become apple 
shaped.
This is the worst that could happen to any hammer but a STW in 
particular.
So, whatever we do, if we start filing we must not only (partly) file 
away the grooves, but we must also take care of the final shape of the 
hammers, like sculptures.
Symmetry is of the highest importance, and to do this job right asks 
very much of even the best technician.
It requires very much experience, a carpenters (craftsman's) eye, a 
very steady hand and a damn good technique. The 'shoeshine' method is 
the only method really as the other manual method with the filing paper 
glued on a small piece of wood will cause irregularities and 
unnecessary damage.
A Yamaha hammers has a pear shape basically like Bösendorfer, and 
Bechstein uses the egg shape. If we don't know this we'll ruin the 
character and thus the sound structure of the instrument. It again 
shows how extremely sensitive hammer filing is, not to speak of the 
final voicing where we eliminate 'noise' and fit hammers etc.

I myself have learned my lessons by having ruined countless instruments 
in the past.
Today I take my time and I need all my experience to do a 'decent' 
hammer filing job and I try to avoid all that filing as much as 
possible for reasons I tried to describe before and above.



>
> Friendly greetings indeed,
>
>
Antares,
The Netherlands

see my website at : www.concertpianoservice.nl