Bechstein hammer bore

[John Delacour]

At 18:51 +0100 15/2/08, Richard Brekne wrote:

>...Just got done doing some preliminaries for a hammer change on a 
>Bechstein B from about 15 years ago...
>
>Any comments or thoughts would be welcome.

What angle do the strings make to the horizontal at note 88 and at 
the top break?  What is the height of the hammer centres?  You have 
the strike-line, so with these measurements and the string heights 
you can deside what bore and rake is required to have every hammer 
hit the string at a right angle.  I always keep the rake constant and 
graduate the bore, but with some Bechsteins you need to look very 
carefully at the clearance in the top section and a bit below.  I 
have a Model C at the moment from about 1925 with the string height 
almost identical throughout but the original hammers were never bored 
right and the high treble has always been useless. In order to get 
the high treble right I am going to have to grind first the lumps and 
then some more off the metal frame.  Nobody is perfect and most 
factories have a standard bore for hammers and standard lengths for 
bass strings, so there is no accommodation for the quirks of an 
individual piano.

Your question reminds me that I intend to do one of my SVG things for 
this job, to enable people to work out hammer bore and angle on line.

JD