Bechstein hammer bore

[Richard Brekne]

Hi JD

I havent gotten as far as checking the hammer shank center pin height 
yet... teacher wanted her office as I was checking other things out.  
And I have to admit I have never taken into consideration the angle of 
the strings to the key bed... I pretty much stick with a perpendicular 
to shank hammer... tho I am most willing to listen to reason why I 
should rather choose hammer perpendicular to string.

I also tend to go for a constant rake ( 90 degrees to shank) and vary 
hammer bore to match string distance to keybed.  On Bechsteins I always 
leave the final 3-4 notes in both top sections dry fitted until I am at 
the piano because of the clearance problems you mention.  It helps to 
have a fairly tight dry fit :)


Cheers
RicB


    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