Bechstein grand

[Stéphane Collin]

Hello Ajay.

I had to file a trifle from the offset screwdriver blades, to make them fit the grooves in the screws.
I like to regulate blow distance in this way : i keep both screws always in tight contact with the rocker (well, not too much of course) ; if the hammer is too high, I add extra pressure on the back screw (and nothing happens), and then I release some pressure from the front screw (and the hammer rises a little bit).  Doing this way (instead of loosening both screws, adjusting one and counter adjusting the other, which can be pain) it is easy to achieve accuracy, and to avoid that one screw is not tight enough, which would cause rocker wobbling and noise.  For accuracy in evenness of hammer height, it is also important to have the whippen spring close to correct tension (he really must fully support the weight of the hammer and shank and all frictions to work out to get the hammer in rest position, but no more), and to have jack height between the whippen arms correct (jack must be able to return in rest position, or very close to it, even after the lightest blow and release).  Else, on two different blows, the hammer would rest at two different heights, and you would get crazy.  Also, after turning any of the screws, take the screwdriver out and tap a little on the key, so you can see the actual rest position of the hammer, which you then correct blindly.  This is, I think, because the frictions involved in the equilibrium position of the whole action are higher when the system is static (the parts don't move) than when the system is dynamic (the parts move, and friction is then lower).  Tapping the key will simulate dynamic behaviour of the action, thus achieving the correct rest position.

Sorry for my maybe unclear english.

Regards.
Stéphane Collin.


----- Original Message ----- 
From: "Ajay Mistry" <ajaymistryin@yahoo.co.in>
To: <pianotech@ptg.org>
Sent: Monday, June 09, 2003 6:55 PM
Subject: Bechstein grand


| Hi I have got a Bechstein grand for repairs whose
| whippens are linked with wooden links to the keys
| instead of capstans can any one help me as to how to
| adjust the hammer blow for this action is there a
| special screw driver for this purpose 
|           Please do help
|                           Thanks
|                                        Ajay Mistry.
| 
| =====
| Ajay Mistry
| 
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