[pianotech] over centring actions

[lewis Newman]

Thanks for that Ron, thats interesting.

If over-centering is seen as an advantage, what are the limits before encountering negative consequences,and what would these consequences be?

Lewis.


________________________________
 From: Overs Pianos <sec at overspianos.com.au>
To: lewis Newman <musicbased at yahoo.co.uk>; pianotech at ptg.org 
Sent: Wednesday, 22 February 2012, 22:03
Subject: Re: [pianotech] over centring on bechsteins.
 
Lewis,

> I have noticed that all the bechstein actions i have checked always over centre, especially in the treble section?-(Obviously taking hammer wear etc into account).
> 
> I assume they set it up this way on purpose for some reason, but i always thought it was best to have the hammer strike the string at 90 degrees...?

Many manufacturers bore their hammers short to achieve an over-centering action. This does have a friction advantage for many, since the contact between the jack and the knuckle is well away from the line of centres for most actions. Short boring the hammers will bring the contact point closer to the line of centres and will slightly reduce action friction - all other factors being similar.

Using a smaller knuckle diameter is another way of helping an otherwise ordinary geometry situation. However, one needs to check that there remains sufficient adjustment to achieve an appropriately close drop height, if considering a smaller knuckle.

Ron O.
-- OVERS PIANOS - SYDNEY
   Grand Piano Manufacturers
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