[pianotech] over centring actions

[David Skolnik]

Ron -
Promise to listen to the link later. For now, can we clarify what we 
mean by over-centering? (to stay focused, I have already considered 
and ignored any name-related meanings)
Is it the orientation of the shank at hammer/string 
contact?  orientation of hammer to string at contact?  both?

I'm assuming that correct strike point is being achieved.  Also, I 
seem to recall that the challenge in the Bechstein treble was the 
thickness and/or proximity of the block to the strike point, where, 
without the over-strike approach, the hammer would end up rubbing on 
the block.

Thanks

David Skolnik
Hastings on Hudson, NY

At 02:04 AM 2/23/2012, you wrote:
>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
>_______________________
>
>Web <http://overspianos.com.au>http://overspianos.com.au
>mailto:ron at overspianos.com.au
>_______________________
>
>A web page with images of recent work and almost-audio-CD quality 
>mp3 sound files of the Overs piano can be found at;
><http://overspianos.com.au/more_info.htm>http://overspianos.com.au/more_info.htm
>
>So put on your headphones, plug them into your freshly restarted 
>computer and sit back to over 20 minutes of pure piano.
>_______________________
>
>

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