Keyframe Bedding

[David Skolnik]

In response to:

Date: Tue, 08 Jul 2008 02:10:25 -0400
From: David Skolnik <davidskolnik at optonline.net>
Subject: Re: Keyframe Bedding
>- are dags essential to proper function of the action? i.e.: would 
>back rail [necessarily] slap in their absence?

>At 07:41 AM 7/8/2008, Ron wrote:
>Dags aren't even necessary to the proper function of the action, 
>much less essential. They're there to keep the action in place during moving.
>
>Consider: If the dags held down the back action rail and prevented 
>slapping without binding, the fit would have to be absolutely 
>perfect, with no tolerance for wear or seasonal dimensional changes.
>
>Ron N

I was responding to this, from Dale Erwin:

Sent: Mon, 7 Jul 2008 2:33 pm
Subject: Re: Keyframe Bedding

>The back of the frame is held down by the dags & the ends by the key blocks
>   Actually this is also a bit of a buffer or safety factor for 
> climate changes. This way the bolts will hopefully stay in contact 
> with the bed in each season & not be so prone to change with humidity & temp.
>   Dale

My assumption has been as Ron stated, thus calling to question a 
basic factor of the tensioning procedure described.  Also, I assumed, 
some time ago, when I began to see new Steinways with excessively 
turned-down glide bolts, that the rational was, in fact, to minimize 
seasonally generated bedding problems, however, when re-regulated to 
correct for the symptoms I listed:
>         - increased resistance of una corda shift
>         - premature squeaking at glide contact
>         - increase in friction and wear of keyblock plates and 
> frame guide pins

I would lose most, if not all after-touch.  I saw it as no more than 
a manufacturing expediency.

Thus far, I can accept the need to limit as much as possible energy 
transfer to the key frame. I don't, at this point, understand 
treating the frame as a resonant structure, whose properties would be 
enhanced by the introduction of 'tensioning stress'.  If that 
stressing does, in fact, enhance the frames rigidity, it seems 
desirable only to the extent that it does not negatively impact the 
action's functioning, as described.

David Skolnik
Hastings on Hudson, NY


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