[pianotech] damper tray support

[David Love]

If you move the axis forward in line with the damper lever centers the bulk of the weight of the assembly moves toward the rear and the tray will almost want to tilt backwards left to its own devices.  Thus the addition of a second spring is necessary.  I find something intuitively wrong with this set up.  It does seem to work more smoothly because there is less weight bearing on the pedal.  It also forces the addition of spring resistance in place of actual weight.  I'm not sure that's a better system.  

David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson
Sent: Tuesday, July 21, 2009 5:08 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] damper tray support



> Gene,
>
> Not sure about the pivot block idea, but Delrin or some other dense 
> plastic would be workable, and a bearing could be fitted to it pretty 
> easily.
**** Thanks
>
> But my question is, why do you want to move the pivot point?  I'm not 
> clear by what you are meaning by the "same plane as the lift lever center 
> pin."  If you are referring to the damper lever center pins axis being 
> different than the tray pivot axis, then there are good reasons to keep 
> these two separated.

**** Yes - these two axis when brought together make for a much smoother 
functioning back action.
Have done 5 now and like the results very much.
As part of the mod I will also remove leaf springs and replace with coil and 
place it near the pitman - pitman also gets modified - replaced with 
threaded rod - no rubbing on the key bed or scrubbing on the tray. Learned 
it from Brett Dearing and Dale Fox.
The only down side that I observed is that the coil return spring - I get it 
from Steinway - is not always strong enough.

Gene
> Don Mannino
>
>
> ---- Gene Nelson <nelsong at intune88.com> wrote:
>> Hello all,
>> Just wondering if anyone has ever built damper tray support blocks with 
>> anything other than wood?
>> Possibly something with a small bearing in it?
>>
>> Every back action job so far gets modified so that the tray pivots on the 
>> same plane as the lift lever center pin.
>> The Renner kit requires the addition of something more than is supplied 
>> in the kit to make this happen.
>> In this case in the treble I do not have the space and may need to 
>> relieve some material from the treble dam.
>>
>> The attached photo of the old tray kind of tells the story (the old leaf 
>> spring is history) - I need about an additional 8mm to make the new 
>> assembly work. So I thought possibly a metal L bracket with bearing or 
>> end rod with swivel bearing or ???
>>
>> Thanks for any ideas.
>> Gene
>