[pianotech] Damper tray block

[Jon Page]

I go for the least friction at the end of the keystroke or closer to 
letoff. The damper doesn't lift until the key is in about a third of its 
travel which allows momentum to initiate damper lift. So a decreasing 
friction component is better in my view. Less wear on the end felt too. 
Accounting for the angle of
the end felt, there is the slightest downwards angle to the u/l at full 
lift so as not to rotate on the corner of the felt.

I sand the undersides when the tray is removed. Otherwise, I'll feel the 
edge of the u/l and sand/ease any square edge there might be at the tip, 
another source of friction.

I'll be lowering the pivot hole 5mm on this M. The dampers are lifting 
too soon now. I'll remove the pivot blocks and redrill a hole 5mm lower. 
This will in turn raise the tips of the u/l, probably too much to bring 
to lift correct, so I'll more than likely have to lower them (this 
happened once before on a B).

I measure the height of the end felt at full dip, the height to which 
the u/l is lifted. Then I lift the u/l to be parallel to the keybed and 
measure that height (accounting for the felt angle). Subtract the key 
lift height and that is how much to lower the tray pivots to bring the 
u/l to 'parallel' when lifted. If the new hole is too close to the old 
one, as it is on this M; I use a 1/4" plug cutter and cut a plug from 
the bottom portion of the pivot block and plug the old hole after 
drilling it out to 1/4".

  Regards,
  Jon Page

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On 9/29/2012 11:19 AM, Jon Page wrote:
> Having the underlevers (u/l) parallel at rest would still add sliding
> friction only it would also be crushing the corner of the felt when
> lifted.

I don't suppose it would hurt to decide whether you wanted the least
friction at the beginning of the stroke when you need to get things
moving, or at the end where you are already moving and need to get
things to stop.
Ron N