noisy dampers (wires)

[Jon Page]

I received a call from a piano owner about poor damping.

The piano was a 'new' gray market Kawai purchased from a 'deeler'
(who might as well be selling TV's and Toasters for all he knows
about pianos) in need of top action regulation and damper seating
attention. I was called because the deeler said everything was working
properly: "It's supposed to be that way".

The wires had an oxidation which dragged through the guide rail bushing
as Ed described below. They were also exerting pressure on one side of
the bushing.  The heads also needed to be centered over the strings and
the bends below the rail improved to allow free vertical movement of each unit.

Cleaning & polishing the wires, lubing the guide rail bushings, felt prep and
wire bending brought the dampers back to functioning properly.

Let me describe my method for squaring off the damper.  For a height 
setting gauge:
a 1 1/8" dowel cut to a 1 1/4" length with a hex head machine bolt (fits 
easily in tool box).
This slides along the keybed to set the underlever height.  This works for 
most pianos and
underlevers, but I also have a 'tongue' apparatus for underlevers which are 
not easily accessible.

I also use this short dowel as a square. Holding the damper slightly above 
the string,
I 'square-off' the wire with the guide rail, then adjust the bend in the 
wire at the head to center
the damper over the strings. Then with a straight-edge against the side of 
the head, I make
sure that the wire going through the guide rail is parallel to the damper 
head. Recheck...
Then lower the damper in place without the wire in the underlever.

With the damper seated, I 'square-off' the wire again and make the 
appropriate bends in the
wire length to align it with the hole in the top flange. (To square it at 
this operation, I either use
the 'dowel on the wire' or a 'hammer/shank square on the strings' method).

This produces a damper with free motion. I've experimented with a slight 
over-bend in the wire
after seating and found the damper to become slightly sluggish.  Maybe they 
have found in the
factory that by having the wire lean on the bushing speeds up the 
installation process and use
it as an excuse for, "It's supposed to be that way" but I have found that 
better damping is achieved
with meticulous attention given to friction reduction, straight motion and 
felt grooming.

As a check, I'll place a small square on the strings and lift the damper to 
insure that it travels straight.

Regards,

Jon Page


At 08:59 PM 01/29/2001 -0500, you wrote:<snip>
>While taking these wires out, I noticed another common bug to be remedied.
>Many of the wires were bent so that, while being straight with their
>neighbors, they pressed quite firmly against the sides of the guide bushing.
>It was like a violin being firmly bowed with a well rosined bow. This
>condition will wear out the bushings in less than a year.  I know, I have
>seen it happen, a lot.  (Just like nicked front pins, for which there is NO
>excuse, will wear out that keybushing in 1/6 the normal amount of time.)  but
>I digress...
>     Easing the wires and polishing them left nothing but the
>felt-against-string noise, and since I had used an eraser on the  plain
>strings where the wedges entered,  there was very little  of this.  Teacher
>was happy, and could move on to complaining about the softness of tone  <sigh>
>   <snip>
>    I think the regulation and condition of the parts can have as much to do
>with damper quietness as the felt.  Poorly regulated and corroded wires wear
>the bushings out a lot faster, and make a lot of noise as they do it.  As the
>bushings wear, the wire moves over, and the wedges begin dragging sideways.
>And let's not forget the two center pins in the underlevers being held 
>against a strain.
>Ed Foote