Yamaha Method of Damper Regulating

[Tom Cole]

List,

I just ran across a newsletter article that I penned several years ago
that I thought would be of general interest. 

YAMAHA METHOD OF DAMPER REGULATING

Recently, Laroy Edwards gave a talk on grand damper regulating in which
he explained the Yamaha factory method of regulating the dampers to the
keys. I had heard this procedure before and since I didn't understand
it, even on the second hearing, I thought that I would have him explain
it to me over the phone so that I could write it down, chapter and
verse, to have as a reference.

The description sounds a little complicated but the doing is actually
quite easy. The concept is to raise one of the levers so that it is
contacted by the key at the half-blow point. Then, all of the levers may
be adjusted to that same height.

First, ensure that all of the damper wires are free in the damper blocks
and all of the levers are resting on the lift tray. Next, tighten one
screw on a damper wire. Block up the lift rail at a point where you
think the levers are at the correct position (use a damper wedge in the
pedal hole or turn up the adjusting screw on the pedal rod). The damper
with the tightened screw now stands some distance off of the strings.

Make a gauge (a 6" x 1" x 1/8" piece of Plexiglas works well). Measure
in from one end 1/2 the hammer blow distance and draw a line (for
example, hammer blow in a Yamaha is 48 mm so you would draw a line at 24
mm). Rest the gauge on a hammer next to the note with the raised damper
and press on the key with the raised damper. Find the instant when the
key just touches the damper lever, by feeling the raised damper with a
finger, and observe whether the hammer is even with the line on the
gauge. If not, raise the lift rail (if the key contacts the damper lever
too early) or lower the lift rail (if contact is too late). When it is
right, withdraw the action and begin tightening the damper wire screws.


There is a technique that checks both black and white keys for correct
damper timing and also ensures that the damper lift tray is not warped.
The method used in the Yamaha factory is to tighten 3 screws at the end
of each section instead of just tightening one damper wire screw, as
above, and assuming that the tray is straight. Then if damper lift
varies anywhere, a decision can be made whether or not to straighten or
replace the tray, shim the felt, etc.

-- 
Thomas A. Cole RPT
Santa Cruz, CA