Yamaha Method of Damper Regulating

[David ilvedson]

Tom,

Why can't I simply raise or lower the pedal rod head or 
shim/remove material until I have a sample hammer lifting at 
approximately 1/2 blow distance, if that is what I'm after.  
Then pull action, loosen screws, assure dampers are securely 
resting on the strings and free in the top flange, tighten and 
adjust for twisting heads etc?  Why all the mumbo jumbo?  I 
remember this from the Little Red Schoolhouse and it seemed 
overly complex. 

David ilvedson, RPT
Pacifica, CA



> Date:          Mon, 09 Nov 1998 18:38:39 -0700
> From:          Tom Cole <tcole@cruzio.com>
> To:            pianotech@ptg.org
> Subject:       Yamaha Method of Damper Regulating
> Reply-to:      pianotech@ptg.org

> 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
> 
> 
> 
David Ilvedson, RPT
Pacifica, CA
ilvey@jps.net