[pianotech] Gluing Damper felt and shimming trays

[erwinspiano at aol.com]

           Ed
  This is a good and organized system. Thanks for explaining it clearly. This technique is necessary when working with old systems.  At the same time it clearly show how archaic  these old systems are  when compared to more elegant systems that employ a small capstan for even tray lift. That said it is clear that key lift is the first priority and paper shimming techniques can still apply but after that thing get really easy in adjusting an even pedal lift. Like...5 minutes your done.  Although I haven't employed the use of one as of yet, the WNG tray may be my answer to installing this handy device with much less engineering. Now If Renner & Tokiwa would just get with it!

  Cheers
  Dale


Ed foote wrotes
 Greetings, 
             This doesn't create a problem, since  I shim the tray felt so that 
ll end-section keys lift their underlever at the same time (usually half of 
ammer travel).  While doing this,  the underlevers are resting on the tray, 
hich is raised to whatever height the key ends require.    (I have damper heads 
n these trials, but they are way off the string, there to let me know when the 
nderlever is contacted). If the lift at C5 is perfect, but at the same tray 
osition, A0 lifts as soon as the key is touched, the tray felt needs to be 
himmed up until A0 lifts properly. If at the same time, E6 is way late, either 
he felt needs to be thinned, the tray lowered, (causing C5 and A0 to get more 
hims), or the tray pivot point re-examined.  
   Once the sections are shimmed I can drop all the damper wires into the posts 
nd snug them down.  They are usually very close together, and require some 
ndividual adjustment only.  Sometimes, say, when A0 needs to be shimmed up .60" 
nd note 20 only needs to be lifted .030", the shim can be either tapered, or 
he difference split, meeting in the middle.  Those strips of red hard paper are 
eadily split, as are the Renner part's boxes.  It isn't hard to hit a 1/4" 
trip  with a piece of 80 grit sand paper and taper it in a matter of seconds. 
 Once the tray lifts all the damper heads on the ends of the sections so 
losely I can't distinguish a difference, key timing differences are below the 
hreshold of detection. ie, If I were to split the difference in the above 
xample, notes 1 and 20 would be optimum, note 10 would be lifting .015" early  
nd note 11 would be .015" late( lifted by the key ends).  Whereas it may be 
etectable if a damper lifted on the tray .030" early, between keys, I don't 
hink so. Normal felt wear is greater than this.   I usually taper, anyway, but 
attlefield conditions sometimes require chopping up whatever I can find on the 
loorboards of the car and sticking it in there with a dab of chewing gum to 
old it...  
nother advantage of this approach is that once the tray is shimmed even, the 
ntire damper timing can be changed very quickly, using the trapwork and the 
ray as the jig.  
egards, 
 





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