[pianotech] Sluggish key diagnosis

[Tom Driscoll]

Mike,
   Assuming the key pins are polished and lubed , the keys are not "Pully" , the whippen cushions are not too indented and the capstans are polished and lubed and the damper spoons are not rusted or hanging up in damaged damper lever cloth , and the action centers are free--- Whew ! ---------  Lift the key until the bushing  clears the top of the balance rail pin and when dropped the key should fall on it's own weight. A good benchmark is that it should not fall like a rock ,but slide down the pin slowly.Ream with the Yamaha or like tool to ease the hole if necessary . Then lift the key off the balance rail punching with the bushing still in contact with the balance rail pin and drop the key . It should also fall on it's own weight. Ease as necessary with your key bushing pliers. Then with the action in the piano depress the sustain pedal and then depress the key . Hold it down on the front rail punching for a count then release quickly .(I do several at a time and the slow ones really show up)  If the keys return to rest slowly then ease the front rail key bushings as necessary. Pay attention to the sharps and all the keys above the dampers as they are the most likely to be sluggish. 
The order is important.  For example  we have all seen over eased  key bushings and sluggish keys due to over tight balance rail holes.
Best wishes,

Tom Driscoll
  Subject: [pianotech] Sluggish key diagnosis


  I'm rebushing the keys of a Baldwin Hamilton studio and would like to get the list's help with this:

  Starting with the first 10 keys as a group, I steamed out the old bushings (using a pressure cooker without a jiggler on top), used Spurlock's .146 in mortise sizing cauls overnight and rebushed with 1.20 mm bushing cloth and hide glue, placing the cloth 3/16" into the mortises.  The steaming seemed to swell the balance rail holes and my bushings seemed tight when I placed the keys back in the piano.

  Can you tell me what indicates a sluggish key to you and what steps do you take to isolate where the problem is (front rail pin bushing, balance rail pin bushing, balance rail pin hole, etc)

  Thank you,

  Michael Staples
  PTG Associate Member

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