[pianotech] Locating & Re-Locating Plate

[Dale Erwin]

Nice Concise post Ed. We use a similar method.
  Just wondering if you have tried the WNG  plate suspension system. I have eliminated the "acoustic dowels in favor of the WNG plate suspension system. It is my desire to have zero or as little plate flex. The ease and versatility of the Wng bolts offer unlimited micro adjustment for downbearing /plate height.  
   I was very good at installing the dowells too but can not discern that any acoustic advantage is missing.
  I think may possibly hold the record for the most WNG bolts used to date or at least thats what they tell me.
 

Dale S. Erwin
www.Erwinspiano.com
209-577-8397

 

 

-----Original Message-----
From: Ed Foote <a440a at aol.com>
To: pianotech at ptg.org
Sent: Sat, Jul 10, 2010 12:23 pm
Subject: Re: [pianotech] Locating & Re-Locating Plate


Phillip asks:
 


Before removal, I generally mark a piano plate location using wedges and taking several plate-to-rim measurements. I've often wondered how much "play" a refitted plate will actually have since it's held in with a few dozen screws and bolts. What preparation and notations should be taken before removing a plate?

       If the block is to be fitted tightly into the case and stretcher, with the plate in the original position, I drill four index holes, same dia. as a #7 bridge pin,(two on each end) in the corners of the plate, directly into the block. Then I lift the plate enough to place a pair of cardboard templates on top of the block, fitted exactly into the corners against the stretcher and sides.  I tape these two templates in place, reinstall the plate and drill holes through the cardboard. Pull the plate, fit an oversized new block and screw it to the plate.  Drill through the holes again, into the new block.  
        Remove new block, fit the cardboard templates over #7 pins that have been installed in the holes and draw a pencil line where the stretcher and sides are.  Cut the block ends, taking the pencil line with the kerf.  You will be within .010" of a tight fit.  The cut to fit against the stretcher is made with a line drawn against a straightedge laying against the cardboard's proximal edge.  When cutting that one, leave the pencil line.
      For insurance, I also measure plate height at the pinblock ends and I use a wedge between the tail of the plate and the case to make certain there is not slight rotation of the plate.  On many Steinways, you will find a plate rise at the tail when the rim and nose bolts are removed. I don't know if this is prestressed originally, plate warpage (doubtful,since I don't think cast iron warps), or perhaps the case has worked during the piano's lifetime. In event of a rise, I put a wedge under the tail and record the rise, since when I reinstall the block, I do it with it fastened to the plate, and if there is a rise to the tail, I want to keep it that way.  I put the 'rise' wedge back in so that the block will remain at its original angle as it is bedded down on the inner case and stretcher with West epoxy.  Next day, I remove the plate, install dowels  thru the block into the inner rim, and go on with the rest.
Hope that helps. 


 

Ed Foote RPT
http://www.uk-piano.org/edfoote/index.html
 
 
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