PIano, joinery question..

[jeth chiapas]

• Hello all.. I posted this in the musical instruments forum but no replies so I figure here it should get more views and hopefully responses. It is in essence a question about joinery more than being specific to the instrument itself.
  
  I have been asked to repair a rather sad Yamaha upright piano. I have no specialist experience in this area but have been deemed capable, hopefully so.
  The piano is in a sorry state, the veneered chipboard carcass is gradually disintegrating from the bottom up owing to the extremely humid climate here and yearly trips out to the theatre.
  
  I read around online a little and got the general idea of how to dissasemble the piano, which I have now done, though whilst all examples I came across suggested the outer carcass should come away quite easily in this case it didn't. The side panels were glued to the main frame which holds the soundboard along its rear edge.
  
  My question concerns how to go about fixing the new carcass to this frame. I had planned to use solid wood for the new 7/8" thick side panels but am now not so sure that is a good idea. The panels are 12" wide and if joined as was then a 4 inch strip along the back edge would be glued to the laminated plywood frame. The front edge carries the wings for the keyboards and is floating.
  Is a solid wood panel going to be safe if it can move over 2/3 of its width but is fixed solid along its edge in this way?
  
  The other options are putting a reasonably thick veneer on some MDF but I had hoped to avoid using more materials that are vulnerable to humidity. Decent ply is not available down here.
  other thoughts are some butterfly/dovetail cleats to hold the panels to the frame screwing solid only on the very back edge.
  
  I would appreciate any advice, like I said, it's joinery really but then I know little about pianos and am feeling unsure about the job.
  
  
  

[Andrew Teich]

With few responses from the woodworking forum why don't you go to the pianoworld forum. They have a tuner/technician page and you might have more responses there from piano rebuilders. I know there are a few people that are active on both sawmill creek and pianoworld but the names escape me at the moment.

[jeth chiapas]

Thanks Andrew, for some reason i didn't get a notification of your reply, just came across it now.
As I say, this is really more of a standard joinery question, just wondering if folks would risk a 12" panel fixed along a 4" section on one edge. I will have a look over at pianoworld anyway to see if I find anything relevant. Thanks again.