Piano Re-skin advice...

[jeth chiapas]

Hello all.. was unsure if to post this here or in the genral forum where I guess it would get more exposure, it is in essence a question about joinery but I'll place it here for now and see if anyone with specialist knowledge has anything to offer.

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.

[Arnold E Schnitzer]

I would think a marine-grade plywood might be the way to go. There will be little seasonal movement, therefore more stability. And marine ply is made with waterproof glues. You mentioned that there is no good plywood available where you are, but if you are in a humid area you are probably near a body of water, and I'd be surprised if there are no marine lumber suppliers around. Try looking up boat builders in your area. Otherwise you might consider making a small press and laying up your own plywood parts, providing you have a good resaw machine. Good luck!

[Ernie Miller]

I'm afraid this might be a classic case of 'putting the cart before the horse'. Considering the case damage you've described, I would be concerned about the possibility that this piano can no longer function as a musical instrument. Is it still tunable? Is the pinblock cracked? Are the bridges intact? Is there any downbearing? Is the action brittle? Are the hammers wobbling? These are just a few of the questions I would seek answers to before committing myself to repairing the case.

In my 35 years as a piano tech, I've seen this story unfold too many times. People buy a piano - spend a lot of time and effort refinishing the case - call a piano tech to 'give it a tune-up - and find out that their newly refinished piano cannot be made to work (at least without a rather large rebuilding bill). Do yourself a favor and have the piano checked out before doing any more work. And, by all means, be careful. Those strings are under a tremendous amount of tension and cast iron plates can crack. Better safe than sorry.

Ernie