Soundboard Repairs

Without The Iron Frame

 Now that the iron frame has been removed from the piano, I was able to get started on repairing the soundboard and the notorious split.

As the photos show, there was quite a bit of dust and dirt on the board itself (there usually is on grand soundboards, being so exposed) but this was soon removed.

 

Dirt and Water Damage

After Cleaning

View Of Split in Soundboard

Two More Splits in the Bass Bridge

Opening The Split

Shim Glued and Inserted Into Split

Shim Flattened and Old Varnish Removed

Once the soundboard had been cleaned, two more splits showed up in the bass bridge.  It was impossible to see these when the iron frame was in place, as it completely covered them up.

Seeing these splits, I felt even more certain than ever that this was the cause of the buzzing sound which had been the biggest problem with the piano in the first place.

The next step was then to open the splits up more.  This is done so that the chances of the split getting larger by itself are all but eliminated, but also to make the split a uniform depth and width, so that we can insert strips of wedge-shaped wood, called shims, which fill in the split.

There is a special tool especially for this very process.  The shimming tool is basically a sharp spike cut in the same shape as the wooden shims, so that a technician can open the split to the exact shape of the shims which will be inserted.

The shim is then cut to the correct length, the edges shaped to fit the end of the split, and then is glued into place.

Once the glue is dry, the shim (a lot of which is still proud of the soundboard) is planed down level with the soundboard.  Abrasive paper finishes the job and gets the shim to blend in as accurately as possible with the rest of the soundboard.

The whole process of repairing the split inevitably takes off some of the old polish from the soundboard, so whenever a split is repaired, the soundboard needs to be repolished.  As is clear from the photo to the left which shows the shimming tool in action however, the old polish on the soundboard had become crazed with age anyway, so repolishing would have been recommended anyway at this point, even without splits.

The majority of the old polish is removed by scraping it off with a blade shaped for the purpose.  What remains is then removed by various different coursenesses of abrasive paper.  The varnish is removed from the bridges too.  Once flat, any small marks are filled with woodfiller, grain filler is then applied and the board is ready to be sprayed/repolished.

Repolishing the Challen soundboard will have to wait for several weeks as there is already a large Bechstein concert grand in the spray room which needs to be completed before another piano can be moved in.  In the meantime, I decided to begin the action work and key restoration