Soundboard down

The soundboard has been successfully installed. Most of the time, harpsichord building is a solo endeavor, but to glue in a soundboard you need help. That's because hide glue has a very short "open time" -- that is, once you brush it on it sets up very quickly, so you've got about 90 seconds to brush glue on all the side rails and the 4-foot hitchpin rail, put the soundboard in, and brace it with go-bars. No one can do that alone, so for this one I enlisted the help of several friends, the harpsichord equivalent of a barn-raising.

In order to extend the open time of the glue slightly, I heated up the wood of the case with heat lamps, like so:



Then the troops gathered round, and we did the job. That's me carrying the soundboard at about 30 seconds in.



The final product:



Many thanks to Kevin, Ron, and Per for their help with the installation.

Countdown to installation

Installing the soundboard is the single biggest event in the harpsichord construction process, and it requires a lot of preparation. The soundboard will be glued to the frame with hide glue and held in place on the go-bar deck with about 50 go-bars, which will provide tremendous vertical pressure. To keep the whole thing from collapsing, I prop up all the internal surfaces with wooden blocks of various sizes and shapes, as shown below:




When the installation happens, glue will be slopping everywhere, so I tape off all the surfaces which will come into contact with the glue. I've also built a set of cauls which will go between the delicate soundboard wood and the go-bars.




Installing a soundboard is a bit like launching the space shuttle; you plan it weeks in advance, then watch the weather anxiously as the big day approaches. If it's too cold or wet, you have to scuttle the launch and wait for a drier day.

In bloom

This instrument will have a soundboard rose. The rose is an optional decoration with no definitive acoustical properties, but it has been part of Flemish harpsichords for centuries, and I figure the great builders of the past wouldn't have bothered with it if it didn't enhance the sound in some way. The first step in creating a rose is to make a template. I used an existing rose with a standard angel-playing-a-harp figure and added my initials, SR, which I made from modeling clay. I set the whole thing on a solid backing made from the same clay and prepared to make a negative, or mold, from which I could make additional roses. I set the master inside a wooden frame about 1 inch high, like so:



Then I mixed up the mold material, which looked like blue goop and had the consistency of toothpaste.



I poured the blue goop into the wooden frame, where it slowly settled into place.



The goop took a day to cure, and when I unclamped the wooden frame it was a perfect negative of the rose shape.



I mixed up the rose casting material and poured it into the mold:



The casting material takes only about 20 minutes to cure, so I made several roses. I'll pick the best one and install it in the soundboard, where at some point in the future I'll gild it with gold leaf.

Spare ribs

The ribs are now on the soundboard, and all that remains to do to the soundboard before it's ready to install is to cut the rose hole. The ribs (the horizontal bars pictured below) help to stiffen the soundboard and keep it steady under the tension of the strings, and the cutoff bar (the other bar, diagonal to the ribs) defines the sounding areas of the bass and treble. First I glued them to the underside of the board, using go-bars to provide vertical pressure:



After the glue dried I scooped out the ends with a chisel, which is traditional.