Hi all,
In this Part we will add interior braces that will stiffen the case and make it strong enough to withstand the tension of the 102 strings that we will soon install. We’ll be adding two sets of interior braces – the upper braces and the lower braces. In addition we’ll add a front case molding and two keyboard runners. Let’s do it!
The front case molding contains two pieces. In the first photo the front piece is glued onto the front of the case Bottom and fits into the bottom of the rabbets we cut into the front end of the spine and cheek. This piece is ¾” tall and ½” thick.
The second piece is glued to the Bottom and to the rear of piece #1. It is 1 ¼” tall and ½” thick with a profile routed into its top edge. The next photo shows piece #2 being glued in.
Next we will install keyboard runners at each end of the keyboard cavity (the area just behind the case front molding we just installed). The keyboard stiles will rest on these runners. They are ½” thick by 2 ¼” wide and are clamped from above. The next 2 photos show this glueup.
Next we will install the Upper and Lower Bellyrails. In the next photo the Lower Belly Rail (labeled B) has already been installed. This rail is glued directly over the joint between the rear part of the Bottom and the front part of the Bottom and reinforces this joint. It also serves as the rear of the keyboard cavity. The photo shows the Upper Belly Rail being glued in. The front edge of the soundboard will be glued to the top of this rail. It’s top edge is exactly 1 7/8” below the top edge of the case. More on this later.
A partial rabbet and a dado have been cut into the Upper Belly Rail before its installation. The next photo shows this dado which will accept the rear end of the lower register guide (I know you don’t know what that is yet but it will become clear when we build and install the registers in a later post – stay with me).
The next photo shows the partial rabbet cut into the left-most 6 inches of the Upper Belly Rail. The Upper Belly Rail is 11/16” thick. When we glue the soundboard in we want the upper end of the soundboard to be as flexible as possible. The rabbet allows us to glue the soundboard to a smaller area rather than the entire 11/16” thereby giving the soundboard a little more flexibility in this area.
The next photo shows the remaining four bottom braces that have already been fit to the case sides. They are thinned down in the middle to save weight but retain their full 3” height at the ends where they will be glued to the case sides.
The bottom braces are glued to the Bottom and the case sides with screws. They’re placed in their proper position and their profile is drawn onto the Bottom and Sides. Holes are drilled in the Bottom and Sides using the drawn profiles as guides. Then glue is applied and the braces are screwed in place from underneath the Bottom and from the outside surfaces of the sides.
The next photo shows the Belly Rails and bottom braces after installation.
A line must be drawn all around the inside perimeter of the case at exactly the same height as the top surface of the Upper Belly Rail (1 7/8” below the top surfaces of the case). Strips of wood called soundboard liners will be glued into the case with their top surfaces flush with this line creating a ledge around the perimeter of the case for the soundboard to rest on. The next photo shows this line at the bentside to cheek joint.
Next we install the soundboard liners. Remember back in Part 4 when we made the bentside on the bentside jig? We bent another piece at the same time. This piece is the front part of the bentside soundboard liner (usually called the 8’ hitchpin rail). In case you forgot what it looks like – here it is.
While we will be installing soundboard liners on the cheek, bentside, tail, and spine, only the bentside and tail liners will have hitchpins driven into them. These hitchpins will have the far ends of the strings looped around them and will be subjected to a lot of tension. As a result, these liners MUST be well glued. Many harpsichords have failed because the tension of the strings pulled on the hitchpins with such force that the soundboard liners began to pull away from the case. This, of course, destroys the tuning and is a fatal flaw requiring extensive rebuilding to correct. Better to get it right in the first place. The next photo shows the curved part of the bentside liner being glued onto the bentside.
We cannot use screws for clamps because they might interfere with the hitchpins when we drive them into the liners. Even if we removed the screws after the glue dried there would be a hole in the liner. If a hitchpin were driven into one of these holes it wouldn’t be held tightly enough to resist the string tension. So we use clamps instead and rely on the glue alone (which is more than strong enough for the job). The next photo shows the tail liner being glued in. We’ve skipped the rear section of the bentside liner for the time being.
Now we will install the rear portion of the bentside liner which is cut at an angle and butts up against the tail liner and locks it in place. The tail liner is subjected to more tension than any other liner and this “locking” helps it resist being pulled forward.
The next photo shows the cheek liner being glued in. It butts up agains the curved portion of the bentside liner and locks it in place. The small notch in the front end of this liner will accept another rail glued to the bottom of the soundboard.
Finally, we install the spine liner which also butts up against the left end of the tail liner and locks it in place. The spine liner will have no strings attached to it and, therefore, is not placed under tension. All we have to do is get it installed at the right height as its only function is to provide a ledge for the soundboard to sit on.
That concludes the installation of the bottom liners. Here’s what the harpsichord looks like now.
That’s it for now .... I’m going to sleep.
See you next time,
Ernie
Part 1 - The Keyboard Part 2 -Keyboard con't. Part 3 - Keyboard con't. Part 4 - The Case (Bentside) Part 5 - Case Bottom Part 6 - Case Sides Part 7 - The Lower Braces Part 8 - Case Finished Part 9 - Building the Registers Part 10 - The Stand Part 11 - Jackrail & Moldings
Part 12 - The Music Desk Part 13 - Building the Bench
In this Part we will add interior braces that will stiffen the case and make it strong enough to withstand the tension of the 102 strings that we will soon install. We’ll be adding two sets of interior braces – the upper braces and the lower braces. In addition we’ll add a front case molding and two keyboard runners. Let’s do it!
The front case molding contains two pieces. In the first photo the front piece is glued onto the front of the case Bottom and fits into the bottom of the rabbets we cut into the front end of the spine and cheek. This piece is ¾” tall and ½” thick.
The second piece is glued to the Bottom and to the rear of piece #1. It is 1 ¼” tall and ½” thick with a profile routed into its top edge. The next photo shows piece #2 being glued in.
Next we will install keyboard runners at each end of the keyboard cavity (the area just behind the case front molding we just installed). The keyboard stiles will rest on these runners. They are ½” thick by 2 ¼” wide and are clamped from above. The next 2 photos show this glueup.
Next we will install the Upper and Lower Bellyrails. In the next photo the Lower Belly Rail (labeled B) has already been installed. This rail is glued directly over the joint between the rear part of the Bottom and the front part of the Bottom and reinforces this joint. It also serves as the rear of the keyboard cavity. The photo shows the Upper Belly Rail being glued in. The front edge of the soundboard will be glued to the top of this rail. It’s top edge is exactly 1 7/8” below the top edge of the case. More on this later.
A partial rabbet and a dado have been cut into the Upper Belly Rail before its installation. The next photo shows this dado which will accept the rear end of the lower register guide (I know you don’t know what that is yet but it will become clear when we build and install the registers in a later post – stay with me).
The next photo shows the partial rabbet cut into the left-most 6 inches of the Upper Belly Rail. The Upper Belly Rail is 11/16” thick. When we glue the soundboard in we want the upper end of the soundboard to be as flexible as possible. The rabbet allows us to glue the soundboard to a smaller area rather than the entire 11/16” thereby giving the soundboard a little more flexibility in this area.
The next photo shows the remaining four bottom braces that have already been fit to the case sides. They are thinned down in the middle to save weight but retain their full 3” height at the ends where they will be glued to the case sides.
The bottom braces are glued to the Bottom and the case sides with screws. They’re placed in their proper position and their profile is drawn onto the Bottom and Sides. Holes are drilled in the Bottom and Sides using the drawn profiles as guides. Then glue is applied and the braces are screwed in place from underneath the Bottom and from the outside surfaces of the sides.
The next photo shows the Belly Rails and bottom braces after installation.
A line must be drawn all around the inside perimeter of the case at exactly the same height as the top surface of the Upper Belly Rail (1 7/8” below the top surfaces of the case). Strips of wood called soundboard liners will be glued into the case with their top surfaces flush with this line creating a ledge around the perimeter of the case for the soundboard to rest on. The next photo shows this line at the bentside to cheek joint.
Next we install the soundboard liners. Remember back in Part 4 when we made the bentside on the bentside jig? We bent another piece at the same time. This piece is the front part of the bentside soundboard liner (usually called the 8’ hitchpin rail). In case you forgot what it looks like – here it is.
While we will be installing soundboard liners on the cheek, bentside, tail, and spine, only the bentside and tail liners will have hitchpins driven into them. These hitchpins will have the far ends of the strings looped around them and will be subjected to a lot of tension. As a result, these liners MUST be well glued. Many harpsichords have failed because the tension of the strings pulled on the hitchpins with such force that the soundboard liners began to pull away from the case. This, of course, destroys the tuning and is a fatal flaw requiring extensive rebuilding to correct. Better to get it right in the first place. The next photo shows the curved part of the bentside liner being glued onto the bentside.
We cannot use screws for clamps because they might interfere with the hitchpins when we drive them into the liners. Even if we removed the screws after the glue dried there would be a hole in the liner. If a hitchpin were driven into one of these holes it wouldn’t be held tightly enough to resist the string tension. So we use clamps instead and rely on the glue alone (which is more than strong enough for the job). The next photo shows the tail liner being glued in. We’ve skipped the rear section of the bentside liner for the time being.
Now we will install the rear portion of the bentside liner which is cut at an angle and butts up against the tail liner and locks it in place. The tail liner is subjected to more tension than any other liner and this “locking” helps it resist being pulled forward.
The next photo shows the cheek liner being glued in. It butts up agains the curved portion of the bentside liner and locks it in place. The small notch in the front end of this liner will accept another rail glued to the bottom of the soundboard.
Finally, we install the spine liner which also butts up against the left end of the tail liner and locks it in place. The spine liner will have no strings attached to it and, therefore, is not placed under tension. All we have to do is get it installed at the right height as its only function is to provide a ledge for the soundboard to sit on.
That concludes the installation of the bottom liners. Here’s what the harpsichord looks like now.
That’s it for now .... I’m going to sleep.
See you next time,
Ernie
Part 1 - The Keyboard Part 2 -Keyboard con't. Part 3 - Keyboard con't. Part 4 - The Case (Bentside) Part 5 - Case Bottom Part 6 - Case Sides Part 7 - The Lower Braces Part 8 - Case Finished Part 9 - Building the Registers Part 10 - The Stand Part 11 - Jackrail & Moldings
Part 12 - The Music Desk Part 13 - Building the Bench
Last edited:
