Hi all,
What's a register? Take a look at this photo.
The player presses down on the front end of the key (not shown). The rear end of the key rises. Sitting on the rear end of the key is the jack which, of course, also rises. It’s path is guided by the lower and upper registers The plectrum (plucker) is near the top of the jack and sticks out from it. Eventually, the plectrum contacts the string and plucks it.
Here’s a pretty good photo of the jacks and upper registers.
The square holes in the register are just about the same size as the jacks that pass thru them. if the holes are too wide the jacks would be free to flop around in the hole and the plucker may miss the string altogether. If the holes are too narrow, the jack would stick in the register and may not return to rest position after the pluck. The placement of the holes in the register is critical. If the hole is too close to the string the plucker would overlap the string too much and the sound would be quite harsh. If the hole is too far away from the string the plucker may not reach the string at all. Worse yet, if one hole is too close to the string and the next hole is too far away the action would have no consistency and the player would have no control at all.
So the problem is to build 4 registers (2 upper and 2 lower) that have square holes just slightly larger than the dimension of the jack (.157 x .392). In addition, the placement of these holes (52 holes in each register) must all be the same distance from their respective strings AND the bottom of each jack must rest in the center of its key. Actually it’s much simpler than it sounds. We’ll start with the 2 upper registers. Here’s how we’ll do it.
In the old days, we used to take a strip of wood – place it on the rear of the keyboard – and mark the center of each key on the strip. This told us where each hole in the register would have to be in order for the jack to sit centered on its key. Now, we’ll do it another way – we’ll use the computer to tell us where to put the holes in the register. Take a look at the next photo.
What you’re seeing is a strip of poplar wide enough for the 52 slots we must cut. Onto the top of the strip I’ve glued a computer CAD printout of the correct spacing for the slots for this instrument. The red circles represent holes which must also be cut into the register (for reasons I’ll explain in a later post). The next photo shows the whole strip sitting on top of the instrument.
No, we’re not going to attempt cutting out a square hole in a piece of wood. Instead, we’ll make something that looks like a comb and glue the missing side on later. First, we drill the holes at the drill press. Notice that ½ of each hole will disappear when we cut out the slots, leaving a half hole behind each slot.
Here’s what the register looks like after all the holes are drilled.
The rest we’ll do on the scroll saw. The table is tilted 10 degrees. All of the slots we will cut will be angled so that the jack will fit (perfectly, I hope) only at the top of the register.
There are two reasons for this but they wouldn’t make any sense right now. We’ll get back to them later. All of the black lines (left side of each slot) are cut.
After this is done, the table is tilted 10 degrees in the other direction and all of the blue lines are cut (taking half of a hole with them).
Here’s a ¾ view of what we’ve accomplished so far.
Now we’ll set the scroll saw table to 0 degrees and nibble away the rest of the material in the slots.
The next photo shows our completed ‘comb’.
In the next photo I’ve temporarily clamped a strip of wood to the open end of the ‘comb’ and placed a jack in a hole to check the fit. This one is slightly tight. A couple of passes with a small file will make it perfect.
The next photo shows the ‘comb’ next to a strip of poplar that we’ll glue to the open side to close it up.
The next photo shows the two pieces clamped between two pieces of stock using the same clamping system we used when we built the case Bottom.
The lower registers are made in the same way but they’re much easier to build. First of all no hole is necessary. Secondly, the fit need not be as precise – in fact, the jacks should fit with some play in this register. Thirdly (if that’s a word), both bottom registers are made out of one piece so basically we’ll be making a two-sided ‘comb’ and adding the two sides later. Here’s a poplar strip with the paper template glued on top of it.
Here’s the lower register with one side already cut.
And now, the completed 2-sided ‘comb’.
In the next photo the 2 sides are glued to the ‘comb’.
The next photo shows the lower registers installed in the harpsichord. If you remember when we built the Upper Belly Rail we cut a dado near its bottom. We also made pinblock support brackets with a rabbet cut into their front edges. Now you can see why. The rear edge of the Lower Register fits into the dado in the Upper Belly rail. Its front edge sits in the rabbet in the pinblock support brackets. Not shown is a small screw driven into the rabbet in the right pinblock support bracket. A slot has been cut into the right front edge of the Lower Register. This allows us to move the Lower Register from left to right to align it perfectly with the Upper Registers. When its position is correct, the screw is tightened to keep the Lower Register from moving.
The next photo shows the two Upper Registers installed in their positions in the gap. I put a jack into the rear register just to show how it sits in the register.
Remember back when we built the case sides we cut a small window into the spine side of the instrument. The last photo shows the purpose of this window. Once the strings are installed it is impossible to get either of the Upper Registers out of the instrument. In case a repair has to be made to either Upper Register, they can be slid out of the instrument through this escape window without having to remove the strings.
And there you have it. Next time we'll build the stand.
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
What's a register? Take a look at this photo.
The player presses down on the front end of the key (not shown). The rear end of the key rises. Sitting on the rear end of the key is the jack which, of course, also rises. It’s path is guided by the lower and upper registers The plectrum (plucker) is near the top of the jack and sticks out from it. Eventually, the plectrum contacts the string and plucks it.
Here’s a pretty good photo of the jacks and upper registers.
The square holes in the register are just about the same size as the jacks that pass thru them. if the holes are too wide the jacks would be free to flop around in the hole and the plucker may miss the string altogether. If the holes are too narrow, the jack would stick in the register and may not return to rest position after the pluck. The placement of the holes in the register is critical. If the hole is too close to the string the plucker would overlap the string too much and the sound would be quite harsh. If the hole is too far away from the string the plucker may not reach the string at all. Worse yet, if one hole is too close to the string and the next hole is too far away the action would have no consistency and the player would have no control at all.
So the problem is to build 4 registers (2 upper and 2 lower) that have square holes just slightly larger than the dimension of the jack (.157 x .392). In addition, the placement of these holes (52 holes in each register) must all be the same distance from their respective strings AND the bottom of each jack must rest in the center of its key. Actually it’s much simpler than it sounds. We’ll start with the 2 upper registers. Here’s how we’ll do it.
In the old days, we used to take a strip of wood – place it on the rear of the keyboard – and mark the center of each key on the strip. This told us where each hole in the register would have to be in order for the jack to sit centered on its key. Now, we’ll do it another way – we’ll use the computer to tell us where to put the holes in the register. Take a look at the next photo.
What you’re seeing is a strip of poplar wide enough for the 52 slots we must cut. Onto the top of the strip I’ve glued a computer CAD printout of the correct spacing for the slots for this instrument. The red circles represent holes which must also be cut into the register (for reasons I’ll explain in a later post). The next photo shows the whole strip sitting on top of the instrument.
No, we’re not going to attempt cutting out a square hole in a piece of wood. Instead, we’ll make something that looks like a comb and glue the missing side on later. First, we drill the holes at the drill press. Notice that ½ of each hole will disappear when we cut out the slots, leaving a half hole behind each slot.
Here’s what the register looks like after all the holes are drilled.
The rest we’ll do on the scroll saw. The table is tilted 10 degrees. All of the slots we will cut will be angled so that the jack will fit (perfectly, I hope) only at the top of the register.
There are two reasons for this but they wouldn’t make any sense right now. We’ll get back to them later. All of the black lines (left side of each slot) are cut.
After this is done, the table is tilted 10 degrees in the other direction and all of the blue lines are cut (taking half of a hole with them).
Here’s a ¾ view of what we’ve accomplished so far.
Now we’ll set the scroll saw table to 0 degrees and nibble away the rest of the material in the slots.
The next photo shows our completed ‘comb’.
In the next photo I’ve temporarily clamped a strip of wood to the open end of the ‘comb’ and placed a jack in a hole to check the fit. This one is slightly tight. A couple of passes with a small file will make it perfect.
The next photo shows the ‘comb’ next to a strip of poplar that we’ll glue to the open side to close it up.
The next photo shows the two pieces clamped between two pieces of stock using the same clamping system we used when we built the case Bottom.
The lower registers are made in the same way but they’re much easier to build. First of all no hole is necessary. Secondly, the fit need not be as precise – in fact, the jacks should fit with some play in this register. Thirdly (if that’s a word), both bottom registers are made out of one piece so basically we’ll be making a two-sided ‘comb’ and adding the two sides later. Here’s a poplar strip with the paper template glued on top of it.
Here’s the lower register with one side already cut.
And now, the completed 2-sided ‘comb’.
In the next photo the 2 sides are glued to the ‘comb’.
The next photo shows the lower registers installed in the harpsichord. If you remember when we built the Upper Belly Rail we cut a dado near its bottom. We also made pinblock support brackets with a rabbet cut into their front edges. Now you can see why. The rear edge of the Lower Register fits into the dado in the Upper Belly rail. Its front edge sits in the rabbet in the pinblock support brackets. Not shown is a small screw driven into the rabbet in the right pinblock support bracket. A slot has been cut into the right front edge of the Lower Register. This allows us to move the Lower Register from left to right to align it perfectly with the Upper Registers. When its position is correct, the screw is tightened to keep the Lower Register from moving.
The next photo shows the two Upper Registers installed in their positions in the gap. I put a jack into the rear register just to show how it sits in the register.
Remember back when we built the case sides we cut a small window into the spine side of the instrument. The last photo shows the purpose of this window. Once the strings are installed it is impossible to get either of the Upper Registers out of the instrument. In case a repair has to be made to either Upper Register, they can be slid out of the instrument through this escape window without having to remove the strings.
And there you have it. Next time we'll build the stand.
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
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