Hi all,
This post is the continuation of Part 15A.
The next step is critically important to the proper functioning of the instrument. We must accurately mark the positions of the two nuts on the pinblock as well as the position of the 102 tuning pin holes. To do this, we cut out the pinblock portion of the printed blueprint and tape it to the top of the pinblock.
First we’ll position the two nuts. Small holes are drilled thru the nuts – one at each end and one in the middle of each nut. Small rectangular pieces of scrap soundboard spruce, with a hole drilled into their centers, are used as clamping pads. The nuts are placed in their proper positions on the plan and a thin wire nail with a large head is driven through the holes we drilled into the nuts and into the pinblock. These holes in the pinblock will serve as positioning holes when the time comes to glue the nuts down. The next photo shows the nuts nailed to the pinblock.
Next, using a small hammer and an awl, we’ll mark the positions of the 102 tuning pin holes by tapping through the center of each hole on the blueprint, leaving a small hole on the surface of the pinblock for each of the 102 holes.
After these holes have been marked, the nails are pulled out of the nuts and the nuts are removed. Then the blueprint is removed from the pinblock which now has 108 dimples on its surface – 102 for the tuning pins and 6 which are the nut positioning holes. Here’s what it looks like.
Now we’ll go to the drill press and drill the 102 tuning pin holes. The tuning pins must angle backwards about 5 degrees from vertical. This helps them resist the pull of the string tension. My radial drill press tilts in every direction except the one I need, so I use a simple, shop made drill press table which is angled at 5 degrees.
The holes are drilled with as much uniformity as possible. Each hole is drilled half way – the bit is lifted to clear the chips – the hole is completed. We’re trying to get the holes as uniform in size as possible because this will affect how easy or difficult it is to tune the instrument. We’re not terribly concerned about the pins being too loose because, unlike a piano which may have 160 lbs. of tension pulling on each tuning pin, the string tension on a harpsichord is much, much less. As long as you can’t turn the tuning pin with your fingers, it’s tight enough. Too tight, on the other hand, is really bad on a harpsichord. The amount a harpsichord tuning pin is turned during tuning is so small that a too-tight pin makes fine tuning difficult, if not impossible. By the way, we’re drilling the holes with a 3/16” bit (.1875) to accept a tuning pin that has a diameter of .198. Here’s the pinblock being drilled at the drill press.
And here’s the pinblock after all the holes have been drilled.
Now it’s time to do something very simple ..... if you do it at the right time. We need to cut a small 3/16” dado into the bottom surface of the 8’ nut. A brass control lever must go underneath this nut and the dado allows for this. I once glued this nut down without cutting this dado. Can you imagine how hard it is to cut a dado on the bottom of a piece of wood that has already been glued down? It took forever. Being as smart as I am, the next year, on the very next instrument, I did the same exact thing – what an idiot! Anyway, this time I remembered to do it before it got glued down. Here it is.
Next, we’ll glue the nuts to the pinblock, using the positioning holes to align them in their proper places.
After the glue sets, the positioning nails are removed and the holes plugged with glue and a toothpick. And here’s the result of our work – the pinblock installed in the case (but not glued and screwed down yet). I’ve cut and fit some spruce to cover the screws at the end of the pinblock.
And that’s it for this session. We’re now exactly 9 weeks into this project and some decisions have to be made about what level of detail to include in future posts. This is especially true in the case of finishing and decorating. I’m sure no one wants to see 15 photos of paint drying. On the other hand, paint and decoration is a big part of a harpsichord. I’ll rely on all of you for guidance. Let me know what you want to see (or what will bore you to death) and I’ll try to tailor my posts accordingly.
Till 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 Part 14 - Building the Soundboard Part 15A - Pinblock & "Nuts" Part 15B - Pinblock & "Nuts" con't.
This post is the continuation of Part 15A.
The next step is critically important to the proper functioning of the instrument. We must accurately mark the positions of the two nuts on the pinblock as well as the position of the 102 tuning pin holes. To do this, we cut out the pinblock portion of the printed blueprint and tape it to the top of the pinblock.
First we’ll position the two nuts. Small holes are drilled thru the nuts – one at each end and one in the middle of each nut. Small rectangular pieces of scrap soundboard spruce, with a hole drilled into their centers, are used as clamping pads. The nuts are placed in their proper positions on the plan and a thin wire nail with a large head is driven through the holes we drilled into the nuts and into the pinblock. These holes in the pinblock will serve as positioning holes when the time comes to glue the nuts down. The next photo shows the nuts nailed to the pinblock.
Next, using a small hammer and an awl, we’ll mark the positions of the 102 tuning pin holes by tapping through the center of each hole on the blueprint, leaving a small hole on the surface of the pinblock for each of the 102 holes.
After these holes have been marked, the nails are pulled out of the nuts and the nuts are removed. Then the blueprint is removed from the pinblock which now has 108 dimples on its surface – 102 for the tuning pins and 6 which are the nut positioning holes. Here’s what it looks like.
Now we’ll go to the drill press and drill the 102 tuning pin holes. The tuning pins must angle backwards about 5 degrees from vertical. This helps them resist the pull of the string tension. My radial drill press tilts in every direction except the one I need, so I use a simple, shop made drill press table which is angled at 5 degrees.
The holes are drilled with as much uniformity as possible. Each hole is drilled half way – the bit is lifted to clear the chips – the hole is completed. We’re trying to get the holes as uniform in size as possible because this will affect how easy or difficult it is to tune the instrument. We’re not terribly concerned about the pins being too loose because, unlike a piano which may have 160 lbs. of tension pulling on each tuning pin, the string tension on a harpsichord is much, much less. As long as you can’t turn the tuning pin with your fingers, it’s tight enough. Too tight, on the other hand, is really bad on a harpsichord. The amount a harpsichord tuning pin is turned during tuning is so small that a too-tight pin makes fine tuning difficult, if not impossible. By the way, we’re drilling the holes with a 3/16” bit (.1875) to accept a tuning pin that has a diameter of .198. Here’s the pinblock being drilled at the drill press.
And here’s the pinblock after all the holes have been drilled.
Now it’s time to do something very simple ..... if you do it at the right time. We need to cut a small 3/16” dado into the bottom surface of the 8’ nut. A brass control lever must go underneath this nut and the dado allows for this. I once glued this nut down without cutting this dado. Can you imagine how hard it is to cut a dado on the bottom of a piece of wood that has already been glued down? It took forever. Being as smart as I am, the next year, on the very next instrument, I did the same exact thing – what an idiot! Anyway, this time I remembered to do it before it got glued down. Here it is.
Next, we’ll glue the nuts to the pinblock, using the positioning holes to align them in their proper places.
After the glue sets, the positioning nails are removed and the holes plugged with glue and a toothpick. And here’s the result of our work – the pinblock installed in the case (but not glued and screwed down yet). I’ve cut and fit some spruce to cover the screws at the end of the pinblock.
And that’s it for this session. We’re now exactly 9 weeks into this project and some decisions have to be made about what level of detail to include in future posts. This is especially true in the case of finishing and decorating. I’m sure no one wants to see 15 photos of paint drying. On the other hand, paint and decoration is a big part of a harpsichord. I’ll rely on all of you for guidance. Let me know what you want to see (or what will bore you to death) and I’ll try to tailor my posts accordingly.
Till 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 Part 14 - Building the Soundboard Part 15A - Pinblock & "Nuts" Part 15B - Pinblock & "Nuts" con't.
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