Cap molding

The cap molding covers the top edge of the case, overhanging about 1 mm on each side.

Here's the profile used for the cap molding:


It's based on the same profile used for the bridge and soundboard moldings, except it has two decorative edges instead of one.

Originally I had planned to apply a set of moldings to the inside upper edge of the case, but I discovered, before getting to that point, that Italian harpsichords don't necessarily have an inner molding unless they're made in the false inner-outer style (i.e. a set of veneers are glued to the interior of a painted wooden box to make it look like a separate wood-coloured instrument resides within the box). It's a good thing I didn't go ahead with this, not only because of the workload, but because the resulting cap molding would have been extremely wide. As it is, the molding has to cover and overhang two thicknesses of case material, which requires a width of 3/8" plus 2 mm.

Before gluing the cap molding down, I cleaned up the case edges with a special edge-trimming plane. Since the case edge is so narrow, I thought a normal hand plane would be hard to keep flat. The built-in fence on the edge-trimming plane helps the plane cut a square edge.

I steam-bent the bentside cap molding to get it approximately to the right curvature, then glued it down:


Tiny 1/2" brads were nailed through the molding and partly into the case edge to help resist the shear forces of the molding trying to straighten out. I think I will clip off the heads of these and drive the remainder of the shaft below the surface of the molding, just to provide some extra holding power.

The brads also help to act as positioning pins so that the overhang of the molding is equal on both sides. There's no easy way to keep the molding in the correct position without using positioning aids of some sort.

All the other cap moldings were done the same way, except that the brads were pulled out once the glue dried. Glue alone should be enough to secure moldings that aren't bent to shape.

Next, I'll swell the nail holes with water to close them up as much as possible, sand the molding, and plug any remaining holes with yellow wax.

Cosmetic details

A little fragment of molding decorates the back edge of each keywell block:


This piece of molding covers the slightly inaccurate joint between the bentside and cheek:


An identical piece covers the bentside-to-tail joint. I found these case joints tricky to make absolutely tight, without gaps: something to improve upon in future. In the meantime, these little sins are now safely hidden.

Keywell blocks

Since the keyboard is narrower than the space it fits into, the remaining space is taken up with a pair of keywell blocks plus a transposing block. The keywell blocks are shown below, glued up against the decorative front edges of the case:


In order to make sure the first and last keys don't rub against these blocks, 2 mm shims were glued to the left and right edges of the key frame:


The removable transposing block, shown below, allows the pitch of the instrument to be changed by shifting the keyboard sideways to fill the space left over when the block is removed. The block is held in place with two rare-earth magnets that are attracted to nail heads inside the keywell.


The keyboard shifts by one jack position, which allows a pitch of A=415 Hz when to the left and A=440 Hz when to the right.

Determining the proper thickness of the keywell blocks is an important part of making sure that the keyboard is properly aligned with the jacks: if not, the jacks could slip sideways off the key ends. I did this by progressively planing the blocks down and putting them in place, then sliding the keyboard left and right and observing how the jacks sat on the keys in both the left and right positions. When everything looked good, I glued the blocks in, then planed down the transposing block to fit the leftover space.

Register controls

The on/off positions of the registers are controlled by capstan screws at the left and right sides of the harpsichord. Here is the set located at the cheek:


The thickness of the brown block is the same as that of the jackrail supports, which ensures the screw heads won't be blocked by the supports.

By inserting a thin rod into the holes, the screws can be turned in and out. The register ends butt up against them, controlling their sideways motion.

To locate these screws I had to cut down the registers, which were still a bit too long, and this meant I had to have a fair idea of where the on and off positions would be. I determined this by progressively trimming the register ends and trying my prototype jacks in various slots after each cut.

Shifting the registers on and off is controlled by this pair of register levers on the spine side of the instrument:


The handles are brass lamp finials, used to screw down lampshades in a decorative manner. They fit into two brass bars, which I drilled for the necessary screw sizes and polished. At the far end, the registers were drilled for #8-32 machine screws which self-tapped their holes as they were screwed in.

Since the jacks will face in opposite directions, the on and off motions for the registers are opposed. Moving both levers in the same direction silences one stop and turns on the other, while pinching the levers together turns both on.

Jackrail

The jackrail sits over the register gap and keeps the jacks from flying out of the instrument when the keys are pressed. Its ends slide into grooves milled in the jackrail support blocks.

I made the jackrail from a scrap piece of the quartered western red cedar used for the baseboard, and glued pieces of Alaska yellow cedar to the three visible sides. Then I routed a decorative molding along the top edges, using the same bit that provided the profiles for the soundboard moldings and bridge:


The jackrail is 3/8" thick. The ends were reduced to 1/4" to fit the jackrail support grooves.

On the underside I'll staple one or two layers of 1.5 mm felt cloth to stop the upward travel of the jacks. The cloth doesn't need to absorb the full force of playing the keyboard because the head stop under the keys takes some of that impact too. What's needed is for the jackrail to arrest any further travel of the jacks once the keys have stopped moving. This avoids the unpleasant feeling of the jacks hopping upwards, bouncing off the jackrail and landing back on the key ends, which results in an odd jiggling sensation under the fingers.

Jackrail supports

The jackrail keeps the jacks from flying out of the instrument when it's played. Two supports glued to the case walls above the register gap hold it at the correct position.

Now that the jacks are done, I've checked to see how high they rise when the keys are fully depressed. I will set the jackrail position based on this measurement.

Here's one of the two jackrail supports:


Both supports are made from Alaska yellow cedar about 11 mm thick. A 1/4" groove in each will receive the ends of the jackrail. I plan to cut off the non-scrolled end at a 45 degree angle, which will look nicer.