As promised, I've been in the shop nearly every day since my erstwhile recovery from pneumonia. And, as you may recall, I was in the throes of completing new upper and lower registers in some beautiful European beech I picked up at the local Crosscut Hardwoods because it is, after all, "The Woodworker's Candy Store®." I was able to finish the slotting of all registers this past weekend using my fancy new jig (you know, the one I made from scrap wood).
I described how the jig works in my last post, so I won't belabor it here. Suffice it to say it worked great. Yet...there is a dicey aspect to all of this: cutting the 10-degree relief slants into the bottoms of the slots. This is done to provide room for the jacks to tilt freely (i.e., without binding) when one of the upper registers is slid to the side so the plectra for that rank (8' or 4') are moved just enough they miss the strings and vice versa. This effectively turns the ranks "on and off".
The diceyness (yeah, I just made that up) comes when cutting the slants because I've already cut the straight slots. When cutting the reliefs, I simply line the existing slots up with one of the table saw blade teeth and run it through the blade again with the Incra miter gauge set at a 10-degree angle. This isn't much fun because the tiniest slip will ruin a slot. Clamping is not really possible because the clamps tend to pull the registers up at an odd angle. So, I basically ran them through while holding the register to the miter gauge with my free hand. It wasn't the greatest approach, but it worked and I was able to complete all of the cuts over the course of two days with no mishaps (I know, a first).
Because no two cuts are ever the same, I had to clean the slots up with a nifty razor knife I frequently use for just such a task. Once the slots were free of cut anomolies, I dove into the glue up process.
When I posted the photo above on Facebook, I said, "I love the smell of fish glue in the morning," a direct rip-off from Apocaplypse Now, but you've gotta find fun in the shop where you can, right? And, yes, I'm using fish glue on most of this instrument. And, no, it doesn't smell - at all. I have detractors with regard to this, yet the only thing I fear with using this glue is excessive humidity or submersion in water. Extremely high humidity is a real concern. If you're submerging a harpsichord in water, you have issues beyond playing the thing. For this task, I'm using Norland High Tack Fish Glue. I just love the stuff.
As you can see from the photo above, I use frog tape to secure the parts before clamping them for the finish. This is a pretty common luthier strategy and one I highly recommend. I had cut the parts a little rich so I would have wiggle room to smooth them once they came off the clamps, which is what you see me doing in the photos below.
I'm quite happy with the end results.
The only thing left is to cut a relief notch for the jack tongues into each of the slots (more on this later). I'll need the hollow square hole punch I ordered specifically for the task. While it's in transit to Tortuga Early Instruments Worldwide Headquarters, I'll be turning my attention back to the soundboard and its attendant bridges and braces.
Until next time...