Having left the sides in the form overnight, I spent today making and gluing tail and head blocks; arching and trimming the sides; inserting the end graft, and; carving the dovetail joint where the neck attaches to the body.
Tail and Head Blocks
The tail block is a small (approx 12 mm thick, 82 mm wide, 93 mm tall) block of Spanish cedar that bridges the joint between the sides at the ‘butt’ or ‘tail’ end of the guitar. The head block (20 mm thick, 77 mm wide, 84 mm tall; also Spanish cedar) is the equivalent at the neck end of the body.
Spanish cedar is a stable wood (especially when quarter sawn), and, like other cedars, is extremely strong and light weight. (Cedars are also rot resistant, however, I am hoping I will not need to rely on this quality in guitar making.) Spanish cedar is also a traditional neck wood.
I trimmed the sides to length, then proceeded to slice and dice a leftover piece of Spanish cedar (from my last Baroque guitar) into blanks for the tail and head blocks. I will spare you the boring details; suffice to say that there was a lot of marking, squaring, hand sawing, and sanding early on this morning. With the blanks roughly cut to size, I needed to fit them to the curve of the sides. This involved a lot of sanding and checking for fit against the form. Then glue, clamps, wait for glue to dry…
As always, it is necessary to make even the inside of the guitar as beautiful as possible, so the inside vertical edges are rounded off with chisel and sandpaper. Leaving sharp edges on the inside of a guitar is never a good idea, as it likely will have a detrimental effect on the sound. Also, in 50 years when the guitar needs repairs, I would like the repair shop to admire my work, rather than criticise a messy interior.
Trimming and Arching the Sides
The back of the guitar is arched lengthwise. I used the plans to determine the measurements of the sides at various places (ranging from 82 mm to 94 mm), marking these points in reference to the flat, top edge of the side (which was straightened on the shooting board yesterday. (side note: this will later lose its uniformity before the top is glued to the body). I then used masking tape as a flexible ruler to join the points marked around the sides of the guitar:
Other times I have just drawn on a line using a straight piece of heavy paper, but the tape seemed like a good idea today. I used a coping saw to cut about 2-3 mm away from the tape line all the way around the guitar. This is a bit dangerous because the sides are quite flexible and liable to crack, so I supported the sides with clamps and my free hand, and worked carefully and slowly.
The saw cut needed some significant clean up, so I used a sanding board to level the edges (the back is arched, but the side edges should still be smooth, and level horizontally). This sanding took the sides down to the level of the masking tape. This sanding is always a really noisy job – the sides vibrate with every pass across the sanding board, squeaking and squawking, and basically sounding like they will explode.
But they didn’t, and the sides came away in one piece, ready for the next stage in the process.
The End Graft
This is a decorative stripe used to beautify the seam at the tail of the guitar where the sides join. It can also camouflage any miscalculations in side length, and poorly constructed tail blocks. This is also sometimes a place to display fancy inlay work.
I chose to use a simple stripe design at the tail, more in keeping with the original Stradivarius design, a simple black-maple-black stripe. I simply cut out a small strip from either side of the joint and pressed in my purfling stripe:
Carving the Heel-Body Joint
One of the most interesting things about looking at historical guitars is figuring out how the builders thought. Stradivarius was primarily a violin maker, and you can see this in the details of the guitar. For example, the woods – maple back and sides, spruce top, pine tail and head blocks – all traditional violin woods. The purfling detail around the guitar is also reminiscent of a violin. And the neck to body joint is clearly taken from the maker’s work with violins. When I finish this construction in building the neck, this will make more sense, but I will try to describe it here.
The neck attaches to the heel with a scarf joint (45° angle on both pieces, join together to make a sharp perpendicular joint). The heel is set into the guitar with a dovetail joint.
It is this joint that I started today by cutting the female portion into the head block of the guitar. It will make a lot more sense in the photograph:
I have left a bit of room at the sides for adjustment, and I have about 0.5 mm of extra depth which I can play with when fitting the neck.
After a long day, the sides are almost ready to receive the back. Lining (also called kerfing) will be next, and obviously the back needs to be braced before I can proceed.