Bracing

The humidity in the basement is sitting steadily at about 40%, which is fantastic for gluing braces, so I took the opportunity and braced the soundboard and back yesterday.

The plans I am using as a basis for this guitar are fantastic, however, they are missing one crucial element: the heights of the braces. The brace locations themselves are clear, if possibly inaccurate (the plans include this disclaimer, saying that brace locations were determined with an X-ray, and therefore could be slightly off). For the first Baroque guitar I built with these plans, I presented the question of brace height to Michael Schreiner, a respected early instrument builder from Toronto. From other plans he suggested that the braces could have been about 25 mm high. The braces in the first guitar are about 25 mm high, with tapered ends.

This time around, I figured I would do similarly. Then I went looking for brace wood. And I read part of a lute building book (Historical Lute Construction by Robert Lundberg). Lutes are traditionally braced with grain running parallel to the soundboard, opposite to the perpendicular grain used in modern classical guitar construction. Lundberg suggests that part of the reason for this grain direction is that most of the brace wood would have been salvaged from cut-offs from the soundboard. This seemed to be a very economical method of obtaining brace wood, so I took a look at my leftover soundboard wood. It is beautifully quarter-sawn with perfectly tight, straight grain. Using the (perhaps misguided, I will admit) logic that guitar construction was not yet standardized by any means, and that guitar construction was likely influenced by lute builders of the time, I chose to brace this guitar with grain running parallel to the soundboard. (below you can see a rather poor diagram of the two choices of grain direction, as created by me and Paint)

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The Stradivarius Baroque guitar is actually fairly strongly braced when compared with some other guitars from the period. There are 3 cross struts on both the top and the back, all about 5 mm thick and of questionable height, as discussed before. These cross struts run across the upper bout, waist, and lower bout on both plates.

I chose to use as much leftover soundboard wood as possible for the braces. I managed to salvage enough wood for three braces from the cedar for this guitar. The remaining three braces I cut from another piece of cedar, from my first classical guitar. To prepare the braces I marked and cut out the braces with a coping saw, and cleaned up the faces and thinned them to 5 mm. I then trued one edge (the gluing edge) with a sanding board. All except the soundboard upper bout brace were slightly arched for strength. Although this was not necessarily a practise at the time, it does increase the strength of the instrument. The arch is subtle, so I feel that the sacrifice of tradition for strength and longevity is acceptable at this early stage in my development as a luthier.

I then glued the braces one at a time in place, respecting the center marks I had previously made on the plates. I clamped the braces with a combination of cam-clamps and medium sized spring clamps (see below).

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Once dry, the braces are chiselled to height, tapered, and sanded smooth. A more careful and intelligent woodworker would probably choose to use a block plane to achieve an even height on all braces, however, I am not that woodworker. I love a good chisel, so I chiselled all of my braces to about 20 mm high, then sanded them flat. Then I used the same Japanese chisel to taper the ends (from about 2 – 2 1/2 inches away from the ends). Then I chiselled away the corners along the length of the braces. I finished by sanding them with 220 grit sandpaper.

The soundboard also is reinforced in a few places with small pads of soundboard wood. Three pads are located around the soundhole for strength, and another two located asymmetrically on the belly of the guitar. I cut these out of soundboard scraps, sanded the glue side flat on a sanding board, and glued them to in place. Once glued, they needed thicknessing to about 2mm (again, I used a chisel here, perhaps not the most appropriate tool), and shaping. Basic principle of shaping braces and pads: sharp corners are frowned upon, generally.

Before completing the soundboard, I carefully glued the rose in place.

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The back required a little less work than the top, as seems to always be the case. After the braces were sanded smooth, I merely had to glue strips of paper along all of the seams from piecing the back together.

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And with that, the top and back plates are braced and ready to go!

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The Rose: Part 2 and Completion

Having finished the first layer of the rose around the end of September, I glued the carved piece to a second thin piece of cherry, marked the design and drilled holes to start carving layer 2. I also thinned the carved layer to about half of its original thickness by sanding.

Then I had a change of mind and decided to redesign the rose. I took out parts of my carefully carved top layer with a chisel. I had decided to move these parts of the design down a level to give the rose a more open appearance.

The second layer was carved in much the same manner as the first layer, with needle files and lots of patience. I also had to clean up the mess that removing parts of the first layer had left, as well as some glue squeeze out from attaching the layers together.

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In the image above, you can see where I removed the top layer from the design closest to the edge of the circle.

Before proceeding with the third layer, I cleaned up, as much as was possible, the glue, pencil marks, and stray bits of wood with sandpaper, a small Exacto knife, and needle files. I also thinned the second layer a bit on a sanding board.

 

The third and final layer of the rose is cut from a piece of ‘coverstock’ weight paper in a cream colour. Perhaps not the most historically accurate, but it is an easily obtainable, inexpensive paper, and the weight and texture is easy to work with for this project. Because the rose is not entirely symmetrical, I traced the actual rose onto the paper, rather than use my original design. I then sketched out my ideas in pencil, and proceeded to cut out the design.

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Most of the paper cutting was achieved with a basic Exacto knife with a standard sharp blade. The circles were cut with punches I had made for my previous rose out of metal tubes:

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These are quite easy to make: take any sized metal tube (the inside diameter should be the size of hole you require); stick it in a drill press; use a metal file to create the initial taper as the drill press spins the metal tube, and finally; polish and sharpen the taper and edge with fine sandpaper or Japanese water stones. The punches work with a sharp tap from a hammer and leave a rather clean edge.

The design for the rose has no relation to historical roses, and is rather a personal mark on the guitar. I thought the birds an appropriate addition to this rose. Let me know what you think!

The final stage was to carefully glue the paper to the wood layers. For this a very thin and even coat of glue must be applied to the entire back surface of the wood rose. It must be thin, lest unsightly glue squeeze out and ruin forever the hours of careful design and carving work! The paper layer is carefully aligned with the wood layer – and there is only one shot at getting this right, no chance to shift the paper around if it does not land in the right place – and pressed into place.

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The rose is complete and ready to glue to the soundboard. Next: bracing!

 

Carving the Rose: Layer 1

The rose is perhaps my favourite part of the Baroque guitar. While it is time consuming to construct, the intricate and beautiful designs are extremely rewarding.

Take a look at the original rose by Stradivarius. The floral layout served as inspiration for my design.

Here is the rose that I designed and constructed for my first Baroque guitar:

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This time around I decided to use a more floral rather than circular design.

First I prepared the pieces of cherry for the first two layers (the third is a heavy paper). The wood was left over from sides of another project. It is beautifully straight grained and unfigured.  I cut two pieces about 10 cm square. At this point they were around 4 mm thick, so I attached them to a sanding jig for thinning:

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The jig is just a piece of pine with two handles (on the underside in the picture). The cherry pieces are attached with double sided tape. I just flip the jig over, run it over a sanding board for a while, and voila! the pieces are evenly thinned. I thinned the pieces to about 2 mm, which is thick enough to withstand carving. After the layer is carved, I will thin it further, to just over a millimetre thick.

After sketching my design out on paper, I transferred the first layer design to a piece of cherry:

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Then I drilled holes in all of the negative spaces to prepare for carving.

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Which resulted in a strange looking pattern of holes:

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Using needle files (pictured below) I stretched the circles and removed all the excess wood. I mainly used four files: a small oval file, a one sided flat file, a triangle file, and a larger oval file. A couple of the sharper points needed to be touched up with an sharp knife, but most of the work was accomplished with these four files.

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This resulted in the first layer of the rose complete (albeit a little rough and still too thick):

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The next stage will be to glue this (with grain perpendicular) to the second piece of cherry, and then to carve the second layer of the rose in a similar fashion to the first.

Rosette

I finally had the opportunity to spend a bit of time in the workshop again, so I spent an afternoon inlaying a rosette and cutting out the soundhole.

The rosette on a Baroque guitar is rather different than the fancy mosaic or otherwise highly figured rosette of a modern classical. The focus on Baroque guitars is the beautiful and intricate rose, while the rosette is a few simple lines.

(for clarification: the rosette is the decoration around the soundhole; the rose is the fancy bit of carving that fills the soundhole on early guitars and lutes).

 

For this process I use a circle cutter made by my father:

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Logistics: first I drill a 1/8 inch hole at the centre of the soundhole, which fits the pin of the circle cutter. The circle cutter is adjusted to the correct radius. Then the pin of the circle cutter goes through the soundboard and into a workboard designed for the purpose. I work from the widest rosette ring to the soundhole. The blades have an angled cutting surface, so the flat side of the blade goes on the outside of the channel being cut. 

For this guitar, I wanted 2 rings of thin black-white-black inlay, so I cut two 1.5 mm wide channels, one with a radius of about 49.5 mm, the other with a radius about 43 mm, two cuts each. Because these channels are so narrow, cleaning out between the edge cuts made by the circle cutter is a rather delicate operation. I do not have a chisel narrow enough, so I ended up using some small knife blades to do some initial wood removal by hand, and then finishing up with the wrong end of the circle-cutter blades. These blades are actually from a purfling cutter, and happen to be almost exactly the right thickness, so I put the blade in the circle cutter upside down, and ran it around the channel a few times. Not a method which I can easily describe, nor a method that I would ever recommend. However, it worked today.

I had ready-made black-white-black purfling strips, so the actual inlay work was quite simple. Cut the strip to length, apply glue, press into channel. Then clamp. Wait for an hour or so. Use a chisel very carefully to remove the excess purfling (when glued in it was proud of the surface about 1.5 mm). And voila! a beautiful and simple rosette. 

With this done, I made the final circle cut for the soundhole, with a radius of 40 mm, this time actually cutting through the soundboard.

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Next is the rose! This was probably the most exciting and enjoyable (and most time consuming) part for me on the last guitar, so I am looking forward to the process. 

constructing the sides

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:

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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:

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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:

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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.

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