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. 

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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:

HPIM2416

 

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:

end graft
end graft

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:

HPIM2425

 

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.

HPIM2431

 

 

thinning and bending the sides

The sides started out as two oversized book-matched pieces of birdseye maple. I had the wood cut from a thick slab over a year ago at A&M woods in Cambridge Ontario. This is the same wood I used on the 003 steel string guitar. One of the pieces was over a 1/4 inch thick, the other roughly 3/16ths.

I trued one side (the ‘good’ side) on both pieces, levelling the surfaces by sanding and scraping. (note: be sure to mark the good side clearly: hopefully the ‘rough’ side will look as clean as the ‘good’ side when thinning is finished) Then I proceeded to thin the sides to just under 2 mm thick, around 75 thou.

Although the sides are not glued to each other, one edge does need to be relatively straight, and the best way to do this is to use another shooting board:

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Here you can kind of see the shooting board set up, with a base board, a second narrower board (hidden under the sides to raise the wood) and an end-stopper-block. The sides rest on top, pinched together with a couple small spring clamps. My hand holds the long, straight, square sanding block which is used to true the edges.

With the edges straight, the sides were ready to be marked for bending. I always mark the waist with a strong line drawn with a square. I also marked the centres of the lower and upper bouts for reference. All of these marks are on the ‘good side.’ On the rough side, I scribbled an area a few inches to either side of these marks.

These scribble marks were just to mark an approximate area to thin slightly more than the rest of the sides. I scraped probably about an 1/8 to a 1/4 mm of wood from all of these bends. This was just to make bending easier, especially with a finicky wood like birdseye maple.

After all of these preparations, I put the sides in a trough of water to soak prior to bending:

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After an hour or so of soaking, they were ready to bend. I use a bending iron (below) made by my father out of a copper pipe and an electric heating element. This is a slightly less dangerous version of the more common pipe and propane torch method.

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The trick to smooth bending is to work quickly and calmly, paying close attention to what the wood is ‘telling you.’ Meaning, never force the wood; allow the pipe to heat up the wood and gently coax the wood in the direction you want it to go. The wood should almost be in constant motion, so as to avoid creases and burns, which are particularly dangerous on blond woods like maple. Over-bending (bending the wood further than is ultimately desired) is useful in the sharper bends at the waist, and the centre of the bouts. Wear gloves to prevent burns, and use a straight piece of wood as needed to apply pressure.

When the side was close to the desired shape, I quickly set it in the form and clamped it into place. As the wood settles, cools and dries overnight, the side will take the shape of the form permanently.

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Tomorrow I will attach the sides together with tail and head blocks… then it will start to look like a guitar.

Back and Top Plates

After two days in the workroom sanding, planing, and scraping, I can say that the top and back are thinned and ready to be decorated and braced. Of course, the bracing cannot happen until the humidity is conducive to the task (preferably around 50%, which it will be in the fall/winter). The rose and rosette can happen any time, however, my tools for this are currently two and a half hours away.

Details on the back construction:

Having glued up the back stripes, I cleaned up one face (read: lots of dried glue scraping). Then I traced the back template onto the wood, using a previously made half template taken from the plans. I cut out the back (with an extra 1/2 inch of wood all around) using a coping saw. Then the back was thinned from the ‘wrong’ side (the inside face) to approximately 2 mm (79-83 thousandths of an inch). This involved lots of scraping and some sanding, to which my tender thumbs and sliced up little finger knuckles can attest.

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Back stripe detail
back plate
back plate

 

Details of top construction:

The top is made of a nice, but unknown species of cedar. The grain is tight, straight, and well quarter-sawn. I started with two roughly cut book-matched pieces, which I jointed on the shooting board (for a slightly convoluted description of this process, see the previous post). Once the pieces fit together without gaps, I glued the top together (one glue seam down the centre of the top).

Once dry, I cleaned up the ‘good’ (outside) face of the top, traced the same template onto the top as I had for the back, and cut out the top plate using a coping saw. Then it was to the (slightly tedious and exhausting, but necessary) process of thinning using plane, scraper and sanding block.

The reason for so many tools is fairly simple. The block plane takes off wood quickly, but I am not good enough with this tool to take off wood evenly. Plus, it is finicky to set up properly, and with the grain in soft woods often changing direction, planes are not ideal for final thinning. Scrapers are excellent – they can be used on almost any wood with any strange grain pattern. However, they can do a serious number on ones hands! After a long scraping session, my thumbs are in pain from the pressure and heat of the metal (even though I wear gloves), my knuckles are sliced up from catching on the side of the wood, and my finger tips are all slightly tender. This is why I switch it up and use a large sanding block some of the time to give my hands a rest. Sanding blocks still have their dangers (watch out for your fingernails… and catching skin underneath a moving sanding block is really painful, as I discovered today), but they do an excellent job at flattening out large surfaces quickly. Another reason for switching it up between the three tools is simply to mask some of the tedium of this job…

The top was thinned to a point of flexibility, rather than a specific thickness. Cedar is generally more flexible than spruce, so it is a bit thicker than my last Baroque guitar top (Engelmann spruce, at about 80 thou (2mm)), with an average thickness of just over 90 thou. Of course, this will come down a bit with more fine sanding and scraping in the finishing process.

Once thinned, I prepared the top for cutting out the soundhole and rosette channels:

drafting top layout
drafting top layout

Next stage on the back is bracing, which will happen in a few months. On the top, I can cut out the soundhole, insert the rosette stripes and make the rose before bracing.

The start of a new guitar

Welcome friends and strangers! Having returned from a fantastic guitar festival in Germany, I could hardly wait to start a new guitar building project, so within 24 hours of returning home, I was in the basement of my parents’ house, looking at wood for a Baroque guitar after Stradivarius. This will be my second of this model (I will post photos of the first at some point). I will be building when I can, however, it will be slightly sporadic because of university and living away from home (and more importantly, my workshop). I will use this blog as a means of recording my progress on the guitar.

A description of the guitar:

  • back: 7 piece birdseye maple and lacewood stripes
  • sides: birdseye maple
  • top: most likely cedar, but possibly spruce
  • neck: Spanish cedar
  • fingerboard: ebony
  • rose: 2 layers carved pear or cherry with a layer of paper
  • scale length: likely 640 mm, with tied, moveable gut frets

Progress Thus Far

Having roughly planned the project, I set to work cutting up the basic pieces for the plates of the guitar. The 7 pieces of the back were measured to fit evenly across the bouts of the guitar (tapering away from the butt end of the guitar). Before gluing the back up, I had to thin the pieces to a uniform thickness using a tool from Lee Valley:

thinning the back pieces
thinning the back pieces

Once the 7 pieces were uniform in thickness (about 3 mm) I set up a ‘shooting board’ to joint the edges of each piece. A shooting board includes a flat base board, a second, more narrow board on top, and a stopper block at the end. The back piece which needs to be ‘shot’ is placed on top, resting against the end stopper block. Then I used a very flat, square sanding block to carefully smooth and straighten the rough cut edge, checking against a straight edge. With a 7 piece back, there are 12 edges that need to be straightened and checked against each other.

After these pieces were prepared, I glued the back up in pieces. Here is a picture of the final joint being glued:

gluing up back pieces
gluing up back pieces

The cam clamps on either end just hold the pieces down to the work surface. Pressure is applied to the joint by the wedges (on the right hand side). Each of the joints is decorated by a black-white-black purfling stripe.

Next step is to prepare the top plates for glue, which includes more jointing and some flattening.