Assembling the body

After working for such a long time on various components, it's amazing how quickly the guitar becomes something undeniably guitar shaped. In this post I'll show how the sides are glued to the top.

The top and sides are joined by hundreds of individual pieces of spruce. Some guitars use a single strip, with notches cut to allow the 'kerfing' to bend presumably to save time. This was one of the slowest operations in the entire construction. A lot o time was spent between cutting the spruce strips to size, shaping the rounded profile, cutting each piece individually and cleaning the rough edges and then individually gluing each of the hundreds of pieces into place.

First the sides were clamped into place with spool clamps that I made myself. The DIY spool clamps worked out at about a quarter of the cost of the similar clamps offered by Stewart Macdonald. They are made of threaded rod, with two pieces of cork-faced dowel and a wing-nut.

In this photo you can see the clamps holding the side to the base of the solera. You can also see I have started to test fit the spruce pieces, to see how many will be needed for each section.

Once the spacing was figured out (although I'll admit I ended up accidentally deviating from the plan during the gluing process). Each piece was glued with PVA glue, and held in place for a few moments until dry.

The sides are firmly held in place by the spool clamps, the heel and the end block.

Here is a close-up of the final result. The spruce rests up closely against the rosewood sides, and holds the top firmly. I don't think the pieces need to be so close together here, but it doesn't seem to have caused any problems in the finished instrument.

Once the top and sides are firmly glued, I moved on to working on the back lining. The back lining is made from the same spruce material as the top pieces, but is solid. Two strips are cut and bent for each side, before being laminated together. This is done as bending a piece this think is tricky. Once the two pieces have been laminated, they are cut to the correct profile, and glued onto the sides. The sides have been trimmed to the correct height and back profile at this stage.

The final step is to cut notches for the back braces to sit into. These need to be precisely cut as they are very visible through the soundhole of the guitar. They also act as alignment guides when gluing the back.

The back is glued in place using the same spool clamps.

I really love this photo as it shows how beautiful the inside of a guitar can be. 

The spanish heel

There are a few types of guitar neck joint. The two traditional ones are the dovetail and spanish heel which are common for steel string guitars and classical guitars respectively. Since this is a reasonably faithful homage to Hauser's classical guitars, it has a spanish heel. Unlike the dovetail, where the neck and body are separate, the spanish heel effectively joins the neck, top and sides permanently. As previously seen, there are two slots cut into both sides of the heel, in which the sides are held captive. In this photo the heel is being glued to the top.

The top and neck have been aligned exactly prior to this, with registration pins ensuring that they do not move during gluing. If the top was not correctly aligned with the centre of the neck, the bridge would need to be glued away from the centre line of the top (which would look weird).

Once the heel and the top are glued, the sides can be cut to size. One side is cut to fit into the slanted slot at the heel, and after being precisely clamped to the top's perimeter, the end is trimmed to the centre line. There is a little margin for error here, because the end block will have an end graft hiding the butt-joint, but it's still important to get it close, or the shape of the guitar will be subtly changed.

After both sides have been cut to length, the wedges can be cut. In some spanish heel designs, the slots have parallel sides. In this case a pair of wedges is used. Because of the neck slot cutting jig shown earlier, the slots on this heel are already tapered, so a single wedge can be used. The mahogany wedges are trimmed and tweaked until a very close fit is established. I would have trusted these wedges without any glue at all, but I put some in anyway just to be safe!

After the glue is dry, the wedges are trimmed down to the surface of the foot. You can see just how close the fit is. Those wedges will hold the sides until the end of time. If you look closely you can also see the subject of the next post, which shows how the top and sides are held together.

This stage of the build really shows the beauty of the traditional solera building jig. The open sides of the jig allow easy access to the entire guitar during the alignment of the sides, the jig doesn't need to provide much support, because the guitar itself provides most of the rigidity needed once the sides are held captive by the neck.

The back

I need to get my skates on and finish the documentation for this guitar. It's been finished for months, but this blog is only halfway through!

First the two bookmatched pieces of rosewood were glued together in a wedged gluing jig. The jig has tapered rails with overhanging edges that allow the centre spars to be wedged in tightly. The further forward in the jig they are, the tighter they press down on the joint. Waxed tape is places below the glue-line to prevent it from sticking.

After the glue has dried the oversized centre strip is cleaned up. This photo shows a nice shaving of the central flamed maple strip and the 3-layer veneer sandwich on either side. Not all guitars have centre strips, but Hauser style guitars are known for bold and simple lines like this.

After the back has been cut to shape, reinforcement is glued to the centre strip. This can be mahogany, or in this case spanish cedar. Cross grain strips are used to compliment the long grain running along the back. This helps prevent cracking, and ensures extra strength.

Both the centre reinforcement, and the back braces are glued in the go-bar deck like the top braces. The main difference here is that the back is resting in a specially dished jig which provides the curve or 'bombado' for the back.

After the back braces are glued they are shaped similarly to the top braces. The back braces are much taller than the top braces however. In this photo you can also see that a thin layer of shellac has been applied to the central cedar strips. Also note the blank area where the foot of the heel will be glued.

Bending the sides

Before I started my first guitar, bending the sides seemed like one of the most mysterious parts of the puzzle. That something as rigid as wood could be made to bend and flow so smoothly seemed slightly magical and quite unlikely. All the information I could find said things like "the only way to learn to bend wood is by doing it" and "at a certain point the wood starts to bend". This was not useful. I wish I could offer more useful advise than that, but honestly it was much more intuitive than I had feared, and it is quite simple. You get a hot pipe (seen here is an electric bending iron I bought from Stewmac.com), you dampen, wet or soak the sides depending on the type of wood. And when the heat and the water combine to make steam, the wood starts to become 'plastic', and will eventually bend quite easily.

I was lucky to not break my first set of sides, which was good as they are beautiful Indian Rosewood. The first step was to square up one side on a shooting board with my block plane. One side of the wood had a nice red steak, so I chose to keep that side close to the top to echo the red in the rosette (and eventually the bindings). The shavings from this were so many beautiful shades of red and rose that I kept them all.

Because the waist is the tightest radius, that is usually bent first. In this photo the waist bend is cooling while clamped to a form made in the shape of the guitar. The bend was made by placing a damp cloth on the surface of the wood, and then pressing it against the bending iron. Once the steam had permeated the wood it was possible to bend it by applying pressure to both sides.

After lots of tweaking (I think the first side took over and hour to do), the side fits perfectly onto the  wooden form. Because I am building my guitar on an open solera style, the sides need to be very close to the final shape. Other styles of building allow for a bit more wiggle room since the sides will be glued while held in the correct position.

Next I'll show how I started to assemble the guitar.

Brace yourself pt. 2

This post will document the completion of the top bracing. Here I am using a finger plane to shape the fan braces one at a time. The plane has been designed specifically for this task (see previous posts for details), to allow it to cut very close to the top. The fan braces have a curved profile from end to end, and a round profile along their width. There is much debate as to which shapes and size give the 'best' sound. The bracing pattern I am using here, is the 'fan' style, common to most traditional instruments. Since I am building this guitar in the style of Hermann Hauser, I am using the pattern from one of his instruments as a reference.

Here are the fan braces after shaping, and a particularly magnificent curled shaving. Final finish was done with sandpaper.

Here is the top fully braced, and held in the building jig/solera. You can see cutoff braces have been added below the fan braces, and three large braces added near the soundhole. These three braces are known as 'harmony bars' and support the top where it is weakest around the soundhole, and also underneath the fingerboard which is susceptible to warping. This area of the guitar does not significantly vibrate, and so does not contribute hugely to the sound of the guitar.

Here you can see the arched profile of the fan braces, and the sound hole reinforcements. I have begun to shape the harmony bars too.

Finally here is all the bracing complete. It's almost a crime how much time I put into fine finishing the part of the guitar that nobody will every see! In the next post I'll be moving on to bending the sides.

Brace yourself

I'm back! I'm only updating this because people have been nagging me (You know who you are), otherwise I'd claim to be too busy. Actually this blog has already been a useful record for myself to remember the order of particular steps.

Anyway, here's some pictures, cause that's what you're here for.

An important part of the process is to make the top plate the correct thickness. The thickness of the top is one of the major factors in determining the sound of the guitar. Here you can see the tools I used after the rosette was installed (some thicknessing with a block plane happened before the rosette step). A scraper is simply a piece of steel sharpened in such a way to allow you to make very fine shavings by scraping. The sanding block is a piece of mahogany lined with cork to provide a flat, but not overly rigid form.

Here you can see the top has been cut out. It's resting on the bracing dish. This jig is carved with a slight dish to allow the top a subtle dome shape when assembled upside-down. 

This is my little workshop. It's 165cm x 165cm (about 5 1/2 ft). It's small, but it just about does the job. I've annotated the picture on flickr, so if you like to see what everything is (or look at extra photos), here's a link: http://www.flickr.com/photos/estone/5310699964/in/photostream

Need up is bracing the top. The braces offer support and rigidity to the top, allowing the top itself to be thinner, which increases volume. These braces are made from European Spruce, like the top. Here you can see the billet for the fan braces. The braces are split/cut exactly along the grain for maximum strength.

In this photo the braces are all being glued simultaneously using my homemade go-bar deck. The deck itself is two pieces of plywood separated by four legs with latches to hold the bracing dish in place. The go-bars are PVC tubing with a spring and some dowel to provide pressure.

Fan braces! You can also see the bridge patch underneath. The bridge patch provides support to the bridge on the other side of the top. The fan braces had to be exactly shaped to fit over its curved profile. In the next post I'll finish shaping the fan braces, and add the remaining bracing to the top.

Rosette

Aside from the herringbone pattern and adjacent veneer pattern, the rosette is also made of a central ring of tiles. The tiles are made from veneer, glued and recut in order to make the pattern. In the first photo you can see the component veneer sandwiches needed to make the + pattern. I glued up three different veneer blocks of five maple and black veneer sheets.

I glued up two different logs with the same veneer sandwiches, but in a different order. This gave me an X pattern and a + pattern. Then I cut the logs into small tiles.

Using a circle cutter tool designed by Geza Burghardt I cut a channel in the soundboard. Before this I had carefully located and drilled a hole at the correct place. The circle cutter allows a precise depth of cut to be made, in this case about 1.5mm.

With the outer and inner boundaries cut, a few intermediary cuts allow for easy removal of wood. The channel was cleaned up with a chisel.

With the channel complete, I test fitted each of the tiles. To make the square tiles fit in a round channel, I gave each a slight taper.

The tiles were glued in place with 2 part epoxy mixed with ebony dust. The ebony dust made it completely black, which hides the small gap between the two tiles. In this photo you can see some of the epoxy on the spruce. Once the tiles had been allowed to cure in place overnight I cleaned up the excess epoxy, and extra height of tile with a small plane.

The inner and outer channel for the herringbone bands were then cut with the circle cutter and chisel. Then the herringbone and assorted coloured veneers were bunched together and pushed into the channel. White PVC glue was used to persuade them to stay there.

After drying overnight under a nice flat caul the rosette is ready to be revealed. I was so excited to see how it turned out when i started cleaning it up.

The shavings that were created during the cleanup are one of my favourite aspects of the build so far. They're such pretty 'waste'. So that's the rosette. After this I'll be moving on to the other side of the soundboard, and the braces that make it stronger, and dictate the kind of sound that it has.