This post is not directly related to Dan’s guitar but I have to share meeting with Muriel Anderson, an internationally known guitarist and recording artist. She was actually booked in a small independent music store near Tampa for a workshop and concert last week. We attended this wonderful evening and spent a great deal of time talking to her about music and harp guitars.
Muriel has recorded a CD with flamenco duo Tierra Negra. It is called New World Flamenco and it is awesome – highly recommended!
Most custom guitars are finished with either nitrocellulose lacquer, UV-cured polyester, French Polish (shellac) or a polymerized oil varnish. With the exception of shellac, all of these finishes are harmful to your health and to the environment. The last six or seven years has seen the maturing of water-based lacquers that are durable and safe. I have been using a water-based lacquer from Crystalac for many years now. Although it is much safer than almost any other finish, I still take precautions to protect my lungs from any micro-particles or chemicals.
I have built a portable spray booth that I use for finishing. It sits on top of a table and has a powerful fan that sucks the overspray into a common A/C filter and has special braces for securing the body and neck.
My spray schedule will consist of 12 thin coats of sealer (commonly known as sanding sealer) which is just thinned lacquer and then 12 coats of top coat lacquer. I will try to spray four coats per day three hours apart. After all the lacquer is applied, it will need to cure for one week before buffing.
Water-based lacquer sprays tiny beads on the guitar. Within seconds they spread out to form a solid coat. The build-up of 24 coats will result in a solid protective finish without adding much weight or damping to the top.
The daily spraying will continue for the next four days.
Many species of hardwoods have open pores in their grain. This presents a challenge when trying to finish them with a lacquer or varnish because these finishes do not fill the open pores very well and this leaves tiny voids that do not appear smooth in certain light. Ziricote and Ebony are closed-pore woods so nothing has to be done to prepare them for final finishing. Mahogany on the other hand is an open-pore wood and needs to have the pores filled before finishing. Many different kinds of fillers are used but the process is similar: force the filler in the pores with different strokes from different angle. I am currently using Zpoxy, an epoxy-based substance that does a great job at filling pores.
After the pores stop accepting any more filler I do a final smoothing out so there are no peaks in the Zpoxy and I hang it up to dry.
Once the Zpoxy dries, I will sand it back to the wood leaving only the filler in the pores. Sometimes I have to repeat this process to completely fill the pores (especially with Rosewoods) but a close inspection with the magnifying glass reveals the pores are sufficiently filled.
The guitar construction is now finished and ready for the lacquer. I must first clean the shop of excess sawdust and debris and then I will set up my spray booth.
The heelcap is the decorative hardwood on the heel of the neck where it joins the body. It is frequently an artistic statement by the guitarbuilder. Froggy Bottom Guitars has a wilderness scene on their heelcaps. I visited them years ago in rural Vermont where they have been building beautiful guitars for 40 years. My heelcaps, on the other hand, match the back’s wood and purfling to create continuity between the neck and body. I laminate thin Ebony and Maple veneers with Ziricote and glue them to the heel with a single clamp.
I leave slight overhangs around the perimeter of the heelcap and they will be sanded even with the heel after the glue dries.
After the sanding is finished, the neck is smooth all the way to the end of the heel.
One last task with the neck – the headstock. I mentioned the angling of the string channels in the slots of the headstock. I finished sanding them using sandpaper wrapped around dowels and now the wood veneers are exposed and are elegant.
During the building of a guitar, it is not unusual for the body to experience scratches, scrapes, and nicks. This is especially true with softwoods like the Cedar top. I use a magnifying glass and bright light to go over every inch of the guitar before the final sanding.
After the body dries completely from the steam and sawdust filling, I do the final sanding using 220, 320, and 400 grit sandpaper.
Now back to the neck. Dan’s hands are not large (but they are very fine hands) so we need to shape the neck for comfort and maximum playability for him. We already have a shorter scale length so the distance between frets will be shorter than a larger scale instrument. I have elected to shape the neck similar to a James Goodall Grand Concert model. It is similar to a Taylor neck – I have used both templates and I really think Dan’s fingerstyle guitar suits the Goodall best.
My approach to carving the neck is using facets – carving to lines to eventually arrive at a “C” shaped neck. I first measure the neck blank width and depth and plot it on paper. I then use a compass to draw the “C” within the dimensions. I draw intersecting lines and measure from the center, ends, and top and then I transfer these dimensions to create facet lines on the neck.
This process is repeated until there is a rounding of the neck. This hand plane removes the most wood and it is only used to “hog off” the initial facet.
I then use my neck template to start comparing to the shape at the first and tenth frets.
The 80 grit paper and the back-and-forth sanding motion works the wood to the template shape.
When the initial shaping is accomplished, it is time to check the neck angle and orintation and to glue on the heel cap. First I need to finish the headstock. The bottoms of the slots in the headstock need to be angled toward the fretboard so the strings have a path to the tuners.
I wrap 100 grit sandpaper around a 3/8″ dowel and work the angle until completed. Pictures to follow in the next post.
After the binding is installed and the final sanding is started, it is tradition to check the movement of the top to “predict” how responsive it will be. When my father was alive, he looked forward to holding the match in front of the soundhole while I tapped on the top where the bridge will be. Legend has it if the match is blown out by the air within the first two or three taps then the top is sufficiently responsive and will produce beautiful, complex overtones. I have passed the match-holding tradition to my youngest son Eric (who just graduated from Notre Dame). During the process he was Skyping his friend Shelly who happened to be in Mexico and could witness the process.
The match was blown out on the first tap – we have a very responsive top!
In preparation for the topcoat finish, final sanding of the top, back and sides is accomplished in two phases. The first phase is to sand the binding even with all sides and I use a scraper first followed by a 100 grit sanding block. I then sand the backs and sides with a 150 grit sanding block. I use 220 on the top.
I now switch from woodwork to metalwork to install and dress the fretwire. I have an arsenal of specialy tools to assist in this phase. A bound fretboard like Dan’s takes over twice the effort to fret because the fretwire does not extend to each end of the fretboard like it does in an unbound board. The part of the fretwire that is installed in the fret kerfs is called the tang. The tang must be cut to the total width of the opening and then the crown of the fretwire must extend to the ends of the fretboard, overhanging the binding.
The fretboard was radiused 14 degrees so the fretwire should also follow that radius. I built a little jig that gently bends the fretwire.
The fretboard was radiused 14 degrees so the fretwire should also follow that radius. I built a little jig that gentlly bends the fretwire.
I cut the fretwire to span the first fret kerf and nip off the tang to fit in the kerf.
I then run a bead of luthier’s glue on the bottom of the tang. The glue does not actually help much as an adhesive but the moisture in the glue slightly swells the Ebony in the kerf to help grip the tang.
I insert the fretwire in the kerf and use the copper end of the fret hammer to pound in the tang.
I repeat this process until all the frets are installed. Then I use the fret cutter to snip off the ends of each wire.
After the glue has had a day to set, I then angle the fretwire in about 35 degrees toward the center of the fretboard. I use a special fret file for this.
In order for the strings to intone correctly, the frets must be perfectly level or else two adjacent frets will play the same note or there will be excessive buzzing. I use the fret leveling file to run across the tops of the frets.
I use a fret rocker to test the middle fret between the two adjacent frets. If it rocks even slightly I need to file down the middle fret. I do this across the entire fret. This process takes between one and two hours.
Many of the frets are no longer crowned so I must re-crown them. I have two crowning files that re-shape the top of the fretwire.
All this filing has left the edges rough and sharp. I don’t think Dan will want to run his talented fingers over sharp frets to I must dress the frets. I have chosen a nice polo shirt and khaki pants for this. OK, OK – I’ll stop with the stupid jokes and stick to guitar building.
After the fret ends are smooth, I run sandpaper up and down the frets to remove the file marks and to polish the frets. I start with 150 grit, move to 220, 320, 400, 600, and end with 800. The frets look like new!