Introduction: Building an Acoustic Guitar
As with any new project I've attempted, each step along the way is unfamiliar to me and some steps are deserving of my apprehension, while others equally as worrisome turned out to be a piece of cake. This project is a learning experience. How well the guitar will play and sound, I will not know until some time after I have finished.
For more detail on the build and difficulty I experienced see:
For photos of my two most recent guitars AND a description of the material costs you can expect IF you try a project like this:
Step 1: Getting Started
The first task was to decide what to use for reference material. I chose a book entitled " Building Your Own Acoustic Guitar: Complete Instructions and Full-Size Plans" by Jonathan Kinkead. I selected that book after reading about a few others on Amazon but my purchase was rather impulsive. It walks the reader through building a style of guitar similar to the Martin OM(orchestra model), which is a smaller guitar with a more body. The book includes lots of photos and even full scale plans, which are handy, but, while sufficient, lacks information I need.
The next task, which was the source of some consternation, was to select the wood to use for the body of the guitar. The book recommends specific wood, Sitka Spruce for the top and Rosewood for the back and sides. I, being the rebel, didn't want to do that, so I chose different wood.
I chose Western Red "Sinker" Cedar for the top (or sound board as it is called) and Claro Walnut for the sides and back. I purchased both from suppliers on E-bay. The Cedar top is supposed to create a "warm" sound. I don't really know what that means but that didn't seem like a bad thing to me. "Sinker" means it came from a Cedar log salvaged from a lake or river bottom and is therefore, probably pretty old. That idea appealed to me. Claro Walnut is highly figured walnut from the American Northwest.
Step 2: Making the Wood the "proper" Thickness
Time to dive in. The sound board and back wood arrived, each in two pieces that needed to be joined together. It is desirable to minimize the visibility of the glue line, so the edge of the wood needed to be trimmed flat and even to make them fit tightly together. My book recommended using a block plane.
I used sand paper, clamped to a flat surface with a long right angle block of wood also clamped to that surface to complete this job. My thought was that if I ran the edge of each piece of wood back and forth on the sand paper and along the block of wood, the edge would end up flat.
To clamp the wood pieces together I placed two long and square pieces of wood like a frame, on my flat surface(a 2X4 foot piece of 3/4" MDL) and held them in place with clamps. Once the glue was set after a day, it was time to make the sound board and back the proper thickness.
I decided I could get the wood to the proper thickness by hand sanding. My book suggested 2.5mm for the top and 3mm for the bottom. With rubber cement adhesive, I attached a piece of 80 grit sand paper on a flat piece of 8X10 inch plywood onto which I fastened a crude handle. I placed the wood to be sanded loosely between two long blocks of wood clamped on to my flat surface. At the ends of the wood, to keep it in place while I pushed and pulled the sanding block, I clamped a thin piece of wood on one end and aluminum yard stick on the other.
I used the same process to get the side wood to the "proper" thickness.
I used the plans that came with the book to trace half of the body shape onto a piece of cardboard then transferred that to a small sheet of 1/8 inch thick clear polycarbonate plastic to use as a template. I used the template to trace the shape of the guitar body on the wood.
Next I trimmed the wood to shape within a 1/4" of the line, with a band saw.
Step 3: Sound Hole, Rosette, Back Inlay Strip and Bracing
Time to cut a hole in the sound board. I searched online blogs and found how other people accomplished this. It seemed as if a high speed rotary tool and router bit would give me the best results. I looked at Dremel tools but after reading reviews I purchased the Black and Decker RTX-B at about 1/3 the cost of a Dremel.
I overlaid the paper plans on the top cedar sound board and marked the sound hole center by pressing a tack into the wood. Then I drilled a pilot hole slightly larger than the diameter of the circle cutter pivot pin. I did the same on a scrap piece of plywood and set up the attachment for the inside diameter of the rosewood and abalone rosette I purchased also from Amazon for $7.
After carving the inside diameter circle in the scrap wood I checked the depth and diameter and marked the circle cutter tool brace arm with a permanent marker. Then I cut the outside diameter and all the material in between it and the inside diameter, checked the fit of the inlay, marked the brace arm. I did the same for the sound hole diameter on the scrap wood. I now had 3 marks on the tool for the adjustments. Starting with the inside diameter, then the outside, then removing the in between wood, then cutting the sound hole, the top was ready to glue in the rosette.
On the back, often there is a decorative strip inlayed to cover the seam. I thought I would inlay a strip of curly maple cut from the scrap pieces included as packing in order of the back and side wood. I wanted to put the thin black and white accent prufling strips along each side of the maple strip. I routed a channel for the maple strip. I decided to make my own wider accent strips from Mulberry that I cut from my own trees a few years ago. It is a yellowish color.
Inside of an acoustic guitar is bracing for the top and bottom. I believe this is just to make the thin wood stronger but positioning of the bracing, its thickness and properties of the wood used can affect the sound of the guitar. I decided to use cedar, maybe this would add to the "warmth of the sound". I purchased a piece of 5/4 deck planking that looked like it had most of the grain running longitudinally. Then I followed the bracing shown in the plans to cut the pieces out of the plank with my table saw, trying to keep the grain longitudinal.
I traced out the bracing pattern on the back side of the top and bottom body pieces. Before gluing down the bracing I "strategically" removed some material, with the mini-drum sander bit for my rotary tool to allow the strength to remain but eliminate some of the sound deadening bulk. Clamping an gluing the bracing on the top required a menagerie of creative clamping methods and extensions and wedges. The back requires a slightly different menagerie since the bracing was slightly curved.
Step 4: Making the Mold and Bending the Sides
A fixture or mold is needed to hold the top, back and sides in place while gluing them together. The method I chose was to use two sheets of plywood separated by spacers. I used a 3/4", 2 foot by 4 foot project panel from Home Depot and scrap pieces of 2X4 cut to size for spacers. This gave me a 24" X 24" mold, which was sliced in half then bolted together again with tab extensions.
Now to bending the sides. I read lots online about this step, went back and forth on my decision before I actually did it. I decided, finally, to use a bending fixture made from the scrap pieces cut out of the mold plywood, which, just happened to be, the shape of the guitar body. I build the fixture with 2 pieces of the shaped plywood separated by spacers. Then I covered the bending surface with aluminum flashing. I also added a rounded piece of wood with eye-bolts and wing nuts, to help hold the side wood against the mold at the deeply curved waist in the body. To create the steam I built a small square box with a hole in it for steam to enter. Steam was created using an old coffee pot, with a small piece of copper pipe replacing the glass bubbler, which sat on a small camp stove.
Once the side to be bent was in the steam box for several minutes and there was an abundance of steam escaping from its joints, I slowly clamped the wood onto the mold. It bent easily. I was pleased as well as relieved. The next day I placed the first side in the mold fixture and clamped it in, then moved on to the next side.
The next step was to trim the side to length and glue them together with the neck block and bottom block. The neck block was first trimmed to size. It came with the maple neck I purchased. The bottom block came from a short length of 3/4" maple I purchase at Home Depot. These four pieces were glued then clamped in the mold. I now had something resembling a guitar body. The sides needed to be tapered with a gradual curve from the bottom towards the neck block, which is why it was trimmed earlier. I made a template from 1/8" hard board, with tapered spacers glued on, to fit around the outside of the body. I put pegs in holes on the inside of the mold to hold the sides up above the top surface, level with the template at one end and above the template on the neck end. Then I used a tiny block plane to remove side material to match the taper.
Step 5: Kerfing Strips, Tail Piece Inlay and Fitting the Neck
Kerfing strips a are long, slotted strips of wood, usually Mahonany or Basswood, that when glued onto the inside edges of the body sides, add more strength and rigidity. I could have made my own but I decided to purchase them from Stewart-MacDonald since they were relatively inexpensive($3.20 a piece for a 15 inch strip, I needed four). First I soaked the strips in water for several hours to make them more flexible. I then applied a generous bead of Titebond glue and placed them along the edges of one side of the body with about 1mm protruding. They were held in place with clothes pins clamped on about every 1/2 inch or so. After the glue dried, I usually give it a day, I flipped the body and did the same to the other side. The next day I trimmed the strips that protruded slightly so they were flat and flush with the edges of the sides. I also added some small vertical bracing strips to the side. Looked pretty good,
I purchased a pre-carved neck from Penta Guitar Works on e-bay. This guy has several styles, wood selections and scales available. I was impressed with the neck I received. It was a bolt on neck in Flame Maple (what I always call curly maple), included an routed truss rod channel, neck mounting block and large peg head suitable for almost any design.
Now I had to figure out how to attach the neck. I found a nice description here: http://www.liutaiomottola.com/construction/Bolton...
I ordered the exact parts(hex head bolts, washers, and inserts) described, from McMaster-Carr. I was ready to go, but this step was intimidating also because I needed to be precise. Not my forte. First, I cut away side panel wood covering the neck block mortise and dry fit the neck. A slight amount of sanding was required. Then I marked the position for two holes on the tenon of the neck. Then I marked the neck block, which was now attached to the body to line up with the holes I marked on the neck. I used a ruler.
I did have to use my small drill press with the base turned backwards to get things to lined up, and to ensure my holes were square with the neck. This also required some creative clamping methods. I then drilled clearance holes for the bolts in the neck block and threaded the inserts into the holes in the neck tenon to about 1/16" below the surface.
Step 6: Truss Rod and Tail Piece
The truss rod is a long steel rod embedded in the neck that can be adjusted to increase or decrease tension on the neck which will move the stings closer or further away from the frets. If they are too close they can buzz while the instrument being played. If they are too far away it becomes difficult to play.
I chose a basic Gibson style rod with the adjustment nut meant to be at the peg head, and covered with a thin plate. This is common with electric guitars. My neck had a well in the peg head carved for this. The rod came longer than I need, threaded on one end and with one brass adjustment nut and one cylindrical steel nut. The rod was meant to be cut to length and threaded. The cylindrical nut was meant to be inlet into the upper end of the neck. Not what I did. I cut the rod and threaded it with a 10-32 thread and placed the cylindrical nut inside the guitar behind the neck block. My bracing inside the body was cut with a hole, designed for adjusting the tension from inside the body.
This will be added when I permanently mount the neck.
The tail end of the body where the sides meet creating a seam, is often covered with an inlayed strip of wood. I decided to use the yellowish Mulberry wood. I used my B&D rotary tool with a 1/8" router bit to carve an inlay channel. I used wooden strips as guides clamped to the body to get the triangular shape I wanted.
Step 7: Assembling the Body, Binding the Body
Now comes the time to assemble the body, in other words glue the top and bottom to the sides. Both the top and bottom should be about 1/4" wider all the way around than the width sides. I started with the top. Laying the body sides onto the back of the soundboard and aligning its center line, I marked the places where the bracing came in contact with the kerfing. Then I marked the bracing where it extended outside of the body. I then cut away the bracing at the marks so it would fit inside of the guitar body and also cut away the kerfing where the bracing would contact it. I very carefully used my B&D rotary tool with a 1/8" router bit to gouge out clearance for the bracing ends. I used an Exacto knife to cut the bracing ends away.
A generous bead of Titebond was squeezed out onto the top to the kerfing and the sound board was pressed on, trying to keep the centerlines aligned. Creative clamping methods were applied
I used the same process attaching the back, but this is even more of a blind fit and it has more of a curve than the soundboard. Instead of fussing with clamps I thought I came up with a different way to clamp the back on. I marked the outline of the body on a piece of 1/4" plywood and cut it about 1/2" inside of the line. Next I drilled clearance holes for 2-1/2" long drywall screws about an 2 inches apart all the way around it about an inch outside the line. Then I marked the holes on the mold surface and drilled smaller holes to drive the screws into. I glued on a piece of guitar shaped hardboard left over from my side tapering template. After applying glue and lining things up the best I could I screwed down my improvised clamping board.
Step 8: Binding the Body
Next came a step that involved the router and potential damage to all my work so far if I did not proceed carefully. I needed to cut a channel along the edges of the soundboard and back for binding strips. I think these protect the edge of the guitar from dents and also add some decoration. I chose to use curly maple hardwood strips, plastic probably would have been easier to work with but I'm a big curly maple fan. In keeping with what has become the basic, plain Jane theme of my guitar, I chose not to put the thin prurfling accent striping on the back. I put them only on the front, which meant I needed a two step channel.
First I had to trim the overlap left on the top and back. I decided to cut most off with a band saw then finish with a flush cut router bit. I ended up borrowing a hand held trim router.
The maple strips had been soaking in water in the bath tub all night and now I was ready to glue them in. I started with the simpler(no accent stripe) back. Applying a bead of glue to the channel and I pressed in the maple strip and held it in place with tape, dabbing off excess glue as I went. I added more tape to areas that looked like they needed it. Once that was done I flipped over the body and started on the front.
Step 9: Preparing the Neck
The butt of the neck extended past the body so it needed to be trimmed. I thought I'd make a decorative cap from 3 contrasting pieces of wood, Mulberry, KOA, and Maple. I cut the neck butt to length then traced its shape onto the 3 pieces of wood.
Next, I laid out the locations of the tuning pegs on the peg head. I made a paper template from my plans and checked the distance of the hole locations from the side of the peg head with a ruler. Then I drilled small pilot holes. The peg head was extra long so I cut it shorter and added a bit of decorative contour top the top.
After some fine tuning, pun intended, by removing a little wood with sandpaper to make the neck fit as flush as possible to the body, I removed it and applied some stain. I use Behlen American Walnut Solar-Lux NGR(non grain raising) stain. I first did a little finish sanding with 240 grit until I was tired of sanding, the bushed on one coat of stain, leaving the fret board area unstained. After it dried I sanded again with 240 grit and brushed on another coat. When the 2nd coat dried I rubbed down the neck with steel wool. I jumped the gun a little in staining the neck now. I had to re-sand and stain when I created the inlay (next). I also found that when I test fit the nut I had purchased the neck was a tad too wide. More re-sanding and re-staining.
Once satisfied with the appearance I drilled out the pilot holes to accept the Gotoh Chrome machine heads. I measured their diameter with micrometers and found a drill bit close to the same size, which was 3/8" I drilled a test hole first in scrap wood to make sure it would not be to large. I used a reamer tool to make the tuners fit snuggly into the holes.
Step 10: Peg Head Inlay
I had some room left at the top of the peg head. Most guitars have the makers logo or some custom guitars have the makers name.
First I drew it out on paper then colored in the different areas of the inlay. I liked it so I cut out each little piece and glued it to some scrap wood that happened to be all similar in thickness. Once the glue dried I cut out each piece on my band saw, then sanded to the “precise” shape. I laid out the pieces on a sheet of card stock then glued them in place, making sure to use plenty of glue where the pieces met.
I cut out a rectangle around the inlay then glued it to a block of wood. My intention was to sand down the inlay so that all the different pieces were the same thickness. I rubbed the block with the inlay attached on my large sanding block that was held in a vise.
I now had the inlay shaped like a star, or cross if you prefer, and I traced its outline on the peg head. Next I used a small chisel to cut, and scrape and finesse the wood out of the peg head where the inlay would go. After many trial fits and more scraping I finally glued the inlay in place and slightly above the surface of the peg head. I mixed some graphite powder with Titebond glue then clamped the inlay in place. I sanded it level with the peg head surface then re-stained the areas of the peg had that need it. I finished it off with steel wool.
Step 11: Fret Board
Building the fret board became a time consuming task. I needed to make a few decisions before I started. Did I want to buy a blank piece of rosewood, cut the slots and radius the surface myself or purchase a pre-slotted board with a radius? I decided to purchase. By the way the radius on the surface is supposed to make the guitar a little easier to play, so a flat fret board probably would have worked. Second decision, did I want to put and edge binding on the board? Yes, I think it looks better, but makes inserting the fret wire a little more difficult. Third decision, did I want to attach the fret board to the neck before or after installing the fret wires. I chose after, because I wanted to use my drill press as a McGuivered fret wire press and I need the board to be flat.
The first thing to do was to cut the fret board to match the neck profile. I laid it on the neck leaving a little space for the nut, then clamped it to the neck, just eye balling the fret slots for perpendicularity. I then traced the neck on the back of the board and also the sound hole arc. I decided to make the bottom of the fret board near the sound hole have a slight arc. I guess that was a fourth decision. I then cut the fret board slight outside the marks with a bands saw. I used a small hand plane to clean up the edges.
Next I cut some maple for the side binding out of some scrap that came with my guitar back and side wood order. It was cut slightly wider than the thickness of the fret board. I then marked its thickness on the back of the fret board and use a plane to remove additional rosewood to make room for the binding. I thought of using a trim router to do this but decided to go with caution and did it using a plane and sandpaper. The maple binding was then glued and clamped to the fret board, sides first, then the little curved piece at the end of the board near the sound hole. I had to resort to some more creative clamping. After the glue set I leveled the binding using sand paper.
I used a ¼” Fortsener bit to make relief for the Abalone fret dots. I tested the fit of the dot in a drilled out cavity first, then just drilled out each hole with my drill press to a depth that left a bit of the dot protruding. I drilled then tested, then drilled more, and tested, then more if needed for each dot. I glued the dots in place with super glue. I used the same method for the side dots except I used an ordinary drill bit and just estimated the depth I needed, then sanded them flush once the super glue set.
I made a tool to use in my drill press for a method to press in the fret wire. It was just a ¾” wide piece of scrap Ash with a ¼” bolt on one side, head cut off of course. I marked a 16 inch radius curve on the little piece of Ash by using the 16” radius sanding block I purchase from Stewart-MacDonald Luthier supply. Then I use the drum sanding bit to take off the wood under the line. For each piece of fret wire I cut the length with a 1/8” to spare on each side of the fret board. Then with a dremel grinder and small file I removed the barbed portion on the underside of the wire so that the edges would lay over the side binding. Working on 2 fret slots at I time I use a small square file to give each slot a slight bevel then tapped the wire down with a hammer and block of wood just enough to hold it in place. I finished pressing it in with my rigged drill press. I also used a small piece of aluminum flashing between the wood pressing jig and the fret wire.
Once all the frets were pressed in, I trimmed the edges with wire cutters then filed them flush with the fret board binding. Since the frets are only held in the slots by the barbs, there is a slight gap left in the slot. I wicked super glue into the slots using whip tips which I purchased from Stew-Mac. These handy little tips slide right onto the bottle tip.
Step 12: Attaching the Fret Board
First the slot that contains the truss rod needs to be filled. I use strip of oak, because I had a thin piece laying around. I routed a cove on one side and filled it with silicone sealant. Just a small bead, to keep the steel rod from vibrating. I the smeared glue on the side of the strip and clamped it in place. Once the glue was dry I planed and sanded the oak strip flush with the neck surface.
I smeared glue on the neck surface and a little on the sound board (top) where the fret board would lay then clamped down the neck, wiping off the squeezed out glue with a wet paper towel as I went. I needed to use a C-clamp to attach the fret board to the body, since there is a slight bend required due to the set back angle of the neck. I hope the strings will clear the frets in this area.
Step 13: Truss Rod Adjuster Cover
Like I mentioned earlier, the tension adjustment for the truss rod on my guitar is located on the peg head....so it needs a cover. I made one from the scrap wood I had around by routing a shallow channel in the base wood and filling it with contrasting wood. It is a simple shape but a bit over sized. I had some difficulty making the adjuster nut flush or below the surface so the the cover would lay flat.
Step 14: Pick Guard
I decided to take a little side trip so to speak, and made a pick guard. I had a piece of scrap walnut with interesting figure in the grain so I used that. I first made a paper template and set it on the guitar to see how it looked. Next I sanded the scrap walnut to about 1/16" in thickness, it was already pretty close. Then I traced the shape of the paper template onto the wood and cut it out with a band saw. With a little sanding, the rough edges disppeared and a little more sanding made it fit the sound hole circle. I will attach it after finishing.
Step 15: Attaching the Bridge
Attaching the bridge is probably one of the most important steps to get right in the entire build. The distance from the nut has to be precise to get the proper intonation. The centering has to be accurate so that the strings are spread evenly across the fret board.
I purchased a premade rosewood bridge, pins and saddle on Amazon. First I laid the bridge on the sound board with the saddle in place and held a string from the nut to the saddle to check the action height (distance the string set above the frets)
I first placed a piece of blue painters tape on the sound board where the bridge would sit, and laid the bridge on top of it. Very carefully I measured the distance from the nut to the edge of the bridge. I need 25.4 inches (25-3/8 = 25.375). I used a length of braided fishing line strung from the nut to the bridge pin of the low E and high e strings to find the centering. Then I taped it down and cut the underneath tape to shape for masking the wood during the lacquer application. I was ready to apply the finish,
Step 16: Finishing
I decided to use Behlen stringed instrument lacquer in aerosol spray cans. It was recommended to apply at low humidity and temperatures between 60 and 80F. The fumes from this stuff are hazardous and very volatile. I used a respirator mask and goggles when applying. Since this it was February when I came to this step I built a small spray booth in my garage from spare plywood and plastic sheeting in which I placed an electric heater and light. It is also recommended that 10 coats of lacquer is applied, with light sanding between each coat. I applied 4 coats of Behlen vinyl sealer first with light sanding after the first two coats. I then applied 7 coats of lacquer with light sanding between every 3 coats. I waited a half hour between coats and a day between every three coats before sanding.
After letting the finish harden for a week I wet sanded the top with 1000 grit paper and water with a little Murphys Oil soap added to the water the paper soaked in overnight. I only did this to the top. I preferred an more satin finish for the sides and back so I just lightly rubbed those surfaces with steel wool. After wiping the water from the top I used Turtle wax rubbing compound from an auto supply store to polish the finish. I polished by hand with a cotton rag then again later with a wool buffing bad in a drill. The finish looked OK but, sort of crude. I was shooting for that Willie Nelson look.
Step 17: Back to Attaching the Bridge
When I laid the bridge over the masking tape I rechecked the distance from the nut, but this time I considered the compensation. The saddle is set at an angle for compensation and it’s distance from the nut should be 2mm longer than the scale length(25.4) on the high e string and 6mm on the low E string.
I made the adjustments measuring from the nut to the saddle, then drilled 3/16 holes in. holes for the end pins to hold it in place while I glued it down. I carved the shape of the bridge top using a drill press sanding drum in a small block of wood, and drilled clearance holes for the pins. I used this with a little padding to help clamp the bridge down during gluing. I straddled the guitar body with a longer piece of wood and clamped the edges to the guitar body, pressing down on the bridge block.
Step 18: Final Steps
I oiled the fret board with Old English Lemon oil, 2 coats, and one coat on the bridge, then rubbed off the excess with paper towel. I attached the pick guard with double sided 3M adhesive. I installed the truss rod end cover.
Now comes the moment of truth, stringing the guitar and hoping it sounds ok. I almost didn’t want to do this because I thought maybe it would sound dull. I used Martin medium strings. After I tuned it an strummed it I was amazed at how it sounded. It had a rich sound(kind of warm an bright I guess) with lots of sustain. I checked all the stings down to the body, no buzzing. This guitar may be a little rough and ugly but is sounds beautiful to me.
I am happy.
The photos show my commercially made guitar and my home made guitar
Be sure to vist
to read about the mistakes I made.
Step 19: Sound Clip
recorded with audacity on my laptop, added a little reverb, and a raw sound file from the voice recorder on my phone.