Jim is a retired software/electrical engineer who enjoys the outdoors. He likes to challenge himself with creative projects at home.
There is plenty of information available online about how to build an acoustic guitar, so I thought I'd focus on the challenges I encountered as I built my own. As with any new project I've attempted, each step along the way is unfamiliar to me. Some turned out to be just as difficult as I thought they'd be, while others, equally worrisome, were a piece of cake.
This project was a learning experience. How will the guitar play and sound? I will not know until some time after I have finished. Will I use the experience I've gained to build another? Not sure, but after I built my first wooden canoe, I built another and two kayaks, so I'll just say . . . maybe.
My first task was to choose reference material. I picked a book titled Build Your Own Acoustic Guitar: Complete Instructions and Full-Size Plans by Jonathan Kinkead, but my purchase was rather impulsive. This author walks the reader through how to build a guitar similar to the Martin OM (orchestra model), which is smaller than the common dreadnought, with a shallower body. The book includes lots of photos and even full scale plans, which are handy, but it lacked information I needed.
For instance, the author thoroughly describes how to complete a certain step but does not go into the "why" so much. He doesn't explore alternate methods too much either. I'm a little rebellious and don't always have the tools I need, so providing explanation and alternatives are two things I would have liked to see in the book.
One other difficulty: The author is British. They way he describes some things, and the words he uses, make it a bit hard to interpret at times. The dimensions are all in metric and English, however the English dimensions are in very fine, hard-to-read, print.
All that said, the book is sufficient and I did use it, along with online resources including blogs and "how-to" information provided by Stewart-McDonald and other luthier supply sources.
Materials I Used
I go into more detail about the materials I used, and how much they cost, in another article. But briefly, here's what I used in this guitar build:
- different types of wood (see below)
- wood glue
- lemon oil
- a rotary tool and router
- a circle cutter
17 Steps to Making an Acoustic Guitar
- Selecting the Wood
- Trimming and Fitting the Wood Pieces
- Sound hole, Rosette, and Back Inlay Strip
- Assembling the Bracing
- Making the Mold and Bending the Sides
- Making the Kerfing Strips and Tail Piece Inlay and Fitting the Neck
- Assembling and Binding the Body
- Preparing the Neck
- Making the Peg Head Inlay
- Making the Fret Board
- Attaching the Fret Board
- Making the Truss Rod Adjuster Cover
- Making the Pick Guard
- Attaching the Bridge
- Attaching the Bridge II
- Final Steps
1. Selecting the Wood
Selecting the wood to use for the body was the source of some consternation. The book recommends specific wood: Sitka spruce for the top and rosewood for the back and sides. Being the rebel, I didn't want to do that, so I chose different wood. There is a lot written about different tone woods and how they affect the sound of the guitar. Deviation from the normal popular varieties of tone woods is heresy to some makers, while others consider it a sign of creativity. Once you think you want to deviate from the norm, deciding what wood to used can be a daunting task. Cost was a big consideration for me, as some woods can be very expensive.
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 eBay. The cedar top is supposed to create a "warm" sound. I don't really know what that means, but it 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. Walnut in general is supposed to be similar to rosewood or mahogany. It is said to create a bright sound. I don't know what that means, but "warm and bright" sounds pretty good to me. I also like the rich, dark color of walnut and the fact that the wood I chose is not exotic or imported.
I paid about $30 for the cedar top and about $75 for the walnut sides and back. Depending on the type and grade of wood (A to AAAA) you can expect to pay from about $25 to a few hundred for the top and from about $60 to several hundred for the sides and back.
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I felt satisfied that I had started the project and made some decisions, which is sometimes the most difficult part of starting any new project. So at this point I had wood for the top, back, and sides.
2. Trimming and Fitting the Wood Pieces
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 have a few block planes, but they are dull and I've never really been very skilled at using them for finer, detailed work. Remove a lot of wood, yes, okay, I'm good with that, but making edges perfectly flat—not in my skill set.
I clamped sand paper to a flat surface with a long right-angle block of wood (which was 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. So I thought.
The problem in drawing the wood back and forth is that I exerted uneven pressure on the wood. When I placed the edges of my wood pieces together, and held them up to the light, I saw light coming though the joint. You're not supposed to, if you have a perfect joint . . . so they say.
I continued this process but still could not make the joint "perfect". I resorted to sanding parts of the joint surfaces by hand until I got it good enough. I still saw faint light through parts of the joint, but I knew I would not get it any better by continuing.
To clamp the wood pieces together, I placed two long and square pieces of wood (2 x 4 foot, 3/4" thick) on my flat surface and held them in place with clamps. The distance between these was slightly less than the final distance across the two pieces being joined. When the edges of each piece of wood were placed against the frame and then pushed down at the middle joint, there was sufficient pressure to hold them and squeeze out some of the Titebond Original glue. I placed some weight on top to the wood to hold it down.
Once the glue had set for a day, it was time to make the sound board and back the proper thickness. My book suggested 2.5mm for the top and 3mm for the bottom, but it didn't tell me the consequences, difficulties, or disadvantages of leaving them thicker or making them thinner.
The book suggested that the way to get the wood to the proper thickness was to use a thickness planer or drum sander—two power tools I do not possess. It also said I could use a hand plane. That was something I was not about to try because . . . well you know about my skill with a block plane, or lack thereof, and all my planes were too dull, and I didn't want to sharpen them.
I decided to try hand sanding. With rubber cement adhesive, I attached a piece of 80 grit sandpaper on a flat piece of 8 x 10 inch plywood, onto which I fastened a crude handle. I placed the wood 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 an aluminum yardstick on the other.
I began to run my homemade sanding block back and forth across the wood, flipping the wood over end-to-end occasionally to try and keep things uniform. I had to remove about 2 to 3mm of thickness. It took a long time. The problem was that in drawing the sanding block back and forth, I exerted uneven pressure, resulting in some spots being slightly thinner than others.
It wasn't terrible, however, and when I got close to the final dimensions, I quit. I figured I'd leave some thickness for finish sanding.
I used the same process to get the side wood to the proper thickness. I tried for less than 2 mm since the sides needed bending and thin wood is easier to bend.
I used the plans that came with the book to trace half of the body shape onto a piece of cardboard and then transferred that to a small sheet of 1/8 inch thick clear polycarbonate plastic to use as a template. Finding the glue joint in the top and bottom pieces of wood, I used the template to trace the shape of the guitar body on the wood. Good thing the glue joint was not so perfect that I could not find the center line. Next, I trimmed the wood to shape within a 1/4" of the line with a band saw.
One more step complete!
My apprehension was beginning to build, however, thinking about the next steps. For those, if I made an error too big, there would be no way to fix it.
3. Sound Hole, Rosette, and Back Inlay Strip
Now things were getting serious. Time to cut a hole in the soundboard. I searched blogs and found out 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.
To my purchase from Amazon, I added the Dremel circle cutter attachment, which is compatible with the B&D rotary tool.
Cutting the Sound Hole
I overlaid the paper plans on top of the cedar soundboard 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 had purchased (also from Amazon). The book suggested inlaying thin purfling (decorative) strips for the rosette, but I liked the looks of this one and thought it may be easier to inlay.
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, and marked the brace arm. I did the same for the soundhole diameter on the scrap wood. I now had three marks on the tool for the adjustments.
I started with the inside diameter, then the outside, then removed the in-between wood, and then cut the sound hole. The top was ready for the rosette. As it turned out, this was NOT the best way to do it. I was slightly off on the brace arm marks, resulting in an outside diameter for the inlay which was slightly too large. I should have transferred the cuts to the sound board once I got the jig set up on scrap wood before moving it.
Filling in Around the Rosette
This was the first of what was to be many mistakes. I added a fill around the rosette made up of super glue and walnut sanding dust, of which I had plenty. I dabbed super glue with the head of a pin, dropped a pinch of sanding dust on top, and then sanded it down immediately with 240 grit sand paper. I repeated the process until the gap was filled, but the fill still looked a little coarse.
Adding the Back Inlay
Often there is a decorative strip inlayed on the back to cover the seam. I thought I would inlay a strip of curly maple cut from the scrap pieces included as packing with the order of back and side wood. I wanted to put thin, black-and-white accent prufling strips along each side of the maple strip, so I routed a channel for the maple strip. Perfect fit, looking good. Then I widened the channel for the accent strips. Success again, I thought.
Here was the problem: The back was about 2.5 - 3mm thick and the strips were about 2mm + wide, so the inlay channel was shallow. The narrow accent strips just wouldn't stay in the shallow channel. Now I had a channel that was too wide, so I decided to make my own, wider accent strips from a mulberry that I cut a few years ago. It was a yellowish color.
While widening the channel for the new strips I accidentally gouged the maple strip that I'd already glued in, but I kept on. Once the new yellow mulberry strips were glued in, I leveled them and sanded the back, accidentally sanding completely thorough the maple and mulberry strips at one end. I was tempted to end the project then and there, but I filled the gouge and decided maybe to put a decal on the back over the missing portion of the accent strips . . . or just leave it for character.
Inside an acoustic guitar there is bracing for the top and bottom. I believe this is just to make the thin wood stronger, but the positioning of the bracing, its thickness, and the properties of the wood can affect the sound.
My book called for Sitka spruce bracing. I didn't have Sitka spruce and I wasn't going to purchase pre-cut Sitka spruce bracing, so I decide 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. Sounds like I know what I'm doing, right? I don't.
The book also suggests curving the bracing to give the top and back a slight arch. Now it didn't suggest a radius for that arch, but it did say you could avoid this with the top and just make it flat, which I did.
I did add a slight radius to the bottom bracing by making a template on a piece thin wood. I placed a metal ruler between a finishing nail driven into my flat work board for the center, then one about nine inches to either end of the longest brace and 1/4" below the center nail. Next, I flexed the metal ruler between the nails, traced the line onto the template wood, and cut it on my band saw to transfer to the back bracing. I sanded the bracing to the curved lines with the drum sanding bit in my drill press.
Clamping and gluing the bracing on the top required an array of creative clamping methods, extensions, and wedges. The back required slightly different methods, since the bracing was slightly curved. All seemed to work out however, but I did end up removing more of the bracing bulk before gluing the whole body together, as I fondled and tapped on the soundboard, listening for any hint of resonance.
Okay, making some progress. Wondering if the cedar bracing will work out and if the wood is thin enough to make the body "sing."
5. Making the Mold and Bending the Sides
Making the Mold
A fixture, or mold, is needed to hold the top, back, and sides in place while they are glued together. The book I followed suggests two methods of constructing the mold: One is to cut the shape of the body into several small, thick sheets of plywood and glue them together, resulting in a heavy, 4-inch thick, fixture. The other is to use two sheets of plywood separated by spacers. This was the method I chose. It gave me the opportunity to use the Porter-Cable pneumatic finish nailer that my neighbor found in the garbage and gave to me in need of repair.
I used a 3/4", 2' x 4' project panel from Home Depot and scrap pieces of 2 x 4 cut to size for spacers. This gave me a 24" x 24" mold, which was sliced in half and then bolted together again with tab extensions. The guitar shape was a little uneven, but only slightly. It seemed to work out fine.
Bending the Sides
Now for bending the sides. I read that this can be a daunting step in any project, and indeed it was. It was suggested in the book, and in many blogs, to use a bending iron. This is basically a piece of tubing which is heated to several hundred degrees, over which the thin side wood can be bent to the desired shape in small incremental steps, using the shape in the mold as a guide to compare your bending progress.
First, any wood bending requires steam. This is achieved by soaking the wood for several hours in water and then applying heat. The disadvantages I saw with using a bending iron, although the traditional method, were:
- I didn't have one. I could make one. Several suggestions are available if you search online. Some seemed simple and clever while others, eh . . . I'm not so sure about. I could buy one for a couple hundred bucks. Ahhh, I don't think so.
- Making the shape exact seemed difficult with this method.
- The wood could easily get burnt, and so could I.
I read lots online about this step, went back and forth on my decision before I actually did it. I had bent some wood successfully when building my canoes and kayaks using a different method. Finally, I decided 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 two 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, that on a small camp stove. I read that when steaming walnut, sometimes the figuring in the wood becomes faded. I decided to do it anyway and even soaked the wood in water first.
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. It went well also. I clamped it into the mold and let them dry for a few days.
All was good . . . except when I removed the sides from the mold I found I had been too aggressive with the clamping and had slightly deformed one of the sides by causing a noticeable indentation from the wood. I tried re-wetting and clamping to smooth it out with only slight success.
Trimming and Gluing
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 (more on that later.) 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.
There were lots of opportunities to make irreversible errors here, but luckily the errors I made should only affect aesthetics, and not function. My dream of a beautiful, hand-crafted, high-end guitar was gradually diminishing into one a hand-made guitar that functioned and had lots of "character."
The lower image is of Willie Nelsons guitar "Trigger," by the way. It is a beat-up, autograph-covered Martin N-20 acoustic. At least I hope mine will sound okay and not end up as a merely decorative bunch of wood pieces glued together.
6. Kerfing Strips, Tail Piece Inlay, and Fitting the Neck
Kerfing strips are long, slotted strips of wood, usually mahonany or basswood, that add more strength and rigidity when glued onto the inside edges of the body's sides. 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. Then I 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 gave it a day and flipped the body, then 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 thought.
Kinkead's book has a chapter on making the neck and installing it. I glanced through this chapter and decided to do something different (not surprising.) I did not want to spend the time carving the neck and the dovetail joint it described, so I purchased a pre-carved neck from Penta Guitar Works on eBay. 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) and it included a 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 some nice instructions online.
I ordered the exact parts (hex head bolts, washers, and inserts) from McMaster-Carr. I was ready to go, but this step was intimidating because I needed to be precise. Not my forte.
First, I cut away the 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. I marked the neck block, which was now attached to the body to line up with the holes I had marked on the neck. I used a ruler and found a problem: The online instructions specified bolt lengths for a block without mortise. Mine had a mortise, so the bolts should have been shorter. I drilled the holes in the tenon deeper than specified. Problem solved! I did have to use my small drill press with the base turned backwards to get things to lined up and to ensure that 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. Time to try bolting on the neck. Perfect alignment. That almost never happens. Happy.
The truss rod is a long steel rod embedded in the neck that can be adjusted to increase or decrease tension on the neck to move the stings closer or further away from the frets. If they are too close, they may buzz while the instrument is being played. If they are too far away, playing becomes difficult.
I fretted over what to do (pun intended). There are many fancy, square dual rod selections available from different suppliers. 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. Not what I was going to do. I also cut a thin strip of scrap oak to fill in the neck channel over the truss rod. This would be added when I permanently mounted the neck.