Intro: Build an Acoustic Guitar
I made this guitar for my science Olympiad event. Science Olympiad is a competitive tournament where students participate in different scientific events against other schools. One of my events is called Sounds Of Music where you have to build two different instruments without using professional parts. This event taught me about engineering as well as wave and music theory.Our regional tournament was in March 2013 and one of our instruments was a guitar. It was a very simple, crudely made guitar but it worked. Surprisingly, my teammate and I actually placed 2nd overall in that event out of 25 teams. The top 6 teams in the region advanced to the state tournament in mid-April and our team placed 6th overall! This was the first time in our school's history that we made the state tournament! So with an extra month to prepare, I decided to build a new and better guitar. This is a very creative project with multiple ways to get the steps done, so make the guitar in your own way. Be sure to vote for me in the Make-To-Learn Youth contest.
Step 1: Tools and Materials
Materials needed- Plywood for the guitar body- I used 1/4". The amount depends on how deep you want the guitar to be. I used 15 24"X24" sheets 1/2" Oak dowel rods- Put in the body to help with alignment and to add strength. The length depends on the depth of the guitar. It should be less than 2 feet. 1X2 Stock- about 3 feet in length. Shaped to become the neck of the guitar. 1/2" hardwood-makes up the bridge, the nut, and is useful for other parts. Wood Glue- The main adhesive for constructing the body and attaching the neck Super Glue- Used for attaching the nut and the bridge Tuning pegs- Each tuning peg is a 1/4"X 2 1/2" Eye screw, 2 washers, and a 1/4" wing nut. Fret Material- any thin 1/8" material that can easily be cut and glued. I used red and black 1/8" acrylic cut on a laser cutter. Tools Needed- Machine to cut wood- Automated machines like laser cutters and CNC mills work best, but anything that can cut plywood will work fine. Files- Both coarse and fine files are used to shape the neck Sandpaper- Used to give the neck a smooth finish Drill Press- Used for drilling out holes in the bridge and for the tuning pegs. Drill bits- various sizes Belt Sander(Optional) Great for shaping the bridge and giving things a smooth finish Spring clamps- Useful for securing things while glue is drying
Step 2: Designing and Cutting the Body
Because I couldn't find any free blueprints for guitar body shapes, I had to design my own. Using the general shape taken from images online and measurements from actual guitars I was able to create my own pattern. I based the body shape off of a dreadnought guitar because it is one of the more versatile, more popular guitars. The guitar design I made has 5 different parts- the top piece with the sound hole, the back piece, standard pieces for around the edge, edge pieces with a slot cut out for the neck, and pieces made to support the neck. I designed my patterns in Corel Draw so they could be utilized for laser cutting. The patterns were pretty easy to make. I just used the 3 point curve tool to trace the general body shape and then used the measurement tools to created the features for each different piece. For ease of assembly and durability of the guitar, I decided to place oak dowel rods in the corners of the body so the pieces could be stacked and lined up easily. This technique is best utilized with computer controlled machines, such as laser cutters or CNC mills. Figure out how many pieces of wood you want stacked on top of each other and how many for type of piece. For example, I had 3 pieces of plywood cut out with a slot for the neck and two to support the neck. Remember the thickness of your wood, I used 1/4" plywood, when calculating the depth of the guitar. Once I had the patterns made, I sent them to the laser cutter for cutting. They came out perfect and the guitar began taking shape. For those who don't have access to laser cutters or other computer controlled cutting machines, you can definitely cut the body parts with a band saw or other woodworking tools. Just be sure to work slowly for the most accurate results. The patterns I made are listed below.
Step 3: Assembling the Body
Assembly is pretty straightforward. Just cut 4 dowel rods a little bit longer than the depth of the guitar to go in the holes you cut in the corners. Then just do a practice fit. Stack all the pieces in the order you want them and make sure everything is lined up correctly. Remove the pieces from the dowel rods but keep them in the same order and apply small amounts of glue between the pieces. Continue stacking the pieces back up but DON'T GLUE THE FRONT ON. Glue the back on when done and put heavy object on top to compress the body for strong glue bonds.
Step 4: Shaping and Attaching the Neck
Take the 1X2 piece of wood and shave it down to a near semi-circle shape. Leave about 4" untouched at the end for a flat area to attach to the body. I shaped the body by starting with a coarse file to give it the basic shape. I worked my way up with finer files until eventually using sandpaper for a smooth finish. This process makes the neck really smooth and allows your hand to slide along smoothly. Once shaped, take the neck and glue it to the supports on the body. Allow to dry for about 2 hours. Support the neck from now until gluing the top on to keep the body from warping or breaking. I glued a small piece of 2X2 below the neck supports to help with the warping and to add stability. I realized that when the top is on, the neck will be 1/4" lower. So I glued a strip of 1/4" plywood on the neck that was about 23" long. This makes the top surface of the guitar level.
Step 5: The Nut and the Bridge
The distance between the nut and the bridge is about 26". This is the length of the standing wave when vibrating. Measure 8" down from the top of the body toward the center and about 18" up from where the body and the neck meet. Draw a line at both of these points. For the nut, I used Corel draw once again to cut out a rectangle and to cut groves in it for the strings to fit in. The grooves are about 1/4" from each other. Once cut out, sand the nut to about 3/16" tall. Super glue this to the line drawn on the neck. Clamp the nut down and let the glue dry. For the bridge, I cut the nut out again, but this time sanded it down to only 1/4" tall. This difference in height between the nut and the bridge allows for more room to strum the guitar when playing. Super glue this piece down on the line drawn on the body. Clamp and let dry. This gives us our 26" length between the nut and the bridge. Once dry, remove the clamp and make the part of the bridge that holds the strings. I traced the shape of a bridge from a picture online on the 1/2" hardwood and cut it out. It should be about 5" wide. Then, using the nut as a guide, I marked where to drill holes for the strings to run through. I drilled the holes with a small drill press so the small balls on the ends of guitar strings won't fit through. Once the holes are drilled, I shaped the bridge with a sander to give it a more flowing shape. Then, I glued it behind the bridge with both super glue and wood glue, as this is the most crucial glue joint in the entire process. If not enough glue is used, the bridge will be ripped of the body of the guitar from the great tension of the strings. Once the glue has dried and everything is right, glue the top on with wood glue and weigh the top down for a strong bond.
Step 6: Tuners and Frets
I didn't cut down the neck before I glued it in so it was about 8" too long, so I cut it off now. I then drew out my tuner layout. They are in two rows, each 3/8" from the edge. The tuners are offset so they don't hit each other and about 3/4" away. I then marked for holes about 1/2" in front of the tuners. These are for the strings to run through and reach the tuners. I drilled the holes for the tuners with a 5/16" drill bit and the holes for the strings were about 1/8". The tuners are assembled with the loop on the bottom side of the neck. On top of that goes a 1/4" washer and then through the neck. On top goes a 1/4" washer and finally a wing nut. This is repeated for all 6 tuners. The frets are 1/8" X 1/8" X 1 1/2" material. Mine are made from red and black acrylic cut on a laser cutter. For placement, I just used an online fret calculator such as http://www.studybass.com/tools/chord-scale-note-printer/ or http://www.stewmac.com/fretcalculator?gclid=CMnShKaoy7YCFQNlMgodZB4AdQ. They give you all of the measurements to correctly place the frets on the guitar. Just measure the distance, draw a line, and super glue the fret in place. Clamp it down for a secure bond, as these pieces will receive a lot of wear. And that's it, your guitar is done!
Step 7: Stringing the Guitar
Now that your guitar is finished, you need to string it. Just run the strings through the bridge, over the neck, over the nut, into the string hole and through the tuner. Wrap the end of the string around the eye screw a few times and begin winding. If the eye screw won't turn, loosen the wing nut a little bit to allow it to turn. Just make sure to retighten it so the tension doesn't turn the tuners by itself. String all six string and then tune them. You can upgrade your guitar in many different ways. You can add a strap (which I plan on doing soon), add a pick guard, or whatever you choose. You can now admire your work and play away on your new guitar.
Step 8: Make to Learn Questions
What did you make?- I made a homemade guitar. The body is made from stacked plywood and reinforced with oak dowel rods. The body amplifies the sound given off by the vibrating string. The neck is made from a 1X2 and glued inside the body of the guitar. The tuning pegs are made from eye screws. The eyes screws allow the tension of the string to be adjusted and thus changing the pitch. The nut and the bridge are made from wood and create a standing wave. When plucked, the string vibrates between these two points, creating sound. The bridge also helps send vibrations into the body of the guitar to be amplified. The frets are made from black and red acrylic. The frets are pre-measured measurement points that when pressed upon, shorten the string and play a higher note when plucked. I made this guitar with a laser cutter, a drill press, a band saw, sander, and files How did you make it?- I got the idea for this project after placing 2nd in our regional Science Olympiad tournament. We had a much simpler guitar then and I wanted a better looking guitar for the state tournament. I worked with my partner in the Science Olympiad event. As I went along, I was trying to figure out how to secure the strings to the bridge without using pins, as seen on modern acoustic guitars. I researched by looking at pictures online until I was inspired with the current design. Where did you make it?- I worked on the guitar both at my home and after school in my shop teacher's classroom. This project connects to my Science Olympiad event, Sounds Of Music, where you have to build two homemade musical instruments. What did you learn?- I learned a lot about sound and music theory from this project. I have never played an instrument before and learned how to write music, the physics of waves, and how sound is transmitted and received in the ear. Throughout the build, I was worried about if the neck joint to the body would be sturdy enough to support the neck. I was surprised by how the top of the guitar was able to support the strain on the joint quite easily. I was also troubled by how to place the frets. But after some research, I found many calculators to find the distance between frets. I also struggled with how to secure the strings to the bridge. But once again, research on the internet found the answer to my problems. I am proud of the entire project, I think it is one of my best works. But I am especially proud of the shape of the neck and how smooth it is. I am also proud of the bridge design and how well it works. If I had to do this project again, I would make the neck a little bit wider. Currently at 1 1/2", it is a little bit too thin for my taste. I would prefer to have it 2" wide. I would also want to finish the wood with a nice stain to give it more aesthetic appeal. Overall, I think the guitar looks pretty good.