Introduction: Machine Your Own Guitar
If you're thinking about designing and building a custom guitar, or even if you're just curious, this Instructable can give you some valuable knowledge and a look at utilizing tools in a different way than maybe you would think was possible, with amazing results.
Applied learning colleges and universities often have a machine shop handy, and if you're a student and you ask nice enough, they might just let you use their tools to build your very own guitar with unparalleled precision.
I managed to put this project together for about $100, parts and finishing products included. This is because the neck I used was a donor from an old Fender "Stratocopy" and the wood was a leftover oak stair from my uncle. Recycling! If you purchased a nice quality complete neck, and a nice slab of wood,this project could bump up to $450, and up to $600 for premium pickups and electronics.
Now, since mills are large, expensive and potentially dangerous machines I am going to write this Instructable assuming you have little/no milling experience, but have someone close by to assist and answer your machine-specific questions. I won't be able to help with that kind of specific questions.
Alright, lets get to work!
Step 1: Materials and Tools
- Approx. 1.5" thick hardwood slab, large enough to accommodate your design
- Prefabricated bolt-on guitar neck
- Double coil humbucker pickups ($33 for two on eBay)
- Tune-o-matic bridge ($12 on eBay)
- String tail-piece ($6 on eBay)
- Jack plate ($3 on eBay)
- 1/4" mono jack
- 2x knobs ($3 each on eBay)
- 2x 100k audio-taper potentiometers (pots)
- Les Paul rear plate ($6 on eBay)
- Strap pins
- Sacrificial piece of 1/4" to 1/2" thick plywood
- Triangle wood wedge
- Large sheet of paper
- Wood conditoner
- Wood stain
- Urethane wood finish
- Paint thinner
- Assorted mill cutters
- Assorted Forstner bits
- Mill slot-clamps and assorted clamping bars/rests
- Drill press*
- An extremely long 3/8" drill bit
- Band saw**
- Sanding block or palm sander
- Wood rasp
- Soldering Iron
- Bubble level
* Unfortunately this will be required unless you want a major redesign
** A jigsaw will work fine, band saws just make life easier
Step 2: Layout and Design
Initally, I wanted to do a semi-custom design, but I chickened out and decided a Les Paul would be safer. I was concerned that I would size it up wrong, and designing for ergonomics is difficult.
I quite simply got some large brown paper and traced my production Les Paul on it, and cut it out.
I encourage you to design your own body shape, but keep in mind that the more complexity you add the more work its going to be to make. Sharp, deep cuts inward will be quite difficult and time consuming to make, since they'll have to be partly done by hand. Also, make sure your design fits on the wood you have!
My oak stair was only 11" wide and over 36" long, so I cut it in half and glued the segments together to give me a 22" by 18" piece. Because of this, the wood grain is running perpendicular to the guitar length. If possible, have the grain run along the length of the guitar, so that it doesn't break in half. My guitar ended up being strong enough to handle the forces of the strings, but it's likely it will break easier if dropped.
Step 3: Rough Cutting
Milling is going to be a messy and time consuming job. Lets not waste time milling more wood than we have to! Plop your huge slab of wood on a bandsaw and roughly separate the guitar from the slab. Cut wedges of wood out of the nooks and crannies, leaving roughly 1/4" of material behind. Don't worry about curves or contours, just clean up the wood roughly.
Step 4: Mill Setup and Milling Contours
The first thing to do is to set up the body on the milling bed. If there is a vice or rotary index table on it presently, you'll have to remove it.
Cut that piece of sacrificial plywood with the band saw into a rectangle which has the same length and width of the guitar body. This will be our protector so our wood doesn't get covered in dirt and grease. Cut off a couple more bits of plywood to use on the top to prevent clamp damage. While we mill the outer contours of the wood, we will be milling into this plywood slightly. This way we don't miss any of the edge.
Move the X and Y of the bed so that the bed location is maxed out left and outward. Clamp the guitar piece down so that you can move the bed to start cutting away wood from the top of the neck mounting area. Its likely the guitar will have to be positioned four times before the milling is complete. Also, make sure the clamps won't be in the way of the cutter. Check that the wood is level with a bubble level.
Insert a 1/2" diameter or higher cutter into the mill. Set the mill to a speed around 800rpm ,which will be good for this job, since wood is nothing for a machine designed to work steel. Raise the Z axis so that the tip of the cutter is past the wood, and slightly into the sacrificial plywood. Lock your Z axis in this position, if you can.
Turn on the mill and begin moving the bed right and upwards until you meet the wood. Watch your pencil line as you work both the X and Y wheels, carving a rough curve all around the contour of the guitar. If you don't feel comfortable working both axes at the same time, move the X axis slightly, then the Y axis slightly, and repeat so that you leave small wave-shaped cuts all along the edge. You don't need to reach the line perfectly, but the closer you are, the more hand work you'll have to do to finish it up. If you want to keep your wood finish, its extremely important that you do not overstep the line. Having to add filler will ruin the look of bare wood and you'll be forced to paint the guitar.
Eventually you will run out of room. Either your X or your Y axis will max out at the opposite side you started from, and you will need to reposition the wood. Remember to move the sacrificial plywood with the guitar, or else it might not sit flat. Repeat until all the contours are complete.
Once you're happy, we can move on to the handwork.
Step 5: Contour Cleanup
Its almost guaranteed that things will look pretty bad after the guitar comes off the mill. Very wavy and terribly sharp-edged. A wood rasp will make quick work of it, though.
Use the rasp to clear up the rough waves and bring your wood right to the pencil line. Try to keep the sides as straight as possible, and don't use the rasp on an angle.
Once you're happy with the shape, break out the palm sander and start sanding the edges smoother. You can sand it to your finished smoothness now if you want, or you can wait until after all the milling to finish this step.
Once completed, we've got some math to do!
Step 6: Neck Placement and Center Line
Now that we have our basic blank body, we need to figure out where we will place the hardware and pickups, starting with the neck.
The neck has to be straight, and on a slight angle so that the raised bridge will set the string height ("action") evenly along the length of the fretboard. On the neck there is a flat part where it will connect to the guitar, so place the neck on top of the guitar to try and get a feel for how far into the guitar it should extend. Mark this on the wood with a pencil.
Next, place the neck on the table next to the body, and line it up as straight as you can with the body. Take a long ruler and lay it from the middle of the nut* of the guitar through the center of the last fret marker dot on the fretboard. Carefully mark the line that is going through the middle of the guitar. This will be our center line, to make sure all the hardware and strings will be straight down the neck.
*The nut is the small plastic piece with grooves in it for strings to go in at the end of the neck.
Place the neck back on the wood with it aligned straight with the center line, and squared with the depth line we marked earlier. Trace around the neck contour with a pencil. This will be our milling guide.
Now, we need to determine the angle of the neck. To do this, we will need a 1:1 scale drawing of the guitar from a side angle. First, draw an equivalent length and thickness rectangle to represent the body. Measure the length of the whole neck from the center of the nut to the very end, and draw a rectangle to represent that, overlapping into the body rectangle by the amount we determined they would overlap earlier.
There is mathematical significance to the open string length and the 12th fret length: it divides the string in half. That is to say, the distance from the nut to the middle of the 12th fret is the same as the distance from the middle of the 12th fret to the bridge. This is true for all guitars. Measure this distance on your neck and write it down.
Assemble the guitar bridge and place it on the paper to get a feel for how high it will sit. Tune-o-matic bridges are on screw mounts to their height can be adjusted, so set them to about medium height. Mark the height this will put the top of the bridge at on the paper.
Now, using a long ruler, draw a line from where the nut would be to the height of the bridge. This line represents the strings. We want the neck to angle along with the strings just like this. Using a protractor, measure the angle between the bridge and the strings. It should be something like 88 or 87 degrees. 90 degrees - 88 degrees = a 2 degree slope is required on the neck pocket. Please take a look at the image below if you are having a hard time understanding the angles.
Double-check your components are perpendicular to the center line, and squarely centered along it. If all is good, move on to Step 7!
Step 7: Trigonometry and Pocketing
To achieve the neck pocket angle, we will need to mill the pocket with the wood propped up on an angle. To do this, we need a triangular wedge of wood, like a door stopper, to place at the right height.
Please see attached image to understand what I mean. You will need to punch the numbers into a scientific calculator to find the height of X. Use this formula:
X = Length of Plywood * Sin2°
X is the height on the wedge you will need to rest the plywood on. Simply measure from the bottom of the wedge to the sloped side and draw a line where the thickness is the same as the value for X.
Clamp it in place once everything is aligned like the Actual diagram below. Be sure to align the body so that it the center line on the wood is straight with the Y axis of the mill.
Now, you're probably wondering how deep to make this pocket. Measure the thickness of your neck at the mounting point. Subtract 1/4" and this is how deep the pocket should be.
Bring the cutter over to the edge where the pocket will be. Move the axes until the cutter is touching the wood. Set your Z axis to zero for this location. Move the cutter away from the wood and lower it to your calculated pocket depth, and lock the Z axis.
Turn on the mill and mill the pocket as close as you can get to the marked pocket contour. Move the cutter back out of the pocket and shut off the mill. Move the bed as far toward you as possible, and test-fit the neck. If it fits, great! If not, continue to mill it bit by bit until it does fit. It might take you half a dozen tries to get it to fit the way you want it. Once its in place, check that it lines up with the center line acceptably while you hold it in place.
If your neck has no holes, great. Use a soft-jaw clamp to hold it in place in the pocket, properly aligned. Get a drill bit that is a smaller diameter than the neck mounting screws you have. Drill through the back of the body and into the neck. Don't drill all the way through the neck! Once through, remove the clamp and neck and redrill the holes in the body with a drill bit of larger diameter than the screws. If your neck does have holes, you'll have to find a way to transfer their locations onto the pocket so you can drill the holes through the body. I did this with some paper and a pencil, poking holes where the neck holes already were. Then I traced the neck perimeter, and cut it out with scissors. Then I placed it inside the pocket and marked where to drill in the wood. Perfect!
Screw the neck in place and see how it looks! If the alignment is off, you will need to use a round file to file out a few holes in the body, and wedge some slivers of wood into them to push the alignment back straight. That, or re-draw your center line.
Step 8: Placing Hardware
Its time to place the other hardware.
Mark where the bridge should go as per the 1:1 drawing. Mark drill points so that the center of the bridge will be on top of the center line when complete.
One of your pickups will probably have a longer chord than the other. This one is the neck pickup. Remove the actual pickup coils (chrome) from the mounting frame (black.) Place the bridge pickup on the center line so theres about half an inch of space between it and the neck pocket. Trace around the chrome pickup so we can see an outline where we need to mill the pickup pocket. Repeat for the bridge pickup, placing it about half an inch before the bridge.
The tail piece can go 1.5" behind the bridge.
The electronics plate can be placed arbitrarily on the back, so long as it doesn't interfere with the pickups or other hardware. Figure out how you want to place your potentiometers, then decide where to put the plate. Trace the plate outline onto the wood. Mark the holes for the plate too, so you don't remove too much wood in the next step.
Step 9: Pocketing for Pickups and Electronics
The pickup pockets are much simpler than the neck pocket. The easiest and cleanest way to do them is to drill them with a forstner bit and then clean up the pocket with the mill.
Measure the height of your pickups. They should be about 3/4" or so. Since they will protrude from the wood surface, we can drill the holes to about that depth, and still have room for wiring. Put a 3/4" forstner bit in the drill press and drill a series of holes around the perimeter of each pocket. Leave the two bits on the side for the mill. Most of the material should be removed. Repeat for the other pickup.
Flip the body over and drill out the big pocket for the electronics. Drill it about 1" deep. Don't drill quite to the pencil line so that there will be a ledge for the cover plate to rest on. See below image for more info. Also drill two deep holes to fit the potentiometers into. Take care to not drill right through. Your drill press should have a depth gauge that will help you know how deep you are. See below image for visual explanation. Drill a shaft hole for the pots all the way through the guitar, too.
Head on over to the mill and put on a 1/4" cutter or so. Clamp the body back on the mill with the plywood beneath. Check that the body is level. Move the cutter into the first pickup pocket and raise the bed until the cutter touches the bottom. Run the cutter around the perimeter, to clean the pocket edges. Get into the two tab sections on the sides.
Once the pickups are done, flip the guitar over to the back side. If you wish, you can mill the inside of the pocket, but if not, just mill a ledge around along the pencil line that's as deep as the thickness of your back plate. Mine was about 3 millimeters.
Measure the diameter of your tail piece and bridge mounting inserts, and drill slightly larger holes for their marked locations.
The next step is drilling the wiring hole.
Step 10: Drilling an Extremely Deep Hole
This is a difficult step. Start by drawing a straight line on the wood that will link the external jack through the back cavity, and continue on to the bridge pickup without hitting the bridge holes or tail piece.
For this you're going to need a drill bit thats 18" or longer. The one I had was actually a homemade unit, where a 3/8" drill bit was welded to the end of a steel rod. I believe store-bought versions are available. There are a few more complex workarounds for this, if you don't feel to ambitious to pull this off.
Then, lower the drill press down so you can fit the body in. Place the body in a padded vice with the marked drill line vertical. Using a normal size 3/8" bit, drill an angled hole into the body where you want the output jack to be. It should be close to the back cavity, and you should be able to drill all the way into that cavity. This will make life easier later on.
Lower the press down far enough that you can put the large drill bit into the wood and be able to get it into the chuck. Once it is lined up and the bit is in the chuck, clamp the vice in place so that it won't move. Its very important that everything is straight, or else the bit could come out the side of the guitar while drilling.
Start drilling down into the guitar. Make sure that the drill is perfectly straight when going in, and not flexing on an angle, otherwise the drill might burst out the side of the guitar. Move the bit up and down to clear the spirals of debris as you go.
Eventually you should see the drill enter the bridge pickup pocket. This will be the wiring hole for the pickup cables.
Step 11: More Drilling
The hard stuff is out of the way!
Place a 1" forstner bit into the drill press. Raise the bed back up and re-clamp the body in the vice so that you can drill straight down into the spot where the extremely long hole begins, but not following the direction of the hole. This will be for our output jack.
Drill a hole about 1" deep at this location. Place your 1/4" jack into the jack plate and see if it fits. If all is good, pull the body out of the vice.
Re-assemble the pickups into their housings, and place them in their respective pockets with the wires balled up beneath them. Mark the four corner mounting holes for them with a pencil. Drill holes of 3/32" diameter for the pickup screws.
Using a 3/8" drill bit in a cordless drill, drill a sloped hole from one pickup pocket to the other. Take note of the shape of your pickups and the location of the wires to determine where this hole should be.
Drill the mounting holes for the back plate and jack plate now as well.
Pick spots for the strap pins (normally above the neck and at the very back) and drill 3/32" holes to mount them in later.
Place the tail piece and bridge in place, bolt on the neck and test out the guitar with strings tuned to tension. If it doesn't break, great!
Step 12: Stain and Finishing
Despite your best efforts, the wood as probably become very dirty throughout all this work. Take your palm sander or a sanding block and sand all surfaces of the wood until it is clean. Put some paint thinner on a clean cloth and wipe away all the dust. If you have compressed air, use it to blow dust out of the pockets and holes.
The process for finishing is going to be a few coats of Pre-conditioner, followed by two coats of stain, and then five coats of urethane clear-coat on top. This will take a few days to do.
Start by finding a place where you can hang the body where it won't be disturbed. Double check that there aren't any grease fingerprints or dirty spots that will get sealed in before you start!
Apply pre-conditioner as per instructions on the can, using a good quality brush. Most likely it will tell you to apply two or three coats within 15 minutes of each other, then to apply stain within two hours after the last coat of conditioner. Clean the brush using mineral spirits or paint thinner.
Within those two hours, brush on a generous coat of stain. Let it sit for about 15 minutes, then wipe off excess with a clean cloth. Let dry 24 hours and then repeat this process. Clean your brush in between so it doesn't harden.
24 hours after applying the second coat of stain, we can begin urethane clear coating. Apply a thin coat of urethane to all surfaces, being very careful to watch for drips and runs. Go slowly and make sure that you don't get any drips accumulating at the bottom of the piece. Once coated, let it dry for 4 hours before very lightly sanding surfaces with 220 grit sandpaper. Wipe off the dust with a clean cloth and then apply the next coat of urethane. Repeat this process until you have five coats of urethane. Do not sand the final coat. If you want a further, deeper gloss, you can continue adding coats in this manner.
Step 13: Assembly and Wiring
To wire the guitar, you will have to pull the pickup wires through that long hole in the body. To do this, tie a piece of string to a long thin screwdriver, or a metal rod, and push it all the way through from the output jack hole to the pickup pocket. Once it comes out, untie it and tie each pickup wire to it. Be sure to route the neck pickup wire through its own hole first! Pull the wires through the hole and into the back cavity. Now you can screw the pickups in place so they don't fall out and pull their wires back.
Place the potentiometers in their holes and attach the washer and nut on the front side. Tighten them in place, and attach the knobs via their set screws.
Wire up the circuit as per the diagram or schematic below. To wire the 1/4" jack, mount the jack in the jack plate, then solder wires to the two connectors. Then, push the wires through into the back cavity. Then solder them in place. Put electrical tape on exposed wires so they don't short each other out.
The tail piece and bridge may need to be wood glued or epoxied into their places. Hit them lightly with a mallet to make sure they're seated fully.
Attach the neck and tighten the neck screw firmly, install the bridge and tail piece, and string it up. Test with an amplifier to see if the wiring is correct, and then screw shut the back plate.
Step 14: Finished!
If everything works, great! Your guitar is complete and ready to play!
I hope you enjoyed this Instructable. It's quite complex but not too difficult if you use a little common sense and problem solving. Thanks for reading!
Please let me know if you see any issues with what I've written, have any safety concerns or other issues. Thanks.