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How to make an acoustic guitar

Author: Ted Brown
Photos: Ted Brown
Illustration: Len Churchill
Published: October 2024
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The only thing more satisfying than playing a guitar is playing a guitar you’ve made.

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  • DIFFICULTY
    5/5
  • LENGTH/TIME
    5/5
  • COST
    4/5

How to make an acoustic guitar is a subject better suited to a book, so this article will provide only a broad overview—not com­plete instructions— for the experienced woodworker. The photos will also give an insight into the process.

Any hardwood will work to make a guitar body. The harder the wood, the more responsive the guitar tends to be. I’m using Indian rosewood for the back and sides, along with a bookmatched set of Sitka spruce panels for the top. Start with gluing up the back panels. They should be quarter sawn to mini­mize seasonal wood movement.

Back Panel
Quarter sawn material is usually used for the back. Here, the braces are attached to the inner surface of the back.

Back Panel

Radius Dish
A common tool in guitar construction, a radius dish is usually 24" in diameter and will shape a guitar body or other part to a certain radius. Abrasive paper is on the inner surface of the dish.

Radius Dish

Steam Bending the Sides
A form is used to steam bend the sides to shape.

Steam Bending the Sides

Installing Kerfed Linings
Although it’s hard to see with all the clamps, kerfed linings are being clamped in place. The kerfs allow the material to bend to the shape of the guitar sides.

Installing Kerfed Linings

Sanding the Backside Radius
A radius dish assists with sanding the back of the guitar sides to the right shape.

Sanding the Backside Radius

Carved Bracing
To add strength to the top, bracing is added to its undersurface. The bracing is tapered and shaped more thinly on its outer edges.

Carved Bracing

Apply the Top
The top is installed using a go-deck to assist with clamping.

Apply the Top

End Graft Detail
An artistic approach can be taken when designing and installing the end graft.

End Graft Detail

Bindings and Purflings
Bindings and purflings can now be added to the edges of the guitar.

Bindings and Purflings

Rout the Neck Mortise
A jig is used to guide the router, while it’s equipped with a straight bit, to machine the mortise in the neck.

Rout the Neck Mortise

The Neck Billet
The neck billet, made up of contrasting colours of wood, is ready to be shaped and fit.

The Neck Billet

Ramp Jig
A belt sander, fit with a dedicated jig to sand an angle into the rear face of the headstock, shapes parts accurately and consistently.

Ramp Jig

Truss Rod
The truss rod has been installed in the neck and is clamped in place.

Truss Rod

Set the Neck Angle
Here, the neck angle is set with a dedicated gauge. This stage has to be done accurately for best overall results.

Set the Neck Angle

Tapering the Fretboard
A simple tapering jig takes care of accurately machining the fretboard to the right shape and angle.

Tapering the Fretboard

Cutting Fret Slots
An angled jig and a simple sled make quick work of machining all the slots for the frets.

Cutting Fret Slots

Fretboard and Bindings
The slotted fretboard, with its two bindings, is ready to go.

Fretboard and Bindings

Shape the Neck
The neck is shaped on the bandsaw.

Shape the Neck

Hand Shaping
Planes, spokeshaves and rasps are the main tools for shaping the neck. Notice the three shop-made gauges used to check progress during shaping.

Hand Shaping

Glue the Neck
Here, glue and bolts hold the neck in place for good.

Glue the Neck

Accuracy Counts
The bridge is located with a dedicated jig that positions the bridge a certain distance away from the neck.

Accuracy Counts

Fretboard Camber
A cambering jig is used to assist with creating an even camber along the length of the neck.

Installing the Frets
A brass hammer works great when installing the frets.

Installing the Frets

The back

Joint and glue up the 22″ × 8.5″ × 0.2″ back pan­els. Thickness sand the back panel to 2.7mm. On the inside, install a 1/16″ thick × 3/4″ wide (cross grain) centre seam brace running the length of the joint. The fibres run across the joint making it very solid to handle vibration.

To maintain the shape of the back and add strength, attach quarter sawn red spruce braces shaped to a 15′ radius.

Four braces

Mill four braces 16″ long × 3/8″ wide × 3/4″ tall. Create a 15′ radius on the bottom of the braces using an abrasive radius dish jig. A radius dish is a common tool used in guitar making. Each dish is 2′ in diameter, and is cut into various radii based on your require­ments. Dishes for shaping the backs of guitars, for example, have a 15′ radius. They have 50 grit sandpaper attached to their face to rapidly cut the sides of the guitar to shape.

Cut notches on the central seam brace, then install the four braces at equal intervals, ladder style. Place the back on a 15′ radius work board to establish the back curve while gluing the braces. Use go-bars on a go-deck to hold the braces in place as the glue cures. Hand-carve the braces to an “A” cross section to save weight using palm planes, block planes and chisels. Taper the braces from the centreline to the edges of the back.

The top

Tops are typically spruce, but any light softwood will work. Sitka spruce is the most common species used. A top comes as a book­matched set at 22″ × 8.5″ × 0.2″. Glue the top together, and then cut the groove for the inlaid rosette.

Joint and glue the top panels. Using a 1/8″ bit, rout the inner and outer edges of the rosette groove. Using a wider bit, clear between them, all to a depth of 2.6mm. Make up a 3mm thick hardwood rosette ring to fit in the groove, making the size of the ring such that it easily fits into the groove in the spruce top. The ring is sized so there is a 1/16″ gap between the ring and the edges of the groove on both sides. Glue the ring into the groove.

Re-rout the inner/outer grooves using a 1/8″ bit. Install decora­tive purflings (thin wooden strips) into the 1/8″ grooves with their ends at the top of the sound hole, as the fretboard will cover the joint. Now glue in the purflings with CA glue.
On a thickness sander, sand the face of the top until it’s flush, then flip the top and thickness it to 2.7mm. This thickness num­ber is not fixed and will vary based on the flex of that unique wood set. This is where tuning by the luthier comes into play. Test the panel for flex to determine ultimate thickness. It should be responsive, but not floppy. Using the same router set-up, cut out the sound hole at a 4″ diameter.

Sides

The sides of a guitar are steam bent. In this case we’ll use a ther­mal bending machine.

Dimension sides to 34″ × 4-3/8″ × 0.08″. Create the bottom body taper by band sawing the bottom of the sides starting at 13″ from the front. Taper to a dimension of 3-3/4″ at the front of each side. Spritz the sides with water, wrap them in aluminum foil to prevent staining, and then bend them one at a time on a thermal blanket bending machine over the form for your guitar.

Place the curved sides in a building mould, then attach the end blocks. The neck block receives the neck mortise, so it is stout at 3-3/4″ high × 2-1/2″ wide × 1-3/8″ thick. The rear block is 4-3/8″ high × 3″ wide × 3/4″ thick. Cut both blocks with the grain run­ning laterally so they move with the sides seasonally. Gently round the outside face of each block on your belt sander to mimic the rounded shape of the guitar ends. This is only about 1/32″.

With end blocks glued in, and sides in your building mould, place them on a 15′ radius dish, and rotate back/forth to establish a 15′ radius on the bottom of the sides.

Attach kerfed linings to the top and bottom edges of the sides. Flush the bottom edge again using the radius dish. Notch the bottom edges of the sides to allow the back braces to protrude through. The 1/4″ thick linings provide increased glue surface to attach the top and bottom to the sides. Attach the top linings in the same way. Install vertical braces (3-1/2″ × 3/8″ × 1/8″) every 4″ or so along the sides for extra strength.

Using a go-bar deck, glue the back to the sides, ensuring the cen­treline of the back is aligned to the centre of the mould.

Return to the top

The top is the heart of your guitar. After creating a radius on the bottoms of your braces, glue them to the underside of the top. Carve the braces to an “A” cross section to reduce weight. In gen­eral, we carve the main X-braces in a ramp towards the edges. The tone bars we scallop into a “suspension bridge” shape. Finger braces along the edges of the lower bout get thinned to about 3/16″ thick. The transverse brace above the sound hole is just rounded slightly because we need maximum strength to resist the leverage of the neck. The main X-braces have a bridle joint where they cross below the sound hole.
Radius the top of the sides using a 50′ radius dish. With a gent’s saw and chisels, notch the top of the sides to allow the top braces to pass through. Glue on the top using a go-deck. Congratulations, you have “closed the box.”

Trim the excess parts of the top and bottom flush to the sides using a trim router. Rout out the area at the back of the guitar sides and install a decorative end graft.

Bindings and purflings

Cut a double rabbet in the top and bottom edges of the guitar to accept bindings and decorative purflings. Glue in the purflings and bindings to finish the edges of the body. Hold the bindings in place with stretchy masking tape while the glue dries. File and scrape the bindings flush to the top and bottom surfaces.

The neck

Rout the 1″ wide × 3-1/4″ long mortise in the front of the body to accept the neck tenon. I use a straight tenon and a draw bolt to fasten the neck. Install a fixed nut into the tenon and drill a hole through the neck block of the body for the 1/4-20 draw bolt to pass through.

Making the multi-ply neck

Glue up five pieces of wood into a neck billet. I like to use walnut or cherry as the main outer wood, and maple as a centre strip for strength and aesthetics. The outside pieces are 25″ × 4″ × 1-1/2″, the centre maple strip is 1/4″. I add black veneers for aesthetics, placed on either side of the maple. The aggregate thickness of the billet is about 3-1/4″.

Joint the top of the billet on the jointer. Bandsaw the 15° ramp for the 7″ long headstock. Hand plane the top of the headstock flat. Glue a 7-1/4″ × 3″ × 1/16″ decorative veneer, plus a maple commercial veneer beneath it, to the top of the headstock. Using a belt sander and ramp jig, thickness the headstock to 1/2″ by remov­ing material from the back side of the headstock. Steam-bend a decorative 1/16″ back side veneer so the curve matches the volute shape. The volute is the curved wood protrusion at the bottom of the headstock. It adds strength to the neck at the transition to the headstock. Glue your shop-made veneer with a commercial maple veneer below it to the back side of the headstock.

Rout a 1/4″ groove, centred in the top of the neck, to accept a truss rod. Rout the groove to 3/8″ wide for the last 3″ at the head­stock end to accommodate the adjustment nut assembly.

Fitting the neck to the body

It’s crucial that you flatten the front of the guitar body where the neck joins. This is done with scrapers and sanding blocks. Place the butt of the neck on the flat, then using a neck angle gauge, deter­mine the angle change required to the end of the neck. On the sanding machine, sand the butt of the neck with our neck angle jig to establish the desired neck angle. The resulting tilt on the neck butt is about 3/32″ over 3-1/2″.

Now, use the tenon cutting jig to rout the 3″ long × 1″ wide × 1/2″ deep neck tenon. The depth of the tenon is a full 1/8″ shorter than the 5/8″ mortise to allow several iterations of neck angle adjustments.

Install the truss rod into the groove in the neck using silicone to hold it in place and dampen vibration.

The fretboard

Mill the fretboard to 18-1/2″ × 1/4″ × 2-5/8″. Cut two binding strips from the edge of the board at 1/16″ thick. Cut the billet into a trapezoidal shape on the table saw with the fretboard jig.

Change blades on the table saw to a 0.023″ thick fretting blade. Use a squaring box with a ramp on it to present the tapered fret­board at 90° to the blade. Using double-sided tape, attach a 25-1/2″ long notched scale to the fretboard. Cut each slot 3/16″ deep, and index from slot to slot using the notched scale that locks onto a reg­istration pin in the squaring jig.

Glue the bindings back onto the edges of the fretboard. When dry, clear any squeeze-out from the slots with a knife. Clean up the front end of the fretboard at the nut location. Glue the fretboard to the neck, with the nut in situ to ensure the nut slot size is correct.

Rough trim the neck

Lay out the side profile and use a support jig to cut it on the bandsaw. Cut the top profile on the bandsaw. Trim close to the fret­board and cut the curved shape of the headstock.

Use a spindle sander to clean up the edges of the headstock.

Carving the neck

Mount the neck on a carving stand and begin rounding with a spokeshave. Continue with wood rasps to round-over the shaft of the neck and the heel. Using a set of three shop-made gauges, check the cross-sectional profile of the neck. Mark the high points, then remove them with your rasp. Sand the neck to smooth the surface. Check your overall thickness of the neck, including the fretboard. I make the neck 24mm thick at the ninth fret, tapering to 21mm at the second fret to give the player a light feel. I use a modi­fied “V” shape, as it feels less bulky than a “C” shape.

Fitting the neck

I use a straight tenon along with a draw bolt on all my guitars. Drill a 1/4″ hole through the neck block 2″ down from the top of the guitar, in the centre of the neck mortise. Place the neck into the mortise and run the 1/4″ brad point drill bit through the hole from inside the guitar until it contacts the tenon. Tap the drill with a hammer to identify the centre for the fixed nut position on the neck. Now remove the neck and drill a 5/16″ × 1″ hole in the tenon and install a fixed 1/4″ × 20 nut. Go back to the body and re-drill the bolt hole to 3/8″ to make installation of the bolt easier.

Alignment of the neck

This is one of the hardest tasks when building a guitar. We must ensure we have the correct neck angle so the strings will meet the saddle at the correct height. We must also ensure the neck is aligned on the centreline of the guitar. To perfect the neck angle, remove light shavings from the neck shoulders on either side of the tenon. If the neck angle is too low, for example, remove more material toward the end of the heel of the neck. Check to make sure your neck still fits tight to the body, and that it has stayed on axis laterally. Verify neck angle with a neck angle gauge.

Apply a finish

At this point I would finish the body and the neck with a French polish before attaching the neck. This article focuses on the con­struction of a guitar, and the finishing is a big topic, so I’ve chosen not to get into the details of finishing.

Attaching the neck

Scrape off the finish that may have been mistakenly applied where the fretboard sits on the top of the guitar. Put glue on the bottom of the fretboard extension and on the sides of the tenon. Install the neck and pull it up tight with the draw bolt. Use two clamps in the sound hole to hold the fretboard snug to the body. Use another clamp to firmly push the neck into the mortise verti­cally, using cauls to prevent dents.

Installing the bridge

Make a hardwood bridge 6-3/8″ long × 1-5/8″ deep × 9mm thick. Rout the 1/4″ saddle slot with a 1/8″ tilt over its 2-7/8″ length. Drill six 3/16″ pin holes 7/16″ apart for the pins, in a line parallel to the slot, 3/8″ towards the rear of the bridge. Shape the bridge to your liking and cut the thickness of the ends to about 1/8″ for weight savings.

Using a bridge alignment jig, place the bridge so the front edge of the saddle is at 25-1/2″ from the nut. Put masking tape all around the bridge. Scrape off the shellac under the bridge for a good glue joint. Remove all the masking tape, leaving only the tape locating the two front corners of the bridge. Glue the bridge down and hold it in place with lightweight go-bars so there is just enough pressure to clamp the bridge, but not so much that the top gets depressed.

The next day, drill through each 3/16″ pin hole so the hole extends through the bridge plate inside the guitar. Using a tiny Japanese slotting saw, cut the 1/8″ long string slots in the bridge. Use a tapered reamer that matches your pins to ream each hole into a cone shape to accept the end pins.

Creating the fretboard camber

Cambering the fretboard is done with the neck glued to the gui­tar. Use a sharp smoothing plane to cut a camber into the ebony, cutting the edges down about 1/32″ initially. Sand the top of the fretboard using a 14″ radius cambering jig with coarse sandpa­per attached. Stop periodically and place pencil lines across the fretboard at every second fret. Sand with the jig to see where it contacts the fretboard. Hand plane the high spots, then go back to sanding. Continue until the entire fretboard is being contacted by the sandpaper. Ensure you keep the fretboard edges the same height all along its length. Finally, sand with 220 grit paper on the jig to smooth the surface.

Installing frets

Fret wire comes pre-curved at a radius slightly tighter than that of your fretboard. Cut the ends of the tangs off so that the fret ends can hang over the bindings. Add in a wee bit of Chair Doctor Glue to swell the joint. Pound in the frets with a brass hammer. Using the 14″ radius jig, lightly sand the tops of the frets with 220 grit paper. This will make all the frets the same height. Now re-crown the frets using a crowning file. Using a small flat file, file the ends of the frets flush to the fretboard. Soften the fret ends using a small needle file by rounding the ends. Sand the frets smooth using sandpaper and running briskly over the frets from one end of the fretboard to the other. Use 400 and 600 grit paper. Polish the frets using #0000 steel wool. Run a sanding block along the fretboard edges with 400 grit paper to further soften the fret ends.

Nut making

The nut should fit snugly in the nut slot. Place a pencil mark 1/8″ from either end of the nut for the outer string locations. Using a nut slotting scale, lay out the other four slot locations. Cut tiny slots with a gent’s saw to start each slot. Using nut files, cut the slots for each string. The depth for small strings should be 100% into the slot, and the bass strings should be 60% into the slot. Ensure the highest location in all slots is at the fretboard side of the nut for proper intonation and to prevent buzzing.

Saddle making

We start with a 4″ × 1/2″ × 1/4″ saddle blank. Cut the blank to length and round the ends on a disk sander so the blank sits into the slot. Using the radius jig from fretboard shaping, we lay out the same 14″ radius arc on the top of the saddle. File the top of the saddle to that arc. Place the saddle in a vise for the rest of the shap­ing. Draw a centreline down the length of the saddle. File off the back side of the saddle at 45°; I only use the front 1/8″ for intona­tion. Mark the locations of the strings on top of the saddle. Lay out the intonation line as shown and file the material away creating a 1/32″ ridge for the strings to break over. File behind the line to get clearance so strings break sharply over the saddle. Using a 1/4″ wide file, cut away the material to properly place the B and high E strings.

Installing the tuners

Before finishing, drill the tuner locations with a 10mm bit. Now install the tuners. On the back side, install the locking screw that prevents the tuner from rotating. Install the washer and nut from the top and snug them up.

String up your new guitar

Shape the end of each string into an arc, place it into the slot, and install the bridge pin. At the headstock end, run the string through the post, make the first wrap over top of the post hole and the remainder of the wraps below the hole in the post to lock the strings. Pull each string to tension, stretch the strings by hand, tune again, and you are there – the first time you will hear your new cus­tom guitar.

Parts of the guitar

 

 

 

acoustic guitar

 

 

Top bracing detail

Side and back

acoustic guitar

Neck and fretboard

acoustic guitar

Saddle detail

acoustic guitar


Ted Brown - [email protected]

Ted is the owner of Blackwood Guitar Co. in Mallorytown, Ontario. where he makes custom guitars and teaches guitar making.

1 comment

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  2. Thanks for the detailed description of how an acoustic guitar is made. All of your instructions, on paper and in person along with your care, attention to detail, skillful teaching and passion for guitar building allowed me to complete your course successfully and make my own handmade guitar. It looks and sounds amazing and I will treasure it and the experience of building it for the rest of my life. It will always be my go to guitar. I can’t thank you enough for sharing your passion and expertise during my acoustic guitar building experience. Without it what I accomplished would not have been possible.

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