Introduction: Twin Bass and Guitar From a Slab of Walnut

About: I work wood but I also have studied chemistry

Hello, and welcome to yet another electric guitar instructable!

There's a lot of them out there, but I thought this one was worth publishing for two main reasons.

First, the design is quite different from everything I have seen on I'ble so far. The design is not mine, it was made available online by master luthier R. M. Mottola on his website. More on this later.

Second, I made both of these instrument bodies from a single slab of walnut. This means no neck/body joint, beautiful curves, more freedom in design, and also that making them and especially sanding and finishing them, was a major pain in the butt. I wanted to share that pain with all of y'all.

Anyways, this is the story of how I made matching pair of instruments, a P-Bass and a "Telecasterish" guitar, so that my brother and I can look cooooool while we suck at playing music collectively. The idea was that they would both come from the same piece of wood, with complimentary inlays and matching hardware. Making these was a whole lot of fun. But not only.

Please keep all limbs within your browser, adjust your headset, and let's dive in!

I made the bass first, hence most illustrations/explanations are of the bass but the guitar is made following a very similar process.

Building those two instruments took me about 100-130 hours in the workshop total, plus a lot for research. It went faster thane making an acoustic guitar for sure, but still quite an undertaking. As someone once kinda put it in those words I think (Accurate Quotes Inc., pat. pending): "In luthery, nothing of value will be gained by going fast or cutting corners". Take your time, you're not trying to sell those. You'll thank yourself later.


Materials Unless otherwise mentionned, everything came from StewMac

One big ol' slab o wood (2 and 3/4 inches thick). I picked walnut, from my local hardwood supplier.

Fretboard blank, matching thick veneer for pickguard and electronics compartment cover

Nut blanks

Guitar strings

Wood glue, super glue, epoxy glue, more glue and gluuuuue (from your local hardware store)

Sand paper, 150 through 1000 grit (feel the pain, right here and then my friend)

A finishing compound of your choice, I went for Nitrocellulose in a can from StewMac because I can't afford a compressor, it's convenient and it looks cool in the end.

Mother of pearl for inlay, plus some side dots

Hardware Unless otherwise mentionned, everything came from StewMac

Tuning machines (Gotoh)

Various screws and nuts

Fret wire (I chose a gold color for added pizzazz, and to match the rest of the hardware)

Guitar and bass strings (several sets of each, as at least one will be used for conditioning the instruments strings do break)

Pickups (I did not make my own as I'm just not that into electronics anymore, but this is a whole new world of crafting if you are interested in this kind of stuff! I bought mine from EMG. Telecaster style, and P-bass style)

A bass and guitar bridges (Gotoh, GOLD )

Two pairs o' big ol' golden knobs for all your knobbing needs. Or for the volume and tone control.

Hand tools

Ruler, divider, square, pencil, marking knife, stock chalk, all of the good stuff to measure and mark lines

A mallet, a hammer

Planes, sharp. (1) jack, (1) block is all you need realistically. I also used a finishing plane to ease the sanding process

A spokeshave is neat to have for the neck shaping

One long drill bit to reach trough the body (25 cm or 10 inches should be good)

Rasps & files

Chisels, sharp. A small 'un and a big 'un should be good

A handsaw with a thin kerf to match your fret wire (just measure what you got in your workshop, one should already match your needs and you will save 40 bucks)

Possibly, card scrapers

Power toolsAs always, not necessary but boy do they make life easier sometimes

A handheld drill

A router makes your life so much easier

A jigsaw with a looooong blade, else a coping saw will do fine

I don't wish I had: an electric planer/jointer. Hand planing is when I get to know the wood I'm working with, and I'm not doing this as a business, so I don't thrive for efficiency and speed.

I wish I had: an orbital sander. Same remarks as above, but hey sanding things by hand seriously whoever invented this come meet me at 8 tomorrow in the parking lot behind McDonald's on 7th I'll give you a piece of my mind about hand sanding

Step 1: The Slab

Once upon a time I bought a huge slab of bone-dry Tennessee black walnut.
Just shy of 3 inches thick, 25 inches wide and 6 ft tall

Weighed in at about 120 pounds, cost me just about a dollar per pound. I would love to say that I chose it for the unique patterns of the grain and because it was quartersawn and because it rung with the sound of music as i stroked it with my fingertips, one ear on the wood and the other listening to the winds that made it strong by twisting and turning the tree in the endless battle of life, fortifying the trunk as years, centuries passed and the wood grew but stronger only to be felled on a full moon by the master axe woman, who has lived in the mountain for a hundred years and hauled it to her handmade cabin on her sled pulled by the wolves she was raised with.

The truth is, it was the only piece thick enough to fit my project. I wanted to fit a 1 3/4 inch thick body in there, with a neck and head attached. The head/neck angle is anywhere from 13° to 17°, and I calculated that I would need a piece at least 2 1/2 inch thick to be able to build the whole things from one block of wood.

As I broke my back, and nearly a window, fitting the slab in my car along with a piece of hickory gifted by the nicest foreman I met, a token of solidarity from him as he pictured the daunting and frivolous task I was undertaking, I knew I had made the right call. This was the mother slab. Soon to sing.

Step 2: Laying Out the Instruments


The slab was left untouched in my garage for a month.

Official justification:the wood is as precious as life. It needs to breathe in its new environment and get used to the smell and sound of the craftsman as it anticipates its future calling, and the metamorphosis from raw tree to refined instrument shall happen in due time.

Reality: I had no clue where to even begin with.

I did a lot of reading and looking into designs, and started ordering supplies.


I settled on this design by R.M. Mottola. He put the plans for free on his website, and even made puzzle pdfs that you can print on a standard printer and tape together to end up with a full scale plan.

For the bass, I printed the normal size, 32" scale 4 string bass and used this as a template for the shape, position of the fingerboard and pickups.

For the guitar, I printed the piccolo 25.5" scale which happens to be the scale of a telecaster. I used this for the neck, but I printed the body at 90 % of the full size bass to not have it be so small.

Then, I modified it to a telecaster-like layout, using templates found on google for standard telecaster measurements. I widened the fretboard to accommodate 6 strings and laid out the routing for the pickups, bridge, knobs and switch.


Ok we got a good pair of plans, now we need a flat surface to draw on! I brought out the jack plane, and took it to both faces of the slab.

A lovely moment was when I found out that the grain was highly figured and would turn out lovely, with some flaming and twirls and all the good stuff. A not so lovely moment was when I found out the grain was highly figured and I knew I was going to have to hand plane and hand sand this hardwood myself.

A couple of hours and a few blisters later, with intermittent sharpening and cursing, an almost square slab came out, at 2 3/4 inch thick. Before laying down the instruments on there, I inspected for holes, knots and imperfections and made sure everything would fit on there

Plain simple!

I then cut out my templates with scissors and drew them on the slab, quadruple checked everything from wormholes to lengths and then moved on to the next step. join me in the long bladed jigsaw extravaganza that was the next 3 hours of my life.

Step 3: Cut the General Shape Out

Have you ever used an underpowered tool? This is how I learned patience. -Gandhi, allegedly

I bought this jigsaw on craigslist for 20 bucks, and grabbed some long 4 inch blades from the hardware store. What a master plan. Turns out the jigsaw would have been underpowered to cut through 1/2 inch plywood, and this was almost 3 inch thick mightily twisted walnut.

Those. Were. The. Three. Longest. Hours. Of. The. Year.

Coincidentally, they were also the last three hours of the jigsaw. It lost a couple parts in the process, heated quite a bit even though I was taking breaks every 5 minutes to 1) dip the blade in water to not lose the tempering because of friction heat build-up 2) coat the blade in candle wax to limit said friction and 3) prevent my arms from vibrating into oblivion.

I still broke three blades, the jigsaw and had to finish with a coping saw but it worked out fine!

Amateur tip: try to be as close to our template as you can, giving you an extra 2 mm on each side of the fretboard. This will save you a fair bit of a headache later on.

Step 4: Bring Body to Final Thickness

Following a bunch of instructables, I made a thickness planing router jig to remove the bulk of the material and bring the body part of the instruments to final thickness.

I first made sure I had a very flat reference surface, the front of the instrument, by planing it carefully.

I laid it on the bench and went at it with the router, bringing in about 5 passes the body thickness to a bit more than 1 3/4 inch, and the neck to an even inch.

I left the headstock untouched, as this is where we will be carving out the headstock angle later on using precise geometry and curse words.

Step 5: Make It Flat-ish on the Back Side

I then refined the shape by taking a plane to the back side, revealing the beautiful grain on this side as well.

Not much more to it than that. I did it while watching a show, and so should you.

Step 6: Rough Shaping of the Head and Headstock Angle

Now we are going to give the head a proper trim. First, we choose our headstock angle. After a lot of reading about angles (they go from 0° to 90°, pretty much. Yep, seriously.) I decided to go for a standard 13° for the bass and 16° for the guitar. Much info was obtained from forums, such as this great thread. I first laid out the angle on my rough headstock using a combination square, then cut outside the line with a handsaw. I then sneaked up on the line with my finishing plane, checking the angle by holding the square flat on the neck and looking across to see light gaps between the head and the square (see pictures).

I then marked down the center line of the neck and headstock, and refined the junction between them with a chisel.

Step 7: Shape That Neck

Neck profile is a big deal. At least according to pros.

At my level of refinement in guitar playing, I can with confidence and slight pride say that I am able to tell the difference between a neck, and no neck. Latter is lighter, yet much harder to play, and you do lose some sustain.

Joke apart, take a look at resources online and figure out what you think will work best for you. Best part of making your instrument? You can make it custom AND if you start with one of the bulkiest profiles (deep C for instance), you can try out your instrument and tune the neck profile as much as you want before applying the finish. How marvelous.

I personally learned to passably play guitar on a thicc classical neck, I'm talking big ol' baseball bat, a phat chunk of a tree, so I stay within my comfort zone and oversize my necks. Big hands, less cramped in space, less worries on your first guitar that the neck is going to break when you apply string tension, and I can always remove some wood later if my taste changes.

Once you've decided which profile is best for you, you can make a profile gauge by taking 2 minutes with a scroll saw and a thin leftover piece of wood. Make two templates, one for the top and one for the bottom of the neck. Then work the wood down to your template using you tool of choice, chisel, rasp, spokeshave or your teeth and nails, then remove the wood in the middle so that the transition is smooooth. Well done.

Amateur tip: don't forget to account for fingerboard thickness in your neck design! And don't make it so thin at the head end that you will poke through exposing the bottom of your truss rod................... Don't ask me how I know................................................................................................

Step 8: Head Shaping

Now is time for creativity. Make your own shape, it is one of the signatures of an instrument maker along with the inlay and purfling. Always dreamed of carving a 1:10 scale dragon with flaming eyes? Now is the time. I'm quite boring myself, I simply grabbed two rolls of tape of different diameters and outlined the instrument's heads by outlining these two curves.

With the front and sides of the head done, I moved on to the back. If I didn't, my instruments would have ended up with the wood equivalent of a mullet and we all know that no matter howhardpeopletry, it is not coming back in style. Using first a finger plane (you can use a chisel), I removed most of the wood, bringing the head thickness under the tuners at about 15 mm but leaving some meat in the middle. I then refined the connection to the neck, leaving some sort of a spine in the back.

I wanted to highlight the fact that the whole body/neck/head of the instruments were one single piece, and this is not really something that you could see in a scarf joint unless extra wood had been added.

Step 9: Install a Truss Rod and Fingerboard

With all the top half of the instruments looking good, now is time to install a truss rod and fingerboard!

I go in detail about these aspects of the project in this instructable, so I won't type much here.

I did use a router rather than chisels for making the truss rod channel this time, it simplified the process a whole bunch. I routed through to the head to expose the adjusting nut of the truss rod up there, and made a small cover for it later on. The truss rod is dropped in wrapped in Teflon tape to prevent vibrations, and a thin strip of poplar was added on top and glued to the neck then planed flushed. This allows the fingerboard to have some more gluing surface and also helps spread the force of the truss rod when adjusting it so that t doesn't break your fingerboard.

Step 10: Laying Out the Hardware

This step is pretty straightforward but will impact how your instrument looks, but more importantly how it feels and sounds.

The most critical things to locate accurately are the bridge and pickup(s). Refer to templates of the same kind of guitar you are making, measure everything three times and tie a string between the nut and saddle to see where which parts land and to make sure, visually, once more, that things are where they are supposed to be.

Less critical but ergonomically relevant, locate your switches, knobs and eventual pick guard. I made a pickguard out of rosewood veneer and screwed it in place.

Once you are satisfied by a component's position, outline it precisely with a sharp pencil. Do this for all of them, take a half hour break and come back to measure everything once more, so that you don't route a big hole somewhere that it doesn't belong :)

Amateur tip: make sure you measure from the right places: scale length starts under the nut, not above, thins kind of stuff.

Step 11: Route for Pickups, This Is Not a Drill

With the peace of mind obtained through quadruple checking everything and the steadiness of hand obtained through your 12 years of training as a buddhist monk, it is now time to freehand route the pickup cavities.

Then, using the long drill bit from step 1, you will have to make sure that a line exists from your jack output all the way to the topmost pickup, that goes through the electronics compartment (see next step) and slowly drill through there, as horizontally as you can.

This hole will allow you to run your cables to the pickups and leave a hole in the side of the instrument to install a jack output.

Step 12: Electronics Compartment

Once you know where your components are going, you can make a compartment to hold the electronics. This is pretty straightforward, take a router and go slowly. Make sure your cables are long enough to reach everywhere.

As the guitar pick ups are active, I added some scrap wood to hold a 9V battery in the compartment. I made covers to match the fretboards and pick guard, with rosewood.

Amateur tip: it's much easier to start by making the cover, using a coping or scroll saw and outline it on the body of the guitar to routeout the cavity than to do it the other way around!

Step 13: Round Over Edges

This went fast, I simply used the router to round all edges of the body with a 1/2 inch round bit. I then cleaned everything up with a rough half round rasp, then a fine one. This makes the guitar lighter and more comfortable to hold.

Step 14: Don't Fret Over This Step

Ah fretwork.

Look at these videos which explain much better than me what the process is like.

Briefly, the first step is to make sure all the frets are in the same plane and level by running a big flat file over them

Then the corners are cut (inb4 "but you said not to cut corners earlier" I know. It's okay just this one time), so that what will remain of your precious fingers after all this time spent in the workshop will be able to play a tune without losing bits and pieces of flesh on the edge of the fretboard.

Then, the frets are crowned (made like a dome, getting rid of the flat part on top left by the flat file) and polished to a pretty shiny finish.

Taping the fingerboard off will save you headahes later on (getting metal filings out of pores, repairing file marks...)

Step 15: Refine Neck/body Joint

Now it's down to making the wood look good. Using rasps and chisels I sculpted the angles in a way that I liked, and tried my best to remove all imperfections. Don't worry, some will still show up under the finish. They ain't all gone. Maybe I need more patience.

Step 16: Test Run!

Once all of the previous steps are done, we are ready for a test run! This is not only gratifying, as the wood turns into a stunning way to illustrate how incapable I am at playing music, but also practical: it allows for one more step of troubleshooting before finishing.

Among the things that I found out: the bass was too heavy, I needed to remove material and make it thinner, accentuate the wedge where my picking hand rests for better ergonomics and remove material from the neck. I did all this, plus the next step which was a solution to a slightly more annoying problem.

It will also allow you to check for intonation, or how in tune the guitar is over the whole fret board, on each string. Intonation problems, provided the scale length is correct, are mostly fixed by either tuning at the saddle or lowering the action so that the string is less elongated as it is pressed down.

Step 17: Lower the Bridges

Fun times. The bridges I bought for both the guitar and the bass were made for fretboards much higher than mine. Which meant that I could not set the action of the strings (how much you have to press them down before they touch a fret) at less than 6 mm. Ideal action is a fraction of a millimetre.This was a big deal and I considered several options.

1) remove all frets, plane fretboard away, add a spacer between the neck and fretboard, reshape the neck to the right thickness and actually might as well burn the whole thing at this point and start from scratch because of how long that would take

2) buy a lower bridge, expensive but doable. But I liked the aesthetics of the ones I had and had drilled pilot holes for the screws and strings already

3) machine the bridge to be able to lower the strings more. Two main problems: this exceeds my metalworking/machining abilities, and then the break angle of the string might be too low, which can cause problems.

4) Route a pocket the size of the bridge a couple of millimetres deep, sacrificing some of the looks for practical reasons. This was my only reasonable option, and it worked out great! There are always several solutions to a problem and taking time to consider them rather than rush to the first one save me a a whole lot of time, expense, and frustration.

I carefully chiselled out the profile of the bridges, and routed the inside of the pocket in two passed with a flat bit.

Amateur tip: If you carefully bring the router to the chiselled edge, you will remove that last chip and end up with a perfectly crisp line, much better than if you just mark it down with a pencil.

Step 18: Side Dots

They're useful. I don't have them on the face of the fingerboard but only on the side facing up, where I can see them. Those are 2 mm diameter mother of pearl dots, that cost about 13 cents a piece. I drill a hole, drop them in there with a drop of super glue and call it done.

Later in the finishing process, while the wood generally get sanded to 320 grit, this area gets sanded to 1000 to bring the shine and reflection in the dots.

Step 19: Inlay Pt. 1: Design and Cutting Pearl

Alright now for the inlaying. A cool part, and my first time inlaying mother of pearl!

Inlaying 101: the idea is that you cut a thin layer of a material to the shape of your liking, then route out a hole a hair less deep than the material is thick, and sand everything flush to give a smooth surface.

Because the bass and guitar were twins from the same piece of wood, I wanted to give them matching inlays. I chose a snowy mountain for personal reasons, with a moon in the sky reminiscent of the design fo R.M. Mottola: Mezzaluna, the half moon, because of the shape of the body

To make matching/contrasting inlays, I proceeded as follows:

I glued two blanks together, stacked: one blue, one white. I then drew my pattern on there

Using an off-cut of the bass hear, I made asort of a jeweller's bench pin to be able to use my coping saw and precisely cut out the pattern. I clamped it on my bench. With your blade set in the coping saw, teeth facing down, you cut through your pearl and the downward force holds it onto the bench pin, and you rotate the part around the blade of the saw. The less clearance, the more support the wood can provide to the pearl! See pictures attached.

I cut the base of the mountain separate from the peak part, and mixed and matched to make two contrasted mountains. I tried several designs, thinking of using the other part of the blank that I cut to make a sort of reflection under the fret but then decided to keep it simple.

Step 20: Inlay Pt. 3: Inlaying the Fretboard

I then cleaned up the cuts, made sure everything matched nicely, and outlined the mountain on the fretboard right above the fifth fret.

I chiselled the lines sharply, ever so slightly snug and used my smallest chisel and my marking knife to remove the wood, test fitting the piece every so often.

Once the mountain fit in the pocket and stood slightly proud of the surface, I dropped some superglue in the wood and pressed my inlay in there.

To fill gaps, I filled them with some super glue and quickly rubbed some matching sawdust in there.

Amateur tip: do this before you start filing the pearl, as else you will fill those gaps with white dust and they will stick out like a sore thumb.

Then I filed everything flush, and sanded down to 1000 grit to bring the pattern of the pearl out.

Frets were dressed, as described in detail in my acoustic guitar instructable.

The fretboard was then oiled with mineral oil and beeswax for protection. Almost donezo!

Step 21: Finishing

Much has been written on the subject of finishing wood, especially guitars, in better ways and with more details insight than I could ever muster, and definitely more exhaustively than anyone would care to read here.

I can however reward you, dear reader who made it till the end of this project, with one great article about guitar finishing.

While some research and much speculation has been done into the physics of sound and how wood/finish choices affect those, it seems to be a consensus now among reasonable people (to be defined later) that the following are true:

All other things (geometry, electronics, shape etc.) equal, wood choice will tremendously affect tone in an acoustic or classical guitar or a violin, almost imperceptibly so for an electric guitar. In an amplified instruments, most of the sound quality will be a result of electronics, strings, amplifier, setup, and player.

The type of finish used, provided that the thickness of the layer of finish is similar and not too think that it will damp sounds, will have no effect on an electric instrument, and very likely no perceptible effect whatsoever on an acoustic or classical guitar, although thinner finishes could more desirable as they would improve responsiveness from the instrument. However, on a violin or cello etc., choice of varnish apparently can change the sound to a drastic extent and (don't quote me on any of this) apparently this could be a result of notes being played continuously with a bow, with the body of the violin acting not only as an amplifier of the sound of the string but also as a provider of harmonics and I'm going to stop here because I'm sure I'm wrong. Anyone who knows about this is welcome to come teach me in the comments section as I would love to learn about all this.

ANYHOW all of this to say that for an electric guitar, your choice of finish should be purely aesthetic/economic/related to the feel of the texture of the instrument in your hands.... But probably not acoustic.

I went for the classical, convenient, slightly expensive but oh-how-stunning glossy nitrocellulose lacquer finish. I first filled the pores in the walnut using a clear water based pore filler, and then followed StewMac's finishing schedule.

Don't forget to tape off any routed areas and your fingerboard. I'm now waiting on the guitar tocure (2-3 weeks) so I can sand and buff it.

Amateur pro tip: before applying your finish, sand the whole shabang down to 320 grit, apply water to raise the grain, and sand again. Then,vacuum dust out and look for imperfections and sanding marks from larder grits. Remove those, repeat process. Then wet the whole surface of the wood and do a final inspection! The reason for this is that water, just like a clear finish, will highlight imperfections instead of hiding them, and you will want to take care of them before applying your lacquer/oil etc. Finally, remove any finger oil/greasy doritos residue with some naphtha and do one final final inspection, pout your gloves on and only then go on to seal that bad boy for eternity in a sarcophagus of clear plastic.

Step 22: Beauty Shots

All done! Thanks for reading all the way and bearing with me throughout the process. Leave a comment if you want to say hi or have a question, and until next time!


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