Introduction:
This instructable describes how to build a neck-through electric bass guitar with only a minimal number of electric tools. I built it on eight months on my free time. It is far from perfect as I am not a luthier but the result is really nice to play and sounds good. I hope reading this will help you and inspire you to build a bass on your own !

Notes:
English is not my first language, feel free to ask for more explanations or to correct a mistake.

Step 1: 3D Model

To have a better idea of what you want your instrument to look like, it's a good idea to work with a 3D model first.

It is also possible to get plans from existing instruments (J-bass, etc). I chose the first solution as I wanted to make my own measurements, especially for the neck.

For this 3D build you need to know every single measure, here are some I used :

scale: 34"
neck width at nut: 40 mm
neck width at fret 22: 63.5 mm
body width: 40 mm
number of frets : 22
fretboard radius: 11"
thickness between body and top of the fretboard: 8 mm
distance between string on the bridge: 19 mm

Step 2: Woods and Tools

I bought my wood from a website specialized in wood for guitars. It was already cut in basics guitar shape.

The maple were used for the neck, the wenge for the fretboard and the alder for the sides of the body.

I did not use a lots of tools (mostly because I don't own them), here is a small list:

Absolutely necessary:

caliper
several chisels
hand plane
several files (for the wood and for the nut)

To speed up the build:

belt sander
orbital sander
jig saw
router

Step 3: Cut the Neck Shape

I started by cutting an angle of 8 degrees for the headstock.

Then I drew the width of the neck an the shape of the headstock.

The neck is 40 mm wide at nut and 63.5 mm wide at fret 22. For the headstock I draw a shape I liked, after checking the position of the tuning machines. I made sure to kept the strings aligned from the bridge to the tuning machines.

I used a jigsaw to rough cut the shapes before sanding smooth everything.

Note:
You can see a wood veneer glued on the headstock. I won't detail this because I chose to remove it afterward. It is also better to install it closer to the end of the build in order not to damage it.

Step 4: Install the Truss Rod

I chose a double action truss rod (650 long, 10 high, 6 width)at a local shop. I cut the slot with a chisel and 1 millimeter deeper than the truss rod.

I used a piece of walnut from an other project to cover the truss rod, shaped it and glued it with CA glue and sanded everything flush.

Step 5: Make and Glue the Fretboard

I draw the center line of the fretboard and the position of every fret. You can find the measures here. Be sure to triple check everything, this is the most important part of the build.

I used a kiridashi (but any sharp and precise tool would do) to make a little cut on each fret position.

After a final check of the measure I used a fret saw (blade of 0.6 mm) to cut a few millimeters for the fret using the marks. I glued the fretboard to the body with standard wood glue. I used pieces of wood to protect the fretboard, with the neck still unshaped, allowing a good clamping.

Note: Be especially careful while clamping, the fretboard can easily slide on the neck with the pressure.

Step 6: Shape the Neck

After cutting and sanding the sides of the fretboard, I started working on the back of the neck.

The easiest is to choose a straight part of the neck, shape it and then do the joins with the head and the body.

I used a file to make the two limits of the straight part at the correct height, then cut in between. I marked symmetric lines on the sides and removed the wood in between. I repeated the process until having a roundish shape. Finally I clamped the end of the neck on my workbench and sand it with stripes of sandpapers.

Step 7: Finish the Neck

To finish the neck, I shaped the transition between the back of the neck and the head of the bass. I did not used a special method here, just followed the curves of the neck and the headstock to create a smooth transition.

Then I chose the position of the tuners using Blu-Tack to stick them temporary before drilling the holes. As I said earlier, be careful to keep the strings straight on the headstock.

Finally I worked on the fretboard, first sand the radius (I forgot to take pictures, sorry). A good method is to draw crossed lines on the wood with a pencil, when every mark disappear while, the middle of the fretboard is sanded. Be sure to keep the neck straight on the middle and on the sides. I checked that with a straight metal beam.

To install the frets I made something to put below the neck in order to hit the frets on the fretboard without damage. I took a random piece of wood, sand a cylinder in one face and stapled a piece of bike tube onto it. I used a mallet to install the frets. Cut a piece of fret a bit longer than necessary, start by over bending it, hit both sides in place with the mallet, finish by hitting the middle and cut the exceed.

Step 8: Start the Body

I glued the two alder pieces on the sides of the neck after checking the position of the future body shape and adjusting the squareness of the woods with a plane.

The pieces of alder were higher than the neck, allowing me to plane the front and the back of the body at the level of the neck.

I then used the scheme I printed at real size (from the 3d model) to report the shape of the body before rough cutting around it with a hand saw (the blade of my jigsaw was too narrow for that cut).

Step 9: Route the Body and Cavities

I finished the sides of the body with a router. I don't own a drill with a bearing on top of it, thus I used a red marker to see easily where I needed to remove material with a classic drill.

I used the same method to drill the pickup cavity and the electronic cavity.

I used a leftover piece of alder to make a protective place for the cavity.

Step 10: Finish the Body and the Headstock

With the body cut to its almost final shape, I made the join of the neck. Similarly to what I did with the headstock join, I followed the shape of the neck to create a join with no angle and nice to play. I then used a rasp to round the sides of the body, before sanding it smooth.

I placed my electronic onto the cavity and drilled the holes. I also had to adjust the dept of the cavity and remove a bit more material keeping just the space to screw the protective plate.

I chose to mark my signature on the headstock. I started by drawing it at the correct size, then carved it a few millimeters depth with a Dremel. I sanded some wenge to fill it with dark dust, then used CA glue to keep it in place. I finally sand everything to get the result you see on the last picture.

Note:

I eventually decided to removed the veneer on the headstock before that step. I didn't take any picture of that.

Step 11: Details

Here are a few more little steps in no particular order :

drill the holes for the electronic cavity plate
drill the holes for the strap locks
wire the electronic (first on a piece of cardboard cut to the size of the cavity, it's way easier)
drill the hole for the pickup cable to go to the electronic
drill the holes for the bridge after carefully positioning it
drill the hole between the electronic cavity and the bottom of the bridge for the mass cable
tape the whole electronic cavity and protective plate with aluminium tape (electromagnetic shield)
sign the bottom of the pickup cavity
add fret markers on the side of the fretboard with the same method that for the signature on the headstock with maple dust
make wooden knobs for the electronic switches
make the bone nut (I adjusted it later)

Step 12: Sand, Oil and Wax

I leveled the frets by sanding them with a straight metal beam with sandpaper glued on it. I used a marker to color the frets to seen which ones are sanded and which are not. When every fret is sanded, the top on them is a bit flat, I colored the frets again and rounded the sides with a small triangular file util I saw only a thin colored line on the top. I also sand the two extremities of each fret flush with the fretboard, and finished them with thinner sandpaper.

I started the finish part by sanding everything from P50 to P200. I then applied 4 coats of teck oil - 2 coats distant from 6 hours, wait 24 hours, sand everything, and repeat the process- only on the alder and maple, wenge looks darker with oil and doesn't need it anyway. Teck oil is not a guitar finish, more a cheap outdoor wood oil but I like the way it yellows the wood and it's efficient.

After the oil was dry, I sand the entire instrument from P50 to P500 to get a really smooth final touch. Then I used a colorless wax on the whole instrument, except the fretboard (same reasons than for the oil). I will put it regularly, at each strings changing for instance.

Step 13: Mount and Adjust

Eventually I mount every hardware part on the bass and wait a couple of days for the wood to adapt to the strings pressure.

Then comes the adjustments, here the steps I followed :

For each string, press the 3nd fret, there must be only a really small gap between the string and the top of the 2nd fret. If not, slide of the string and use a small rounded file to make the slot in the nut deeper and repeat as much as necessary.
Use your right arm/elbow (right handed persons) to push the strings onto the last frets, then on the middle of the neck the strings should be around the distance of a credit card from the frets. If not you need to tighten the truss rod, use an allen key and turn clockwise only a bit. Let the wood time to adapt for a day and repeat the process as much as necessary
Tune your bass perfectly and play every fret on each string, if your hear a buzz, you should raise the string a bit on the bridge (usually with a small allen key), tune up and test again. Adjust the height of each string as you want.
Adjust the string harmonic by playing the 12th fret with a tuner, if the note is higher, increase the string length with the screw on the back side of the bridge, if the note is lower decrease it. You may need to repeat step 3 after that.

Note :
I am not a luthier, as for every part of this build, I used adjusting methods I gathered on the Internet after studying a lot of them, there are probably better methods but here are those I used at this time

Introduction: Neck Through Bass Guitar