Designing a guitar,
and making the
templates.

The short version

Get this stage right and everything after it falls into line. Get it wrong and you will fight the guitar for the rest of the build. That is the whole reason I start here and take my time.

The good news is this is the cheapest place to make a mistake. You are drawing on a cheap sheet of MDF, so a bad line costs you a pencil mark, not a neck blank. Make all your mistakes here, on paper, where they are free.

One word runs the whole session for me: quality. In plain terms that means accuracy, strength, longevity and comfort. And it means remembering that something can look great on the board and still feel wrong in your hands. Those are two different things.

What you need

This is a short list, because this stage is about accuracy, not tools.

• 1/2″ MDF. 5/8″ is fine too. Thinner is not. A sheet is cheap at any big box store.
• Digital calipers. Fret positions, bridge posts, tuner holes. Honestly, most of this job is just calipers.
• Carpenter square.
• A metal yardstick, not a wooden one. Wood moves and is almost never dead straight.
• T square. Handy, but you can live without it.
• A calculator and a fine tipped Sharpie.

That is it. Nobody needs a shop full of gear to draw a guitar.

The numbers, in one place

Everything I work out below is in this table, so you have it all in one spot.

Measurement	Figure	Note
Fret constant	17.817	Divide the remaining length by this, every time
Scale length (this build)	25.5″	Fender, Ibanez, Jackson. PRS 25″, Gibson 24.75″
Nut width	~1 5/8″	1 3/4″ to 1 7/8″ if you come from classical
Bridge string spacing	53.5 mm	Center of saddle to center of saddle. Suits nearly any bridge.
String inset at the nut	1/8″ each side	Strings do not sit at the fretboard edge
Fretboard overhang past last fret	1/4″ to 3/8″	Any less and the wood breaks out when you seat the last fret
Humbucker cavity	2 7/8″ × 1 5/8″	Base plate is 2 3/4″ × 1 1/2″, the rest is clearance
Single coil cavity	~1.10″ wide	Includes 1/16″ clearance each side
Tuner hole	3/8″	Measured 0.387″. Drill slightly over, the finish shrinks it.
Tuner spacing	1 1/8″	Set by the rear housing width, not the post
First tuner from nut	3/4″ to 1″	Never right up against it

Setting up the board

Draw your centerline first, and find it properly. Everything on this drawing is measured off that one line. If it is wrong, nothing else can be right, so this is not the place to eyeball it.

Most guitars are under 40″ end to end, so I come in about 10″ from one edge and put the nut line there. That leaves room for everything.

Now label the line. Write NUT right on it. You are going to put a lot of lines on this board before you are done, and I promise you the one you did not label is the one that trips you up an hour later.

Scale length

Pick whatever scale you want. The common ones are:

• 25.5″, Fender, Ibanez, Jackson
• 25″, PRS
• 24.75″, Gibson

All else equal, a shorter scale feels looser and slinkier, a longer scale feels tighter, at the same pitch and string gauge. Pick the feel you like.

Measure from the nut line and mark your bridge line. Use an arrow, not a little tick. A bare tick does not tell you which side of it you meant, and that half a pencil width of doubt adds up over a whole neck. Then check the two lines are parallel by measuring at both far ends. Both should read your scale length. Label it BRIDGE.

Fret positions, the 17.817 rule

Here is the only piece of math you really need. Take the string length you have left, divide it by 17.817, and that is your distance to the next fret. Subtract, divide again, and keep going down the neck.

On a 25.5″ scale it starts like this:

Step	Calculation	Gap
Fret 1	25.5 ÷ 17.817	1.431″
Fret 2	(25.5 less 1.431) = 24.069 ÷ 17.817	1.350″
Fret 3	(24.069 less 1.350) = 22.719 ÷ 17.817	1.275″

Keep three or four decimal places and work your way down. Every gap is measured from the last fret's arrow, not from the nut.

The two checkpoints that keep you honest

Every number is rounded a hair and every gap builds on the one before it, so in theory a small error could creep in and grow. Two checks catch it before it can:

• Fret 12 lands at exactly half your scale length. On 25.5″ that is 12.75″.
• Fret 24 lands at 19 1/8″ on a 25.5″ scale.

If your 12th fret is not sitting at half the scale, stop right there and find the mistake before you mark one more line. Every fret past it inherits the error, and you will not like where that ends up.

Nut width and bridge spacing

Nut width is down to preference. Around 1 5/8″ is normal. If you come off a classical or flamenco guitar, 1 3/4″ to 1 7/8″ will feel more like home. If you are running a locking nut, you are stuck with whatever sizes that maker offers, so check that first.

Halve your number and mark each side of center. One tip that saves a headache: flip your calipers over to millimeters for this. 1 5/8″ is 41.4 mm, so it is just 20.5 mm each side. Much easier to work with than fractions.

Finding where the bridge actually goes

Bridges do not all sit in the same spot, and you cannot guess it. If the maker gives you a template or a PDF, use it. If not, do this:

1. Slide a saddle all the way back, lock it, mark it.
2. Slide it all the way forward, lock it, mark it.
3. Take the midpoint between those two marks. That leaves you room to adjust in both directions, usually about 1/2″ of travel.

Then measure from the front edge of the saddle, the point where the string stops touching it, to the center of the mounting post. On the bridge in this build that came out to 13.89 mm. Mark it MOUNT.

The neck taper draws itself

This is the part I love. Mark half your bridge spacing on each side of the centerline down at the bridge (26.75 mm for 53.5), then measure across to double check yourself.

Up at the nut, take your string positions and add 1/8″ on each side. Your outer strings do not ride the very edge of the fretboard. That little gap is what keeps them from sliding right off when you play hard.

Now join the nut to the bridge on both sides. There it is. That is the exact taper of your neck, and you did not design it. The measurements did it for you.

One more thing here. Past the last fret, run the board out another 1/4″ to 3/8″ and label it EF. Skip that margin and the wood will chip out on you when you seat the final fret.

Pickups

Measure the base plate, not the coils. A humbucker base plate is about 2 3/4″ × 1 1/2″. I route the cavity at 2 7/8″ × 1 5/8″ to leave room for paint, winding tape and general real world slop. The pickup should drop in and move a little without rattling around.

The spacing math

For the HSH layout on this build it works out like this:

• Two humbuckers at 1 5/8″ = 3.25″
• One single coil at 1.10″, so 4.35″ of actual pickup
• Space I have, keeping 1/4″ clear of the mounting posts: 5 3/8″
• 5.375 less 4.35 leaves 1.02″ of slack
• Four gaps to fill, neck, between, between, bridge, so about 1/4″ each

It comes out clean. If yours does not, that is the math telling you something has to give, and it is better to hear that now than after you have routed.

Why neck pickups sound the way they do

You will hear people say a 24 fret neck ruins the neck pickup by pushing it past some sweet spot. That is not really it, but there is something real underneath the myth.

The string moves the most right around the 12th fret. More movement means more output and more low end. A 22 fret neck just parks the neck pickup a little closer to that spot, and that is why it sounds warmer and louder. It is the same reason the neck pickup on pretty much any guitar sounds fatter than the bridge pickup. Nothing magic about it.

A word on routing shapes

You can buy pickup cavity templates from StewMac, LMI and plenty of others, which saves you cutting your own. The single coil is the fussy one to draw. Do not sweat the sharp inside corners, because a router bit is round and it radiuses those corners for you automatically. Do flatten off the point on the single coil shape though, since a real pickup is not sharp there. And do not forget the mounting ears on a humbucker. They stick out past the body of the pickup and they need room.

Body shape

Draw whatever body you want. Just respect three rules, and these are structural, not about looks:

1. Keep the upper horn forward. Set it too far back and the guitar neck dives, and you spend the whole gig holding the headstock up instead of playing.
2. Do not make the lower horn too shallow. If you do, you cannot get your hand in there to reach the top frets.
3. Never run the upper horn all the way to the end of the fretboard. That leaves the joint area weak and the neck will snap there. Around the 23rd fret is as far as I take it.

Controls

There are the usual conventions. Volume sits about 3/4″ to 1″ off the pickup edge, tone about an inch past that, switch past that. But where you actually put them is up to you, as long as you follow two rules.

First, draw the body before you place a single control. Not one knob goes down before the outline exists.

For a blade switch, the mounting screws sit about 1 5/8″ apart with roughly a 1″ slot between them. Nothing is final until you drill, so leave this loose and settle it with the body sitting in your lap.

The nut comes before the headstock

This order throws people, but it makes sense once you see it. Your string positions at the nut decide where the tuners go, and the tuner positions decide the headstock shape. So the nut has to come first.

Mark your nut thickness. A bone nut and a locking nut are not the same, so work from the actual part you are going to fit. With a locking nut you can stand it on its side and trace the slots right off it.

Run your string lines up past the nut, but keep them parallel to each other instead of following the neck taper. Label them. These are the lines you locate your tuners from.

Tuners

Two measurements come straight off the tuner:

• Hole size. I measured 0.387″ here, so 3/8″. Drill it a touch over, because finish builds up inside the hole and shrinks it. You want snug, not tight, not loose.
• Spacing. This is set by the width of the rear housing, not the post. 1 1/8″ on these. Get them too close and the tuners bump into each other.

A circle template from any stationery shop gives you a clean 3/8″ and has crosshairs for centring. Leave 3/4″ to 1″ between the nut and your first tuner.

Six in line, three and three, four and two, your call. On a three and three, offsetting the second row halfway between the first is a decent starting point, but physically set the tuners down and check they do not touch before you commit. On this build my first attempt collided and I had to redo it.

Headstock

Once the tuner positions are locked, the headstock almost draws itself. Measure out from the edge of the outer holes, 3/16″ here, mark those points, and run a curve through them with a protractor, then mirror it so both sides match.

I did not really design this headstock at all. With every position already fixed by the parts and the strings, the guitar drew it for me. Honestly, that is a fair way to describe this whole session.

Cutting the template out

You need two templates. A top one carrying the pickup routes, control positions, bridge route and neck pocket, and a rear one carrying the spring channel, the electronics cavity and any extra material at the neck joint. If you have not started drawing yet, shove the whole design off to one side of the sheet so you have room for the second template.

How I cut them

1. Bandsaw to within 1/8″ of every line first. Less material for the router to eat means cleaner cuts and your bits last longer.
2. Joint a scrap to a known straight edge and tape it down along your line with thin double-sided tape. Not the foam kind, that lets the piece shift on you.
3. Sacrificial piece underneath, everything clamped tight.
4. Flush trim bit with a bearing, riding the straight edge.
5. Two shallow passes, not one deep grab.

On bits and routers

Stay away from very long or very wide bits. They grab, chip, pull and throw the work. A bit with a slight shear angle cuts cleaner than a dead straight one. Feed direction matters too. One way the bit runs with the cut and leaves a rough finish, the other way it pulls into the work and cuts better, but that same pull is what can drag a taped down template loose, so pay attention.

And you do not need a fancy router for this. A cheap one does template work just fine. What you cannot do is build guitars without one at all, so if you buy one tool, buy that.

Finishing the edges

Drag a razor blade along the edge to shave off the paper thin fuzz the router leaves behind. That razor blade is probably the most useful cheap tool in my whole shop. Drum sander for the tight curves, hand sanding or a random orbital for the rest.

When you think you are done, run a finger all the way around the outline. Any dip, flat spot or weird transition you can feel now will show up on every single guitar you build off this template. So fix it now, while it is one piece of MDF and not fifty guitars.

Last thing, and I mean this, label everything

By the time you are done this board has dozens of lines on it, and half of them look alike. On this session I put a set of pickup ear marks down in the wrong place and did not catch it until the centring would not add up, purely because I had not labeled them.

Write on the board. Nut, bridge, mount, EF, strings, pickup, switch. It takes a few seconds and it is the whole difference between a blueprint and a puzzle you have to solve twice.