Padauk Headless 'Long Scale' Guitar Build

MARVlN

It's a working day and I've a deadline looming, so thought the obvious thing to do is start documenting a build that I began planning in July, and began building in August.

The main thing I was aiming for was versatility

• Both magnetic and piezo pickups
• Onboard active three-band EQ preamp for the magnetic pickups
• ~31" scale length for tuning to C#, providing Eb, D and E tunings by moving a capo, whilst ensuring that E standard is my preferred ~26" scale length.
• LED fretmarkers to support the changeable tunings
• Drop D tuner
  
• Fanned fret (a relatively mild fan, a-la Strandberg). For the E scale length, this is about 26 - 26.5" with a neutral (i.e. perpendicular) zero fret

Then from a styling point of view, I'd gained a real liking of Padauk as a wood (and not as a chocolate bar) - it's a lovely red hue that changes with age. I decided to make the guitar from a single block of Padauk, and use that opportunity to carve a more 3D body than is normal for guitars - most are essentially 2D.

These requirements took a bit of thinking about, so led to some experiments with the bridge and markers first and foremost - there's no commonly available headless bridge that has Piezo saddles (certainly not at sensible money), so I would need to make my own. The dot markers have been a bit of an experiment for me in the past, with little success. This time programmable LED markers felt like the natural step, but would require a micro controller, and careful integration with the neck.

A lot more to come - I have something relatively guitar shaped at the moment. For now, here's the preliminary sketch of the body:

WezV

This looks like it will be a lot of fun!

Roland

I love builds which have purposeful design features. This is going to be interesting. 

MARVlN

Thanks both - I'm not sure 'fun' is what the build has been so far (I jest...), but as always it's a great learning experience. This is build #4...

MARVlN

Time to update - it's another busy day at work, but a meeting has just been cancelled...

First off, a look at the piece of timber - it's a pretty chunky thing, sawn more or less on the quarter (I've got enough left over to probably do 2 more necks). Gorgeous colour and grain.

Next up was to test the bridge philosophy. Anyone familiar with headless bridges knows that they generally consist of:

• a threaded piece of tubing, that the string runs up, but holds the ball end
• an adjustment nut, that threads onto the threaded tube
  
• an outer tube, to provide structure, to prevent the inner tube from turning (usually using a screw on a ground flat surface), and somewhere for the adjustment nut to act against - opposing the string tension.

As the nut is tightened, the inner threaded portion is pulled outwards, bringing the ball end of the string with it, increasing tension on the string, and therefore raising the pitch.

Most headless bridges have an integral saddle (I think the main exception is the Steinberger bass bridges which seem to be in two parts), which is where integrating piezo is a bit difficult as they are usually a pretty non-standard design.

My idea was to rotate the adjustment parts through 90°, so that the adjustment nuts are accessed through the back of the guitar. This avoids the 'arse crack' that some refer to with headless designs, but also allows for a more traditional bridge and saddle arrangement, as essentially we've got a 'through stringing' setup.

The amount of movement actually required to bring the string to tension is very small, so most headless bridges only have about 15mm of usable adjustment - easily accomodated in an average guitar body.

I tested the theory roughly in an old piece of ash. This was v1, which is changing slightly (writing in the past tense makes this easier) based on these lessons - but the basic concept is still the same.

The tuner 'assembly':

The inner threaded tubing has a ground flat along most of its length. The flat-point M4 grub screw is deliberately long, and acts on this flat, first to capture it in the outer tubing, second to prevent the inner tube from turning when adjusting the tensioning nut (not shown), third, to prevent the whole assembly rotating in the wood.

In situ:

This is a shot 'from the back' of the 'body' (scrap piece of wood)

How much adjustment is available (this is overkill, and the actual nut will be a touch more usable):

String to tension:

Bit of a Heath Robinson set up, but it managed to go to tension (and you can see how little adjustment was required to do so from the exposed thread).

With that proof of concept, I finalised the design, got my jigsaw out and set about cutting out the blank. The various designs have been overlaid on the top here:

Next update will be less wordy and more picture-y, hopefully!

Chris.B

Fascinating - I'm looking forward to seeing this project progress into a finished guitar.

WezV

that wood looks great, did cutting it out leave you looking like an Oompa Loompa?

MARVlN

WezV said:

that wood looks great, did cutting it out leave you looking like an Oompa Loompa?

It certainly did later when I got out the disc sander - the basement looked like I'd painted every horizontal surface orange, and that was with a dust extractor!

MARVlN

Next step, routing the truss rod cavity and making the fretboard. This includes working out how the LED markers will be integrated.

Lovely piece of streaky ebony, enough to do the 'headstock' as well as the 25 fret board.

Cut the outline roughly with my little bandsaw cleaned the sides with a plane and then sanding beam, then taped my printed fret slotting template in place and cut the fret slots using a fret slotting saw and an aluminium fence as a guide.

Next, I wanted to experiment with how to get the LEDs to shine through. I'd made two previous attempts, one was by running optical fibres down the fretboard, giving side dots only. This requires routing away channels for the optics to sit in. The difficulty is in the transition from fretboard to neck to body (where an LED would be located). The other attempt was embedding LEDs in the fretboard, similarly relieved to accommodate, then running the wires down. The transition was again difficult, but easier as I only had to transfer electricity... I did complicate matters by wanting the right dots to light up based on the key/capo position, meaning a complex wiring job and lots of fibres or LEDs.

Anyway, I decided to make my life a bit easier by embedding addressable LEDs in the neck. This simplifies the wiring, allows me to use a microcontroller (like an Arduino) for LED control, and gives more room to work.

All I needed to do was get the light from the LED in the neck, through the fretboard.

My original idea was use a fibre optic across the board parallel to its fret, in a channel that would leave a half-moon of fibre optic once sanded. A hole through the fretboard lining up with the LED would then allow the light to enter the optical fibre and refract to the ends, acting as dot markers on the top and side simultaneously.

Practiced on an old fretboard, ruined by my last LED attept. Summary - fiddly to route (see wiggly slot to right), hard to ensure a constant shape/thickness, and it didn't light up very well.

Thought for a bit, then had a brainwave - drill two intersecting holes - one on the side and one through the board. Embed optical fibre in both. LED shines into the hole and light is produced from both optics.

Success! Good even light and looks pretty cool too in my opinion.

MARVlN

Time to get closer to finishing that fretboard.

First I needed to drill the dot markers, and I used the opportunity to mark precisely where the LEDs would need to be, by drilling through the board into the neck.

With that done, I marked the LED locations in pen, then routed the LED channel and truss rod channel. To get a more stable surface for the router, I used the 'negative' of the body as support.

Next step was to drill the side markers. My pillar drill is very small and cheap, and accuracy isn't its (or, frankly, my) forte, so to give it a fighting chance I used a levelling beam as a vertical fence to at least attempt to get a consistent distance from the faces of the board. The side hole just needs to intersect reasonably with the through hole. Thankfully that worked pretty well.

I'm using 3mm optical fibre, which I glued in with superglue (not all material is safe to use with superglue apparently - so always worth a test first!). After cutting I sanded the inside ends of the fibre up through the grits and polished to ensure the light would be as unimpeded as possible. I then slightly undid this by trying to fill the void with superglue. Thankfully the end result is still good.

Here I began to work on the headstock, and a channel for the nut (only used for string spacing as there's a zero fret). Forstner bits to remove as much material as possible.

Then out with the chisels, remembering that whacking a chisel along the grain is liable to cause splitting. Nothing that the use of some wood glue and clamping can't fix...

Next up, sanding the radius of the board. I've gone with a 10-16" compound radius, done the imprecise way, with a 10" radius block at the head end, and a 16" at the body end, then blending the two together using sanding beams along the string paths. Seems pretty even thankfully, and the compound is definitely there. Also levels the dot markers nicely - when unlit they blend in pretty well into the ebony.

Lastly, I soldered up the 25 individual LEDs (6 connections each - and each one is about 7x4mm...) and laid them into their channel.

Looks neat, didn't work (only up to about LED #6 worked...). Turns out my soldering skills weren't quite up to this level of fine apparently. Couldn't work out where the issue lay either.

Bugger. Time for plan B.

Chris.B

Thank you for documenting this fascinating build.

Good luck with the LEDs and soldering.

axisus

Fascinating build!

I put LED's in a neck - bloody difficult job! No controls for mine but I wired them to follow your hand up and down the fretboard.

MARVlN

Thanks both! Thankfully I'm writing this about 2/3 months down the line, so I know the LEDs work out in the end...

@axisus, that sounds really cool - proper lightshow. How do they work? Completing a circuit when fretting or sensors or?

axisus

MARVlN said:

Thanks both! Thankfully I'm writing this about 2/3 months down the line, so I know the LEDs work out in the end...

@axisus, that sounds really cool - proper lightshow. How do they work? Completing a circuit when fretting or sensors or?

Yeah, frets complete the circuit. Glad that the LEDs are working!

I have a status bass with amazing LEDs, run by a GB basses circuit. There are various flashing programmes. 

MARVlN

axisus said:

MARVlN said:

Thanks both! Thankfully I'm writing this about 2/3 months down the line, so I know the LEDs work out in the end...

@axisus, that sounds really cool - proper lightshow. How do they work? Completing a circuit when fretting or sensors or?

Yeah, frets complete the circuit. Glad that the LEDs are working!

I have a status bass with amazing LEDs, run by a GB basses circuit. There are various flashing programmes. 

Would love to see that. When researching this build I did come across some system where you stick paper-thin LEDs to the fretboard for showing scales and things called Fret Zealot. Not great as a dot marker, but can do some cool things it seems. Built in always better though.

Love a Status. I still find it quite weird how despite a much smaller market bass has all this forward thinking tech that seems to be incredibly niche (at best) in guitar. My first LED attempt was on a bass. I play it even though the dot markers don't work (so essentially there are no fret markers). Makes you learn by feel quickly! Might try a fretless build next...

DartmoorHedgehog

Interesting project. I hate playing with a capo - have to force myself not to look at the neck because my brain latches onto the dots in the "wrong" places.

But mostly I just can't get over how orange that wood is  

MARVlN

DartmoorHedgehog said:

Interesting project. I hate playing with a capo - have to force myself not to look at the neck because my brain latches onto the dots in the "wrong" places.

But mostly I just can't get over how orange that wood is  

Ah, but that's what the LEDs are for - the dot markers will change position with the capo on! As I have exactly the same issue as you, which is why I liked the idea of the Steinberger Transcale, but the dot markers in the 'wrong' places would be such a mindf**k that I simply had (i.e. was forced, honest) to do my own.

And yes, it's very orange. Some oil will really add depth - there's some lovely grain. I've always been cack at spray painting, so finding a pre-coloured wood is very up my street.

Roland

MARVlN said:

… When researching this build I did come across some system where you stick paper-thin LEDs to the fretboard for showing scales and things ...

The idea of “showing the notes you can play” doesn’t fill me with enthusiasm because that traps you into a particular scale. However changing the fret markers to suit the capo position has potential.

DartmoorHedgehog said:

… I hate playing with a capo - have to force myself not to look at the neck because my brain latches onto the dots in the "wrong" places. 

Don’t think of the capo as a transposing device. Think of it as an extra finger for barring.

DartmoorHedgehog

MARVlN said:

DartmoorHedgehog said:

Interesting project. I hate playing with a capo - have to force myself not to look at the neck because my brain latches onto the dots in the "wrong" places.

But mostly I just can't get over how orange that wood is  

Ah, but that's what the LEDs are for - the dot markers will change position with the capo on! t.

I know - when I read that's what you were doing I immediately thought "ooh - that's what I need" (or just don't look at the dots!)

Roland said:

Don’t think of the capo as a transposing device. Think of it as an extra finger for barring.

I very rarely use a capo - it's mostly because somebody gives me a chord sheet in C and says "we sing this in G" (I do a bit of playing for an "old folks singalong" and it's amazing how many songs they come up with that I've never heard). So for me it's literally a transposing device and my brain is "thinking" the written key.  I probably shouldn't be thinking this way - and I do sometimes find it easier just to transpose in my head if it's not too complicated a tune.  The only thing I actually play that uses a capo other than just for transposing is the Detectorists theme (partial capo on all but bottom E).

My daughter's more of a "singer songwriter" type and hardly ever plays _without_ a capo - doesn't bother her at all.

MARVlN

It's the 'not enough time before bed to do something truly useful so I better brain dump on any poor sod reading this thread' time. Known as NETBBTDSTUSIBBDOAPSRTT for short.

Next up is transferring the design onto the body and having a go at bridge Mk1.

Marking up an ebony blank:

Not shown, meticulously measure and clamp the blank in position to drill along the diagonal lines for the saddle screws.

Drill to remove as much material as possible:

Tidy with chisel (you can see the saddle screw holes which have magically appeared) and drill string and piezo wire holes:

Next, route the channel for the piezo wiring underneath the bridge, and start work on the pickup route. I've removed material with forstner bits to start. I'm going off-piste with the pickup mounting too. I've chosen some Hosco Wide Range Humbuckers, but won't be using the mounting tabs conventionally. More on that when I actually took some pictures of that plan. The guides (wooden block and sanding beam) clamped either side are to prevent the router from doing the ears of the pickup template.

Scary bit up next. Padauk is a lovely wood, nice to work, but is quite dense. Not dreadful, but lightening is the order of the day. Always a part of the design, now it was time to stick a big jigsaw blade through the body.

No going back now!

Lastly for this update, routing the channels for a pair of carbon stiffening rods. With the LEDs removing effective material I felt it might not be a bad idea, especially on a very long neck.

They're nearly even and straight too, which is frankly impressive for me. Certainly considering there wasn't exactly much clearance either side for the bass side one.

BigMonka

That is going to look proper epic, great build!