Kitara za na pot

Travel guitar is usually a short version of regular length guitar. In this case the strings are folded at the bottom and machine head is at the back. It is an electric guitar with a relatively wide fretboard (for my thick fingers) – basically a copy of the acoustic guitar that i have.

The final motive is simplicity and precision. Again the Cirkulacija 2 space proved invaluable for this project! CNC2 router was used throughout.

The idea came after a plan to have a performance of a project Herman & Savski in 2018 in Berlin – where one travels with a plane. Immediately a piece of material came to mind – the old rocking chair of my late mother. It was made of layered beech wood, bent everywhere and it seemed in good condition, so decision was made. Also: there were left and right sides – so: two identical guitars. Furthermore: idea of almost the mother’s bone used for a music instrument is quite archetypal!

Quite soon I became acquainted and said goodbye to quite a few puristic/ esoteric approaches about the sound of the material (of the electric guitar). The magnets to be used are two Coxx single core pieces that i have for some time. Piezo bridge pickup will be added later – to have an option to select a more acoustic sound.

Other decisions:
– there is no need for separate fretboard, since the beech wood is so hard
– truss rod has to be there, since the layered material is so elastic
– truss rod was put from behind the neck
– another truss rod was put to counter the tension on the lower (bridge) side of the guitar
– truss rods are simple 6mm threaded rods – fixed at one side to the wood
– i decided for a slight curvature of the fretboard (16inch)

I ordered some 25cm pieces of fret wire. It came out to be so-called “jumbo” thickness. Not ok, but ok. Distances for correct intonation were calculated here

http://www.liutaiomottola.com/formulae/fret.htm#mozTocId169477

and put into CAM and cur by CNC2. The site http://www.liutaiomottola.com has a lot of useful information.

The varnishing of the wood was the least puristic. I used thin transparent (no color) varnish for mechanical protection of the surface. A couple of times. The result was a bit folkish. We don’t want that. So I used thick ebony varnish, which at the moment does not seem to have been a very good idea. So, I scrapped the black and got to some nicer wood patterns on the fretboard. By smearing it with a cotton bud dipped in thinner i got quite rustic finish. Ok.

By miscalculation I ordered so-called jumbo fret wire – and not enough of it. So I ordered some more from another source. This time it was very thin fret wire. Well, one neck now has thin low frets, the other has thick and high jumbo frets. I will see the difference soon enough.

I then glued the neck and the bridge/ body – I couldn’t wait. The fretboard/ fingerboard is ok, the back needs still some sanding – as do the other parts. The machine head was also mounted – I know I will have to unscrew it – but now i need to see the whole.

For the strings coming from the back bottom, then around the bottom and to the bridge – I bought a PE (plastic) round rod of 40mm diameter . It is a low friction turn-around for the strings coming to the front side. I cut the length (67mm), then cut it in half – along the length. I will make channels for the six strings that will bring them to the right spacing for the bridge saddle.

The first string was strung…

One conceptual mistake: the PE provides low friction only for non-wound strings. The tension is not transferred equally for lower strings. I almost ruined the machines teeth. At least for the four wound strings i would need to provide wheeled transmission of string tension. I decided to have all six strings via wheeled transmission. Also: i had to turn the machines so that the tension of the strings pushes the spiral transmission system towards  the teeth – not away from the teeth.This was the reason for almost ruining the teeth.

Otherwise all is well. The two guitars are not identical anymore: one has a zero fret, the other has a bone nut. The two magnet pickups are fixed/ glued. The holder for electronics, battery, output jack and balance potentiometer (the set the measure of magnetic and optional piezo pickups – in the output signal) – is a piece of aluminium in a form of functional spiral.

The bridge is now in the process.
Then comes the evening of the frets…

more to follow…

 

Below are some notes copied from various sources on the net

SCALE LENGTH
guitar string length nut to bridge

Fender Duosonic = 22.5 inch (571,5mm)
Gibson Byrdland = 23.5 inch (596,9mm)
Fender Jag-Stang = 24.0 inch (609,6mm)
*mine acoustic = 24,53 inch (623mm)
Gretsch 6120/Duojet/Setzer = 24.6 inch (624,84mm)
Gibson LesPaul/SG = 24.75 inch (628,65mm)
Rickenbacker 330/360 = 24.75 inch (628,65mm)
Martin 000 = 24.9 inch (632,46mm)

NECK THICKNESS

there are three basic groupings in terms of thicknesses:
Super Thin: any neck with a 17-19mm thickness at the nut
Moderately Thin: any neck with a 20-22mm thickness at the nut
Meaty: any neck with a 23mm+ thickness at the nut

One last comment about neck profile: I prefer a “C” shape because it feels continuous and predictable, whereas a “D” shape has a noticeable flattening out that I can detect with my thumb.

modern oval flat (flattened at the bottom: D shape)
oval C shape (half sphere)

*mine = 20mm w/o back cover for truss rod – 21mm with it

BRIDGE
Guitar “E” to “e” String Spacing at Bridge (Narrow to Wide)

Rickenbacker = 1.98 inches (50.29mm)
Gibson Tuno-O-Matic = 2.0625 inches (52.45mm)
Fender Import Strat = 2.0625 inches (52.45mm)
Floyd Rose = 2.070 inches (52.58mm)
*mine acoustic = 2.1 inches (53.00mm)
Fender Jaguar / Jazzmaster / Mustang = 2.1875 inches (55.56mm)
Fender USA Strat = 2.21875 inches (56.35625mm)

NUT

Guitar “E” to “e” String Spacing at Nut (Narrow to Wide)
*mine acoustic = 1.555 inch (39.5mm)

FRETBOARD RADIUS

Most guitars have a single radius that is consistent across the length of the fretboard. On the small end of the spectrum, we have something like a 7.25” radius, which can be found on some vintage Fender instruments. On the large end of the spectrum, we have something like a 30” radius, which can be found on some classical guitars that aim to be nearly flat, but have a very slight curvature. Halo fretboards are typically in the range of 16” to 20”. We use a smaller radius on our relatively narrower necks and a larger radius on our relatively wider necks. For example, our 6-string guitars typically have a 16” radius

no radius -vintage classic
16 inch – modern electric/ classic + acoustic
12 inch – recent electric
9 inch – sixties – electric

*mine acoustic = 16 inch (406,40mm)

FRET POSITIONS

623.000mm fret scale

fret from nut      fret to fret
1    34.966mm 34.966mm (nut-1)
2    67.970mm 33.004mm (1-2)
3    99.122mm 31.151mm (2-3)
4   128.525mm 29.403mm (3-4)
5   156.277mm 27.753mm (4-5)
6   182.472mm 26.195mm (5-6)
7   207.197mm 24.725mm (6-7)
8   230.535mm 23.337mm (7-8)
9   252.562mm 22.027mm (8-9)
10  273.353mm 20.791mm (9-10)
11  292.977mm 19.624mm (10-11)
12* 311.500mm 18.523mm (11-12)
13  328.983mm 17.483mm (12-13)
14  345.485mm 16.502mm (13-14)
15  361.061mm 15.576mm (14-15)
16  375.762mm 14.702mm (15-16)

FRETS SIZE

The size of the actual fret wire installed in the fretboard makes a difference in feel. It is very subtle, but noticeable. Fret wire is available in a variety of different widths and heights. To simplify things, I’ll just say that there are three widths:
Narrow
Medium
Wide

And three heights:
Short
Medium
Tall

Narrow fret wire has two main benefits. The first is that it can provide better intonation over the lifetime of the instrument compared to wide fret wire. I would argue, though, that most people couldn’t hear the difference (I know I can’t) and some simple fret maintenance would make this a moot point.