Tuning a guitar, you know that in the build of the guitar is affected by the scale, and how well it was designed and implemented in a particular sample. As you know, the middle of a stretched string corresponds to the 12th fret. If the string is not "builds", so she has a different cross-sectional area at different sites, which is typical of worn strings.
The calculation of the scale of guitar craft with the special table. Correlating the characteristics of the scale of my guitar with the testimony of the table, you will receive, data relating to each fret and across the scale as a whole.
It is useful to recall what Mansur dealing with guitarists. The electric guitars it is 648 or 629 mm, classical guitar is 650 mm, and the guitars of Soviet production – 630 mm. Guitar scale length you can measure with a metal ruler, which is usually used by turners, as it is quite accurate. Suitable caliper. Proceed to the measurement. For example, when setting the scale of classical guitar the middle will correspond to the distance of 325 mm.
So add the zero mark metal ruler to the 12th fret and look at the zero fret. If the obtained distance is shorter than half the scale of about half a millimeter, then you're doing it right.
A very different picture will be on the lower nut. Here are the indications for each string will be different, because it affects not the size of the nut, and the point of touch on the strings. To customize the scale of it is very important to define them. The fact that the upper and lower nut is incorrectly placed relative to the frets, as that does not take account of the amendment.
If setting the scale for you is new, then follow the advice of professionals – it should only be done with new strings. Old strings even with accurate measurements will not give a good result. The same goes for frets. Worn frets are losing roundness, what touch will not fall on the center of the fret, which also leads to disruption of the calculation of the scale.