Guitar fret slot positioning

Scripting
1

I’m relatively new to python, and have started learning for the above reason.

I want to be able to model guitar necks (and then cut on a CNC router) relatively quickly, but most of all accurately (which is where the scripting comes in)

The fret slot distances use a constant (17.81…) divided by the string length which is repeated 22+ times with an ever shortening string length. Online I have found a python version of a trusted calculator and was wondering if anyone had tips/ideas on connecting the mathematics in said calculator to something like rs.addpoint (or addline) to create an array of points/lines in the correct spacing.

Below is the fret calculator script.


# From Stewmac
# To calculate the scale length for stringed instruments

# Notes on fret layout
# The most accurate way to lay out your scale is making all measurements
# from the nut (using the "fret to fret" distance only to confirm your layout).
# Laying out frets only by measuring fret to fret will compound error.
# For example, if you're laying out frets by marking with a scribe and your
# accuracy is plus or minus 2 millimeters, you could be off by as much as
# 24 millimeters at the 12th fret.

# Measurements are given from the end of the fingerboard (face of the nut)
# to the center of a fret slot.
# WRITTEN FOR PYTHON 3.3.2
#--------------------------------------------------------------------

Im = ''
const = 17.817 # Do not change this

def fretCal(ScaleLength, nofret):
    '''(number, number)-> float
    Calculates the fret positions for any stringed instrument
    Given 'Scale length', 'number of frets' in inches or mm
    >>> fretCal(19, 18)
    Fret 1 from nut 1.066 inches
    Fret 2 from nut 2.073 inches
    ............................
    >>> fretCal(635, 22)
    Fret 1 from nut 35.64 mm
    Fret 2 from nut 69.28 mm
    '''
    if ScaleLength < 99:
        scale = ScaleLength
        Im = 'inches'
    if ScaleLength > 100:
        scale = ScaleLength
        Im = 'mm'

    for i in range(1, nofret +1):
        ScaleLength = ScaleLength - (ScaleLength / const)
        print('Fret', i, 'from nut',round(scale - ScaleLength, 3),Im)

#--------------------------------------------------------------------

Hope someone can help!

Oliver

2

Hi Oliver,

Perhaps I don’t fully understand your project. If your goal is just to quickly and accurately create a set of points or lines in Rhino spaced accurately for fret scales one simple way is to generate the series one time for a scale length of 1 and then use “scale” to the desired length. Really no need to recalculate every fret location each time. But perhaps you have something more elegant and automated in mind.

3

It’s all there- with minor mods it does what you want. I’ve enclosed the working version.

StringedFrets.py (2.1 KB)