Tuesday, 9 August 2016

Calculating fret distances

My python 3 fret calculator You'll need some basic Python-fu to use my version but I've also included a link to another you can use, there are others online as well you can search for.

About 3 years ago I wrote this fret calculator for some fun while studying python programming.
There are a lot of these calculators online and Stewmac have one on their website.

If you are going to try and print my as yet untested Skeleton Ukulele then you'll need to get a fretboard and they come a little longer at the nut end for you to trim back to suit a tenor ukulele length. You will need to trim it back and have some way of knowing how much to trim. If the scale length is say 431 mm 17 inches the distance from nut to the bridge then the 12th fret will sit at the halfway point of  215.5 mm and the distance of the centre of the first fret from the nut will be 24.190 mm

I've allowed for 18 frets in this example but you only use the amount you want obviously.

Taken from the Stewmac website

431.000mm or 17inch fret scale
  fret    from nut    fret to fret  
  24.190mm  24.190mm (nut-1) 
  47.023mm  22.832mm (1-2) 
  68.574mm  21.551mm (2-3) 
  88.915mm  20.341mm (3-4) 
  108.115mm  19.200mm (4-5) 
  126.237mm  18.122mm (5-6) 
  143.342mm  17.105mm (6-7) 
  159.487mm  16.145mm (7-8) 
  174.726mm  15.239mm (8-9) 
 10  189.109mm  14.384mm (9-10) 
 11  202.686mm  13.576mm (10-11) 
 12*  215.500mm  12.814mm (11-12) 
 13  227.595mm  12.095mm (12-13) 
 14  239.011mm  11.416mm (13-14) 
 15  249.787mm  10.775mm (14-15) 
 16  259.958mm  10.171mm (15-16) 
 17  269.557mm  9.600mm (16-17) 
 18  278.618mm  9.061mm (17-18) 


Bridge placement for 431.0 mm scale length

Ukulele (Non-compensated bridge)
Measurement is from the nut to the "break-point" of the string at the peak of the saddle.

433.543mm (± 0.5mm)

Please note that these measurements are based on a mathematical formula for compensation as well as an average of what "plays in tune" for a variety of instruments. Variables such as string height (action) and string gauge can affect the intonation of an instrument, so you may need to slightly adjust the locations given.


When you have your fretboard you can check the true scale length from these results and if the measurements are not the same you may need to add or subtract mm until the measurements are the same.
I've checked the ones I bought and they are 17 inch scale length which is 431 mm

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