- Strähle construction
Strähle's construction is a geometric means of approximating the placement of
lute ,viol , andguitar fret s.It was proposed by
Daniel Strähle in the1743 Proceedings of the Swedish Academy. Academy secretary and founding member, economist, and geometerJacob Faggot appended an analysis which showed the error to be about five times what was musically acceptable. So Strähle's construction was ignored until1957 whenJ. M. Barbour ofMichigan State University showed Faggot's error was about 10× the truth. (By that time readily-obtained precision scales made the method unnecessary.)The method: Draw AB roughly the intended neck length. Construct an isosceles triangle ABC with AC=BC=2AB. Divide AB into 12 equal parts. Place D on AC so that AD=7 if AB=12. Extend BD to E so that BD=DE. The guitar must be sized so that the nut is at B and the bridge at E. A fret is placed where each division-point of AB then projects through BD to C .
The method places the top 12 frets. Further frets are placed by bisecting from those.
References
*Ian Stewart, Another Fine Math You've Got Me Into, chapter 15
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