Quote:
Originally Posted by runamuck
Does anyone know how far a fret can be installed inaccurately before intonation becomes an issue?
Idle curiosity is my only reason for asking.
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I the early 1980's, I put together a formula to calculate it. By the late 1980's I realized the formula was wrong and never bothered to correct it.
It shouldn't be difficult to calculate. Set the allowable error at, say, 2 cents (2/100 semitone), each fret is 100 cents apart, distance is inversely proportional to pitch, measured from the nut, each fret location is length from saddle to previous fret - (previous fret length/twelfth root of two)]. Easy enough to manipulate those to determine what distance yields 2 cents out.
The amount one can be out and still be within the target cents is proportional to the fret spacing - it gets smaller the closer the frets are to each other. It isn't a static number.
Practically, the answer is, "As close as you can get it". As others have pointed out, there are a number of factors that go into "good" intonation: fret accuracy is just one of them. Perfectly positioned frets with poor nut and/or saddle compensation - the norm - is more likely to result in poor intonation than a fret being more than 1/2 mm out of position.