Official Luthiers Forum!

Hi to everyone. Although I’m not new to guitar building, I am new to your
discussion group as a member. I’ve been lurking in the shadows listening
to what you all have to say for quite awhile now (great wisdom abounds, I
must say). Those of you who are members of the New England Luthiers
group know me (though some might not admit to it).

So now I have a question. I’m building a jumbo guitar with a 25.5” string
length. I’ll be cutting the fret slots using an LMI template. Since they’re
machined so that any slot can be used as a zero fret, they use a double-
ended indexing pin, one end of which compensates for the blade width so
you can cut a zero fret. However, I have read comments from some of you
that suggest you shorten the distance from the nut to the first fret by as
much as 1/32”. If then, I make a new indexing pin I can accomplish the
same degree of compensation. Is 1/32” the magic number (sounds like a
lot), or is there some sort of formula someone has derived based on
string length?

And question 2. In the past I have used saddle compensation dimensions
for my dreadnoughts passed on to me 20 years ago by someone long
forgotten. Since this jumbo has a longer string length than my
dreadnoughts, does anyone out there have a formula/guideline for
determining the amount of compensation required from bass to treble?
Obviously, I’d like to avoid cobbling together some sort of temporary
adjustable bridge and then taking measurements. I keep hearing “Oh,
about 1/8” sounds good,” but I’d feel more comfortable with something
with more substance behind it. Of course, action height has a bearing on
this, but let’s assume this is a well-tuned guitar with a reasonably low
action.

I can’t wait to hear the flow of wisdom pour forth!JavaScript:
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seems this question got entered twice!