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PostPosted: Wed Feb 06, 2019 4:44 pm 
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I’ve been using the Stew Mac Gibson fret scale for laying out the fret locations.
I noticed on their website they state the positions were derived by measuring many guitars.
I belive Gibson used the rule of 18 for the fret locations instead of the more exact 17.82 number.
I’m wondering if the intonation is off on the scale?
Any insight?

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PostPosted: Wed Feb 06, 2019 6:39 pm 
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17.82 is commonly referred to as the rule of 18....

And Gibson has a bunch of scale lengths, the most common of which is 24.75 (or thereabouts).

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These users thanked the author Chris Pile for the post: dzsmith (Wed Feb 06, 2019 9:38 pm)
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PostPosted: Wed Feb 06, 2019 6:45 pm 
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There was an article in AL a few years ago about the three main changes in Gibson's 24-3/4 scale. I'll see if I can find it.



These users thanked the author Freeman for the post: dzsmith (Wed Feb 06, 2019 9:39 pm)
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PostPosted: Wed Feb 06, 2019 9:39 pm 
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Chris Pile wrote:
17.82 is commonly referred to as the rule of 18....

And Gibson has a bunch of scale lengths, the most common of which is 24.75 (or thereabouts).


I believe Gibson used the literal 18 to derive the fret locations?
24.75 / 18 = first fret slot.

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PostPosted: Wed Feb 06, 2019 9:42 pm 
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Freeman wrote:
There was an article in AL a few years ago about the three main changes in Gibson's 24-3/4 scale. I'll see if I can find it.

Don’t go to too much trouble Freeman,
I doubt my marking and cutting is very precise.
Just wondering if the scale is based on antique or modern calculations.
Dan

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PostPosted: Wed Feb 06, 2019 10:49 pm 
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Chris Pile wrote:
17.82 is commonly referred to as the rule of 18....


That's not quite true from what I understand. 17.82 is the more ideal number which is the 12th root of two. 18 is a close approximation to the more ideal 17.82 but they are distinctly different beasts.

Rule of 18 fretboards intonate differently than 12th root of 2 fretboards. I have a couple clients that vintage-ise new Gibson LPs to vintage spec and the fretboards I cut for them are slotted to a 24.75" scale calculated using the rule of 18 as opposed to the 12th root of two and the frets definitely don't line up between the two.

Some examples.

1st Fret: 1.389 for 2^1/12 but 1.375 for RO18

12th fret: 12.375 vs. 12.285

21st fret: 17.392 vs 17.298

Definitely different beasts and you can hear the difference.

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These users thanked the author Andy Birko for the post (total 2): dpetrzelka (Wed May 22, 2019 9:14 am) • dzsmith (Thu Feb 07, 2019 10:20 am)
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PostPosted: Thu Feb 07, 2019 8:16 am 
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Gibson has used at least 3 different variations of the 24.75" scale... The shortest actually measuring just over 24-9/16" true scale. True scale is double the length from nut to 12th fret. and has no bearing on actual divisions used to obtain scale....

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PostPosted: Thu Feb 07, 2019 9:33 am 
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Some frets are going to be sharp or flat no matter what method to place them.

As Andy wrote, there is a different placement at the first (and other) fret with different methods of scaling.




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These users thanked the author Ken McKay for the post: dzsmith (Thu Feb 07, 2019 10:21 am)
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PostPosted: Thu Feb 07, 2019 12:00 pm 
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Quote:
I believe Gibson used the literal 18 to derive the fret locations


They surely weren't stupid enough to take that literally....

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PostPosted: Thu Feb 07, 2019 12:04 pm 
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Chris Pile wrote:
Quote:
I believe Gibson used the literal 18 to derive the fret locations


They surely weren't stupid enough to take that literally....


Yes, they were as well as just about everyone else who didn't have a calculator.

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These users thanked the author Andy Birko for the post: dzsmith (Thu Feb 07, 2019 2:45 pm)
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PostPosted: Thu Feb 07, 2019 12:14 pm 
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dzsmith wrote:
Freeman wrote:
There was an article in AL a few years ago about the three main changes in Gibson's 24-3/4 scale. I'll see if I can find it.

Don’t go to too much trouble Freeman,
I doubt my marking and cutting is very precise.
Just wondering if the scale is based on antique or modern calculations.
Dan


Well I couldn't find the article. As I remember one of the changes was going from 18 as the divisor to 17.8xxxxx (whatever the 12th root of 2 is) but there was another change and I don't remember why they did that.

While I was digging in old issues I did run across three or four different articles talking about better fret locations to help deal with string stiffness and all those other little frustrations. Next time I build an electric I may move some frets and compensate the nut...



These users thanked the author Freeman for the post: dzsmith (Thu Feb 07, 2019 2:45 pm)
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PostPosted: Fri Feb 08, 2019 2:08 pm 
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Guitars are frustrating if you don't just pick a method and stick with it.


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PostPosted: Wed May 22, 2019 1:31 am 
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https://www.youtube.com/watch?v=0yCLckbp8ps

This is a great explanation of scale length - Martin vs. Gibson.

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