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Fret distance measurements - calling all luthiers

latestarter

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Nov 9, 2009
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Hi all. I have an interesting scenario.

I've a new fretboard on a LP Jnr, and I have cut the frets to the StewMac calculator numbers. The board has been glued on and and fretted.

Total scale measures out good at 628mm from nut front to saddles. The calc gives a 12th fret measurement (from front of nut) of 314mm.

Set it up, and every fretted note tunes sharp. Grab another LP I have beside me and measure to the 12th. I get 311mm. Grab an Explorer...also 311mm.

What's happened here? Are the online calc, which all give the same numbers, wrong?

Right now I staring down the barrel of a full fret removal, fill the slots, shift the inlays, recut slots different lengths and try and hide it all. In other words, I'm screwed.

Any help, advice, whatever appreciated.
 

renderit

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Jan 19, 2009
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10,951
How about moving the bridge?

Are the notes dead on in steps up the frets?

Fret measurements have been calculated for so long for everything there should not be any guesswork involved anymore.

That said I always did the math by hand and compared the results with others findings...
 

poor man's burst

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Oct 3, 2010
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421
If the 12th fret is exactly at half the string's length (nut to saddle), the guitar will be sharp. String's length should allways be more than twice nut to 12th fret distance. More or less depending on string's gauge, height, type and tuning. In my experience, if nut to saddle is 314mm, highE string's length should be around 630mm and low E string's length around 635mm for standard 10-46 standard strings.
 

latestarter

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Nov 9, 2009
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Cheers for the replies. Two things have become clear;

- Gibson may compensate for the anomalies we're talking about by making the 12th fret less than 314mm, so that's the 311mm. They still run out at 628.6mm ash full length tho.
- poor mans burst, you’ve hit the nail on the head...one needs to add around 2-5mm to the second length. I wonder this isn't discussed more? I feel like there should be a massive warning on the StewMac calculator?

Thanks so much for confirming pmb. Yes Ren, I can move the posts as the build is not complete. Still painful, but glad I've discovered it now.
 
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Sol

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Oct 26, 2001
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Don't Gibson use a scale length slightly shorter than 24.75 ?
 

latestarter

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Nov 9, 2009
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Don't Gibson use a scale length slightly shorter than 24.75 ?
I think what's going on is, they use 24.75 but they shorten the first half to deal with the physics. So, converted to mm (all I know), the 628 isn't 314 at the 12th, it's more like 311mm. Gibson knows this and places their frets at this point.
 

DOTMKR

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Oct 12, 2015
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Grant, when you play the twelfth fret and compare to open or harmonic twelfth what do you get? Can you move the saddles to make these the Same. You really don’t even need a mm ruler to place the bridge. Answer the above and I can help you further. Poor man answered perfectly though.
 

Sol

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Oct 26, 2001
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775
From an Internet search it would appear that over the years the scale length of Les Paul's has changed slightly, from 24.9/16 to 24.5/8 back to 24.9/16 again. Each is shorter than 24.3/4.
Could this be where some of the difficulties arise ?
 
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latestarter

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Nov 9, 2009
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4,173
Grant, when you play the twelfth fret and compare to open or harmonic twelfth what do you get? Can you move the saddles to make these the Same. You really don’t even need a mm ruler to place the bridge. Answer the above and I can help you further. Poor man answered perfectly though.
Hi there - being a wrap tail Jnr there are so saddles to move, and the grub screws weren't going to give me enough. I have already filled the holes and moved the inserts back. HEre's what I ended up with to get proper intonation.

Nut to 12th fret is 314mm.

12th fret to centre line on wrap tail, high E - 317mm, low E - 320mm. It is intonation now.

Bit of a mission! But you're right, the match wasn't making any sense...and as I mention, it seems like Gibson knows that and compensates.
 
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