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This has probably been covered but...

I am ready for bridge placement on a round shoulder dread at 24.9" scale and a 000 12 fret with 25.4". Let's start with the 25.4" scale first. Robbie O'Brien adds 2 mm to the scale length at the high E side. Stew Mac fret calculator hardly adds any compensation at all...

1) what do you add for compensation, 2 mm? ...or something else?
2) is the amount of compensation the same for the shorter 24.9" scale length?

Thanks - I'm wanting to go ahead and start finishing these two, so I need to mask the bridge location.

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Steve: Just had a look at Stew-Mac fret calculator and here are their figures.
25.4..................high e set at 25.489
24.9..................high e set at 24.987
Myself I have a story stick that I use and don't have access now. I also use a wide saddle which gives me a bit of latitude. But these figures seem OK to me.
Tom

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A person who has never made a mistake has never made anything!!!

Seems like string type, tension, gauge, and action would affect compensation amount.
I would like to know if these are factored in, and why the values are different from different sources?
Perhaps there's a standard set of strings the values are for?
Sorry I cannot answer your question, but I am curious about this.

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wah
Wah-wah-wah-wah
Wah

I used to agonize over compensation, measured dozens of guitars and found a lot of variability. Then I bought the Saddle-matic tool from StewMac. It indexes off the 12th fret and shows where the front edge of the saddle slot should be, regardless of long or short scale. I use it all time to check the intonation on customer's guitars as well as setting the bridge location for new builds and repairs.

I use light or medium strings, mostly John Pearse or D'Addario, and set action at 5/64" bass and 2/32" treble at the 12th fret.

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It will probably be alright.

+1 Some tools just make sense to buy. I've had great success with this tool.

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"I've been had again"
Tim Benware
Creedmoor, NC

FYI - I found this on the LMI website...

"Here is a formula that is applied to many standard steel string acoustics:

Find the point on the bridge that is double the length of the nut to the 12th fret and add 1/16" where the 1st string will cross the saddle and add 5/32" where the 6th string will cross. Mark a pinpoint on those two points then draw a line between the points. This will be the forward edge (not the center) of a ramped 3/32" saddle slot."

1/16" is 1.57 mm,close to 2 mm. It gets difficult to accurately measure this small. It appears that builders use various amounts of compensation. ...and there are different variables involved. I have been using the KMG Bridge Setter and the saddlematic. I have not had any problems with intonation on my builds, but after seeing Robbie O'Brien's video instruction on intonation I got me curious to learn more and see what others are doing. There is some interesting discussion on LMI's website...

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

For 25" or so scale steel string acoustics with fairly normal string gauges I shoot for:

then work the saddle from there. So far so good

Compensation is one of those things where there are a lot of ways to do it, because most of them don't really work. As evidenced by the fact that experienced players are well aware of intonation issues and fiddle the tuning to... well... compensate.


Gore/Gilet style nut compensation is the best system I know of. It's sort of like starting with the StewMac calculator values, but then moving both the nut and the saddle closer to the 12th fret until the total string length is just a bit over the calculated scale length. Low E is about 1.5mm longer than scale, high E is only .3mm longer. This, as opposed to using the StewMac calculator values directly, where the low E is over 5mm longer than scale!

Bridge placement should always be measured relative to the 12th fret, rather than the nut. Usually the nut is half a fret slot's width closer to the bridge than it "should" be (it actually helps intonation, though). And with nut compensation, it's 2 or 3 mm closer.

What else do you need...and OMG, it's free...

http://www.stewmac.com/FretCalculator

Be very careful when looking at compensation recommendations.
Some guys will give measurements to the front of the saddle slot whereas Stewmacs is specifically to the breakpoint of the string on the saddle, which can be the middle of the saddle thickness or slightly in front, to give some provision for adjustment.

I've been following the LMI formula.

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George :-)

Stewmac's saddlematic is used to measure to the "front edge" of the saddle not the string breakpoint.

http://www.stewmac.com/How-To/Online_Re ... matic.html

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"I've been had again"
Tim Benware
Creedmoor, NC

But the stewmac fret calculator gives a measurement as below

"Distance indicated is from the fretboard edge of the nut, to the break-angle of the string at the peak of the saddle"

See what I mean about confusing?

Using the stew mac numbers Tom provided (I didn't look them up to verify) they are very close to the 2mm Robbie offers.

Stew mac 24.9 scale high e 24.987
Robbie 24.9 scale plus 2mm (0.0787") = high e 24.9787

Stew mac is actually using more compensation. Is Robbie talking about the front of the saddle slot or the break point? Either way the difference is 0.0083" surely that is within saddle adjustment range.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.