Official Luthiers Forum!

I know....this has been covered with a cheap suit....so I apologize. I have searched and searched but must be using the wrong terms or something.

I am closing in on finishing my first...an OM..with a 24.9 scale length. I am not comfortable enough with my own knowledge level to simply go outside tomorrow and place my bridge and saddle. In fact...I am not even sure as to how to determine the position of the two items.

If I measure from the nut to the 12th fret...do I measure to the leading edge of the fret or the center of the fret...and so on.

I have a read on here that the scale length should end up right at the leading edge of the saddle on the high E side....??

I ain't touchin it till I get a better handle on this. BTW for what it's worth...I have one of John Hall's center finding jigs...and it has the bridge locator thing on it.

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

I have to ask... How did you place the bridgeplate without knowing this already?

I'm a newbie and don't know what people use for compensation on a short scale but I do know you measure at the center of the 12th fret, that way it isn't dependant on fret width(the string should contact in the center anyway).

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Jeremy Douglas

Bridge plate ain't on yet...and it's not seeing glue until I know where the saddle is supposed to be.

Todd - I am in no way going to dispute what you said. I have had a whole list of problems with these plans since I started the build (Antes plans from LMI). I don't have a saddlematic....I do have some bar aluminum in the shop though...how would I make a 'saddlematic'?

If the scale is 24.9....is it REALLY 24 and 900 thou from the face of the nut?

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

Snig,

First, do you know how to set intonation on a guitar? If not, search that first. Once you understand that process setting the saddle position will become clear. So people have perfect pitch and can do this by ear, but the VAST majority use tuners, the better ones are better but any will work. Here is a link to adjusting intonation:

http://www.fenderplayersclub.com/front_ ... nation.htm

On an electric guitar you move the saddles back and forth, on an acoustic you role small round stock until your intonation lines up.

Your 24.9" scale length will be 24.9" plus at the high E string and increase in length, generally, for the next strings, meaning that your saddle will slat to a longer scale length as you towards the lower strings. Then you file the saddle for each string for fine adjustment.

Hope that helps!

Shane

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Canada

Ok
First work out your exact true scale length
Measure from the front of the Nut (side towards the fretboard) to the centre of the 12th fret.
Double this measurement and this gives you the true scale length
Check that this is your nominal 24.9 or not.
Now you need to work out the compensated string length
A good way to do this is to use the stewmac calculator using you true scale length from above
http://www.stewmac.com/FretCalculator/
This will tell you the measurement from nut face to the centre of the saddle at High and Low E strings

There are many ways to set the saddle location. There are a few things that you need to understand so you can see why things are done as they are.
1st scale length:
Scale length is a static dimension , this means it is set and won't change. In this case you have a martin short scale. 24.9
2nd Compensation Angle
This is the angle established on the bridge , this helps to compensate the scale length to the working length of the string
3rd Working Length
The string at rest is at its shortest length , when played the string will arc and as a result the length is in dynamic flux , or in plain words , constant change.
4th Compensation of Saddle
This is where we use the width of the saddle to fine tune the intonation of the instrument On Martins it is 3 degrees.
5 th Intonation
This is the ability of the guitar to play in key consistently up the neck.
6th Compensation Length
This is a little extra length that is figured into the equation so the intonation will be better. The working length of the string needs to be considered into the equation. This little extra will have a big impact and give some adjustability at the saddle for the final fine tuning and shaping the saddle for the final set up.

So what influences the saddle location , As you can see there are many factors that will have to be understood to get the best intonation on the guitar.String gauge will also play a part but here is a quick guide to get you into the ball park.
You need to know the center line of the neck in relation to the body .You can mark this out with tape and pencil . Take the line that the 1st E string will follow and to the front of the saddle you want to be 24.9 + .100 for . for a total of 25.0 then along the lower E ( 6th) you do the same and add the scale length 24.9 comp angle distance +.125 and add the com length .100. If you are planning on medium strings you can go .125 on the comp length. If you are using a 3/32 saddle. If you are using a .125 saddle just use the .100.
Once you place those 2 points you can set the bridge to that location. At this point you will get very good intonation along the neck and into the higher positions. Intonation on acoustics is often a trade off. Action height , strings gauge and physical properties will effect intonation. The human ear is more sensitive to a sharp note than a flat . Once I establish the position of the saddle I will drill a 3/16 hole through the top at the 1st and 6th pin hole and use these to help keep the bridge from torquing when gluing.
This should get you into the ball park and give you a good result. You can fine tune the intonation on the saddle and compensate the saddle to get intonation better , as you go higher up the neck the intonation is more difficult to control as the length gets shorter. Any mistake at this point will become more evident.
john hall
blues creek guitars

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Guys....that's what I needed. Thanks a bunch! It's all as clear as a bell now.

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

Yeh I almost got burnt on the bridge plate placement. I'm building a LMI kit and the Antes plans show a different bridge size than the one provided. There was about an 1/8" difference in the plans and actual placement of the bridge.

To locate the bridge plate you'll probably have to figure out the distance from the body joint to the plate.

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Jeremy Douglas

A nice way to locate your bridge plate is to make a "core template" Basically a cardboard reproduction of the fretboard with the 12th and 14th frets marked and extended down to end with marks at the soundhole center, front of the bridge, scale length, and compensated scale length. You can superimpose this on your top when gluing the bridge plate to verify the location. I usually like about 1/8" of bridge plate ahead of the bridge.
For locating the bridge I usually just butt a straightedge against the nut, mark the center of the 12th fret, and place a second mark at the compensation length. Usually about .12 to .15 depending on the scale. With a pre-routed 3" saddle slot that has 1/8" dropback treble to bass I put the straightedge on the centerline and line the compensated line on the straight edge up with the center of the slot. Using a 1/8" saddle I've never had a problem getting good intonation on very string. Good luck!
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.