Official Luthiers Forum!

I am to the point of placing my bridge on my first build. Yah Hoo! The plan calls for a scale length of 24.75". Should I measure to the center of the corrected saddle? To the short point? I would assume this measurement is critical?

Mike

_________________
http://goatrockukulele.com

Hi Mike, Yes this is critical and it is very confusing too.
First you need to find out what your TRUE scale length is
Often a figure like 24.75 is nominal especially on gibsons.
So measure accurately from the face of the nut to the centre of the 12th fret and double it.
This is your scale length
Now go to the Stemac site and look under information and find the fret calculator.
Plug your measured scale length into the calculator choose acoustic and it will give you a length to measure for High e and low E.
Note that this measurement is to the middle of the slot width not the front edge.

Setting up the saddle position can be tricky. After all your intonation depends on it. Scale length is taken from the nut to the 12th fret. Now to get as good of an intonated guitar as you can double that figure and add 1/10 of an inch if you are using a 3/32 saddle. If you have 1/8 saddle ad 1/8 but do it along the line of the 1st string. This will allow you some compensation room. The bass of the 6th string needs to be 1/8" longer than the treble.
I have been building over 10 years and with 106 under my belt. This will get you as good as you can with a fretted instrument. The saddle will need to be compensated for your guitar. To do the initial set up , I am looking for a 1/2 string height at the front of the bridge. I also set the neck relief first. I want the relief to be between .004 and .010. Assuming you leveled the frets , you can start by roughing out the saddle. With a straight edge on 1st fret I want to gauge the height at the 12th fret. This is just roughing in so I want to have 4/64ths on the treble and 6/64s at the bass. Now you can do your nut. Start with the string spacing , and I work from the treble to the bass but it don't matter. Set the strings and you can start to file the nut slots. Here is where you can really help with the tone and voice of the guitar. The nut slots should be slightly radiused on the bottom. A steel string will not bend to a single point but will have a gentle arc to it. Plan for this so that the string will contact the front of the nut. If you do an angle , the string may not contact the very front of the nut but be just behind it and as a result , you may have a good intonation open but bad when fretted.
I also want the press the string down at the opposite side of the 2nd fret so I can see the clearance of the string from then nut to the 1st fret between the string and the top of the 1st fret. I shoot for .012 on the initial set up. Do that across the nut , and see how it feels. Once I have that set up I will complete the saddle.
Tune the string to open pitch and check the 12th fret intonation. You should have some room to compensate the saddle. In most cases I have to push the B string back a good bit. Much will depend on the action height , the higher the action the more sharp the string will become. Take your time and you should do well. 3/32 saddles are too thin in my opinion , I like to use 1/8 as it allows for more comp room and it won't affect the tonal voice. Also do not get too worked up over the break angle , as the string height has more to do with the power and voice of the guitar. The resultant force of the string to the top is figured by overall height and not just the saddle height to the bridge.
In a perfect setup you would like to see about 3/8 bridge 1/2 saddle.
Good luck.

_________________
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

Thank you for all this great and important information. I would not have been able to do it without you.

_________________
http://goatrockukulele.com

I second the Saddlematic, for the money it is a great tool.