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hi on my first i used a fret board with a 12" radius and just assumed the saddle should have the same. now while getting close to finishing #2 i am looking at stewmac's site and none of the saddles have the same radiuses as the necks.

i am really happy with the action and playability on my first and i've played a lot of guitars in the last 25 years. what is gained by having the saddle at a different radius then the neck?

stewmac's gibson necks are 12" but the gibson saddles are 10" and their martin necks are 16" but the martin nuts are 20". why are they different and why are they different from each other?

this is one of those things i haven't seen covered in any of the books i have so any insight would be greatly appreciated!

many thanks!
-patch

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I think it's in there somewhere...

Most people specify action for the 1st and 6th string and leave the others to one's imagination. I find that if a saddle of the same radius as the fretboard is used, the 3rd and 4th strings are prone to fret rattle if hit with the same force as the other strings. So to even this out, I raise the action a small amount on the middle strings, which is the same as using a smaller radius at the saddle than is on the fretboard. Usually, the nut follows the fretboard on my guitars. You might find that a larger radius on the saddle is used on some compound radius boards to keep a basic conical geometry, but I find I still have to use a smaller radius than the theoretical conical one for the same reasons as mentioned before.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

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yes the should match.
I use the 16 in radius and the saddle , the radius us canted a bit so the action on the strings goes from 2/32 to 4/32.

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John Hall
blues creek guitars
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You Don't know what you don't know until you know it

I have always use the same radius, seems to make sense to me. Of course lately I've been doing a compound radius so that presents a different problem.

Using the same radius only makes sense if the fretboard is not tapered in width. This taper is the reason that a constant radius fingerboard should be coupled with a saddle with a slightly smaller radius. If you don't do this, the action is lower on the middle strings.
A compound radius fingerboard addresses this issue. I make my compound radius by hand. The 'formula' is simple....make the fingerboard uniform thickness on the edges. The thickness in the center is about 1/32" thicker, and is also uniform from end-to-end.

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John

Patch, I'd recommend not worrying about the radius. Set each string individually to a desired height over the 12th fret and let the radius fall where it will.

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Jim Watts
http://jameswattsguitars.com

If you have a cylindrical board, I would start with the same radius and adjust.

The goal is to get the action where you want it on every string and the final radius is irrelevant in my book. I use a compound board and I know the radius of my saddle is flatter than the end of the board but I've never measured it. I started by getting the action right at the 1st and 6th strings and making a smooth transition between based on 12th fret action of each string, not saddle radius.

edit: Jim, you beat me to it.

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+1 to what Jim and Kent said...

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what a great forum! to be able to ask a question and get such good responses from such serious builders is amazing.

this all makes sense thank you very much!

trevor, after i posted this i thought this was probably addressed in your book somewhere but it was way past my bed time to go digging for info.

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