Please let me pick your brains once more!
Wondering how you all radius your saddles and how much you vary from instrument to instrument. Seems there's three different options, and I've seen them all. 1. Match radius to fingerboard. 2. Radius is slightly flatter than fingerboard. 3. Saddle is slightly tighter radius than the fingerboard.
I guess most of us would opt for a flatter (or completely flat) saddle for slide setup. But, ordinarily, which do you chaps tend to go for, and how and when you do something different?
Assuming a cylindrical finger board and not a compound radius, I generally make my saddle radii a bit tighter than what I measure on the finger board. It seems as though I have more trouble with the D and G strings having buzzing issues with a matched radius, when doing a low action set up. The tighter radius gives those two strings just a bit bit more wiggle room and usually does the trick. I never go flatter unless I have a compound radius I need to make or modify a saddle for.
Assuming a cylindrical finger board and string spacing wider at the saddle than the nut, the outer strings will have higher action than the inner strings if you match the saddle radius to the fingerboard. To equalize the action across the fb, you need to flatten the saddle radius. The difference is not dramatic, for my ES-175 with a 12" radius fb, I calculated the saddle should be 12.6".
True that the string spread at the saddle creates a very slight compound radius on a cylindrical finger board. I set the outer E string action where I want them and the center strings land along the curve of the saddle. If saddle shape was the only variable in setting action, I would probably be advocating just using the finger board radius. However, the shape of the finger board and the levelness of the frets, the playing plain, have to be taken into account. If this is not part of the scope of work, then I get more consistent, buzz free results, slightly over arching the saddle. We are splitting hairs with action possibilities, the saddle is one link in the chain.