Dewey,

I'm not questioning your methods or the quality of your work.

I'm merely saying that would an alternate/possible method to cut the radius of the knuckle be to make a mandrell (extended hinge pin if you will) attach it to your rotary table (set up vertically) with a tailstock to support it and machine it that way ???

I'm just suggesting this method for we mere mortals who may not be as good with a file, dividers and a square as you.

No matter how achieve your results please keep us updated as I find this project amazing.