I get how you grind the feet down to ensure a tangent curve to the blank on the top sides of the feet - primarily for thread wrap transition purposes... what grinding / finishing is necessary on the underside if any?
Logically, the underside would be free of imperfections and it's interior contour would be free of stress points against the blank...
I had asked Smitty the same question. No sanding is required on the bottom of the feet. Make sure you don't leave any sharp edges or burrs. It is important that the guide feet lay flat against the blank, this is done by simply bending them. I think one of the advantages of buying the guides at Rod builders is they needed no adjustment. The mail order house guides needed some tuning.
Smitty is Da'man for all things rod building and his flyshop is fantastic. He's got the V4's in stock as well as the Force Waterworks, flatwing hackles, top end rods including my favorite (starts with "S"), and I like supporting an environmentalist. CHeck out his save the whales poster :hehe: