Mandolin bridge buzzing problem

Hey everyone, I'm sure this is an elementary problem for any half decent luthier, but it's hard to find this info so here it goes: I'm making a new one-piece bridge from scratch out of ebony and I'm not sure how to fashion the angle on the top where the strings rest to keep them from buzzing against the top of the bridge. I'm not even sure it's the angle of the bridge-top, perhaps it's that the strings rest in shallow grooves (of course just the weight of the string will make grooves) but all I know is something in my configuration makes the strings vibrate against some part of the bridge-top. Any ideas?

Groove about 1/2 string diameter for the wound strings. Angle splits that between the long sounding run and the angled to tailpiece afterlength. Hold fingertip on string at bridge top and pluck to see whether buzz still there. If it is, isn't the string on the bridge.