Half Dovetails

Hello, lm buiding log cabins and am using milled 'D' Logs 7 1/4" tall and 5 3/4" at their widest point.
l have no idea what the dimetions/angles are is there a rule of thumb to follow?

Much appreciated

Mark....

Blasphemy onthe milled logs! Kidding of course. For my hewn log abode I use a 1:3 ratio for the notch.1" rise for 3" run. I think this is pretty standard.