Bread-Bakers v100.n046.4

I grind all of my flours for making breads, cookies, etc. both hard wheat
and soft wheat. Often I find a recipe that calls for all-purpose flour and
I am sure that I could combine the hard with the soft to achieve the
protein value of all-purpose but I don't know what proportions to use. Can
anyone enlighten me on this subject? Would appreciate.  Dick Carlton,
Brookings, OR