In a medium sized bowl mix flour, baking powder, sugar, cream of tartar and salt. Using a pastry blender, cut the butter into the flour until it resembles coarse crumbs. Make a well in the center of the flour mixture and add the milk. Stir with a wooden spoon until moistened. Turn the dough onto a lightly floured surface and quickly knead by gently folding and pressing the dough 10-12 times or until nearly smooth. Pat the dough out to 1/2" thickness. Cut into 3" biscuit rounds.