Preheat oven to 425 degrees F (220 degrees C). In a large bowl, whisk together the flour, baking powder, salt, and sugar. Cut in the shortening until the mixture resembles coarse meal. Gradually stir in milk until dough pulls away from the side of the bowl. Turn out onto a floured surface, and knead 15 to 20 times. Pat or roll dough out to 1 inch thick. Cut biscuits with a large cutter or juice glass dipped in flour. Repeat until all dough is used. Brush off the excess flour, and place biscuits onto an ungreased baking sheet. Bake for 13 to 15 minutes in the preheated oven, or until edges begin to brown.