Your tonsils are gland-like structures in the back of your throat. You have one located in a pocket on each side. Tonsils are made of tissue that contains lymphocytes -- cells in your body that prevent and fight infections.onsil stones, or tonsilloliths, are formed when this trapped debris hardens, or calcifies. This tends to happen most often in people who have chronic inflammation in their tonsils or repeated bouts of tonsillitis.
A self-centering chuck, also known as a scroll chuck, uses dogs (usually called jaws), interconnected via a scroll gear (scroll plate), to hold onto a tool or workpiece.
2. Position the metal roofing into the desired location. Insert the head of a self-tapping metal roofing screw into the bit on the end of the drill. Hold the drill so that the length of the screw is perpendicular to the metal roofing, and press the tip of the screw against the metal roofing. Depress the trigger on the drill and drive the self-tapping screw through the metal and into the wood below.