To improve my knowledge.. These are not homework questions :) 1. How does 'Trepanning' work and where is it used in the manufacturing industry? 2. What is the need for a 'Lip Relief Angle' in drills? 3. If 15-20 deg helix angle drills are called 'low helix angle' and 35-40 deg are called high, then what about 20-35 deg drills, are these classified as well? 4. What is the 'web size' of a drill? 5. Carbide drills are coated with Titanium Nitride (TiN). is there a particular reason for this? 6. In brazed carbide tipped drills, Tungsten carbide inserts are brazed onto the steel body of a drill. why this particular material? 7. Please explain the 'True Rake Angle' of a boring operation tool. HOW is it a function of side, back rake and lead angle? Also Id be grateful to find a diagram of these?