Why Proper Spot Facing Matters Before Deep Hole Drilling
Why Spot Facing Is Not Optional Spot facing creates a flat surface at the hole entry point that is perpendicular to the drill axis. Without it, the drill enters a curved or angled surface and the tip deflects on contact. That deflection at entry starts the hole off-center. I have seen operators skip spot facing to save time. The logic sounds reasonable — why take an extra pass if the part surface looks flat? The problem is that looks are deceiving. A surface that appears flat to the eye can be 0.1mm out of perpendicular. ...