Question 27 QMED05 - Machinist-Pump Technician

The Correct Answer is C **Why option C ("using a depth stop") is correct:** When drilling blind holes (holes that do not go completely through the workpiece), precise control over the depth of penetration is essential. A depth stop is a physical collar or mechanism attached to the drill press quill (spindle housing) or handle that can be precisely set to halt the downward travel of the drill bit when the desired depth is reached. This mechanism provides the reliable, repeatable accuracy necessary to ensure the hole is stopped at the exact required depth without boring through the work. **Why the other options are incorrect:** * **A) gaging chuck motion:** The chuck holds the drill bit and moves directly with the spindle. Gaging (or manually monitoring) the chuck's motion is imprecise, relies on visual estimation, and does not provide a fixed, physical limit to the depth, making it unsuitable for accurate blind hole drilling. * **B) moving the working table:** Moving the working table changes the initial starting distance between the workpiece and the drill bit. While this is used for setting up the operation, it is not the method used during the actual drilling process to accurately stop the downward progress of the bit at a specific depth. * **D) adjusting the spindle return spring:** The spindle return spring is designed to lift the spindle and quill back to the resting position after the downward feed pressure is released. Adjusting this spring changes the force required to feed the drill and the speed at which it retracts, but it has no function in setting or controlling the maximum depth of penetration.