What type of cutting tool creates round holes most effectively?

The most effective cutting tool for creating round holes is the drill. Drills are specifically designed for generating circular holes in various materials. They feature a pointed tip that helps to pierce the material at the center of the desired hole, allowing for efficient cutting as the drill rotates. The spiral flutes of a drill bit help to remove the material and evacuate chips away from the cutting area, facilitating smoother and faster drilling.

While other tools mentioned can create holes, they are not primarily designed for this purpose. An end mill is typically used for milling operations, which involve creating flat surfaces or complex profiles rather than round holes. A reamer is used to slightly enlarge and improve the finish of an already formed hole, ensuring precision and better tolerances, but it does not create holes from scratch. A lathe tool is used for turning operations to produce round shapes from a workpiece, but it is not suited for drilling holes directly. Therefore, the drill stands out as the most effective choice for creating round holes.