Machinist Apprentice Level One Practice Test 2026 - Comprehensive Exam Prep

Holes made by drilling are not exact sizes in practice. A drill bit comes with a tolerance and the cutting process isn’t perfectly predictable—the bit can wander, wear changes its effective diameter, and the workpiece and machine can deflect slightly during cutting. All of these factors typically leave a hole that is a bit larger than the nominal bit size. For that reason, machinists don’t try to rely on drilling alone for a precise diameter; they drill a hole a bit undersize and then finish it with a reamer or boring operation to reach the exact size. Keeping the drill sharp, using the proper speed and feed, and ensuring the drill press is well aligned can improve accuracy, but achieving an exact size with drilling alone is unreliable, which is why the statement reflects how drilling is viewed in practice.