When specifying hole bottoms, which is typically chosen for ease of manufacturing and seating?

• A. Cone-bottomed
• B. Flat-bottomed
• C. Dome-bottomed
• D. V-shaped bottom

Answer: (A)

Focusing on how the bottom shape of a hole affects assembly and manufacturability, a conical (tapered) bottom is preferred because it provides a self-centering seating surface and a guiding funnel for a mating cylindrical part or fastener. The taper helps parts align as they enter the hole and sit at a consistent depth, which speeds assembly and reduces the chance of misalignment or binding. It’s also easier to produce with common tooling: you can create the feature with standard drilling plus a simple conical finish, without needing precision flat-bottom finishing that can trap chips or require additional operations. In contrast, a flat bottom can be harder to align parts against precisely, a domed bottom offers less stable seating, and a V-shaped bottom concentrates stress and can snag parts during insertion. So the cone-bottomed option combines easy manufacturing with reliable seating.