Which feature is placed to seat a bolt head or nut by creating a cylindrical recess around a hole?

Which feature is placed to seat a bolt head or nut by creating a cylindrical recess around a hole?

• A. Detail View
• B. Through Hole
• C. Counter Bore
• D. Half Section

Answer: (C)

Creating a cylindrical recess around a hole to seat a bolt head or nut is done with a counterbore. A counterbore forms a flat-bottom cylindrical pocket coaxial with the hole, so the head of the bolt or a nut can sit flush with or below the surface. This feature is different from a countersink, which creates a conical opening to seat a screw head, and from a through hole, which is just a hole that goes completely through the part. A detail view or half section doesn’t add a seating recess; they’re drawing or view tools, not features that create a seating cavity. For proper use, the counterbore is specified by its diameter (to accommodate the head) and its depth (to match the head height), ensuring the fastener sits correctly.

Creating a cylindrical recess around a hole to seat a bolt head or nut is done with a counterbore. A counterbore forms a flat-bottom cylindrical pocket coaxial with the hole, so the head of the bolt or a nut can sit flush with or below the surface. This feature is different from a countersink, which creates a conical opening to seat a screw head, and from a through hole, which is just a hole that goes completely through the part. A detail view or half section doesn’t add a seating recess; they’re drawing or view tools, not features that create a seating cavity. For proper use, the counterbore is specified by its diameter (to accommodate the head) and its depth (to match the head height), ensuring the fastener sits correctly.