What type of drawing should be carefully checked for correct hole countersinking?

The type of drawing that should be carefully checked for correct hole countersinking is typically the engineering drawing. Engineering drawings provide detailed specifications about dimensions, tolerances, and the geometric requirements for a component, including the profiles and depths for countersinking holes.

Countersinking involves creating a conical recess in a hole to allow for the head of a screw or bolt to sit flush with or below the surface of the material. To ensure proper fit and function, engineering drawings will include precise details about the countersink angle, depth, and diameter. These details are crucial as they directly affect the assembly and structural integrity of the final product.

In contrast, assembly drawings generally illustrate how parts fit together, layout drawings focus more on the overall configuration and arrangement of components, and fabrication drawings are primarily concerned with the manufacturing instructions for individual parts. While all of these drawings may contain some relevant information, engineering drawings specifically provide the critical dimensions and specifications necessary to correctly perform operations such as countersinking.