Which tool is used to enlarge pilot holes to the required tolerance of .159 - .165?

The use of a double margin drill bit for enlarging pilot holes specifically to the tolerance of .159 - .165 is appropriate due to its design features. A double margin drill bit is engineered with two parallel cutting edges and margins, which allows for enhanced precision and more control during the drilling process. This design minimizes the potential for drill wander and ensures that the hole produced is more concentric and within the specified tolerance range.

Moreover, double margin drill bits are specifically intended for applications where accuracy is critical. They are effective in producing holes that meet exact specifications for subsequent assembly operations, which is crucial in aerospace assembly where tolerances can significantly impact the performance and safety of the final product.

In contrast, while other tools might serve different functions, they may not offer the same level of precision or are not typically used for achieving the desired size tolerance in this specific context. For example, a spade bit is not suited for achieving fine tolerances and is generally used for larger holes in softer materials. A drill press is a machine used for drilling operations but does not inherently ensure that the bit is producing holes to the specified tolerances, and it requires the correct bit to achieve that goal. A reamer, while capable of achieving precise diameters, is generally