What type of file would you use to enlarge round holes?

Using a half-round file is the most suitable choice for enlarging round holes because of its unique shape, which features one flat side and one rounded side. The rounded side can particularly be effective in working within circular openings, allowing the user to smoothly remove material from the edges of the hole. This is essential for achieving a desired diameter or shape without damaging the surrounding material.

The flat side of a half-round file can also be used to dress the flat surfaces, giving versatility in the same tool for both shaping and smoothing tasks. Its design allows for controlled removal of material while retaining the integrity of the hole's rounded shape.

In contrast, flat, triangular, and square files have specific functionalities suited for other tasks and shapes. A flat file is best for surfaces; triangular files are effective for corners and grooves, and square files are used for right angles. They may not be able to conform to the curvature needed in enlarging round holes as effectively as a half-round file does.