Which is the correct method for applying pressure while using a file?

The correct method for applying pressure while using a file is to apply pressure on the forward stroke only, except when working with very soft metals. When filing, the forward stroke is where the effective cutting action occurs, as the teeth of the file engage with the material being shaped. By placing pressure during this stroke, the file can cut more effectively, leading to a smoother finish.

For softer metals, there may be exceptions where additional pressure could be applied on the backward stroke due to the reduced resistance of the material. However, in general practice, applying pressure during the return stroke is not recommended because it can dull the file’s teeth or lead to uneven wear. This method is fundamental to ensure the longevity and effectiveness of the file while also achieving the desired shaping of the material.