What are the best files to use on hard steel?

The best files for hard steel are typically made from high-carbon steel or carbide, as these materials can withstand the hardness of the steel being worked on. Bastard files, which have a rough cut, are effective for aggressive shaping, while second-cut and smooth files are better for finer finishing. Additionally, needle files can be useful for detailed work in tight spaces. It's important to choose the right type of file based on the specific task and the hardness of the steel.