Knife making, how to make a knife from a file. I decided to make a simple file knife today using a Nicholson file. The knife is a simple seax style knife with a razor sharp edge. making file knives is a great way to get into the world of knife making. The file was annealed first making the steel soft and easy to work with, after heat treat the knife is tempered in the oven for 2 hours at 400 degrees.