YOU MUST USE "OLD" FILES..NEVER NEW ONES, ANYTHING BEFORE 1960 SHOULD BE FINE // NEVER EVER USE A BAYONETT, THEY ARE SOFT STEEL AND WILL NOT HARDEN.
YOU MUST SOFTEN THE BLADE BEFORE YOU DO THIS WORK OR YOU ARE GOING TO USE
YOUR GRINDERS , DISCS, TOOLS, UP AT A RATE OF ABOUT 5 TIMES FASTER THAN NESSASARY...FILES ARE HARD !
ONCE SOFTENED, (YOUR WORK LOOKS REALLY NICE), ( most people like to leave some of the file groves for looks)
next after its all shaped and 90 % finished, you need to harden it, getting it soft red and dropping it in a tub of old oil or tranny fluid works ok, ( make sure thats a metal tub) and watch out for flame up when you do that, now that its properly hardended, you must
temper it, put it in your oven for about 3 hours on 350 degrees.. that will relax the harden and give the blade flex, all done clean it up , handle and sharpen it, then oil it and your done