Thanks Charles and Arkie, I am far from knowledgeable on this subject but in my experience, most good metal files from Nicholson are made to be directional which many novices are not aware of. Once the tips get worn or folded from back filing they become dull and just don't file as they should. Back in Metal Shop in the mid 60s my instructor spent an entire class on the proper use of files and told us he would rap our knuckles if he found us using them wrong. I had a big box of old files that were just about completely worn out and I tossed them and the recyclers but wonder if I should have given them to a buddy who does play with smithing and makes some nice knives.