It took me several files to figure out a way to do it. LOL I was able to get used files from where I worked. Had all the maintenance guys save them for me. LOL Went through a lot in a steel mill. Started making them at work on the sly. LOL Then was able to find the big stone and build a grinder of my own. 2-1/2" by 18" stone.Those are pretty good tbone. I made a few from files, but was never real happy with the results.