Maybe I've been cheatin' all along without knowing it. I use my dremel tool. I put four of those little grinding discs together (or however many is just smaller than the tang) and start grinding until I'm just through. Then I turn it over and grind from the other side being careful not to twist the grinder. After my slot is cut, I can get a small file in the brass to widen it until it fits the tang. One thing I have noticed on the helle blades I use, the tang is slightly thinner where the blade has been polished. Therefore, I sand the back of the tang before I file the brass too much. A snug fit at the blade is a must. One other note, I shape my brass guards AFTER I grind the slot. It's real hard to get the slot perfectly in the middle of an already shaped piece of brass. I also cut small notches on the top and bottom of the blade for the guard to sit into. Mike