i read somwhere a while back where somebody would start the filework groove in a ferrule by mounting a cutoff wheel in a drill press, rasing it up to half the thickness of the piece and just cutting a little index line by hand and then opening it up with the chainsaw file. My firest and only ferrule (so far) was madde justlike a guard. i milled out the hole and then just shaped it on the belt grinder, but it was just plain 1018. More of a spacer for a medium sized bowie knife with a standard cross guard.