Advice please, fellow swarf makers. Have had a spell of making Hemingway kits, and have (some) pieces that need graduation markings engraved on them. The Hemingway graduating tool supplies a piece of 3/16" dia HSS, but I need to know suitable angles to grind it to for optimum use with minimum wear, not wanting ruts that look like a tractor tyre has been through them. I am considering an included angle of about 30 degrees; would that be about right? Flat top, or should it have a bit of rake? Grind to a point, or leave a slight flat? All suggestions gratefully considered. TIA.