Keep parts as close to block form as long as you can during machining stages so they are easier to hold. In many cases you can machine all or most holes first to maintain block form. Then start milling features that remove the least amount of material, which helps maintain block form and part rigidity. Angle dressings and large cuts should usually be done last.

An exception to using this technique would be if the part has such a large percentage of material removed from it that it would be prone to warp. If that is the case, you may be obliged to rough in the part first before finishing it.

Start with an old 3/8" three or four flute tap. Grind the long taper at five degrees per side. (ten degrees included angle) Grind the tip angle at thirty degrees per side or your preference. These center punches are compact, durable and have a great "feel."

Sand your stones over a sheet of 80 or 100 grit sandpaper. Silicon carbide sandpaper works better for abrading and dressing stones than aluminum oxide paper because silicon carbide crystals are harder.