It is not really so much that the DD is difficult to use, or that many operators have trouble with getting good results with it, or indeed with any other drill grinding machinery. It is about learning how a drill is made, in detail, learning about the geometry of a drill, in detail, learning how the machine they have in front of them does the work of grinding the drills, in detail, and also understanding, in detail, how changing one part of the setup changes some or all of the others. Then, going to work at learning how to deal with variations of various kinds of drills, in point angle, clearance and relief angles, flute helix angles, and web thickness. Beyond that, what alloy the drill is made of, and how it interacts with various work materials -- and the properties of those materials. It is really necessary to know that information -- and how it changes the way the drill cuts -- before you can apply a well thought out plan for what drills to purchase; making drills sharp again; maximizing production while making holes within tolerance for size and for surface finish (if required) -- at the highest possible cycle rate and with a near zero rejection rate. Some times it makes more sense to just use new drills until they get to a certain amount of wear and then just toss them.
Of course, I morphed on purpose into writing about how things work in large production plants rather than a small job shop, much less a hobby machinist shop. But really, that is who you are often in competition with if you are doing commercial work. You might be doing jobs with far less quantity for a local clientele, but working smart and efficiently, and having happy customers, is still what wins the game. One "OH ****" cancels out MANY "atta boy's" in business. You must be smart, skilled, involved, efficient, and a people person.
All that is why I am nearly always the only person in my shop, and is also why I only have to deal with myself...
( other than I have a knife sharpener like that )
