It takes a few tries to get the hang of it but once you do you will never have to use a dull drill bit again.
If you want to sharpen it on a grinder you will have to have a sharp eye and pay special attention to the angle of the tip. another important point is that it has to be ground evenly all the way down the point or it will not drill correctly. It will either have problems starting or it will start and drill so far then just ride on the dull or misground section. That is why the drill doctor is so nice it reduces the chances of human error.
Don't get me wrong people have been sharpening drill bits with a bench grinder for years and some can do a better job by hand than I could probably do with a drill doctor but I have better results with the drill doctor.
