I was completely unaware of center drills. My order has been placed. Thanks!
Err, a slight error in terminology was made in the initial post describing those drills. Center drills are not
for drilling the center of a hole for a larger bit. Center drills are designed to drill a 60 degree cone in the end of a workpiece to allow for the use of a lathe center for turning operations.
What you use to locate a hole is a spotting drill
. A spotting drill will generally have a wider angle on the tip than a standard twist drill, usually a 120 degree angle for a 118 drill. This is important because it allows the tip of the drill locate itself in the center of the cone drilled with the spotting drill without the edges of the drill hitting the workpiece. The tip of the drill is what guides it, you want it to be what makes first contact. If you try to use a center drill, which will leave a 60 degree cone, the edges of the drill will cut before the point, which will lead to your bit wandering.
All of this is completely irrelevant anyways, because what you need is actually a center punch
. A spotting drill is best used on a ridgid machine to place an accurate starting spot for a longer, less stiff drill. On something like a milling machine, the quill is going to be rock solid and any inaccuracy in the hole location is more likely to come from the drill itself flexing, starting with a short, stiff spotting drill will put the initial spot on target, after which the longer, more flexible drill will center itself on the spot and drill where you want it to. On a less rigid machine, like your drill press, the quill is more prone to moving, so any sort of spotting drill on it wont help. A center punch will put a dimple where you want the hole to go, and then the drill tip will center itself in that divot and put the hole where you want it.
It might all sound pedantic to some, but theres something to be said for using the proper tool for the job. A quick tap with a center punch and a sharp drill where put a hole exactly where you want it 99.99% of the time, even with an inaccurate machine, but trying to accurately locate a hole with an inaccurate machine will be an exercise in frustration, even with the proper drills