Leveling The Drill Press

I keep getting more and more focused on precision--even with tools like a drill press, which are not necessarily terribly precise.  I can at least aim for more precision, however.

The latest effort is to get the drill press exactly level to the floor.  During some of my manufacturing processes, I use a bubble level to make sure that parts are exactly square to the drill bit or tap.  Of course, this assumes that the drill press table is square to the drill press spindle, and that both of these are square to the floor.  I knew that my garage floor is not exactly level, but I learned to compensate for the difference--which direction from exactly level the bubble in the level should be.

The base of the drill press has four 7/16" holes intended for mounting it to bolts in the floor, or to a plate that contains such bolts.  I do not have anything to mount those holes to, so I tapped those holes for 1/2"-13 bolts.  Then I verified that the drill press table was exactly square to the spindle, not by trusting the degree marker on the table, but by putting a square to the table and a long drill bit in the chuck.  Then I put 1/2"-13 bolts in those tapped holes, and turned them until the bubble level on the drill press table was exactly centered.

I doubt that this makes a huge difference--but it means that instead of being off as much as a degree or two when I drill and tap a hole, I suspect that am now off by half a degree or less.