Using a bent piece of stiff wire (a piece of wire hanger works) to check that a drill press chuck is perpendicular to the table isn’t entirely new, but adding a business card to this familiar tip adds near micrometer-like precision without the hassle of squinting to read a dial. To quickly set the table, bend the wire so that its bottom end sits just above the surface. If the wire can push a business card across the top without skipping over the card or touching the table, it means that you’re only a few thousandths of an inch from perfect. (Most cards are printed on .010"-thick, 10 point stock.)
This go/no-go gauge may not be accurate enough for machining rocket parts, but I find it more than adequate for most woodworking applications and easy enough to repeat every time I adjust the height or tilt-angle on my table.
