Lay the table or chair on its side. Select a drill bit of the size recommended by the caster manufacturer and secure it into the chuck of a power drill. The sockets for stem casters may require a 1/4-inch, 5/16-inch or 3/8-inch hole. Drill a hole in the underside of each leg deep enough to fit the sockets.
Push the sockets into the holes and tap their bottoms with a hammer until the teeth on the round bases sink into the wood around the outsides of the drilled holes. Drill deeper holes for any sockets that do not sink in completely with hammer tapping.
Push the caster stems into the socket until they snap locked. Turn the table or chair upright and test its rolling mobility.
Turn the table or chair over on its side. Place the plate casters against the square bottoms of the legs and make a pencil mark on the wood through the four holes in the plates.
Drill pilot holes at each pencil mark that are 1/8 inch less wide than the diameter of the mounting screws. For example, if the screws have a diameter of 1/4 inch, drill 1/8-inch holes.
Put the plates onto the leg bottoms, insert the screws and tighten them half way. Hold each square caster plate in alignment with the square leg bottom while tightening the screws firmly.
Unplug the equipment on the tabletop and remove it from the table. Turn the table on its side.
Remove the bolts holding the rubber pads on the bottom of each metal leg. Fit wrenches over the bolt heads and nuts in the inner leg and turn the bolt heads counterclockwise while keeping the nuts still, until they fall loose. Take the washers off the bolts and pull the bolts out through the bottoms. Peel off the rubber stabilizer pads.
Slip the threaded stems of the casters through the holes in the leg bottoms. Put washers on over the stems in the inner legs.
Thread nuts onto the stems by hand. Tighten the nuts with a fitting wrench. Turn the table upright on the wheels. Carefully place the equipment back onto the tabletop.