A core drill creates a hole in a surface, larger than standard drill bits. Core drills carve out circles in wood, metal, drywall, masonry and many other surfaces. Fitting pipes through walls and doorknobs through doors are two common reasons for using a core drill. A core drill bit is a cylinder shape with cutting teeth on the top edge and attaches to standard power drills for household use. Heavy-duty core drills are available for large-scale projects such as drilling through thick concrete or natural stone surfaces.
Locate the reverse switch or button on the power drill. Depressing this button or flipping this switch causes the drill to turn counterclockwise.
Turn on the power to the drill.
Allow the core bit to spin counterclockwise for 10 to 15 seconds.
Pull the drill out of the wall slowly so as not to damage the wall. Keep the drill running while pulling the bit out of the wall.
Unplug the drill and disconnect the core bit, leaving it in the wall.
Tap the top, bottom and sides of the core bit with a mallet, gently.
Grasp the core bit and wiggle it side to side.
Pull the bit straight out or wiggle it back and forth and walk it out.
Unplug the power drill and detach the core bit from the drill.
Place a thin chisel or metal putty knife as close to the bit as possible.
Lightly tap the chisel or putty knife with a hammer, moving around the entire bit to loosen the tight fit.
Pull the core bit out of the wall.
Avoid stuck core bits in the future by halting drilling 1/8 to 1/4 inch from drilling completely through.