How to Enlarge the Door Knob Hole in a Wood Door

Not all doorknobs have the same size mounting hole. When a doorknob requires a larger opening than the previously installed knob, you will need to enlarge the mounting hole. The difficulty in enlarging a doorknob mounting hole is in using the hole saw used to drill through the door. A hole saw uses a small-diameter drill bit to guide it through the wood. When no material exists to stabilize the saw, it will jump from the hole, gouging and destroying the surface of the door.

12-by-12-inch piece of 1/4-inch plywood
2 self-locking C-grips
Pencil
Hole saw
Drill

Instructions

- 1
  Set a 12-by-12-inch piece of 1/4-inch plywood over the existing hole in the wood door. Secure the plywood to the door by placing one self-locking C-grip above the hole and one self-locking C-grip below the hole. Ensure the grips hold both the plywood and the door in their jaws.
- 2
  Mark the center of the hole by placing intersecting horizontal and vertical pencil marks on the surface of the plywood. Make sure the pencil marks align with the existing hole.
- 3
  Secure a hole saw in the chuck of a drill.
- 4
  Align the tip of the drill bit with the center of the two pencil marks. Pump the drill trigger to slowly send the drill bit into the 1/4-inch plywood. Pull and hold the drill trigger when the hole saw meets the surface of the plywood. Continue drilling until the saw exits the opposite side of the door. Pull the saw from the door.
- 5
  Release the C-grips. Remove the plywood from the door.

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