Doors – How to drill a 2⅛ inch door knob hole over an existing 1½ inch hole


I need to replace the door knob for this interior door:

Door with door knob hole

The door knobs I've found at the stores require a 2⅛ inch hole. Mine is only 1½:

Measuring 1½ door knob hole

Did door knobs used to be smaller? Is there some place I can find a replacement door knob that will fit my door?

If I need to modify the door to fit a modern door knob, will the new hole completely overlap the old? and can I reuse the latch hole?

Best Answer

i used a piece of plywood clamped to the door as an outer-guide. Cut a hole in the plywood, the right size (2 1/8) and then clamp it where you want the new hole in the door. Then using it as a guide on the outside of the hole saw, drill on through the door. voila. no additional tools required beyond the 2 1/8 hole saw, and well, a c-clamp which you should have.