Hole saw guide

Problem: I had to enlarge a hole for a door knob lock set. Unfortunately, hole saws work, by first drilling a pilot hole that is used to guide the hole cutter itself. With the hole already present, the pilot bit was worthless

Solution: What I did was took a scrap piece of 1/4 inch plywood and drilled a hole completely through it will a hole saw of the desired size. I then used double stick tape and stuck the piece of plywood (the outer portion) to the door lining it up by eye. I then used the piece of plywood as a guide for the outside edge of my hole saw. Once the hole is started you can remove the piece of plywood or you can leave it in place. A note, the double sided tape may remove finish. If in doubt, clamp the plywood in place instead of using double sided tape.