Foolproof Hanging with Keyhole Slots
Keyhole slots are a great way to affix wooden hangings, such as a shelf or picture, to a wall. But if the mounting screws aren't perfectly level or spaced exactly the same as the slots, the job can become a nightmare. Here's a solution that works great.
I attach short pieces of masking tape to the top of my level and, using the keyhole slots themselves, I mark the locations of the slots on the tape, as shown in Step 1 below. If I want to center the wall hanging between two objects, I also make a third mark, centered between the two marks.
After finding the mounting location for the shelf, I mark the center of the shelf at the correct height. I place the level's center mark on that mark, make certain it's level, then mark the screw locations using the other two marks, as shown in Step 2. Finally, I drive the mounting screws into those marks. My hangings are always right on the money and level.
—Bill Vanderhoof, Hanover, Pa.