Hinges aren’t made in a mold. They’re bent or formed in a press. That means the swag or bend in a hinge is never identical from one hinge to the next. And that means the gap between the hinge leaves varies just a little, which can have an impact on the fit of your doors.
To adjust hinges, so that a door will fit better in a jamb—and maybe eliminate scraping on the head or the strike jamb—I bend hinges. If you’re working with a solid brass hinge, you might want to chisel the hinge in deeper, or shim it out of the hinge mortise with a piece of plastic laminate. But this technique works great for solid steel hinges.
To spread hinges, which increases the leaf gap, and moves the door away from the hinge jamb, I place a nail set between the leaves and close the door, pinching the nail set. Here’s the thing to be careful about: make sure you push on the nail set and hold it firmly against the barrel of the hinge, otherwise the hinge will push the nail set out across the leaves, and then you’ll be putting too much pressure on the hinge screws—you’ll probably rip them right out of the door. Plus, you’ll scrape the nail set across the hinge leaf and leave an ugly mark.
To squeeze hinges, which decreases the leaf gap and moves the door closer to the hinge jamb, I use a crescent wrench.
First, I drive the hinge pin up out of the hinge until it’s just engaging the top two knuckles—one knuckle on the door leaf and one knuckle on the hinge leaf. Then, I tighten the wrench on the leaf that’s attached to the door—the trick here is to remember you want to move the door, not the jamb. If you bend the leaf that’s attached to the jamb, you’ll close up the leaf gap instantly and the hinge will be leaf-bound. So, tighten the wrench on the knuckles that are attached to the door and bend those knuckles toward the lock stile! Once you drive the pin back in, that bent leaf will shift back toward the hinge jamb!