Leaf, Knuckle, pitch and paint clearance - the intricacies of the humble butt hinge. If you are fitting your own door hinges, here's the lowdown on the technicalities. Probably best not to bore your friends with your new found knowledge though...
The leaf is the flat part of the hinge either side of the barrel.
The thickness of a leaf hinge is referred to as the gauge. Hinge gauge is also called the hinge weight.
In order to hang a door for best fit, the hinge leaf is fitted into a chiselled rebate. The rebate needs to be same thickness as the leaf for a seamless fit.
The barrel of a butt hinge is referring to the part of the leaf of the hinge which wraps around the pin. This includes both leaves of the hinge.
The pin runs down the central barrel. It is a metal rod, usually made of the same material as the butt hinge, but not always.
The knuckle is the part of the hinge which wraps around the pin. Unlike human knuckles, these do not bend, but are the sections along the barrel that are either packed with grease, or washers, or ball bearings in order to reduce frcition and prevent the wearing of metal upon metal.
The Pitch refers to the distance from the end of one knuckle to the same edge on the adjacent knuckle.
This is the space between the leaf and the barrel. If you decide to paint over your hinges, the paint clearance is designed to allow the hinge to open and close without scraping the paint off the barrel.