Why Do Doors Have Hinges?

What Crafty Clover says in this video

Intro

Hey there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do doors have hinges?

The Big Idea

A hinge is a tiny axle that lets a heavy door swing. Without it, you'd have to lift the whole door off the wall! Two metal plates share one pin, and that's the trick.

Mark and Cut

Step one: mark the edge, and cut the mortise. A carpenter marks where each hinge will sit on the door and the frame. Then a shallow pocket, called a mortise, is chiseled out, so the hinge sits flush.

Screw One Leaf

Step two: screw on one leaf. A hinge has two flat plates, called leaves. One leaf gets screwed to the edge of the door.

Hang the Door, Swing and Stop

Step three: hang the door, and swing and stop. The other leaf is screwed to the frame, around the shared pin. The door rotates on the pin, and a latch keeps it closed.

A Closer Look

Let's take a closer look at a hinge! The knuckles are the rolled loops that wrap around the pin. The pin runs through them. The leaves are the two flat plates. And screws hold the leaves in place.

Quick Facts

Quick facts! A butt hinge is the common rectangle you see on house doors. Rusty pins squeak, because metal grinds instead of sliding on oil. Piano hinges run the full length of a lid, so it cannot twist. Laptop lids, jewelry boxes, and robot elbows use the same pin-and-plate idea.

Think Like a Scientist

Now, think like a scientist! Tape a book to a cereal box, with one piece of tape as a hinge. Swing the book open and shut. Then try lifting the book off every time. Which is easier? Why do you think so?

Outro

Hinges turn a heavy door into an easy swing. Give science a turn! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!