Square Keys | McMaster-Carr

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1,554 Products

Machine Keys

Straight keys, with a square or rectangular cross section, are the most common type of key. Install them in keyways to transmit torque from shafts to gears and other components.

Rounded Machine Keys

When installed, these keys fill oval keyways completely, reducing stress on the key and shaft. The rounded ends make it easy to slide gears, hubs, and other components into place. These are also known as feather keys.

Tapped Rounded Machine Keys

Thread a screw through the tapped hole to pop these keys out of a keyway. When installed, they fill oval keyways completely, reducing stress on the key and shaft. The rounded ends make it easy to slide gears, hubs, and other components into place.

Machine Key Stock

Cut this stock to length to create the machine key you need. Straight keys, with a square or rectangular cross section, are the most common type of key. Install in a keyway to transmit torque from shafts to gears and other components.

Machine Key Assortments

Machine Key and Woodruff Key Assortments

Undersized Machine Key Assortments

Since they fit more loosely than standard keys, these undersized keys are best for uneven keyways or when you need to disassemble parts frequently, such as during maintenance or prototyping.

Standard Key Stock Assortments

These assortments include various sizes of key stock—choose a piece and cut it to your desired length.

Undersized Key Stock Assortments

Cut keys to custom lengths. This key stock is undersized, so keys will fit slightly more loosely than standard keys and are best for inconsistent keyways.

Oversized Machine Key Assortments

Slightly larger than the size listed, these oversized keys offer a tight fit in worn keyways.

Oversized Key Stock Assortments

Make a key that is the exact length you need. Because this key stock is slightly larger than standard key stock, keys will fit tightly in worn keyways.