Craft · 6 pages · 12 min

How scissors are two levers

Scissors are two levers on one pivot, and the blades cut by shearing as they pass.

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From the opening

Each half of a pair of scissors is a lever, with the pivot as the fulcrum, the finger bows taking the force, and the blade working on the other side of that pivot. The edges do not drive through the material as one wedge, because they pass each other and shear whatever is caught between their faces. The opening covers pivot is the shared fulcrum, handles multiply the hand force, and blades shear as they pass.

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Inside

Pivot is the shared fulcrum
Handles multiply the hand force
Blades shear as they pass
A loose pivot only pinches
Where the idea stops applying
A distinction worth keeping

Sources

Scissors as paired levers
Shear between bypassing blades

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How scissors are two levers

From the opening

Inside

Sources

Also on the desk