diagrams.ink / Everyday mechanisms / 01
One key.
Five small agreements.
A lock turns only when every pin pair meets at the same boundary. Look inside an idealized pin-tumbler mechanism.
Key withdrawn · plug blocked
Driver pins bridge the housing and plug.
0 / 5 joints aligned
The boundary that matters
The shear line is the interface between the rotating plug and stationary housing. A matching key positions every key-pin / driver-pin joint there, leaving no pin spanning the interface.
A model, not a blueprint
The near half is removed to reveal the mechanism. Pin contact and spring motion are idealized; clearances are enlarged. Profiles and proportions are illustrative, not real key measurements.
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