A crank, a rod, a slider. Below them, the only dimension on this drawing you are allowed to change. Try zero first, since you were going to anyway.
nothing moves. nothing can. perfection has seized.
| Door hinge | ±0.05 mm, or the door screams |
| Rail joints | a finger of air, or summer bends the line |
| Bridge bearings | whole centimeters of permitted wander |
| Piano strings | tuned near, never at, breaking |
| A good team | late Tuesdays, forgiven |
| A long marriage | unmeasured, replenished nightly |
| Browsers, ideally | see: a favicon that wants to dance |
Engineers write tolerance on every dimension because they know a secret the rest of us keep relearning: a machine built to exactly fit does not run. Metal swells, floors settle, people have days. The gap is not the flaw in the design. The gap is the design.
Too little play and it seizes. Too much and it rattles. Somewhere in between is the quiet hum of a thing that expects reality and has left room for it. The intake office next door, dontbestrict.com, is learning the same lesson with paperwork.