Assembly fixture

A fixture is the unglamorous reason mass production works. It holds every part in the same spot every time, so a machine can drive a screw without looking.

Fixtures built for car panels have room to spare. A robot finger joint does not: if the fixture is off by a fraction of a millimeter, the screw cross-threads and the unit comes off the line needing rework.

Reports on the Optimus line say several stations, including those handling hands and joints, are struggling to hold that precision, which is a fixture and tolerance problem more than a robot problem.