To harvest silk from a Golden Orb Weaver (Nephila edulis), the Oxford Silk Group sedates a spider with carbon dioxide gas and pins it down harmlessly. A technician extracts silk from the spinnerets with tweezers and glues the thread to a motorized spool. Once fired up, the motor can draw out 30-80 meters of silk in one session.
In case you’re worried, the spider is fine afterward. Read more at the source.