Part 6 of an International Correspondence Schools instruction paper on silk throwing, continuing the treatment of doubling and spinning with spinner machines. It explains how twist is inserted, with twist change gears (tram, organ and crêpe gearing), gear trains and twist calculations with worked examples and change-gear tables. It also covers production and spindle requirements, machine sizes, drive and belt arrangements, double-deck spinners, reversing the direction of twist, spindle oiling, plumbing and belt care, flyer rewiring, and slack twist. It ends with examination questions.