ABSTRACT
In the design of mechanical systems, inch series bolt and screw threads are designated by their nominal size or diameter, pitch, thread series, thread class, and whether there is an internal or external thread. Aluminum is used in everything from housings to standoffs to gobos to reflectors to mechanical parts such as gears and lens tubes. Gears in automated luminaires can be made of aluminum, stainless steel, brass, or plastic. Brass gears wear well because of their hardness, but they are relatively heavy and more expensive than gears made of other materials. In order for a luminaire to operate reliably over its expected life a variety of materials—including glass, optical coatings, metal and metal finishes, adhesives, lubricants, plastics, and rubber compounds—have to be able to withstand or be protected from immense heat. Optical glass is classified according to its index of refraction, coefficient of dispersion, coefficient of optical transmission, purity, hardness, and more.
