When a helicoid flight is formed, the bar stock crushes; that is, it decreases in width, expands at the section next to the axle, and decreases at the outside. The amount of this crush varies with the size of the flight. A sectional flight has a uniform cross section.
Pitch is the distance between flights measured center to center. Pitch can be made just about any distance desired. Screws may have more than one pitch.
RH or LH
Right Hand or Left Hand. Flights and feedscrew may be made either hand.
ID - Inside Diameter
Inside diameter or axle size is usually made so flights will fit on standard round stock or standard pipe; however, intermediate sizes may be obtained.
Grade of Material
Flights can be produced in carbon steel; however, in order to achieve certain desired characteristics, ant ductile material can be used - stainless steel, manganese steel, alloy steel, abrasion resistant steel, platinum, nickel alloys, and others.
Screw can be fitted with drive connections, sockets, bushings, axle extensions, or collars as required.