Hob – Gear Terminology
A hob is a cylindrical tool with cutting edges on its outer surface which is used to cut gear teeth. A hob is attached to a gear cutting machine called a hobbing machine and cuts teeth on a gear blank as they rotate. A hob is used in the gear form generating method and can cut spur and bevel gears and worm wheels.
When gear cutting, different hobs are in general needed depending for example on the desired gear’s pitch (module, etc.), pressure angle, and the size of the hobbing machine. However, for different number of teeth, it is theoretically possible to use the same hob.
Examples of the practical use of the term “hob” are :
“To cut gears to match module 2, pressure angle 20˚, we prepared the appropriate hob to cut the gears.”
“The cutting edges of the hob became worn and we re-sharpened the hob.”
Other terms related to “hob” include hobbing machine, pinion cutter, carbide hob, form generating gear cutting, etc.
