The historic account that says Adam was given the job to name the animals is interesting. From all I know, he and others went with their gut, and named things based on what they looked like. Hence the names: ‘fly’, ‘bluebird’, ‘wolly mammoth‘. The story of the wobble broach’s name is the same. Its one more thing based on what it looks like its doing.
When the broach is turning in a mill, the edge of the holder seems to wobble back and forth. This is because the angle built into the holder often causes the spindle or end of the body to have one end shorter than the other. As the edges rotate in the direction of the spindle, the eye notices the short and long ends trading places. This gives the appearance of wobbling.
The name has been replaced recently by a more modern term; rotary broach. I think its because the term wobble has a certain ‘uncontrolled’ connotation to it. The term rotary broach more clearly defines the fixed rotating motion of the broach in the broach holder. However, this name change has not been without controversy. Another machine tool is also referred to as a rotary broach, but it is more of a manual surface grinding machine.
The wobble broach has also been called other names. Terms such as wobble tool, hex broach, nibbler, orb, polygon tool, Swiss broach and roto broach have all been used to describe the tool. Hex broach likely refers to the hexagon shape. It is the most commonly ordered shape for a rotary broach. The term roto or rota broach is another misnomer, as there is another turning tool that is more often referred to by that name. Also, the name polygon tool may be confused with a polygon attachment. Polygon attachments are used for making external polygon shapes in a different method than a wobble broach.