Spindle. A shaft that is used to transmit purely rotary motion, and that is usually of small diameter in proportion to its length.
Spiral cutter. A milling cutter having its teeth cut spirally and not parallel to the axis of its bore.
Spiral head. A device for holding work and revolving it in a milling machine.
Spirit-level. An instrument in which an air-space or bubble is utilized to disclose whether the surface upon which the spirit level is laid is horizontal.
Spline. A long feather-way.
Split-pin. A pin that is split so that its end can be opened out to prevent its coming out of place.
Spoke. The arm that connects the hub of a wheel to its rim or felloe.
Spoon-bit. A wood-boring tool that is shaped somewhat like a gouge.
Spring. 1. A piece of elastic metal. 2. The movement or deflection of a piece of metal on a tool, by its own weight or from the strain placed on it.
Spring-tool. A tool so formed as to have a slight give or spring to it.