Spur. A sharp cutting edge placed on some kind of wood-cutting tools to sever the fibre before the cutting edge removes the wood cuttings.

Spur-wheel. A gear-wheel having its teeth upon its circumferential surface.

Square-centre. A lathe centre having four cutting edges at its coned end.

Square thread. A screw-thread that is rectangular in cross-section.

Stanchion (stăn′shun). A vertical frame.

Standard. An upright piece.

Standing-bolt. A bolt that screws into the work, and does not therefore require a nut.

Stave. 1. A piece that forms part of a hollow wooden casing. 2. A pin on a gear-wheel that has pins instead of teeth.

Steady-rest or back-rest. A device for steadying work in the lathe.

Steam-boiler. A boiler used to generate steam and hold it at a pressure above that of the atmosphere.