Modern Machine-Shop Practice Part 285

=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-s.p.a.ce 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.

=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 circ.u.mferential 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= (st[)a]n'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.

=Steam-hammer.= A forging machine in which the hammer is raised or lifted by steam, and is sometimes also forced downwards by steam.

=Steam-s.p.a.ce.= That part of the boiler that is above the level of the water.

=Sticker.= A machine that operates on wood of small cross-sectional area in proportion to its length, such as picture frame moulding.

=Stock.= Material.

=Stocks-and-dies.= Tools for cutting external threads by hand.

=Stop.= 1. A piece that arrests the motion of another piece. 2. A part of a gauge, against which the work abuts.

=Stop-motion.= A device for preventing the overwinding of clocks and watches.

=Straddle-mills.= Milling-machine cutters that are used in pairs and straddle the work, both cutters being of the same diameter.

=Straight edge.= A piece or strip having one or both edges made straight to use as a guide in testing work.

=Stub end.= The end of a connecting rod.

=Stud.= 1. A bolt that screws into the work at one end and receives a nut at the other. 2. A piece that screws into the work at one end.

=Stuffing-box.= The box in which a gland fits.

=Surface-plate.= A plate having a true flat surface to test the flatness of work by.

=Swage.= A blacksmith's tool for smoothing and shaping surfaces.

=Swing-frame.= A frame having a movable stud for carrying the change gears of a lathe.

=Swing-saw.= A saw that is suspended in a swinging frame.

=Swivel-vise.= A vise that may be swiveled or revolved upon its base plate.

T

=[T]= or =tee=. A pipe fitting having two bores at a right angle, one to the other.

=Tailstock= _or_ =tailblock.= That part of a lathe that carries the dead centre.

=Tangent-wheel.= A wheel whose teeth are formed to work with a screw or worm.

=Tap.= 1. A tool for cutting threads in holes or bores. 2. A device for shutting off or turning on the flow of water through a pipe.

=Taper-tap.= A tap that has part of the thread turned off in order that it may enter the hole easily and start to cut the thread. It is sometimes termed the first tap.

=Tapped.= 1. Threaded internally. 2. Having a connection that branches from the main pipe or flow.

=Target.= A frame used in setting shafting in line.

=Temper.= 1. The degree of hardness that has been imparted to steel by heating and suddenly cooling it. 2. A term employed by steel makers with reference to the percentage of carbon contained in steel.

=Tempering.= Tempering consists in reheating hardened steel and thus modifying or reducing its degree of hardness.

=Template= _or_ =Templet.= A piece of metal made to shape, to serve as a pattern for one or more of the work surfaces.

=Thread-gauge.= A threaded cylinder or bore that serves as a standard of reference for the shape and diameter of a screw thread.

=Threading-tool.= A tool for cutting screws in the lathe.

=Throw-line.= The travel of a piece, moved by an eccentric.