The following terms define Building and Machine Parts
raceway: narrow channel for water, tube used to protect electric wires.
rack: frame; toothed bar into which pinion fits.
rafter: horizontal wooden support member for root rail horizontal cross member of panel door or window sash.
railing: several connected rails or posts.
rake: flat, inclined edge on gable roof.
ramp: sloping, sometimes curved, surface that join different levels.
rampart barrier, bulwark.
rebar: steel reinforcing rod for concrete.
register: heating duct unit that directs airflow.
reinforcing rod: round, steel bar used to strengthen concrete.
removable wood form: framework used to form concrete slabs, removed once concrete hardens.
reservoir: receptacle, usually at bottom of structure, used to collect fluid.
revetment: facing of stone or concrete to sustain embankment.
rib: crosswise reinforcing element.
ribbon wood member joined to studs to support floor joists in balloon framing.
ridge beam: ridgepole.
ridgepole: highest horizontal timber in peaked root to which rafters are nailed; ridge beam.
riffle: bars or slats across bottom of sluice that catch nuggets, as of gold.
rigging system of ropes or chains used to support, suspend, or position equipment.
rim edge or border, especially of something circular, often raised.
ring circular element used to hind, reinforce, or seal objects.
riser vertical part of stair.
rod: straight, rigid piece of wood or metal.
roof: top surface of structure.
roofing: materials that form roof surface.
roof plate: top plate.
rough opening: gap in wall, floor, or ceiling formed by structural framing members.
rounce: handle that moves printing press bed under platen.
rowel: revolving disk with sharp points at end of spur.
rung: supporting piece or crossbar, especially on ladder.
rynd: iron bar across upper millstone that supports it on spindle.