Radial lines:
Radial lines are the development lines used to construct a pattern for a shape.
Also known as radial guidelines.
Radial line development:
A method used to develop patterns for objects that have a tapering form and converge to a common point called the apex.
Radians:
Radians specify an angle by measuring the length around the path of the circle.
One radian is the angle (at the centre of a circle) created by an arc of the circumference that is equal in length to the radius of the circle.
Radius:
A radius is a straight line from the centre to the edge of the circle.
Rectangle:
A rectangle is a four sided 2D shape with four right angles.
Recurring decimal:
A recurring decimal is a number which, after some point, the same sequence of
digits repeats infinitely many times. The repetition may begin before, at, or
after the decimal point. The repeating sequence may consist of just one digit
or of any finite number of digits.
Right angle:
A right angle is an angle formed by the perpendicular intersection of two straight
lines - in other words, an angle of 90°.
Right cones:
Right cones are conical shapes which have an apex at 90° to the circular base.
Rolling machines:
Rolling machines are machines with rollers that are used to form sheetmetal
or plate into various shapes.
Rolling sequence:
The rolling sequence is the order in which a cylindrical shape is formed.
Rolls:
Rolls are rolling machines and are used to roll materials such as sheet metal,
plate or flat bars into a cylindrical shape.
Rounding off:
One way to simplify a number is to round it to the nearest 'power of ten'.
Rounding off a number simplifies it by changing digits to zeros. For example,
round off 24.319mm.
The purpose of rounding off is to avoid expressing a value to a greater degree of precision than is consistent with the uncertainty in the measurement. For example, 24.319mm is indistinguishable in most circumstances from 24.3mm.
Running dimensioning:
Running dimensioning is similar to parallel dimensioning but
doesn't use as much space on the drawing. It also doesn't accumulate a tolerance
error as all measurements originate from the same line. Running dimensions on
drawings are not used very often.