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Fundamentals of Graphics Communication, 3/e
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Bertoline - Fundamentals of Graphics Communication Third Edition

Glossary J-L

Please click on the desired term below to view the glossary definition.
jig  (n) A special device that holds and supports the workpiece and guides the cutting tool as the workpiece is machined. Jigs may not be rigidly held to the machine.
JIT  (n) An acronym for just-in-time, a planning strategy used to reduce cycle time and waste in production processes. JIT recognizes waste as anything that does not add value, including storing parts in warehouses. On the other hand, a production process such as drilling is a value added procedure because it increases the value of the product.
joining  (v) The bringing together of two or more parts of an assembly in such a way as to overcome the natural forces that would separate them. Joining can be done with mechanical fasteners, adhesives, etc., and can be either temporary or permanent.
joints  (n) An element in a kinematic model defining the constraints between two rigid parts of the assembly (called the links). Joints define how the links can move relative to each other, in rotation and translation.
just-in-time  (n) See JIT.
KBE  (n) See knowledge-based engineering.
key  (n) A fastening device used to attach shafts to transmit power to gears, pulleys, and other mechanical devices. Common keys are plain, gib head, Woodruff, and Pratt & Whitney. The key is placed into a groove cut into the shaft (the keyseat) and one cut into the hub (the keyway), aligning and locking the parts together. Standard keys are specified using the size of the shaft as the determining factor.
keyboard  (n) A computer input device derived from the typewriter, where keys pressed communicate discrete commands to the computer. Although most often used to input the letters of the alphabet, most keyboards contain special character keys programmed by the user or the software to perform specialized tasks.
kinematic analysis  (n) The evaluation of a design as it changes over time. Of particular interest is multicomponent mechanisms in which parts move at varying rates through different volumes of space. The positions of the parts relative to each other at various points in time are studied through kinematic analysis.
kinetic depth effect  (n) A perceptual effect in which the changing movement of 2-D patterns creates the sense of a third dimension (depth). Related to apparent motion, this effect assists in the interpretation of 3-D objects in animated sequences.
knowledge-based engineering  (n) Software systems that complement CAD by adding the engineering knowledge necessary for product design. A KBE system stores product information in a comprehensive model that is composed of design engineering rules, standard practices, and general rules that describe how a product is designed and produced.
layering  (v) A scheme by which the various graphic elements of a drawing can be grouped together in the CAD database. This facility _is used most often to control what is seen _or editable on the screen and what is printed or plotted. Layering in most systems is nonhierarchical.
lead  (n) A thread term describing the linear distance a screw will travel when turned 360 degrees, or 1 revolution. Lead is closely related to the pitch of a thread.
leader line  (n) A thin, solid line used to indicate the feature with which a dimension, note, or symbol is associated. Leader lines are terminated at one end with an arrow touching the part or detail and a short horizontal shoulder on the other end. Text is extended from the shoulder of the leader.
least material condition (LMC)  (n) A tolerancing term indicating the condition of a part when it contains the least amount of material possible. The LMC of an external feature is the lower limit of the part. The LMC of an internal feature is the upper limit of the part.
left side view  (n) A principal view of an object, created by rotating the viewpoint 90 degrees about the vertical axis to the left of the front view. This view is not typically included in a standard multiview drawing.
legend  (n) The region of a visualization where an explanation is given regarding how the variables are coded. This is usually done by equating a text description to a symbol of the code. The legend is also called the key.
lightness  (n) A perceptual quality of color indicating the absolute quantity of light energy. On a gray scale, the lightest color, pure white, has the highest quantity of light. In rendering, lightness (also called value) is used to indicate the orientation of the surface to the light source.
limiting element  (n) The boundary of the projection of an object. The term is usually used to describe the edge defining the apex of a curved surface.
limits  (n) The maximum and minimum sizes shown by the toleranced dimension. The larger value in a toleranced dimension is called the upper limit and the smaller value is the lower limit.
line  (n) A geometric element that connects two points in space. Although a line itself is 2-D in nature, it may connect points in 3-D space. Lines are typically classified as either straight (linear) or curved. Lines are the most prominent element in technical drawings, defining edges of objects, indicating symmetry, relating text elements to geometric elements, creating borders, etc.
line balloon (callout)  (n) A note added to a drawing to relate an alphanumeric code with a part. A line balloon usually consists of a circle or a regular polygon enclosing the code and a leader pointing to the part. They are used extensively in assembly drawings either to directly specify a part or give an index value that references a parts list or separate catalog.
line graph  (n) A visualization technique, usually 2-D, in which line marks are used to indicate trends in data. In a 2-D line graph, the independent variable is represented on the horizontal scale, and the dependent variable is shown on the vertical scale. The line mark represents the mapping of the two variables.
line of sight (LOS)  (n) Imaginary rays of light radiating from an observer’s eye to the object. In perspective projection, all lines of sight start at a single point; in parallel projection, all lines of sight are parallel. LOS is sometimes referred to as the viewpoint.
line rendering  (n) A technique used in technical illustration for adding realism and readability to a pictorial drawing by altering qualities of the linework on the drawing. The thickness of the line and the positions of line breaks or gaps are altered to differentiate between geometric features of a part or assembly. Line rendering is popular because it is fast, can be done with standard drawing instruments or CAD tools, and can be reproduced by most popular reproduction techniques.
linkages  (n) Rigid bodies (parts) that transmit linear or rotational force. Linkages are multiple links that are combined through joints. Constraints applied to the joints define the movement of the individual links. Common types of linkages include rocker arm, crank, lever, and four-bar.
link charts  (n) A visualization technique used extensively in ergonomics to depict the spatial arrangement of controls, displays, and personnel associated with a work environment. Line marks show the connections between a worker and a control or display or in communication with other personnel. Some of the variables typically coded include frequency of usage and type of information exchange (i.e., auditory, visual, physical, etc.).
links  (n) In a kinematic model, the geometric form representing a unique part of a mechanism. Links are related to each other through joints, which define how they can orient relative to each other.
LMC  (n) See least material condition.
local coordinate system  (n) A transient coordinate system that can be positioned anywhere in space. The local coordinate system is used to assist in the construction of geometry, and the origin is usually defined relative to the feature of current interest.
locus  (n) A graphic element representing all possible allowable locations of a point. The locus of points may be drawn as a line, circle, or arc. For example, a circle is a locus of all points at a distance from the center, equal to the radius of the circle. Loci are used extensively in geometric constructions as a tool for finding the centers of tangent arcs, the endpoints of lines, etc.
logic drawing  (n) See schematic drawing.
logic gates  (n) Electronic components that take input signals and create output signals based on the input states and the logic of the circuit. Types of logic gates include AND, OR, NAND, NOR, and inverters.
long-axis isometric  (n) A variation of the regular isometric pictorial view. In a regular isometric, it appears as if the viewer is looking down on the object from the top; in a long-axis isometric, it appears as if the viewer is looking from the right or the left of the object, with one of the axes drawn at 60 degrees from the horizontal.
LOS  (n) See line of sight.
lower deviation  (n) A tolerancing term describing the difference between the minimum size limit and the basic size.