Glossary T

tablet	(n) A computer input device used to control cursor movement and to select menu items. The tablet can be covered with a thin, plastic overlay that contains the menu options for a CAD software program. Attached to the tablet is the cursor control device, such as a puck or stylus. Specialized tablets, called digitizers, are used to convert a drawing created with traditional tools to a CAD drawing by tracing geometric elements with the puck.
tangent	(n) A condition in which a straight line is in contact with a curve at only one point. Tangents describe the smooth transition from a linear/planar element to a curved one. Geometric construction techniques are used to define tangent curves in an engineering drawing.
tap	(n or v) The machine tool used to make threads in holes. A drill bit (the tap drill), approximately equal to the diameter of the crest, is used to make a hole in metal before tapping an internal thread. The term is also used to describe the process of creating the threads.
technical and office protocol	(n) See TOP.
technical drawing/graphics	(n) A specialized type of graphics used to communicate technical information. Examples of technical graphics include 3-D computer models and illustrations of a technical device.
technical reports	(n) In-depth accounts, containing text and graphics, documenting the design process. Progress reports are created in the early stages of the design process to document the decisions made by the design team and are used to periodically review the status of a project. Final reports are written at the end of the design cycle and are much more detailed.
technical sketch	(n) A type of sketch that depicts only certain features of an object or structure. Sketches are used as part of the design process, in the same way as a technical drawing, but sketches are more informal and are typically used early in the design process.
technologists	(n) Personnel who work with the engineers and are concerned with the practical aspect of engineering in planning and production. The technologist must be able to communicate quickly and accurately using graphics, by sketching design problems and solutions, analyzing design solutions, and specifying production procedures.
template	(n) A die-cut flexible sheet used to assist in the drawing of repetitive features, such as circles, ellipses, threaded fasteners, and architectural symbols. The circle template is used to draw regular-interval sized circles and arcs (e.g., 1-mm increments) quicker than using a compass.
tensor	(n) A general term describing all types of quantitative data. A tensor has two parts: the dimensionality of the coordinate system, d, and the order of the tensor, n. The number of components (scalar values) needed to express the tensor is equal to dn. For example, a 2-D vector is a tensor of order n_=_1 with 21_=_2 components.
tertiary auxiliary view	(n) An auxiliary view projected from a secondary auxiliary view.
text alignment	(n) The vertical alignment of lines of text. Also referred to as justification, lines of text can be aligned along such features as their right or left ends or the centers of the lines.
texture gradient	(n) A perceptual cue that uses changes in patterns to indicate changes in a surface (face). Gradual changes in the patterns indicate changes in depth, curvature, orientation to light, or a combination thereof. Abrupt changes indicate a change of surfaces or objects.
texture mapping	(n) A rendering technique that transfers a 2-D pattern (texture) to a 3-D surface. Although the name implies manipulating the geometry of the surface, the technique is limited to mapping color patterns, such as a logo or a fabric pattern, to a surface to enhance the realism of the model.
threaded fastener	(n) A mechanical fastener incorporating threads as a means of joining parts, either directly by threading into one or more of the parts or indirectly by using a nut.
thread form	(n) A threading term used to describe the profile or shape of the thread cut into the cylinder.
thread series	(n) A threading term used to describe the number of threads per inch for a given diameter.
tick marks	(n) Short, perpendicular lines located along a primary line. Tick marks are used to mark important locations along the line, such as a point of tangency in a geometric construction or the regular divisions of units along a scale line in a visualization.
time series analysis	(n) A visualization technique depicting a sequence of graphs in such a way as to allow comparisons between them. The sequence of images can be shown serially in the form of an animation or in parallel, with all the images either superimposed on each other or shown side by side.
tolerance	(n) The difference between the maximum and minimum size limits on a part. Tolerancing is a fundamental technique in precision manufacturing applications.
tolerance zone	(n) A tolerance term that represents the tolerance and its position in relation to the basic size.
tools	(n) Devices used to create engineering drawings and models, including both hand and computer tools.
tool solid	(n) Transient solid objects used to modify the solid model in a modeling system. Typically representing relative simple geometric shapes, tool solids modify the solid model using Boolean operations.
TOP	(n) Acronym for technical and office protocol, a standard developed to assist in the integration of technical information within an office environment. TOP allows file transfer, management, and access; message handling; standards for document revision and exchange; directory services; graphics; and database management.
topological	(adj.) In 3-D modeling, a term that refers to the connectivity of the model, that is, how the elements of the object (i.e., the faces, edges, and vertices) are organized. Geometry specifies where elements are located in space and how they are shaped; topology describes how these elements are connected to each other.
top view	(n) A principal view of an object created by rotating the line of sight 90 degrees about the horizontal axis above the front view. This view is typically included in a standard multiview drawing.
total quality management (TQM)	(n) The process of managing the entire organization such that it excels in all areas of production and service. The key is that quality extends throughout the organization, in everything that it does, and quality is defined by the customer.
TQM	(n) See total quality management.
traditional tools	(n) Devices used to assist the human hand in making technical drawings, such as drawing lines straighter, circles more circular, etc. Examples are mechanical pencils, straightedge scales, triangles, and compasses. Traditional tools are often compared with computer-based CAD tools.
transition fit	(n) A fit that occurs when two toleranced mating parts will sometimes be an interference fit and sometimes be a clearance fit when assembled. Both the loosest and tightest fits for any two mating parts must be calculated, often using tables associated with standard parts.
trimetric projection	(n) An axonometric projection in which none of the three axes is measured on the same scale or is at the same angle relative to the others. A trimetric drawing is the hardest to draw, but it is the most pleasing to the eye since it represents the most realistic positioning of the object.
true-length line	(n) A line representing an edge that is parallel to a plane of projection and perpendicular to the line of sight.
true-size plane	(n) A plane parallel to the plane of projection and perpendicular to the line of sight. The plane is shown as an edge in the adjacent, orthogonal projection planes.
tweaking	(v) A general term encompassing a variety of techniques that involve changing the geometry but not the topology of an object. For example, the radius of a sphere can be changed without adding or deleting any new faces. The size of a hole can also be changed, as long as the enlargement does not cross the edges of any other faces.