ONLINE GLOSSARY

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• Template. Any pattern that defines the outline of a part in the correct size and shape for the purposes of constructing all or part of an object. In traditional construction, templates are often cut from paper, cardboard or thin sheet stock and then traced onto the final material from which a part is to be cut. With modern computer-based tools, templates can be drawn with a computer and then used to make a part directly via computer-controlled machining such as laser-cutting or CNC milling.
  
  
• Tetrahedron. A three-dimensional geometric shape having 4 faces where each face is an identical triangle, i.e. a three-sided triangular pyramid.
  
  
• Text Tool. A tool in a computer drawing program that permits text to be added to a drawing.
  
  
• Third-Angle Projection. Standard for arranging multi-view drawings practiced in the United States, Canada, and Great Britain. This system places the front view at the center of the drawing with the top view above, bottom view below, right side view to the right and left side and rear views to the left. The front view is labeled arbitrarily and is not necessarily the actual front of the object. This can cause some confusion. A completely different arrangement called first-angle projection is practiced in the Europe and the International community.
  
  
• Through Holes. Holes bored (i.e. drilled) completely through an object.
  
  
• Tint. A screened, muted or "washed out" color that is of lighter intensity than the color upon which it is based. For example, shades of gray are tints of the base color black. In the same way, a pastel blue might be considered a "tint" of bright blue. In a computer illustration program, tints can be created by specifying a percentage value of the base color, i.e. medium gray = 50% black. A very light gray can be created as a tint of 10% black. In fact, a 10% tint of an intense base color such as bright red, green, or blue yields a very light color that is ideally suited for drawing construction lines.
  
  
• Title Block. An area in the bottom right corner of a drawing where the name of the draftsman, company, title/subject, page/sheet number, date, revision history, and any other information can be specified.
  
  
• Tolerance. A variation in size or thickness from the expected or stated value. Some manufactured materials differ from their stated dimensions due to variations inherent in the manufacturing process. As a result, tolerance should be taken into account when designing parts that must fit together precisely. See Clearance.
  
  
• Transition. A change in cross section over the length of a part or assembly. A transition can be used to join two parts that have dissimilar cross sections without creating an intersection between them.
  
  
• Transverse Frame. A structural framing member that runs laterally or side-to-side. On boats and ships, both transverse frames and bulkheads are used to form the shape of the hull. (A bulkhead is actually a dividing line between watertight compartments on a ship.) On aircraft, all transverse frames are called bulkheads. These structural frame members are "skinned" to form the shape of the hull or fuselage.
  
  
• True Depth. The depth of a bored hole measured from the surface all the way to point where the tip of the drill bit bottoms out in the hole. Most drill bits have tips that are angled at 120 degrees, creating a cone-shaped depression in the bottom of the hole. The true depth includes this depression. In contrast, the usable depth does not include this cone-shaped space at the bottom of the hole.
  
  
• True Length. The actual length of a line or object. According to the principles of orthographic projection, a line or object can only appear true length in a normal view if it is parallel to the principal plane of projection for that view, or, in the case of an auxiliary view, if it is parallel to the auxiliary plane of projection. See also Foreshortened.
  
  
• True Size. The actual or true dimensions of a plane or surface. According to the principles of orthographic projection, a plane can only appear true size in a normal view if it is parallel to the principal plane of projection for that view, or, in the case of an auxiliary view, if it is parallel to the auxiliary plane of projection. See also Foreshortened.
  
  
• Truncated. Having one or both ends cut off. In some cases, a truncated shape requires that the ends be cut at an angle such as with a truncated cone or truncated pyramid. In these cases, if the shape is cut so that the trimmed face is parallel with the base, it is called a "frustum" instead.
  
  
• Truncated Cone. A cone with the tip cut off at an angle. If the tip is cut in such a way that the trimmed top is parallel with the base of the cone, the shape is called a "frustum of a cone" instead. A paper cup is an excellent example of a frustum of a cone.

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0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Click on a letter to browse through the Glossary terms.
To download a printable version of the entire Glossary, click here.

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Reproduction, in whole or in part, is prohibited without written permission from the publisher.