Assam ASSEB HS Skill Engineering Drawing key terms

A flat rectangular wooden or synthetic surface with a smooth working edge, used to support drawing paper while a T-square or drafting machine is guided along its edge.

A drafting tool with a long straight blade fixed at right angles to a shorter stock; the stock slides along the drawing board edge to draw horizontal parallel lines.

A triangular instrument with angles of 45-45-90 or 30-60-90 degrees, used with a T-square to draw lines at fixed angles and perpendiculars.

A thin template with irregular curved edges, used to draw smooth freehand curves through a series of plotted points that no compass arc can fit.

A V-shaped instrument with two hinged legs, one holding a needle point and the other a lead or pen, used to draw circles and arcs of a chosen radius.

A drafting instrument with two sharp needle points used to transfer measurements from a scale to the drawing and to step off equal distances along a line.

The paper or film surface on which a drawing is produced; standard sizes such as A0 to A4 are defined by ISO 216 so that each size is half the previous one.

The fixed ratio between a length on the drawing and the corresponding real length of the object, stated as reduction, full size or enlargement.

The scale expressed as a ratio of drawing length to actual length, for example 1:50, written without units because both lengths are in the same unit.

A scale in which a rectangle is divided by verticals and a diagonal, allowing lengths to be read to a second or third decimal subdivision of the smallest division.

The convention that assigns meaning to a stroke pattern, such as continuous thick for visible outlines, dashed for hidden edges and chain thin for centre lines.

A short-dashed line used to represent an edge or contour that is not visible from the viewing direction but exists in the object.

A long-dash and short-dash chain line drawn through the axis of a symmetrical feature such as a hole, cylinder or pitch circle.

A ruled panel, usually at the bottom right of the sheet, recording drawing number, title, scale, material, projection symbol, date and the names of drafter and approver.

The standard style of freehand or mechanical capital writing used for notes and dimensions, characterised by uniform height, slope and stroke thickness for legibility.

A lettering style in which each letter is formed with strokes of one uniform width, so the alphabet can be written quickly with a pencil or pen.

A faint horizontal line drawn to mark the cap height or baseline of letters, keeping all lettering on a drawing at the same height and alignment.

A thin continuous line, usually terminated by arrowheads, that shows the direction and extent of a dimension between two extension lines.

A thin line drawn from the feature being dimensioned to the dimension line, showing exactly which points the measurement refers to.

The pointed termination of a dimension line; its length is normally about three times its width so that it reads clearly at the drawing's scale.

The accurate drawing of shapes such as perpendiculars, bisectors, polygons and tangents using only a compass, straightedge and set squares, without measurement error.

A closed curve traced by a point whose distances from two fixed foci always add to a constant; drawn in drafting by concentric circles, arcs of circles or the trammel method.

A method of representing a three-dimensional object by parallel projectors perpendicular to the picture plane, producing front, top and side views on separate planes.

A projection convention in which the object is imagined between the observer and the plane, so the view is placed on the far side; the top view goes below the front view.

A projection convention in which the plane lies between the observer and the object, so the top view appears above the front view and the right-side view appears on the right.

One of the mutually perpendicular reference planes, namely the vertical plane, horizontal plane and profile plane, on which the standard orthographic views are projected.

The line of intersection between two principal planes, drawn in the projection layout as the ground line or as the axis between adjacent views.

The actual, unforeshortened dimension of a line or edge as it exists on the object, obtained in projection by an auxiliary view or by rotation.

The angle a line or plane makes with a principal plane, such as the horizontal plane or vertical plane, determined in projection from its true-length view.

A view projected on a plane inclined to a principal plane, used to show the true shape or true length of a surface that appears foreshortened in the standard views.

An imaginary cutting plane passed through an object to reveal internal features; its true shape appears in the sectional view and its trace is shown by a chain line.

A view that shows the object as if cut by a section plane, with the cut surface hatched and the visible edges behind the plane drawn in full lines.

Thin equally spaced parallel lines at 45 degrees drawn across the cut surface in a sectional view to distinguish solid material from empty space.

The true-shape flat pattern obtained by unfolding the surface of a solid, such as a cylinder or cone, so it can be cut and formed from sheet material.

The curve formed where the surfaces of two solids meet, found by locating points common to both surfaces so that the joint can be drawn and developed accurately.

The portion of a solid, such as a cone or pyramid, that remains after the top is cut off by a plane parallel to the base.

A pictorial projection in which the three axes are equally inclined to the picture plane, so all three are drawn 120 degrees apart and lengths along them are foreshortened equally.

A reduced scale, about 0.816 of true length, used when drawing an isometric projection so that the foreshortening of the axes is represented correctly.

A pictorial projection in which the front face is drawn true shape and parallel to the picture plane, while receding edges are drawn at an angle to show depth.

An oblique projection in which receding edges are drawn to full true length, giving an exaggerated but simple pictorial view of the object.

The standard shorthand on a drawing that specifies a screw thread, giving thread form, nominal diameter and pitch, for example M20 x 2.5.

The agreed simplified drawing practice for standard features such as threads, springs, gears and bearings, so that a detail need not be drawn literally.

A small steel piece fitted into aligned slots in a shaft and hub to transmit torque while allowing the hub to be located along the shaft.

The slot cut in a shaft and in the mating hub to seat a key; its depth and width are standardised to suit the shaft diameter.

A device that joins two shafts end to end to transmit power, either rigidly or with enough flexibility to absorb small misalignments.

A machine element that supports a rotating shaft, carries its load and reduces friction, classified broadly as sliding or rolling types.

A view of a building or object seen from above, cut horizontally at a stated level, showing walls, openings and layout to a stated scale.

An orthographic view of a building's external face, showing heights of floors, roofs, windows and doors as seen from one side.

A simplified building drawing showing only wall centrelines or outlines, used in the early design stage before wall thicknesses and openings are fixed.

Computer-aided drafting: the use of software to create, edit, store and plot drawings as precise geometric entities rather than marks on paper.

A named, independently controllable level in a CAD drawing that groups related entities and carries shared colour, line type and visibility settings.

A group of CAD entities combined into a single named object that can be inserted repeatedly, edited once and updated in every insertion.

A CAD setting that forces the cursor or picked point onto an exact existing geometric feature, such as an endpoint, midpoint or intersection, ensuring accuracy.