CourseWiki/Engineering Graphics and CAD/Reading Drawings

Choosing Drawing Views

Use flat views from different directions, with dimensions and notes, to describe a part clearly.

Drawing views describe one part from different directions

A drawing view is a flat picture of a part seen from one direction. A set of views, read together with dimensions and notes, describes one three-dimensional part so someone can make or inspect it.

A front view shows width and height. Looking from above or from the side can show the front-to-back depth that the front leaves out. In this stepped-block example, the front explains the step heights, while the top shows how far the block extends back.

One stepped block viewed from the front, top, and right. The front has an L-shaped outline; the top shows its front-to-back depth, and the right shows that depth and the step heights. — The picture on the left helps you recognize the part. The three flat views on the right show the same part from separate directions.

Choosing views means selecting the directions that explain the shape clearly. Orthographic Projection explains how the views line up and how their positions tell you the viewing direction.

Choose the front view that explains the shape

The front view is a drawing of the part from the direction chosen as the starting point for the other views. The side shown need not be the one that happened to face you when you picked up the part.

Start with a stable, understandable orientation. Prefer a view that shows characteristic shapes directly and keeps important features out of hidden lines, the dashed lines used for edges blocked from sight. For a stepped part, a profile that shows the steps is usually more useful than a plain rectangle.

The front, top, and side are principal views: views along the part's main directions. Once the front is chosen, the other principal views follow from it. Keep their orientation and alignment consistent with Orthographic Projection and the Glass Box.

One or two views can be enough when the missing information is stated

One view: A flat plate with a constant thickness can be defined by its face view and a thickness note, provided the outline, holes, and other requirements are completely specified. A circle alone does not say whether the part is a disk, a sphere, or a cylinder.
Two views: A constant-depth stepped shape can use a profile and a top view to establish the step widths, heights, and front-to-back depth. A third view may add no new information. A simple cylindrical part can often be described with a side view and an end view.
Three views: Front, top, and a side view are useful when features change across all three directions. Each view should resolve a question the others leave open.

Three is a common arrangement, not a quota. Dimensions, notes, symmetry, and repeated geometry can supply information without drawing every side. The remaining views and written requirements must still define the whole part.

Add a view when it removes a real ambiguity

A view is useful when it answers a question the existing views leave open. For example, the same circular front outline could belong to a thin disk or a long cylinder. A side view or a length note can resolve that difference. If two different parts still fit the drawing, identify the missing information and add the view or written callout that separates them.

Hidden interior: A section view can expose a bore or recess more clearly than a tangle of dashed lines. Its cutting-plane arrows tell you which way to look.
Flat sloping surface: An auxiliary view looks straight at the surface from an extra direction so its shape is clear. Another front, top, or side view may still make it appear shortened. See Auxiliary and Detail Views for that construction.
Small feature: An enlarged detail view makes a crowded feature readable. Read its stated scale; do not compare its apparent size directly with the main view.

Why more pictures do not automatically mean more information

Repeated information takes space and creates more places for a revision to disagree. A useful additional view makes something clearer: shape, depth, location, or access to a dimension. A pictorial can help orientation, but it does not automatically replace the views and callouts needed to define the part.

The historical NASA GSFC manual (1994), §3.1 explicitly permits one or two views when they completely define an object. Its §3.5 describes sections, auxiliary views, and details. This is a useful design principle, not a claim that that manual governs every drawing.

Check the view set before moving on to dimensions; Checklist; Practice

Check the view set before moving on to dimensions

Confirm that the front view exposes the most useful shape.
Account for width, height, and depth without guessing.
Locate every hole, step, slot, or recess in enough views to explain its direction and extent.
Check hidden edges and the projection convention for consistency.
Remove a redundant view only if the remaining views and callouts still define the part.

Then continue to Drawing Dimensioning for placing the size and location information. Use Measurement Language for units and Tolerances and Fits for permitted variation.

Practice choosing a view set

Appears in

DET 102 DET Reading Engineering Drawings