What Is Plane in Engineering Drawing
A 3-dimensional object tin can be represented in a single plane, such every bit on a sheet of paper, using projecting lines and planes. All projection theory is based on two variables: line of sight (projecting lines) and plane of projection.
A line of sight (LOS) is an imaginary line between an observer'due south eye and an object. A plane of projection (i.e., an image or pic aeroplane) is an imaginary flat airplane upon which the image is projected. The project is produced past connecting the points where the lines of sight pierce the projection plane. As a result, the 3D object is transformed into a second view.
If the altitude from the observer to the object is infinite, then the projection lines are assumed to exist parallel, and the projection is called a parallel project. Parallel project is orthographic if the plane of project is placed between the observer and the object, and the plane is perpendicular to the parallel lines of sight.
Y'all can utilize parallel project technique to create both multiview and pictorial (isometric and oblique) views.
- In multiview orthographic projection (encounter details below), the object surface and the projection plane are parallel, and yous tin see simply two dimensions.
- In isometric view (orthographic) the surface is no longer parallel to the projection plane, but the latter is perpendicular to the lines of sight, with 3 dimensions being seen.
- In oblique project (not-orthographic) the object surface and the project aeroplane are also parallel, but the lines of sights are not perpendicular to the projection plane, and yous tin encounter again three dimensions.
If the distance from the observer to the object is finite, then the projection lines are not parallel (since all lines of sight commencement at a single indicate), and the drawing is classified as a perspective projection. In perspective view the object surface and project aeroplane can be besides parallel.
Multiview project
Past irresolute position of the object relative to the line of sight you lot can create different views of the same object. Drawing more than one face of an object past rotating the object relative to your line of sight helps in understanding the 3D class. Having several views on ane drawing yous use the concept of multi-view project, which is based on the orthographic (parallel) projection technique where
- the plane of projection is positioned between the observer and the object,
- the plane of projection is perpendicular to the parallel lines of sight, and
- the object is oriented such that just ii of its dimensions are shown.
Principal principles of creating multiview projections
The plane of projection can be oriented to produce an infinite number of views of an object. All the same, the well-nigh common views are the six mutually perpendicular views that are produced by vi mutually perpendicular planes of projection:
- Front view – the 1 that shows most features or characteristics.
- Left side view – shows what becomes the left side of the object after establishing the forepart view position.
- Right side view – shows what becomes the right side of the object after establishing the front view position.
- Top view – shows what becomes the top of the object once the position of the front view is established.
- Lesser view – shows what becomes the bottom of the object in one case the position of the forepart view is established.
- Rear view – shows what becomes the rear of the object once the position of the front end view is established.
The well-nigh informative (descriptive) view of the object to be represented is normally called equally the principal view (front view). This is view A related to the corresponding direction of viewing A and it normally shows the object in the functioning, manufacturing, or mounting position.
View positions on drawings and corresponding viewing directions
Positions of the other views relative to the principal view in the cartoon depend on the projection method.
The number of views and sections must be limited to the minimum necessary to fully stand for the object without ambivalence.
Unnecessary repetition of details must be avoided.
Conventional view placement
Generally, iii views of an object are enough, all the same, a drawing must comprise as many views as necessary to illustrate the part, normally at right angles to one another.
Frontal plane of projection
In multiview projection, the object is viewed perpendicular to the master faces, so that only one face of the object is depicted in each view. The frontal plane of projection is the plane onto which the front end view of a multiview cartoon is projected.
In the front view you can meet elevation and width of the object, but y'all cannot see its depth.
Horizontal plane of project
The tiptop view is projected onto the horizontal plane of projection, which is plane suspended higher up and parallel to the top of the object.
The top view of an object shows the width and depth dimensions.
Profile plane of projection
In multiview drawings, the right side view is the standard side view. The correct side view is projected onto the right profile airplane of projection, which is a plane that is parallel to the right side of the object. Even so, y'all can likewise apply the left side view if information technology is more descriptive and informative. Moreover, when needed, you tin include both side views into i cartoon.
The side view of an object shows the depth and summit dimensions.
The iii-view multiview drawing is the standard used in applied science and applied science, considering often the other 3 common views are mirror images and practice not add together to the noesis about the object.
The standard views used in a 3-view drawing are the
- summit,
- front, and
- right side views,
bundled as shown in the figure:
The width dimension is common to the forepart and meridian views. The tiptop dimension is common to the front and side views. The depth dimension is common to the top and side views.
For simple parts one or two view drawings will often be plenty. In one-view drawings the third dimension may exist expressed by a note, or by descriptive words, symbols, or abbreviations, such every bit Ø, HEX, etc.
Square sections may be indicated by light crossed diagonal lines, every bit shown above, which applies whether the face is parallel or inclined to the cartoon airplane.
Another example of a 1-view drawing:
Additional views may be added if they improve visualization.
The views should too be chosen to avert subconscious feature lines whenever possible. That means that the most descriptive view should be shown.
Besides, you should select the minimum number of views needed to completely draw an object. Eliminate views that are mirror images of other views.
Why multiview drawings technique is so of import?
To produce a new product, it is necessary to know its true dimensions, and truthful dimensions are not adequately represented in nigh pictorial drawings. For example, the photograph is a pictorial perspective image. However, as you can see, the prototype distorts true distances, while the latter are essential for manufacturing and construction, and in this case the case in question is the width of the road, non the electrical pole!
In mechanical engineering perspective projections misconstrue measurements.
As you lot can see, the two width dimensions in the front view of the block announced different in length in the perspective projection. In other words, equal distances do non appear equal on a perspective drawing.
Thus, since engineering and applied science depend on exact size and shape descriptions for design, the best arroyo is to use the parallel project technique (orthographic projection) to create multi-view drawings where each view shows but two of the three dimensions (width, pinnacle, depth).
To summarize:
The advantage of multiview drawings over pictorial drawings is that multiview drawings shows the true size and shape of the various features of the object, whereas pictorials distort true dimensions which are critical in manufacturing and construction.
ist & 3rd angles (glass box)
What exactly yous should place on the right side projection?
Is information technology that we tin encounter from the left side, or from the correct side of the object?
To answer these questions there are two different ways, based on two different principles
- First-Angle Projection
- Third-Angle Projection.
Third angle is used in Canada and the The states. Outset angle is used in Europe.
In third angle orthographic projection the object may be assumed to be enclosed in a glass box.
Each view represents that which is seen when looking perpendicularly at each face of the box.
The resulted views are identified by the names equally shown.
The front, rear, and side views are sometimes called eleva tions, e.grand., front acme. The peak view may be termed the programme.
If desired, the rear view may be shown both ways – at the extreme left or the farthermost right. When this is not practical to show rear view at he extreme left or right due to the length of the function, particularly with panels and mounting plates, the rear view should non be projected up or downwardly, as this would result in its being shown upside downwards.
Instead, it should be drawn as if projected sideways, but located in another position, and should be conspicuously labelled REAR VIEW REMOVED.
In first angle orthographic projections the object is considered as being rolled over to either side, and then that the right side of the object is fatigued to the left of the forepart elevation:
It is mandatory to indicate the method of multiview projection by including the advisable ISO (International Organization for Standardization) projection symbol – the truncated cone:
You should place this symbol in the lower right-paw corner of the drawing in or next to the title block.
Axonometric projection
Information technology is one of the pictorial drawing projections, which are useful for illustrative purposes, educational aids, installation and maintenance drawings, pattern sketches, and the like.
The Greek word axon means axis and metric means to measure. Axonometric projection is a parallel projection technique used to create a pictorial drawing of an object by rotating the object on an axis relative to a plane of projection.
Axonometric projections such as isometric, dimetric, and trimetric projections are orthographic, in that the projection lines are all parallel, but the angle of views is so chosen that iii faces of a rectangular object would be shown in a single view.
Axonometric drawings are classified by the angles betwixt the lines comprising the axonometric axes. The axonometric axes are axes that meet to form the corner of the object that is nearest to the observer.
When all three angles are unequal the drawing is classified equally a trimetric. When 2 of the 3 angles are equal the cartoon is classified every bit a dimetric. When all iii angles are equal the cartoon is classified as a isometric.
Although there are an infinite number of positions that tin can exist used to create such a drawing only few of them are used.
Enlarged detail
To eliminate the crowding of details or dimensions, an enlarged removed view may exist used.
- The enlarged view should be oriented in the same manner every bit the chief view,
- the scale of enlargement must be shown, and
- both views should be identified by one of the methods shown in the illustrations – with the leader line or with the circle line. The circle enclosing the area on the main view should be drawn with a thin line.
Source: https://www.mcgill.ca/engineeringdesign/engineering-design-process/basics-graphics-communication/projections-and-views
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