What Is Horizontal Plane in Engineering Drawing
A three-dimensional object can be represented in a single plane, such as on a sheet of newspaper, using projecting lines and planes. All projection theory is based on two variables: line of sight (projecting lines) and airplane of projection.
A line of sight (LOS) is an imaginary line between an observer's eye and an object. A plane of projection (i.eastward., an paradigm or picture aeroplane) is an imaginary flat airplane upon which the prototype is projected. The project is produced by connecting the points where the lines of sight pierce the projection plane. Every bit a result, the 3D object is transformed into a 2nd view.
If the distance from the observer to the object is infinite, and then the project lines are assumed to be parallel, and the projection is called a parallel projection. Parallel project is orthographic if the airplane of project is placed between the observer and the object, and the plane is perpendicular to the parallel lines of sight.
You can use parallel projection technique to create both multiview and pictorial (isometric and oblique) views.
- In multiview orthographic projection (see details below), the object surface and the projection airplane are parallel, and y'all tin meet only ii dimensions.
- In isometric view (orthographic) the surface is no longer parallel to the projection airplane, but the latter is perpendicular to the lines of sight, with 3 dimensions beingness seen.
- In oblique projection (non-orthographic) the object surface and the projection aeroplane are also parallel, but the lines of sights are non perpendicular to the projection plane, and you can see again 3 dimensions.
If the distance from the observer to the object is finite, and so the projection lines are non parallel (since all lines of sight start at a single point), and the drawing is classified equally a perspective project. In perspective view the object surface and project airplane tin be too parallel.
Multiview projection
Past irresolute position of the object relative to the line of sight y'all tin can create different views of the same object. Drawing more than i face of an object by rotating the object relative to your line of sight helps in understanding the 3D course. Having several views on i drawing you apply the concept of multi-view project, which is based on the orthographic (parallel) projection technique where
- the airplane of project is positioned betwixt the observer and the object,
- the plane of projection is perpendicular to the parallel lines of sight, and
- the object is oriented such that simply two of its dimensions are shown.
Main principles of creating multiview projections
The aeroplane of projection can exist oriented to produce an infinite number of views of an object. All the same, the most common views are the vi mutually perpendicular views that are produced by six mutually perpendicular planes of projection:
- Front view – the one that shows nigh features or characteristics.
- Left side view – shows what becomes the left side of the object after establishing the front view position.
- Correct side view – shows what becomes the right side of the object afterwards establishing the forepart view position.
- Top view – shows what becomes the top of the object in one case the position of the front view is established.
- Bottom view – shows what becomes the bottom of the object one time the position of the front view is established.
- Rear view – shows what becomes the rear of the object once the position of the front view is established.
The most informative (descriptive) view of the object to be represented is ordinarily chosen as the main view (front view). This is view A related to the corresponding direction of viewing A and it usually shows the object in the functioning, manufacturing, or mounting position.
View positions on drawings and respective viewing directions
Positions of the other views relative to the principal view in the drawing depend on the projection method.
The number of views and sections must be limited to the minimum necessary to fully represent the object without ambivalence.
Unnecessary repetition of details must be avoided.
Conventional view placement
Mostly, three views of an object are enough, still, a cartoon must contain as many views as necessary to illustrate the part, usually at right angles to one another.
Frontal plane of projection
In multiview projection, the object is viewed perpendicular to the main faces, so that but one face of the object is depicted in each view. The frontal airplane of projection is the plane onto which the front view of a multiview drawing is projected.
In the front view you can see height and width of the object, simply y'all cannot see its depth.
Horizontal airplane of projection
The top view is projected onto the horizontal aeroplane of projection, which is airplane suspended above and parallel to the top of the object.
The top view of an object shows the width and depth dimensions.
Contour aeroplane of projection
In multiview drawings, the correct side view is the standard side view. The correct side view is projected onto the correct profile plane of projection, which is a plane that is parallel to the correct side of the object. Yet, yous tin likewise use the left side view if information technology is more descriptive and informative. Moreover, when needed, you can include both side views into one drawing.
The side view of an object shows the depth and height dimensions.
The three-view multiview drawing is the standard used in engineering and technology, because often the other three mutual views are mirror images and do not add together to the knowledge about the object.
The standard views used in a iii-view drawing are the
- tiptop,
- front end, and
- right side views,
arranged as shown in the effigy:
The width dimension is common to the front and tiptop views. The height 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 enough. In i-view drawings the 3rd dimension may be expressed by a note, or by descriptive words, symbols, or abbreviations, such as Ø, HEX, etc.
Square sections may be indicated past light crossed diagonal lines, as shown above, which applies whether the face up is parallel or inclined to the cartoon plane.
Some other example of a 1-view drawing:
Boosted views may be added if they improve visualization.
The views should also be chosen to avoid subconscious feature lines whenever possible. That ways that the most descriptive view should be shown.
Likewise, you should select the minimum number of views needed to completely describe an object. Eliminate views that are mirror images of other views.
Why multiview drawings technique is so important?
To produce a new product, information technology is necessary to know its true dimensions, and truthful dimensions are not adequately represented in virtually pictorial drawings. For example, the photograph is a pictorial perspective image. Nonetheless, as yous tin come across, the epitome distorts truthful distances, while the latter are essential for manufacturing and structure, and in this example the case in question is the width of the road, not the electric pole!
In mechanical technology perspective projections misconstrue measurements.
As yous tin see, the two width dimensions in the front view of the block appear unlike in length in the perspective projection. In other words, equal distances do non announced equal on a perspective drawing.
Thus, since engineering and technology depend on verbal size and shape descriptions for design, the all-time approach is to use the parallel projection technique (orthographic projection) to create multi-view drawings where each view shows simply 2 of the three dimensions (width, summit, depth).
To summarize:
The advantage of multiview drawings over pictorial drawings is that multiview drawings shows the truthful size and shape of the diverse features of the object, whereas pictorials distort true dimensions which are critical in manufacturing and construction.
1st & 3rd angles (glass box)
What exactly you should place on the right side project?
Is it that we can see from the left side, or from the right side of the object?
To answer these questions in that location are two unlike means, based on two different principles
- Beginning-Angle Projection
- Third-Angle Projection.
3rd bending is used in Canada and the United States. First angle is used in Europe.
In third angle orthographic projection the object may be assumed to exist enclosed in a drinking 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 as shown.
The forepart, rear, and side views are sometimes called eleva tions, e.g., front end elevation. The top view may be termed the plan.
If desired, the rear view may be shown both ways – at the extreme left or the farthermost correct. When this is non practical to show rear view at he extreme left or correct due to the length of the part, specially with panels and mounting plates, the rear view should not exist projected up or down, as this would upshot in its being shown upside downwards.
Instead, it should be drawn as if projected sideways, but located in some other position, and should be conspicuously labelled REAR VIEW REMOVED.
In commencement angle orthographic projections the object is considered equally being rolled over to either side, so that the right side of the object is fatigued to the left of the forepart peak:
It is mandatory to signal the method of multiview projection by including the appropriate ISO (International Arrangement for Standardization) projection symbol – the truncated cone:
Y'all should identify this symbol in the lower correct-hand corner of the drawing in or adjacent 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, design sketches, and the like.
The Greek discussion axon means axis and metric means to measure. Axonometric projection is a parallel projection technique used to create a pictorial cartoon of an object by rotating the object on an axis relative to a plane of project.
Axonometric projections such every bit isometric, dimetric, and trimetric projections are orthographic, in that the projection lines are all parallel, but the angle of views is and so chosen that three faces of a rectangular object would be shown in a single view.
Axonometric drawings are classified by the angles between the lines comprising the axonometric axes. The axonometric axes are axes that run across to form the corner of the object that is nearest to the observer.
When all three angles are unequal the cartoon is classified equally a trimetric. When two of the three angles are equal the drawing is classified as a dimetric. When all three angles are equal the cartoon is classified every bit a isometric.
Although in that location are an infinite number of positions that tin can be used to create such a drawing simply few of them are used.
Enlarged particular
To eliminate the crowding of details or dimensions, an enlarged removed view may be used.
- The enlarged view should exist oriented in the same manner equally the main view,
- the scale of enlargement must be shown, and
- both views should be identified by 1 of the methods shown in the illustrations – with the leader line or with the circle line. The circle enclosing the surface area on the master 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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