Engineering Drawing Front View

[Abigael Ortyl]

Asalready said, such a technical drawing has all the information for manufacturing a part or welding and building an assembly. The info includes dimensions, part names and numbers, etc. So once a manufacturing engineer gets the drawing, he can start the production process without a second thought.

First, we have to pause for a second and address our own customers here to avoid confusion. The drawings you submit for instant pricing and manufacturing in our system do not need any of this. The same applies to 3D models. CAD files and drawings made according to our design tips include all the necessary information for making your product. The only time we ask for a drawing is if you want to specify tolerances.

A few decades ago, you would have had to sit down at a drawing board covered with papers of different size, rulers, callipers, etc. Today, all these instruments are still good for manual drafting but no contemporary manufacturer really wants such drawings.

Why? Because most of the machinery uses CNC systems that can read the information straight from the files and produce a cutting program accordingly. Drawings done by hand would just add a lot of manual work for manufacturing engineers.

You can, of course, use CAD for making drawings from scratch. But the easier option is to first make a 3D model and create the drawings from that, as the programs generate the views with only a few clicks. All you need to do is add the dimensions. Having models also makes updating the drawings for revisions simple.

Hidden lines can show something that would not be otherwise visible on the drawings. For example, hidden lines may show the length of an internal step in a turned part without using a section or a cutout view (we explain both later).

Break lines indicate that a view has been broken. If you have a part that is 3000 mm long and 10 mm wide with symmetric properties, using a break-out makes gives all the info without using as much space.

While a good way for giving information to people, CNC machines need full views in order to cut the parts. Otherwise, the manufacturing engineer has to reconstruct the whole part from the measurements.

The lines that are vertical and parallel are in their true length. This means you can use a ruler and the scaling of the drawing to easily measure the length straight from a paper drawing, for example. The same does not apply to angled lines.

It is important to distinguish the isometric view from a perspective view. A perspective view is an artistic one that represents an object as it seems to the eye. Engineers stay true to the dimensions rather than optical illusions.

If you are making a folded sheet metal part, do not forget to add a flat pattern view. The cutting job comes before bending. When it comes to our customers, the easiest way is just to upload a STEP file without any accompanying drawings.

If you are using the standard part environment, the same option is not available. Still, many CAD programs can convert a standard part into sheet metal if the part properties correspond to sheet metal (e.g. uniform thickness, inside radius, etc.).

A section view can easily display some of the part features that are not evident when looking just from the outset. Cross section is the preferred option compared to hidden lines as it brings more clarity. The cross hatching feature is an indicator for cross sectional views.

The detail view gives us a close-up of a selected section of a larger view. This can be especially useful if an otherwise large part includes many important dimensions in a small area. Using the detail view improves the readability of these measurements.

The keyword here is necessary. Avoid using the auto-dimensioning feature that a lot of CAD programs offer because they tend to show everything they can find. For a beginner, it may seem like adding it all ensures that no mistakes can be made.

Actually, it can result in a confusing web of measurements that is left for the manufacturing engineer to untangle. Also, adding all dimensions you can find makes it hard to pinpoint which ones are the most important.

The image above shows a shaft with all the measurements. In reality, it creates a closed system whereby the manufacturer cannot guarantee all these dimensions 100%. Therefore, you have to determine the most important ones. In our case, we chose the end steps to be more important than the length of the central part. Thus, we should delete the 120 mm dimension.

One crucial bit of information that is missing from CAD models is geometric dimensioning and tolerancing (GD & T). For example, when looking to produce a shaft for a bearing system, limits and fits are of high importance. The right dimensions can guarantee a longer life with less maintenance.

We at Fractory are trying to save this time by automating the reading of 3D models for production, be it for different cutting and bending operations or CNC machining. This leaves engineers with the task of producing assembly and GD&T drawings only. The purpose is to keep the focus on engineering better products.

The engineering community is seeing this movement as a new trend. But as we all know, taking the whole industry up to a new standard takes a lot of time. Thus, if you still outsource your production to manufacturing companies that need drawings, you must know the basics at the very least.

A three-dimensional object can be represented in a single plane, such as 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.

If the distance from the observer to the object is infinite, then the projection lines are assumed to be parallel, and the projection is called a parallel projection. Parallel projection is orthographic if the plane of projection is placed between the observer and the object, and the plane is perpendicular to the parallel lines of sight.

If the distance from the observer to the object is finite, then the projection lines are not parallel (since all lines of sight start at a single point), and the drawing is classified as a perspective projection. In perspective view the object surface and projection plane can be also parallel.

By changing position of the object relative to the line of sight you can create different views of the same object. Drawing more than one face of an object by rotating the object relative to your line of sight helps in understanding the 3D form. Having several views on one drawing you use the concept of multi-view projection, which is based on the orthographic (parallel) projection technique where

The plane of projection can be oriented to produce an infinite number of views of an object. However, the most common views are the six mutually perpendicular views that are produced by six mutually perpendicular planes of projection:

The most informative (descriptive) view of the object to be represented is normally chosen as the principal 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.

In multiview projection, the object is viewed perpendicular to the main 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 view of a multiview drawing is projected.

In multiview drawings, the right side view is the standard side view. The right side view is projected onto the right profile plane of projection, which is a plane that is parallel to the right side of the object. However, you can also use the left side view if it is more descriptive and informative. Moreover, when needed, you can include both side views into one drawing.

For simple parts one or two view drawings will often be enough. In one-view drawings the third dimension may be expressed by a note, or by descriptive words, symbols, or abbreviations, such as , HEX, etc.

To produce a new product, it is necessary to know its true dimensions, and true dimensions are not adequately represented in most pictorial drawings. For example, the photograph is a pictorial perspective image. However, as you can see, the image distorts true distances, while the latter are essential for manufacturing and construction, and in this example the case in question is the width of the road, not the electrical pole!

As you can see, the two width dimensions in the front view of the block appear different in length in the perspective projection. In other words, equal distances do not appear equal on a perspective drawing.

Thus, since engineering and technology depend on exact size and shape descriptions for design, the best approach is to use the parallel projection technique (orthographic projection) to create multi-view drawings where each view shows only two of the three dimensions (width, height, depth).

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.

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 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 meet to form the corner of the object that is nearest to the observer.

When all three angles are unequal the drawing is classified as a trimetric. When two of the three angles are equal the drawing is classified as a dimetric. When all three angles are equal the drawing is classified as a isometric.

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