Try to write a description of this object. Test your written description by having someone attempt to make a sketch from your description. Effectiveness of Graphics Language The word languages are inadequate for describing the size , shape and features completely as well as concisely.
You can easily understand that … Lec. Bhuiyan Shameem Mahmood 8. Composition of Graphic Language Lec. Bhuiyan Shameem Mahmood A drawing can be done using freehand , instruments or computer methods. Freehand drawing The lines are sketched without using instruments other than pencils and erasers. Bhuiyan Shameem Mahmood Example Instrument drawing Instruments are used to draw straight lines, circles, and curves concisely and accurately.
Thus, the drawings are usually made to scale. Computer drawing The drawings are usually made by commercial software such as AutoCAD, solid works etc. Engineering Drawing Bhuiyan Shameem Mahmood Elements of Engineering Drawing Engineering drawing are made up of graphics language and word language.
Bhuiyan Shameem Mahmood Graphics language Describe a shape mainly. Word language Describe size, location and specification of the object. Bhuiyan Shameem Mahmood The projection theory is based on two variables: 1 Line of sight 2 Plane of projection image plane or picture plane The projection theory is used to graphically represent 3-D objects on 2-D media paper, computer screen.
Parallel projection Perspective projection parallel converge and Lec. Plane of projection is an imaginary flat plane which the image is created. Parallel projection Perspective projection Lec. Plane of projection Plane of projection Disadvantage of Perspective Projection Perspective projection is not used by engineer for manu- facturing of parts, because 1 It is difficult to create. Width is distorted Lec.
Orthographic Projection One-point Two-Point Lec. Symbols for Third Angle right or First Angle left. Bhuiyan Shameem Mahmood 5 Object views from top Projection plane 1 2 3 4 5 1 2 3 4 Image of a part represented in First Angle Projection Lec.
Two dimensions of an object is shown. Three dimensions of an object is shown. Rotate Tilt More than one view is needed to represent the object.
Multiview drawing Axonometric drawing Lec. Multiview Drawing It represents accurate shape and size. Advantage Disadvantage Require practice in writing and reading. Multiviews drawing 2-view drawing Example Lec. Axonometric Isometric Drawing Easy to understand Right angle becomes obtuse angle.
Circular hole becomes ellipse. Distortions of shape and size in isometric drawing Advantage Disadvantage Shape and angle distortion Example Lec.
Isometric projection Lec. Sectional views Lec. Auxiliary projection Lec. Traditional Drawing Tools Drawing board Lec. Drawing table Lec. Drafting tape Lec. Eraser Lec. Erasing Shield Lec. Sharpener Lec.
T-square Lec. Circle Template Lec. Scales Lec. Compass and divider Lec. Sandpaper Lec. Tissue paper Lec. Clean paper Lec. Drawing Standard Introduction Standards are set of rules that govern how technical drawings are represented. Bhuiyan Shameem Mahmood Drawing standards are used so that drawings convey the same meaning to everyone who reads them. An ideal engineering drawing software free download will help you streamline your designs and the development processes.
Here is some review of 3D design software bellow. Electrical engineering drawing software free download. Autodesk Product Design Suite: This is one of the best engineering drawing software free download. Autodesk provides 3D design and engineering software and services. It offers everything design engineers need. It comes with simulation, visualization, digital prototyping and collaboration tools. Order your sheet metal fabrication online. Immediate pricing and short lead times all over the UK.
An engineering drawing is a subcategory of technical drawings. The purpose is to convey all the information necessary for manufacturing a product or a part. Engineering drawings use standardised language and symbols. This makes understanding the drawings simple with little to no personal interpretation possibilities. As already 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. Still, knowing all the rules and basics of formatting is an absolute must in the industry , as traditional manufacturing companies still need detailed drawings. 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.
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. So, we are left with only one option really — every engineer should use CAD computer aided design software because of its many advantages.
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. A single drawing includes many elements with quite a few variations to each of them. Not every line on an engineering drawing is equal. The different options make it possible to show both visible and hidden edges of a part, centre lines, etc. The most common is a continuous line, also known as a drawing line. This represents the physical boundaries of an object.
Put simply, these lines are for drawing the objects. The line thickness varies — the outer contour uses thicker lines and inner lines are thinner. 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.
Centre lines are used to show hole and the symmetric properties of parts. Showing symmetricity can reduce the number of dimensions and make the drawing more eye-pleasing, thus easier to read.
Extension lines annotate what is being measured. The dimension line has two arrowheads between the extension lines and the measurement on top or inside, like in the image above the line. Break lines indicate that a view has been broken. If you have a part that is 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. When using a cutout view, the cutting plane lines show the trajectory of the cutout.
Here you can see that the A-A cutting line brings both types of holes into the view. Each serves a certain purpose. Bear in mind that adding views should follow the same logic as dimensioning — include as little as possible and as much as necessary. A tip for good engineering practice — only include a view if it contributes to the overall understanding of the design.
Isometric drawings show parts as three-dimensional. All the vertical lines stay vertical compared to front view and otherwise parallel lines are shown on a degree angle.
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