Requirements of engineering drawings

Drawing Sheet Sizes

Engineering drawings need to communicate information that is legally binding by providing a specification. Engineering drawings therefore need to met the following requirements Engineering drawings should be unambiguous and clear. For any part of a component there must be only one interpretation. If there is more than one interpretation or indeed there is doubt or fuzziness within the one interpretation, the drawing is incomplete because it will not be a true specification. The drawing must be...

Sectioning or crosshatching lines

When you go to a museum, you often see artefacts that have been cut up. For example, to illustrate how a petrol engine works, the cylinder block can be cut in half and the cut faces are invariably painted red. In engineering drawing, cross-hatching is the equivalent of painting something red. It is used to show the internal details of parts which otherwise would become too complex to show or dimension. The cross-hatch lines are usually equi-spaced and, for small parts, cover the whole of the...

Example of drawing a small hand vice

Part Drawing And Asembly Dimention

A common artefact in any workshop is a small vice. Such a small engineering vice is shown in Figure 3.1. The main body of the vice is a stubby 'U' shape in which a movable jaw is positioned between the two uprights. The movable jaw is actuated by a screw which is rotated by a small bar. Although the drawing is 'busy', the different lines help to make the artefact jump out from the page. This has been done by the use of different types of line thicknesses thick and thin and different types of...

Line types and thicknesses

The standard ISO 128 1982 gives 10 line types that are defined A to K excluding the letter I . The table in Figure 3.4 shows these lines. Material medium carbon steel. All dimensions in mm. Figure 3.3 Detailed engineering drawing of the 'hardened insert', part number 2 Material medium carbon steel. All dimensions in mm. Figure 3.3 Detailed engineering drawing of the 'hardened insert', part number 2 The line types are 'thick', 'thin', 'continuous', 'straight', 'curved', 'zigzag', 'discontinuous...

Perspective projection

Trimetric Projection

Perspective projection is as shown in Figure 2.2. Perspective projection is reality in that everything we see in the world is in perspective such that the objects always have vanishing points. Perspective projection is thus the true view of any object. Hence, we use expressions like 'putting something in perspective' Projectors radiate from a station point i.e. the eye past the object and onto the 2D picture plane. The station point is the viewing point. Although there is only one station...

Functional and nonfunctional dimensions

Although every aspect of a component has to be dimensioned, some dimensions are naturally more important than others. Some dimensions will be critical to the correct functioning of the component and these are termed functional dimensions. Other dimensions will not be critical to correct functioning and these are termed non-functional dimensions. Functional dimensions are obviously the more important of the two and therefore will be more important when making decisions about the dimension value....

Iti Engineering Drawing

Iti Engineering Drawing Third Angle View

True or false Answers will be found in the text or in the figures in Chapter 2. 3D engineering drawings should always be completed in perspective projection. Axonometric projection is a particular type of isometric projection. The best pictorial projection is isometric projection. Cavalier projection is to be preferred to Cabinet projection. Third angle projection is to be preferred to first angle. Projection lines need to be included on engineering drawings. A sectional view of a part...

Engineering Drawing Car Jack

Assembly Drawing Bench Vice

Obtain a component that is simple and commonly available and produce a detail drawing of it sufficient for it to be manufactured. Such a component could be a paperclip, key, drawing pin, ruler, centre punch, coat hook, glass jar, special nut or washer or bolt e.g. casellated, lock , spanner, nail, paper cup, plastic cup, CD, needle, cotton reel, cable tie, house brick, cardboard cereal box. 67. Beg, borrow or buy an artefact that consists of an assembly of parts and perform a reverse...