Compendium of Design

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technical drawing

  • AS 1100 Technical Drawing

    AS 1100 Technical Drawing

    Instrumental drawings are based on a set on standards that have been globally agreed upon by the International Standards Organisation (ISO). These standards are then tailored to the specific needs of a country depending on such things as the adopted measuring system (metric or imperial), environmental conditions, manufacturing processes and developments in technology. The Australian Standard 1100 (more commonly referred to as the AS 1100), acts as a convention for all engineers, architects, designers, surveyors, pattern makers and other design disciplines to follow. This ensures that the visual communications, products and environments that they design can be manufactured by anyone around the world. These standards include everything from the paper size that is used, the pens or pencils the lines are drawn with and even the type and total number of drawings that are required for any one part or assembly of parts.

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    The standards offered in the sub-menus of this section of the site are an interpreted and abridged version of the Australian Standards AS 1100.101-1992 Technical Drawing – General Principles. Although the AS 1100 covers all disciplines of technical drawing, especially engineering, some design disciplines such as architecture, apply additional conventions that tailor the technical illustrations and notations to industry requirements. These standards are available separately from SAI global's website or Techstreet.

  • Lines and Line Styles

    Lines and Line Styles

    Line styles and thicknesses are an important component of instrumental drawing. They can indicate the boundaries of a part, a part's hidden features, or the travel path of a machinist's drill, mill or lathe. It is important that the correct line style and thickness is used to ensure your instrumental drawing is not ambiguous to anyone involved in the manufacture or construction of a product or environment, the production of instructions or the use of the product or environment. The advantage of changes line thicknesses can be seen when a drawing requires lots of dimensions, the thicker outline stands out from thinner dimension lines.

    Line Styles and Thicknesses

     

    Line Style Example Purpose
    Continuous - Thick   Thick line

    To indicate visible outlines

    Continuous - Thin Thin line

    Fictitious internal lines
    Dimension lines
    Projection lines
    Hatching
    Leaders

    Continuous - Dashed  Dash line  Hidden Features
    Chain line - Thin  Chain line  Centrelines
    Pitch lines
    Path Movement
    Developed Views
    Material for removal
    Chain line - Thick at ends and at change of direction  Chain line thick at ends   To indicate a cutting plane for sectioned views

    Line Thicknesses

    The thickness of lines are based on the size of the drawing sheet using used. The table below shows the appropriate line thicknesses applicable to the various sheet sizes.

    Sheet Size Line Type and Thickness (mm)

    A B C D E F G H J K
    A0  0.7  0.35 0.35 0.35 0.35 0.5

    0.35
    0.7

    0.35 0.7 0.35
    A1  0.5  0.25 0.25 0.25 0.25 0.35 0.25

    0.25
    0.5

    0.5 0.25
    A2, A3, A4  0.35  0.18 0.18 0.18 0.18 0.25 0.18

    0.18
    0.35

    0.35 0.18

     

    Line Presentation in Technical Drawings

    The presentation of lines in instrumental drawings is important as it maintains clear communication of intention and avoids ambiguity. It is therefore important that the following guidelines are used when drawing the applicable line styles;

    General Standards

    The scale of line thickness and length of dashes and spaces should be uniform across a drawing.

    The thickness of line(s) used should not become thinner than 0.18mm if the drawing sheet was reduced to A4

    Chain Lines

    When indicating centre points, centreline dashes should intersect at the origin of the feature
    Centrelines should extend a small distance past the feature of the drawing
    Centrelines should cease at any other line of the drawing
    Chain lines that indicate a cutting plane should begin and end with long dashes as best fits the drawing
    Chain lines that form an angle should cross or meet at the corners

    Dash Lines

    Dashed lines should start and end with dashes in contact with the visible or lines from which they originate
    If a dashed line meets a curved line tangentially, then it should be with a solid portion of the line

  • Sectioning

    Sectioning

    There are occasions when a drawing cannot provide adequate information to indicate the form of an object or environment. In these circumstances an additional view must be drawn in combination with, or instead of, the normal outside views. The new view is called a sectional view.

    Sectional views represent a view that has been sliced along a cutting plane to reveal a product or environment's inner detail.

     

    AS-1100: Sectioning

     

    Hatching

    Whenever a sectional view is drawn, the remaining solid or material components are indicated by hatch lines. Drawn at 45°, hatch lines should be drawn as thin lines and evenly spaced over the entire part.

    AS-1100: Hatch lines drawn at 45&deg

    Spacing of Hatch Lines

    Hatching lines should be evenly spaced and as best fits across the object or component of the part or environment being sectioned. If the hatching coincides with one or more sides of the part then an alternative angle can be used.

    AS-1100: Hatching
    Hatching a part with 45° geometry.
    AS-1100: Hatching
    Hatching two adjacent parts.
    AS-1100: Hatching
    Hatching three adjacent parts.

    Types of Sectional Views

    Thin Sections

    Thin sections are used to show the thickness of thin parts without having to draw the material thickness out of scale. To ensure that thickness of each part is communicated clear a minimum gap of 1mm between parts is shown.

    AS-1100: Sectioning - Thin sections
    Thin section.

    Half Sections

    Any part or environment that is symmetrical can be drawn half sectioned.

    AS-1100: Sectioning - Thin sections
    Half section.

    Local Sections

    Local sections can used to avoid showing a separate sectional view. The local area being sectioned is indicated by a continuous thin irregular line.

    AS-1100: Sectioning -  Local sections
    Local section

    Successive Sections

    Successive sections can be drawn as removed sections when, through lack of space, the sectional views cannot be shown in normal projection.

    AS-1100: Sectioning -  Successive sections
    Successive section

    Revolved Sections

    Revolved sections are used to the cross section of an arm, rib, spoke, or bar. Revolved sections are shown by drawing the cross sectional view of the part in position with the adjacent detail drawn around the revolved view.

    AS-1100: Sectioning -  Revolved sections
    Revolved section

    Removed Sections

    Removed sections are similar to revolved sections but they are drawn outside of the original part. They can be drawn adjacent to the original part or completely away from it. If drawn completely away from the part, both the section and the cutting plane must be clearly indicated to avoid confusion.

    AS-1100: Sectioning -  Removed sections
    Removed section

    Exceptions to Sectioning

    As with most rules there are exceptions. When a section plane cuts parts such as bolts, ribs, nuts, rivets, shafts, spokes, or wheels then these parts are not sectioned but shown in an external view.

  • Types of Drawings

    Types of Drawings

    When a product or environment has been designed, it is then prototyped or produced by a manufacturer or constructed by a team of builders or engineers. To assist in the creation of the product a set of plans are required. These plans enable the people whose job it is to create the design to do so in a way that meets the designer or client requirements. In order to do this, a drawing method that can illustrate to someone the size and shape of product's form, how many parts the product has and from what material each part or component will be made or constructed from is required.

    What drawings are needed?

    When a designer chooses to have a product manufactured they must provide the manufacturer or builder with enough information to make each individual part and assemble the parts to construct the overall product or environment. In these circumstances a complete set of 'Working Drawings' are needed. A set of working drawings consist of 'Detail Drawings' and 'Assembly Drawings'. In some occasions a 3-dimensional pictorial drawing can also be included to provide additional information if required.

    Detail Drawings

    Detail drawings are used as a primary reference for manufacturing an individual part. They must show all of the detail required to manufacture an individual component including a suitable number of fully dimensioned orthogonal views. It is convention for detailed drawings to contain only one part per drawing sheet; however, multi-detailed drawings can be used when it is more convenient to show a small number of simple individual parts on the same drawing.


    The following information is included on a detail drawing;

    • Dimensions and instructional annotations
    • Drafting standards used (AS 1100)
    • Name and Title of the Drawing
    • Drawing NumberUnit of measure (mm)
    • Tolerances where appropriate
    • Surface texture finishes
    • Special Treatments (heat, metallic coatings, paint)
    • References that reference a part to its particular sub-assembly
    • Type of Material used (Steel, High Speed Steel, Aluminium, Copper, Brass, Polystyrene, ABS)
    • Names of drafter, checker, approver, the dates on which the drafting and other procedures occurred
    • Zone reference system to help locate areas on a drawing
    • Size of the drawing sheetName of company or department
    • Drawing sheet reference, eg. 1 of 2

     

    Assembly and Sub-assembly Drawings

    An Assembly drawing shows how all the individual parts fit together to make an assembly. They are drawn using an arrangement of orthogonal views and cut sections. To show how large complex parts are assembled, large assembly drawings are generally made up of smaller sub-assembly drawings. In the case of a mountain bike for example, the bike's frame would be considered a sub-assemble, the gear cogs and chain considered a separate sub-assembly and so on. All of these sub-assemblies would then assemble to form the finished mountain bike assembly.

    There are two styles of assembly drawings used; General Assembly Drawings and Working Assembly Drawings

    General Assembly Drawings

    General assembly drawings are orthogonal drawings that are used to identify the individual components required to make up an assembly or sub-assembly. When drawing a general assembly the following points should be taken into account:

    • Only the necessary views required to clearly describe how the parts fit together and how the sub-assembly functions should be shown. These views should include a sectional view to avoid the use of hidden lines.
    • Annotations and dimensions that relate to the function of the sub-assembly are provided.
    • Individual components are identified by the use of leaders from the part and numbers enclosed within circles or balloons.
    • A Parts list sorted by the part number in the drawing identifies each part, its drawing number, and quantity. This list should also include any off the shelf parts used within the sub-assembly.
    • Assembly and sub-assembly drawings do not need to list information about the manufacture of individual parts. However, information about how a sub-assembly is to be assembled or important dimensions that could affect its assembly can be included.

    Working Assembly Drawings

    Working assembly drawings are a combination of working drawings and assembly drawings. They are typically only used where the drawing of the individual components, dimensions and the assembly of parts can be drawn on the same drawing sheet without ambiguity. Such drawings are typically only used in industries like furniture design where join details are provided in enlarged separate detailed drawings.

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