Everything you need to know about Cad Plotting and File Templates

Table

    Plotting

    autocad plottingA drawing created in CADD initially exists as a soft copy. A soft copy is the electronic data file of a drawing or model. A hard copy is a physical drawing created on paper or some other media by a printer or plotter. Hard copies are often a required element of the engineering or construction process, and they are more useful on the shop floor or at a construction site than soft copies. A design team can check and redline a hard copy without a computer or CADD software. CADD is the standard throughout the world for generating drawings, and electronic data exchange is becoming increasingly popular. However, hard-copy drawings are still a vital tool for communicating a design.

    Each CADD system uses a specific method to the plot, though the theory used in each is similar. In general, you must specify the following settings in order to plot:

    • Printer, plotter, or alternative plotting system to which the drawing is sent, which is called the plot device.
    • Plot device properties.
    • Sheet size and orientation.
    • Area to the plot.
    • Scale.
    • The number of copies.
    • Software and drawing specific settings.

    Drafting Equipment, Media, and Reproduction Methods is an important consideration when plotting. Some CADD applications such as Autodesk Inventor, Pro/Engineer, NX, and SolidWorks highly automate plotting, especially the process of scaling a drawing for plotting. Other systems such as AutoCAD and Micro Station require you to follow specific procedures to scale a plot correctly. AutoCAD, for example, uses a model space and paper space system. Model space is the environment in which you create drawings and designs at full scale. Paper space, or layout, is the environment in which you prepare the final drawing for plotting to scale. The layout often includes items such as viewports to display content from model space, a border, sheet blocks, general notes, associated lists, sheet annotation, and sheet setup information.

    • Scale Factor

    The scale factor is the reciprocal of the drawing scale, and it is used in the proper scaling of various objects such as text, dimensions, and graphic patterns. Most modern CADD software automates the process of scaling a drawing, allowing you to focus on choosing a scale rather than calculating the scale factor. However, the scale factor is a general concept with which you should be familiar, and it remains an important consideration when working with some CADD applications.

    When drawing with CADD, always draw objects at their actual size, or full scale, regardless of the size of the objects. For example, if you draw a small machine part and the length of a line in the drawing is .05 in. (1.27 mm), draw the line .05 in. (1.27 mm) long. If you draw an aircraft with a wingspan of 200' (60,960 mm), draw the wingspan 200'. These examples describe drawing objects that are too small or too large for layout and printing purposes. Scale the objects to fit properly on a sheet, according to a specific drawing scale.

    When you scale a drawing, you increase or decrease the displayed size of objects. AutoCAD, for example, uses model space and paper space for this process. Scaling a drawing greatly affects the display of items added to full-scale objects such as annotations, because these items should be the same size on a plotted sheet, regardless of the displayed size, or scale, of the rest of the drawing.

    Traditional manual scaling of annotations, graphic patterns, and other objects requires determining the scale factor of the drawing scale and then multiplying the scale factor by the plotted size of the objects. Text is a convenient object to describe the application of scale factor. For example, to plot text that is .12 in. (3 mm) high on a mechanical drawing plotted at a scale of 1:4, or quarter-scale, multiply the scale factor by .12 in. (3 mm). The scale factor is the reciprocal of the drawing scale. A 1:4 scale drawing has a scale factor of 4 (4 4 1 5 4). Multiply the scale factor of 4 by the text height of.12 in. (3 mm) to find the .48 in. (12 mm) scaled text height. The proper height of .12 in. (3 mm) text in an environment such as model space at a 1:4 scale is .48 in.(12 mm).

    Another example is plotting 1/8 in. high text on a structural drawing plotted at a scale of 1/4" 5 1' 0". A 1/4" 5 1' 0" scale drawing has a scale factor of 48 (1' 0" 4 1/4" 5 48). Multiply the scale factor of 48 by the text height of 1/8 in. to find the 6 in. scaled text height. The proper height of 1/8 in. text in an environment such as model space at a 1/4" 5 1' 0" scale is 6 in.

    • Electronic Plots

    Exporting is the process of transferring electronic data from a database, such as a drawing file, to a different format used by another program. Exporting a drawing is an effective way to display and share a drawing for some applications. One way to export a drawing is to plot a layout to a different file type. Electronic plotting uses the same general process as hard-copy plotting, but the plot exists electronically instead of on an actual sheet of paper.

    A common electronic plotting method is to plot to a portable document format (PDF) file. For example, send a PDF file of a layout to a manufacturer, vendor, contractor, agency, or plotting service. The recipient uses common Adobe software to view the plot electronically and plot the drawing to scale without having CADD software, thus avoiding inconsistencies that sometimes occur when sharing CADD files. Another example is plotting an AutoCAD file to a design web format (DWF or DWFx) file. The recipient of a DWF file uses a viewer such as Autodesk Design Review software to view and mark up the plot.

    File Templates

    cad file templateA file template, or template, is a file that stores standard file settings and objects for use in a new file.

    All settings and content of a template file are included in a new file. File templates save time and help produce a certain amount of consistency in the drawing and design process. Templates help you create new designs by referencing a base file, such as a drawing file, that contains many of the standard items required for multiple projects. A drawing-file template is often known as a drawing template. File templates function and are used differently depending on the CADD program.

    Most CADD software provides tools and options for working with and managing templates. For example, AutoCAD makes use of drawing template (DWT) files that allow you to use the NEW command to begin a new drawing (DWG) file by referencing a saved DWT file. A new drawing file appears, with all the template file settings and contents. Other CADD programs have different but similar applications. This automates the traditional method of opening a file template and then saving a copy of the file template using the name of the new file. You can usually specify or reference any existing appropriate file to use as a template, or you can begin a new drawing using a default template.

    cad file templateTemplate options and specifications vary, depending on the file type, project, and design and drafting standards. For example, you might use a template for designing parts and another for assemblies, or a template for metric drawings and another for customary drawings. A template includes settings for specific applications that are preset each time you begin a new design. Templates may include the following, depending on the CADD format and software, and set according to the design requirement:

    • Units settings.
    • Drawing and design settings and aids.
    • Layers with specific line standards.
    • Colour, material, and lighting standards.
    • Text, dimension, table, and other specialized annotation standards.
    • Common symbols.
    • Display settings.
    • Sheets and sheet items, such as borders, title blocks, and general notes.
    • Plot settings.

    Create and maintain a variety of file templates with settings for different drawing and design disciplines and project requirements. Store your templates in a common location that is easily accessible, such as the local hard disk or the network server. Keep backup copies of templates in a secure location. As you work, you may discover additional items that should be included in your templates. Update templates as needed and according to modified settings or new standard practices. When using AutoCAD, for example, use the OPEN command to open a DWT file. Then add content to the

    file as needed. Once you resave the file, the modified template is ready to use. Remember to replace all old template copies with updated versions.

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