7/9/2009. Offset Tool. Offset Tool. Offsetting - Erasing the Original Object. Chapter 8 Construction Tools and Multiview Drawings

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1 Chapter 8 Construction Tools and Multiview Drawings Use the OFFSET tool to draw parallel lines and curves. Mark points on objects at equal lengths using the DIVIDE tool. Set designated increments on an existing object using the MEASURE tool. Create construction lines using the XLINE and RAY tools. Create orthographic multiview drawings and auxiliary views. Offset Tool Command: Offset or O The OFFSET tool is one of the most common geometric construction tools. Use the OFFSET tool to form parallel lines and polylines. For example, existing lines or polylines can be offset to construct the thickness of architectural floor plan walls. Existing circles, arcs, and curves can be offset to form concentric objects. Offset Tool Offset Tool The best way to use the OFFSET tool is to enter an offset value at the Specify offset distance or Through/Erase/Layer] <current>: prompt. The last offset distance used, is the default and is shown in brackets. For example, if you want to draw two parallel circles a distance of.1 unit apart, access the OFFSET tool, and at the Specify offset distance or [Through/Erase/Layer] <current>: prompt, enter a value of.1. Pick the circle you want to offset, and then pick the side of the circle on which the offset occurs Once the OFFSET tool has been used it remains active, allowing you to pick another object to offset using the same offset distance. When you are finished using the tool, press the [Enter] key, the [Esc] key or the space bar, or choose the Exit option. If you do not know the offset value, but two reference points exist in the drawing area, you can pick a first point and then a second point instead of typing an offset value. Offsetting - Erasing the Original Object Offsetting - Erasing the Original Object When you offset an object, you may want to remove the original object. Instead of offsetting the object and then erasing the source object, you can use the Erase option of the OFFSET tool to erase the source object. Initiate the OFFSET tool, enter the Erase option, and choose Yes at the Erase source object after offsetting? Prompt to erase the source object. The Yes option remains as the default until it is changed to No. Be sure to change this option back to No if you do not want the source offset object Enter E to erase the source object 1

2 Changing the Layer of the Offset Object The Layer option of the OFFSET tool allows you to place the offset object on the current layer. For example, if the offset source object is on the Electrical layer and the offset object needs to be placed on the Lighting layer, this can be done during the offset operation if Lighting is the current layer. After initiating the OFFSET tool, enter the Layer option and choose Current at the Enter layer option for offset objects prompt to create the offset object on the current layer. The Current option remains the default until it is changed to Source Changing the Layer of the Offset Object Type L to put offset object on current layer and enter c for current and s for source Offsetting Multiple Times After the object to offset has been selected, the Multiple option can be used to offset an object more than once with the same distance between the objects without reselecting the object to offset. Initiate the OFFSET tool, specify the offset distance, and pick the source object. You can then select the Multiple option and begin picking to specify the offset direction. Point Tool Points are useful for identifying specific locations on a drawing and for marking positions on objects. You can draw points anywhere on the screen using the POINT tool. Once you access the POINT tool, you can pick or type coordinates to place points. The POINT tool has two variations: Single Point and Multiple Points. Command: Point or PO The point style may be selected from 20 different styles. Command: DDPTYPE Point Tool Point Tool Points are useful for identifying specific locations on a drawing and for marking positions on objects. You can draw points anywhere on the screen using the POINT tool. Once you access the POINT tool, you can pick or type coordinates to place points. The POINT tool has two variations: Single Point and Multiple Points. To place a single point object and then exit the POINT tool, access the POINT tool using keyboard entry or select the Single Point option from the Point menu in the menu browser. To draw multiple points without exiting the POINT tool, use the Multiple Points button on the ribbon or the Multiple Point option from the Point submenu 2

3 Marking an Object at Specified Increments It places point objects or blocks at equally spaced locations. Access the DIVIDE tool and select the object you want to divide or type DIVIDE or DIV at the command prompt. Marking an Object at Specified Increments A line, circle, arc, or polyline can be divided into an equal number of segments, using the DIVIDE tool. The DIVIDE tool does not break an object into multiple l parts. It places point objects or blocks at equally spaced locations. The point style determines the type of marks placed on the object. Placing an Object at Specified Increments Marking an Object at Specified Distances The Block option of the DIVIDE tool allows you to place a block at each division point. Select the Block option at the Enter the number of segments or [Block]: prompt to insert a block. AutoCAD will ask if the block is to be aligned with the object. While the DIVIDE tool divides an object into a specified number of increments, the MEASURE tool places marks a specified distance apart. Access the MEASURE tool to mark points on an object. Then pick the object and enter a value for the distance. Blocks might be fasteners, plumbing fixtures, etc Point Measure Tool Marking an Object at Specified Distances The MEASURE tool places marks a specified distance apart on an object. Measure may be accessed by clicking on the icon in the Draw tool areaon the Home ribbon or by typing Measure or ME at the command prompt Access the MEASURE tool to mark points on an object. Then pick the object and enter a value for the distance. The point style determines the type of marks placed on the object. 3

4 Marking an Object at Specified Distances Marking an Object at Specified Distances The point style determines the type of marks placed on the object. Measuring begins at the end closest to where the object is picked. All increments are equal to the specified segment length, except the last segment, which may be shorter. Blocks may be fasteners, architecural details, etc. Blocks can be inserted at the given distances using the Block option of the MEASURE tool. Creating Multiview Drawings -Projection Method Projection of an Object Must visualize a transparent plane between the viewer and the object. This transparent plane represents the plane of projection. Theoretically the observer is an infinite distance from the object, and the lines of sight are parallel. Projectors from all points on the edges of the object extend to the plane of glass In the US 3 rd Angle Projection is used Top and Right Side Views 3 Planes of Projection Frontal Plane (Front view)- shows height and width Horizontal Plane (Top View) shows width and depth Profile Plane (Side Views) shows height and depth 4

5 The Glass Box Glass Box Theory (Con t) Planes of projection are placed parallel to the principal faces of the object There are six planes of projection Together they form a glass box Animation All planes of projection, (except the rear) are hinged to the front plane. The hinges are called Folding Lines Each plane will revolve outward until it is in line with the frontal plane. Glass Box Theory Front, top and bottom views all line up vertically, and will be the same width. Rear, left, and right views all line up horizontally and are the same height. Glass Box Theory (Con t.) 2 View Instrumental Drawings Many parts can be completely described with only two views. 5

6 Layout of Technical Drawings Alternate Positions of Views Views should be spaced so that the center of the views is centered on the page. The distance between views should be such that there is room for dimensions, without appearing cluttered. It is permissible to locate the profile views in line with the top view, (or bottom view) when large areas of space are wasted with the conventional arrangement. Alternate Position of Views Partial Views A partial view can be used when it describes the part, and reduces clutter and crowding on the drawing Revolution Conventions Revolution Conventions Details such as ribs that would be shown foreshortened if projected normally are shown revolved, to avoid confusion over size. 6

7 Removed View Removed View A complete or partial view that is removed to a different section of the drawing is called a removed view This is only permissible when space limitations make normal projections impossible ibl or cluttered. Multiview Drawings Multiview Drawings and Construction Lines Top View Note: Construction lines are useful for ensuring that views are properly aligned. Right Side View Front View Multiview Drawings Construction Lines and Rays The front view is usually the most descriptive view. The following rules should be considered when selecting the front view: Most descriptive Most natural position Most stable position Provides the longest dimension Contains the least number of hidden features The tracking vectors and alignment paths available with the object snap and AutoTrack tools are examples of construction lines. These tools are helpful when creating objects because vector and alignment construction lines appear only when needed. At times the Autocad user may want construction lines to stay visible while they create additonal geometry 7

8 Construction Lines Construction Lines and Rays Construction lines, or objects may be drawn with any drawing tool, such as LINE or ARC. AutoCAD provides XLINE and RAY tools that are specifically designed for adding construction lines to help lay out a drawing. An AutoCAD construction line, or xline, is drawn using the XLINE tool. A ray is drawn using the RAY tool Construction Lines and Rays It is helpful to create construction geometry on a separate construction layer, named CONST or CONSTRUCTION, for example. The layer can be turned off or frozen when not needed, or construction objects drawn on the layer can be easily recognized and erased if necessary. The XLINE tool is accessed by typing Xline or XL at the command prompt The XLINE tool is used to draw infinitely long construction lines, called xlines. Xline Tool Xline Tool The basic xline is drawn by entering or selecting two points through which the construction line passes. After you pick the root point, you can select as many points as needed to create additional xlines. Xline Tool Options The Horizontal, (Hor), option draws a horizontal construction line through a single specified point. The Vertical, (Ver) option draws a vertical construction line through a specified point. The Bisect option draws a construction line that bisects a specified angle, using the vertex as the root point. The Offset option draws a construction line a specified distance from a selected line object. 8

9 Xline Tool Options The Angle, Ang, option draws a construction line at a specified angle through a selected point. To use, access the XLINE tool and activate the Ang option, by entering A. Enter an angle and then pick a point through which the construction line is to be drawn. Another method is to select two points to define the angle. The Reference option of the Ang option allows you to use the angle of an existing line object as a reference angle for construction lines. Xline Tool Angle Option The Angle, Ang, option is useful for creating auxilary views. Xline Tool Angle Option Auxilary Views A construction line can also be made perpendicular to a line object using the Reference option of the XLINE tool s Ang option. Select the line object when prompted and enter an xline angle of 90. Also used to create construction lines. A Ray is a line that starts at a point and continues thru infinity. To access ray type Ray at the command prompt or click on the ray icon in the Draw tool area Ray Tool Lab Activities Drawing Problems, Pages , Chapter 9 -Text Styles and Multiline Text Chapter 9 Learning Objectives Describe and use proper text standards. Calculate drawing scale and text height. Develop and use text styles. Make multiple lines of text with the MTEXT tool. 9

10 Adding Text to Drawings Text Standards AutoCAD provides two basic systems for creating text. Multiline text is created with the MTEXT tool and is used to prepare a single text object that may consist of multiple lines of text, such as paragraphs or a list of general notes. Single-line text is created with the TEXT tool and is used to add single-line text objects. The ASME Y14.2M lettering standard recommends several text heights based on the particular function of the text on the drawing. The height of most text, (dimensions and notes), is.12 (3 mm). Taller text, t used for titles and unique applications, is.24 (6 mm) high. Many companies, depart from the ASME standard and use a minimum text height of.125 (3 mm) and a text height of between.188 and.25 (5 mm to 6.5 mm) for taller text. Text Standards Regardless of the text height, all text should be consistent and easy to read. Vertical text is standard on engineering drawings, although inclined text may be used, depending on company preference. The recommended slant for inclined text is 68 from horizontal. All text should be uppercase. Numbers in dimensions and notes are the same height as standard text. Text Guidelines Plan your drawing using rough sketches to allow room for text and notes. Arrange text to avoid crowding. Place related notes in groups to make the drawing easy to read. Place all general notes in a common location. Locate notes in the lower-left corner or above the title block when using ASME standards. Always use the spell checker. Choose your words carefully. Drawings are legal documents Text Height Ideally, you should determine drawing scale, scale factors, and text heights before you begin a drawing. These items are best incorporated as settings within your template drawing files, but they can be changed as needed. The scale factor of a drawing is important because this value is used to make sure the text is shown onscreen and plotted at the proper height. Scaling Text Manually To manually adjust text height according to a specific drawing scale, you must calculate the drawing scale factor. The scale factor is then multiplied by the desired paper text height to get the model space text height. 10

11 Calculating the Scale Factor Calculating the Scale Factor Suppose, for example, that a drawing is to be plotted at a scale of 1/2 = 1. Since the scale factor is the reciprocal of the drawing scale, you can calculate it by dividing 1 by 1/2 (.5). 1.5 = 2, so the scale factor in this case is 2. Another example is an architectural drawing that is to be plotted at a scale of 1/4 = 1-0. In this example you must first convert both values to the same units, typically inches. The scale is now 1/4 = 12 (because 12 = 1 ). Divide 12 by 1/4 (.25) to find a scale factor of 48 (12.25 = 48). Calculating Text Height Once you have determined the scale factor, you can calculate the height of the AutoCAD text. In a drawing with a scale of 1 = 1, the scale factor equals 1. Therefore, the height of 1/8 text in the drawing will be 1/8 high, because the text height multiplied by a scale factor of 1 equals 1/8. Single Line Text The Single line txt tool may be accessed by typing Dtext or clicking on the single line text tool icon shown below. An architectural drawing with a scale of 1/4 = 1-0 has a scale factor of 48. Text that is to be 1/8 high when printed should be drawn 6 high (1/8 48 = 6 ). Single Line Text Single Line Text Options Before adding your text you must select the appropriate annotation scale. The starting point for the text will then be selected, or the style or justification options may be used. If the Justification option is chosen, (type J), and then select the type of justification. To select a style, type S. Select type of justification required by clicking on option or typing the two letter description, (TL, Tc, etc..) 11

12 Click to select start of text line, enter height, rotation angle and type text. Single Line Text Text Styles AutoCAD text styles are used to set text characteristics. You may have several text styles, depending on the different characteristics needed for the text displayed in your drawings. The different text styles required should be incorporated into the drawing template Creating a Text Style Creating a Text Style To create a new text style, first select an existing text style from the Styles list box to be used as a base for formatting the new text style. Then pick the New button in the Text Style dialog box to open the New Text Style dialog box. Select New To access the text style dialogue box type ST at the command prompt. Click the new button to create a new style Setting Your Text Style 12