2D ESSENTIALSInstructor: Laura Gerold, PECatalog #10614113Class # 22784, 24113, 24136, & 24138Class Start: January 18, 2012Class End: May 16, 2012
Reminders• Extra Credit (Write Exam Question) Due Next Week (May 2nd)• Final Project is due in two weeks on May 9th.• Final Exam is in three weeks on May 16th.
Group Project – Parallel Lines• In your groups, discuss and practice the methods that can be used to draw parallel lines on an object.• Present your methods• Group with the most methods receives an award . . .
Why Do We Need Auxiliary Views?• Inclined Planes and Oblique lines do not appear true size or true length in any orthographic views• In order to show better detail on the inclined and oblique planes, auxiliary views are used• Auxiliary views are taken from an angle that is not one of the primary standard orthographic views Source: http://draftingmanuals.tpub.com/14040/css/14 040_41.htm
What are the differences between primary, secondary, and successive views?• Primary auxiliary views are projected from one of the principal planes (front, top, side). Source: http://www.pleasantville.k12.ia.us/staff/fvanderpool/pages/draftingsg.html
What are the differences between primary, secondary, and successive views?• Secondary auxiliary are projected from the primary auxiliary plane Source: http://joekintercadportfolio.weebly.com/segment-8-supplemental-views.html
What are the differences between primary, secondary, and successive views?• A third auxiliary view can be obtained from a projection of the secondary auxiliary view and so on . . . .
What are the differences between primary, secondary, and successive views?• Group Project • Use a simple object with an inclined surface • Draw the necessary views • Draw a Primary Auxiliary View • Draw a Secondary Auxiliary View • Draw another “Successive View” • Present results
HIDDEN LINES IN AUXILIARY VIEWS• Hidden Lines can clutter an auxiliary drawing and are not shown unless essential to understanding the object.• As a beginning technical drawer, you may want to show all hidden lines for visualization practice
CIRCLES AND ELLIPSES IN AUXILIARY VIEWSCircular shapes appear elliptical when viewed at an angle other than 90° (straighton to the circular shape). This is frequently the case when constructing auxiliaryviews.
Show an Inclined Elliptical Surface True Size• Let’s practice drawing an inclined elliptical surface to true size in an auxiliary view.• Practice with the Example on page 288 of the text book
Group Project – Elliptical Surfaces• Use an object in the room, an object you brought, an object you find outside the room, an object in the book, or make up the necessary views of an elliptical surface.• Draw an elliptical surface auxiliary view
Plotting Curves in an Auxiliary View• Let’s practice plotting curves to draw in an auxiliary view.• Practice with the Example on page 290 of the text book
Group Project – Plotting Curves• Use an object in the room or make up the necessary views of a curved object.• Draw a curved auxiliary view
VIEWING-PLANE LINES AND ARROWSWhen the drawing sheet is too crowded to show the auxiliary view indirection projection you can use a viewing-plane line or a viewingdirection arrow to indicate the direction of sight for the auxiliary view.
Uses of Auxiliary Views• Auxiliary Views are often used to show the following: • True length of a line • Point view of a line • Edge view of a plane • True size of a plane
TRUE LENGTH OF A LINETo show a line true length, make the fold line parallel to the line you want to showtrue length in the auxiliary view. Whenever a line is parallel to the fold line betweentwo views, it will be true length in the adjacent view.
TRUE LENGTH OF A LINE – EXAMPLE• Work through the true length of a hip rafter example on page 295
TRUE LENGTH OF A LINE – GROUP PROJECT• Use an inclined surface that you brought with you, that I have, or that you see around the room.• Practice drawing the necessary views and an auxiliary view with the true length of one of the inclined lines.
POINT VIEW OF A LINETo show the point view of a line, choose the direction of sight parallel to theline where it is true length. 1. Choose the direction of sight to be parallel to line 1–2. 2. Draw folding line H/F between the top and front views, as shown. 3. Draw folding line F/1 perpendicular to line 1–2 where it is true length, and any convenient distance from line 1–2 (front view). 4. Draw projection lines from points 1 and 2 to begin creating the auxiliary view. 5. Transfer points 1 and 2 to the auxiliary view at the same distance from the folding line as they are in the top view and along their respective projection lines. They will line up exactly with each other to form a point view of the line.
POINT VIEW OF A LINE GROUP PROJECT• Use Picture from Previous Slide (Figure 8.26 on page 296 of your text book)• After locating the points, how would you draw the rest of the auxiliary view? Would you use a breakline? Or would you ever just want to show the points?• When do you think this would be useful when creating a set of drawings?
EDGE VIEW OF A PLANETo show the edge view of a plane, choose the direction of sight parallel to atrue-length line lying in the plane. 1. Choose the direction of sight to be parallel to line 1–2 in the front view where it is already shown true length. 2. Draw folding line H/F between the top and front views, as shown. 3. Draw folding line F/1 perpendicular to true-length line 1–2 and any convenient distance. 4. Draw projection lines from points 1, 2, 3, and 4 to begin creating the auxiliary view. 5. Transfer points 1, 2, 3, and 4 to the auxiliary view at the same distance from the folding line as they are in the top view and along their respective projection lines. Plane 1–2–3–4 will appear on edge in the finished drawing.
EDGE VIEW OF A PLANE GROUP PROJECT• Use Picture from Previous Slide (Figure 8.28 on page 297 of your text book)• After locating the edge view of the plane, how would you draw the rest of the auxiliary view? Would you use a breakline?• When do you think this would be useful when creating a set of drawings?
TRUE SIZE OF AN OBLIQUE SURFACEShowing the true size of a surface continues from the method presented for showinginclined surfaces true size, where the edge view is already given. But to show an obliquesurface true size, you need first to show the oblique surface on edge and then construct asecond auxiliary view to show it true size.
TRUE SIZE OF AN OBLIQUE SURFACE• Let’s practice drawing the true size of an oblique surface in an auxiliary view.• Practice with the Example on page 298 of the text book
TRUE SIZE OF AN OBLIQUE SURFACE GROUP PROJECT• Use an object in the room, an object you brought, an object you find outside the room, or Figures 8.32 or 8.33 in the book• Draw the true size of an oblique surface in an auxiliary view
Steps for drawing Auxiliary Views1. Determine the direction of viewing.2. Number the vertices on the inclined plane if needed.3. Draw projectors along the direction of sight. The projectors will be perpendicular to the inclined edge.4. Pick an appropriate folding line or reference plane.5. Transfer measurements from the adjacent view onto the projectors.6. Join the projected points to get true shape of inclined plane.7. Transfer rest of the object onto the Auxiliary view if required to do so, else close by drawing a break line. Omit hidden lines in Auxiliary views.
Auxiliary Views Group Real-World Project• My husband gave a set of plans to a builder for a unique roof, but did not give an auxiliary view• The builder called him to ask how exactly to build it• Should he have used an auxiliary view?• If so, what views would you have shown? Do a quick sketch.• Picture of Finished Building
Auxiliary Views Worksheet• As a group, work on the Auxiliary Views Worksheet
Auxiliary Views Worksheet Answers1. secondary2. at right angles or parallel to the projection lines3. the principal dimension not shown in the view being projected from4. dihedral angle5. to show true size and true shape6. creating the auxiliary view before creating the basic views.7. A. True length of line b. point view of line c. Edge view of a plan d. True size of a plane8. Hidden lines are usually omitted in Auxiliary, unless required for clarification. Beginning draftspersons usually add hidden lines.
Auxiliary Views on Youtube• http://www.youtube.com/watch?v=gzq48vBbODg
Why Do We Dimension Drawings?• Dimensions describe the size, shape, and material of objects• Give detail on how to build an object from the designer to the manufacturer Source: http://www.design- technology.info/IndPro d/page11.htm
UNDERSTANDING DIMENSIONINGThe increasing need for precision manufacturing and interchangeabilityhas shifted responsibility for size control to the design engineer or detail drafter. Practices for dimensioning architectural and structural drawings are similar in many ways to those for dimensioning manufactured parts, but some practices differ. Refer to the following standards: • ANSI/ASME Y14.5-2009 Dimensioning and Tolerancing • ASME Y14.41-2003 Digital Product definition Data Practices Automatically Generated Dimensions. • ASME B4.2-1978 (R1999) Preferred Metric Limits and Fits Views and dimensions can be generated automatically from a solid model. (Courtesy of Robert Kincaid.)
Three Aspects of Good Dimensioning Technique of dimensioning Placement of dimensions Choice of dimensions
Three Aspects of Good Dimensioning • Technique of dimensioning • Standard appearance of lines • Spacing of Dimensions • Size of Arrowheads • Etc.
Three Aspects of Good Dimensioning • Placement of dimensions • Logical Placement to make dimensions: • Legible • Easy to Find • Easy for the Reader to Interpret
Three Aspects of Good Dimensioning • Choice of dimensions • Show how the design is manufactured • Dimension first for Function • Add dimensions for ease of manufacturing
ToleranceTolerance is the total amount that the feature on the actual part is allowedto vary from what is specified by the drawing or model dimension. ALL TOLERANCES ±.02 INCHE UNLESS OTHERWISE NOTED.XAMPLES A Title Block Specifying Tolerances. (Courtesy of Dynojet Research, Inc.)
Geometric BreakdownEngineering structures are composedlargely of simple geometric shapes, suchas theprism, cylinder, pyramid, cone, andsphere. They may be exterior (positive)or interior (negative) forms.
LINES USED IN DIMENSIONING• Dimension Line • A thin, dark, solid line terminated by an arrowhead, indicating the direction and extent of a dimension • Usually Perpendicular to extension lines • The distance is indicated numerically at the midpoint of the dimension line, either adjacent to the dimension line, or in a gap provided for it. • First Dimension Line should be at least 3/8” away from object • Subsequent lines can be ¼” apart and should be uniform
LINES USED IN DIMENSIONING• Extension Line • Thin, dark, solid line that extends from a point on a drawing to which a dimension refers • Typically Perpendicular to Dimension Lines • A small gap (1/16”) should be left between the extension line and the object • Extension line should extend 1/8” beyond the outermost arrow • An extension line does not have arrows
LINES USED IN DIMENSIONING• Example Dimension and Extension Lines Source: http://www.theswg eek.com/2008/05/ 29/hide-show- extension-and- dimension-lines/
LINES USED IN DIMENSIONING• Centerlines • Thin dark line alternating long and short dashes • Commonly used as extension lines in locating holes and other symmetrical features • When extended for dimensioning, cross over the other lines of a drawing with no gaps • End centerlines using a long dash
Guidelines for USING DIMENSION AND EXTENSION LINESa. Shorter dimensions are nearest the object outlineb. Do not place shorter dimensions outside, which result in crossing extension linesc. Okay to cross extension lines, but they should not be shortenedd. A dimension line should never coincide with or extend from any line of a drawing
Guidelines for USING DIMENSION AND EXTENSION LINESDimensions should be lined up and grouped togetheras much as possible.
Guidelines for USING DIMENSION AND EXTENSION LINESa) Extension and Centerlines must cross visible lines of an object in many cases.b) When this occurs, do not leaves gaps
ARROWHEADS • Arrowheads • Should be uniform in size and style throughout the drawing • Length and width should have a ratio of 3:1 • Length of arrowhead should be about 1/8” long • Should be filled in to look better When you are drawing by hand and using the arrowhead method in which both strokes are directed toward the point, it is easier to make the strokes toward yourself.
LEADERSA leader is a thin, solid line directing attention to a note or dimension andstarting with an arrowhead or dot. For the Best Appearance, Make Leaders • near each other and parallel • across as few lines as possible Don’t Make Leaders • parallel to nearby lines of the drawing • through a corner of the view • across each other • longer than needed • horizontal or vertical
Group Project• Look at the drawings on page 401 & 402 of the text• Identify the extension, dimension, center, and leader lines• Note the style and location of the arrowheads
DRAWING SCALE AND DIMENSIONING Drawing scale is noted in the title block. The drawing should not be scaled for dimensions. (Courtesy of Dynojet Research, Inc.)Many standard title blocks include anote such as: DO NOT SCALE DRAWING FOR DIMENSIONS
DIRECTION OF DIMENSION VALUES AND NOTESAll dimension values and notes are lettered horizontally to be read from the bottom of thesheet, as oriented by the title block.
DIMENSION UNITSA note stating ALL MEASUREMENTS IN MILLIMETERS or ALL MEASUREMENTS ININCHES UNLESS OTHERWISE NOTED is used in the title block to indicate themeasurement units… (Courtesy of Dynojet Research, Inc.)
Project Time!• Share your projects with your group.• Discuss dimensioning your project.• Make a list of dimensioning questions you have about your project and turn it in for specific instruction next class