IENG 248 Lecture 03 IENG 248 Orthographic Multiview

IENG 248 Lecture 03 IENG 248: Orthographic, Multi-view Projections 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 1

IENG 248 Lab n Load Solid. Works & Test Solid. Works l See the Solid. Works autoinstall for 2017 version ® Run the “auto install” on your computer l Takes about 1 -1/2 hour (if nothing else running) l Test Installation by starting Tutorials ® Re-install (repair installation) if necessary l May only be used from Campus IP addresses ® Can VPN into SDSM&T to run from off-campus site Computer Lab work starts Today! n Lab project will require teamwork, so start to form 4 - 5 person teams: l Sit in teams by table pods for class (share e-mail) l Share texts by table pods when doing HW / Labs 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 2

IENG 248 Assignments ® Lab 01: Due Next Lab Period l Open Solid. Works, Open the Tutorials l Perform the Introduction to Solid. Works (~ 1 hr) l Print the model, staple & turn in with a cover page ® HW 3: n Due in One Week Turn in the following on EP with a cover sheet l Sketch the symbol for a third angle projection l Complete HO 5. 5 and HO 5. 6 on the photocopies l Draw the following Projects (p. 152) two per page: ® # 3, 4, 16, and 22 (note: numbers are below object) l Draw the following Projects (p. 154) two per page: ® # 6, and 11 (note: numbers are below object) 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 3

IENG 248 Orthographic Projection ® a system of drawing views of an object using perpendicular projectors from the object to a plane of projection 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 4

IENG 248 Projection of an Object ® A projection is a single view of an object Imagine tracing the image of an object on a sheet of glass with a pen n If the projection rays are perpendicular to the glass, the view is orthographic n 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 5

IENG 248 The Glass Box ® To get to a Multi-view drawing: Imagine encasing the object within a glass box and tracing the outline on each face n Note that there are 90 o between each adjacent face n 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 6

IENG 248 Unfolding the Glass box ® To locate the six standard views n 2/27/2021 Imagine that the walls of the box are hinged and unfold the views outward around the front view. Engineering Graphics & 3 -D Modeling D. H. Jensen 7

IENG 248 Standard Views - (3 rd Angle) ® Unfolding the box flat locates the projections n 2/27/2021 Each of the six views aligns with the adjacent views Engineering Graphics & 3 -D Modeling D. H. Jensen 8

IENG 248 Locating Side Views ® An alternative position for a side view is to rotate it and align it with the top view n 2/27/2021 Note that there is still a 90 o fold between the top and side view in the alternative position Engineering Graphics & 3 -D Modeling D. H. Jensen 9

IENG 248 Projection Systems ® Third Angle Projection: Is the arrangement of standard views used in the U. S. , Canada, and Mexico. n For this system, imagine the planes of glass being between the viewer and the object - so one traces the outline, then opens planes flat. n ® First Angle Projection: Is the arrangement of standard views used in the E. U. , and most Asian countries. n For this system, imagine that the object is between the viewer and the plane of glass - so one draws around the object edges like a template, then opens the planes out flat. n 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 10

IENG 248 First Angle Projection ® For 1 st Angle projections then: The right side view is located left of the front view, n The top view is located below the front view, … etc. n l To distinguish between projection systems, a standard symbol is used 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 11

IENG 248 Symbols for 1 st & 3 rd Angle Projection ® The symbol is a simple front & right side view of a truncated cone n The front of the cone is always viewed head-on (targetlike) l So for 1 st Angle projections, the profile view is located to the left, … l and for the 3 rd Angle projections, the profile is on the right 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 12

IENG 248 Transferring Dimensions ® The depth of a projection should be the same in both the Top and Side views n One method to keep the depth proportional is to measure from a parallel reference (like the folding line), and transfer the distance to the vertices from one view to the other. l Folding lines are considered a form of construction line 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 13

IENG 248 Transferring Dimensions - Miter Lines ® Dimensions can also be projected across a miter line - a four step process that does not require measurements… 1. Draw a miter line at 45 degrees, located at a convenient distance to produce the desired view. 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 14

IENG 248 Transferring Dimensions - Miter Lines 2. Sketch light lines projecting depth locations for points to the miter line… …and then down into the side view (as shown). 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 15

IENG 248 Transferring Dimensions - Miter Lines 3. Project additional points… surface by surface… and project the corresponding surfaces from the adjacent view… to locate each intersection 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 16

IENG 248 Transferring Dimensions - Miter Lines 4. Then draw the view by connecting the ‘dots” – each vertex of a surface projection and a miter line projection – using visible lines. 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 17

IENG 248 Hidden Lines ® are similar to the visible lines of a drawing, but have a dashed pattern ® are used to show the intersections of surfaces that are not directly visible from the direction of sight ® each view in a drawing shows the entire object (including hidden & center lines) as seen from that viewing direction 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 18

IENG 248 Conventions for Hidden Lines Hidden lines should join neatly with visible lines except when it causes a visible line to be extended. When two different lines join to form a single line, leave a gap on the less important line. 2/27/2021 Hidden lines should join neatly to form “T” or “L” shaped intersections. Engineering Graphics & 3 -D Modeling Hidden lines should jump visible lines that they do not intersect. It is permissible for a hidden line to cross a visible line. D. H. Jensen 19

IENG 248 More Conventions for Hidden Lines Stagger the dashes on closely spaced parallel hidden lines. 2/27/2021 Hidden line dashes should intersect neatly at clear corners, as in the bottom of this drilled hole. Engineering Graphics & 3 -D Modeling Intersecting hidden lines should form neat corners, as in this countersunk hole. D. H. Jensen 20

IENG 248 Conventions for Curved Hidden Lines Curved hidden lines should not extend a visible curve in the same direction. Leave a gap on the hidden line so that you can easily see where the visible line ends. 2/27/2021 Curved hidden lines dashes should extend to the point of tangency. Don’t end with a gap at the point of tangency. It makes it hard to see the location. Engineering Graphics & 3 -D Modeling D. H. Jensen 21

IENG 248 Choice of View ® orient the object so that the front view shows the shape of the object most clearly (fewest hidden lines) ® chose front view so that it has a large number of normal surfaces. ® show the object in the usual or operating position ® show the right side view & top views unless other views are better (fewer hidden lines) 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 22

IENG 248 Necessary Views ® A sketch or drawing should only contain the views needed to clearly and completely describe the object. n Choose the views that show the shape most clearly, have the fewest hidden lines, and show the object in a usual, stable, or operating position. One view drawing of a shim (thin, flat) 2/27/2021 One view drawing of a connecting rod Engineering Graphics & 3 -D Modeling D. H. Jensen 23

IENG 248 Remember the part in the Glass Box? ® IF DRAWING ALL SIX STANDARD VIEWS … n 2/27/2021 … we imagined unfolding the walls of the hinged glass box outward around the front view … Engineering Graphics & 3 -D Modeling D. H. Jensen 24

IENG 248 Remember the part in the Glass Box? ® … but we don’t need all six standard views! n Which of the views below are necessary? XX 2/27/2021 X Engineering Graphics & 3 -D Modeling D. H. Jensen 25

IENG 248 Partial Views ® When the entire view is not necessary to show the object clearly you can use a partial view. Use a break line to limit the partial view as shown in (a), (b), and (d) below. n For symmetrical parts, you can draw a half-view on one side of the centerline as shown in (c). n 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 26

IENG 248 Right & Left Hand Parts Many parts are used in pairs where opposite parts are mirror -images of one another. A left-hand part is not just a right hand part turned around. It has to be manufactured differently from a right hand part. In order to save time, a single drawing can be used for both a left and right handed part by noting on the drawing such as: “LH PART SHOWN, RH OPPOSITE”. 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 27

IENG 248 Summary ® The six standard views are often thought of as being produced from an unfolded glass box. ® Distances can be transferred or projected from one view to another. ® Only the views necessary to fully describe the object should be drawn. 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 28

IENG 248 Summary: Necessary Views ® Show only the views needed to fully define the shape of the object. ® Choose the views which show the shapes of the features clearly. ® The right side view is preferred to the left side view if they show the object equally well; the top view is preferred to the bottom view if they show the object equally well. ® Showing only the necessary views saves time, makes the drawing less cluttered, and makes it easier to interpret. 2/27/2021 Engineering Graphics & 3 -D Modeling D. H. Jensen 29