Lesson: Engineering Drafting & Multiview Drawing

Authors: Peter Anderson, Wade Goodridge, Sarah Lopez, Natalie Shaheen, Ann Cunningham 

Class Size 

• Written for 15 students with TAs available. Recommend at least an 8:1 student-teacher ratio to help students interpret objects such as the plexiglass cubes, snap cube drawings, etc. 

Lesson Structure 

105 minutes 

• Introduction and Plexiglass cube - 45 minutes 
• Doghouse floorplan - 20 minutes 
• Snap cubes experience - 40 minutes 

Objectives 

Students will be able to: 

• Interpret a multi-view drawing by combining information from the three views that comprise the drawing (front, right side, and top). 
• Correlate features of 3D objects with their 2D representations on a multi-view drawing. 
• Identify the correlation between the views of a multi-view drawing and a set of architectural/engineering drawings (e.g., floor plan, front elevation, side elevation) for a simple structure. 

Prerequisite Knowledge 

• An understanding of basic drawing techniques and tools (presented in the Introduction to Drawing and Intermediate Drawing and Drafting lessons). 
  • Use of sensational blackboard 
  • Use of ball point pen to make tactile lines 
  • Use of straightedge 
  • Use of calipers or ruler 

Accessibility 

• Braille caliper or ruler 
• Sensational blackboard  
• Plexiglass cube with tactile overlays 
• Braille number stickers  

Materials 

• Items for Plexiglass Cube Multiview Drawing Exploration Activity 
  • Wooden objects that fit on the dowel stand in the plexiglass cube - 1 per 2 students 
  • Unfolding plexiglass cube 1 per 2 students 
  • Vinyl overlays for top, right, and front views that correspond with the wooden objects - 1 per 2 students 
• Sensational Blackboard - 1 per student 
• Ballpoint pen, 0.5mm - 1 per student 
• Ballpoint pen, 0.9mm - 1 per student 
• Braille ruler or caliper - 1 per student 
• Paper - 3 sheets per student 
• 1” snap cubes - 10+ per student 
• Doghouse model  
• T-square, notched on one side with a jeweler's file at 1” interval - 1 per student 
• Handouts: 
  • Handout 0: Linetypes BRL (PDF for hardcopy production only)
  • Handout 0: Linetypes LP (PDF for hardcopy production only)
  • Handout 1: Multiview Block 2 BRL (PDF for hardcopy production only)
  • Handout 1: Multiview Block 2 LP (PDF for hardcopy production only)
  • Handout 2: Floor and Elevation Plans (PDF for hardcopy production only)
  • Handout 3: Multiview Doghouse BRL (PDF for hardcopy production only)
  • Handout 3: Multiview Doghouse LP (PDF for hardcopy production only)
  • Handout 4: Dimensioning Example (PDF for hardcopy production only)
  • Handout 5: Snap Cubes (PDF for hardcopy production only)

Note: Refer to Accessible Lab Equipment & Instructional Materials for additional information regarding specialized tools/materials. 

Preparation 

1. Build snap cube models (1 of each shape, per student) to match the drawings depicted in Handout 5.  
2. Set up plexiglass cubes with the associated vinyl overlays. 

Procedure 

Introduction and Plexiglass Cube 

1. Artist / engineer drawing.  
   • Tell. “If you are trying to draw a building to convey its beauty, ask an artist. If you are trying to draw a building to build, laying out accurate locations, ask an engineer. Engineers draw or make a model of anything that they want to build before they build it. The drawing or model serves as a communication tool.” 
2. Why engineers draw.  
   • Tell. “Engineers across the world need to communicate their designs very specifically so that things get built correctly. We begin training engineers to develop simple drawings representing different views of objects. Because it is so important to have accurate and complete information, engineers have specific ways of drawing to make sure there is no confusion or miscommunication.” 
3. Overview of section.  
   • Tell. “Engineers have developed their own language of drawing conventions to communicate specific information. I’d like to teach it to you, and then show you some buildings.” 
4. Line types.  
   • Do. Pass out Handout 0: Linetypes. 
   • Tell. “Different kinds of lines are a key component of the drawing conventions engineers use. They call the different kinds of lines linetypes. Each linetype has a particular lineweight, or thickness of the line. We will use four different linetypes throughout this project. Our linetypes and weights are not exactly the same as those in the industry because we have adapted them to be more tactilely distinct; however, the basic patterns are similar.” 
5. Object lines. 
   • Tell. “Object lines represent features such as edges and are a solid line. We have two of these. One is 1.2 mm wide and one is 2.1 mm wide. The thicker one is used to represent outside edges of an object, and the thin one shows edges within an object. Feel the difference between the thick object line and the thin object line on your handout.” 
6. Hidden Lines. 
   • Tell. “Hidden lines represent features or edges of the object that cannot be directly seen from that view. This is shown with a thin dotted line.” 
7. Dimension Lines. 
   • Tell. “Dimension lines are drawn past the edges of the object and allow us to display the dimension, or measurement, of a specific feature or edge of the object. Our dimension lines will also be shown as a thin dotted line, but with the dots much closer together than in the hidden line.” 
8. Center Lines. 
   • Tell. “Center lines show the location of the center of a rounded feature such as a hole, curve, or cylinder. We draw them through the center and extend them slightly beyond the object’s edge. These will be shown with a dashed line.”
   • Note: if the instructor prepares any Autodesk CAD drawings for the students, the linetype and weights in the image below best represent the standards discussed above. 
   • 
9. Interpret block drawing.  
   • Do. Pass out the drawing of the block. Handout 1. Direct students to take turns interpreting the object briefly.  
   • Tell. “This is an example of a multiview drawing. It uses a technique called orthographic projection. On the page, there are three separate smaller drawings. The top left drawing is the top view. The bottom left drawing is the front view. Finally, the bottom right drawing is the right view.”  
10. Interpret the block.  
    • Do. Pass out the wooden blocks that correspond with the drawing. Direct students to take turns interpreting the object briefly.  
    • Tell. “Place the block on your paper, and move/rotate it so that it lines up with the drawing in the bottom left. This is the front view, so you are now looking down at the front of the object. Now, pick up the block with the top part up and the front facing you. Trace the outline of the top of the block and the outline of the top view on the page. You should be able to feel how the top of the object matches the top view in the drawing”  
    • Do. Direct students to repeat this process with the right view. Note: If a student is having difficulty, they can rotate the block and place it directly on top of the drawing. 
11. Limits of vision.  
    • Tell. “The convention used in these drawings is based on visual perception, which works quite differently than tactile perception. Unlike the sense of touch, the sense of vision cannot see around corners. If you felt only the part of the object facing you that will most closely mimic what sighted people can see.” Note: Students will have a wide range of prior knowledge about how sight works. As needed, work with students one-on-one to show tactilely what surfaces are and are not visible with sight. 
12. Rules of multiview drawing.  
    • Do. Instruct students to observe the object and drawings. 
    • Tell. “There can be more sub-drawings than just the right side, top, and front. We can also have sub-drawings or views of the left side, back, and bottom. The goal is to provide the minimum number of views to convey all the information about the object. If an additional view only shows features already conveyed on another view then it is considered redundant.” 
13. Plexiglass cube.  
    • Do. Invite students to examine the plexiglass cube with the tactile vinyl projections on the appropriate faces of the cube. Have students place their wooden block inside the cube on the pedestal.  
    • Teach. Draw student’s attention to these features: 
      • Vinyl on outside of plexiglass. These vinyl overlays are identical to the multiview drawing we just examined on paper. If you extended edges of the object to the plexiglass face, you would get the image that is depicted by the vinyl overlay.  
      • How the object unfolds. Show the students how the plexiglass box unfolds to demonstrate the origin of the arrangement of the 3 views that comprise the multiview drawing. Unfold the top face of the box so that it is in line with the front face. Do the same with the right face. A multiview drawing takes these three faces of a cube and puts them on a flat page. 

Doghouse Floorplan  

1. Transition.  
   • Tell. “In construction, architectural work and structural engineering we often represent a building using similar projections but we refer to them with different terms. The top view in a multiview drawing is analogous to an architect's floor plan. Similarly, the side view in the multiview drawing is analogous to an elevation in a set of architectural plans.” 
2. Example.  
   • Do. Pass out a sample of an elevation and a floor plan for a simple house Handout 2. After students have interpreted the drawing, direct students to show you with their hands about how big the object would be. Narrate the result by asking, “Does anyone fit in a house that size?” No. 
3. Scale explained.  
   • Tell. “Engineers often make objects that are much larger or much smaller than a piece of paper. For large objects, they scale the picture down so that it fits. This means they divide every full sized measurement by the same number or scaling factor and draw it with those sizes. For tiny objects they multiply every measurement by a scaling factor and draw it larger than real life.” 
4. Doghouse.  
   • Do. Introduce the doghouse and direct students to inspect the model. It is large enough that 3-5 students can inspect it at a time. Meanwhile distribute Handout 3. 
5. Doghouse plans.  
   • Tell. “These plans are for the doghouse you are looking at. The scaling factor for these plans is 1:8 or one-eighth scale. This means one inch on the drawing equals 8 inches in real life. Check with a ruler if you don’t believe me.” 
6. Compare model and drawing.  
   • Students Do. Have students identify features on the doghouse and find those corresponding features on the plans, or vice-versa. Some students will do well to bring their handout with them while inspecting the doghouse, and feel both at the same time. Students may take some time to figure out how the roof overhang is shown in the drawings. 
7. Check for understanding.  
   • Tell. “How would you fit a drawing of a skyscraper onto a normal letter-sized piece of paper?” 
8. Dimension lines.  
   • Do. Pass out Handout 4. 
   • Tell. “A scaled drawing is useful but it requires additional forms of expressing size and locations. Engineers use a dimension line for that. A dimension line just says directly what the full size measurement should be.” 
9. Rules of dimension lines.  
   • Tell. “A dimension line is drawn a little bit away from the edge of the drawing, with a label in the middle of the line that indicates the size of that dimension. More lines go from the edges of the dimension line to the edges of the drawing to show to which part of the drawing the dimension applies. When you are making your own drawings, you can use your Braille dimensioning dots, or other labeling techniques to mark your dimensions.” 

Snap Cubes Experience 

1. Introduction.  
   • Tell. “So now that you know how multiview drawing works we thought it would be fun to practice it on something quick and easy before trying it on your building.” 
2. Snap cubes how to.  
   • Do. Pass out to each student an object made of snap cubes.  
   • Tell. “What we’d like you to do first is to draw this object in the three views. We’ll do the front together.” 
     • “Let’s decide on a front. The front is usually the most characteristic view, the view with the most features.” 
     • Note: Extension - If students are doing well, have them draw this shape at ½ scale. To do this, have them measure a snap cube (ignoring the bumps that stick out). Explain: “The snap cubes are 1” x 1”. So in the picture what size should they be? .5”” 
     • “Let’s draw the front. We don’t need to draw the connections of the blocks or the lines where they meet, but we will include edges between surfaces. (i.e., if one part of the shape is close to you, and the other part is further back, you will draw the line between those parts). Don’t forget to include any hidden lines. Any edge that isn’t already covered by the front gets a hidden line.”  
     • “Now expose the top. Rotate the object 90 degrees towards you. Draw it again.” 
     • “Finally, expose the right. Rotate the object 90 degrees away from you, then 90 degrees to the left. Draw it again.” 
     • Note: While the position of the views relative to each other is critical in engineering drawings, it is not necessarily so here. Our focus is to have students understand an existing tactile drawing and begin to develop their own. 
3. Dimensioning.  
   • Do. Direct students to add dimensions to the front picture of their object and any features on the sides that they think might need dimensions. Use the sticky backed Braille numbers. 
4. Reflection.  
   • Ask. “Did your pictures look like the objects? Would you feel confident building one of these given the three views? Could you build it a year from now using your drawing? Were there any of the shapes that were especially easy to draw? Especially difficult?” 
5. Snap cube from drawings.  
   • Do. Pass out the drawings of cubes (Handout 5) for students to assemble. Explain that the handout shows 2 sets of 3 drawings each. Each set of 3 drawings has a top, a front, and a right side view. Direct the students to deconstruct their existing cubes and build the 2 pictured shapes. When a structure is complete, the instructor will come by and check it. Work with students to check if their shape matches all three views. The students can fold the drawings in appropriate top, right side, and front orientation like a mini plexiglass cube to check their own work. This will require the drawing to be quickly cut to separate both multiviews drawings. 
6. Extension.  
   • Students Do. Students may make pictures of shapes they create then switch pictures with another student to see if they can create the original. This is a realistic functional test of what engineers do. 
7. Tip of the iceberg.  
   • Tell. “Building this skill takes time and practice. Engineering drafting is a whole college course some engineers take. The rules become more complicated as the objects become more complicated, but for now you know enough to draw your structure for this project.” 

Standards Alignment 

NGSS Standards Alignment:

• SEP 2 - Developing and using models. CCC 3 Scale, Proportion, and Quantity. 
• HS-ETS1-2 

CCSS Standards Alignment:

• CC.9-10.R.ST.3, CC.11-12.R.ST.3, CC.11-12.R.ST.7 
• CC.9-12.G.MG.1, CC.9-12.MGD.4 

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