Instructor: Laura Gerold, PE Catalog #10614113 Class # 22784, 24113, 24136, & 24138Class Start: January 18, 2012 Class End: May 16, 2012
Standard – draw (and round) to two decimal places. Never draw or round to greater than three decimal places Steel Fabrication tolerances is 1/8 and Engineered wood trusses are 1/16, you do not want to be any larger than the actual material sizes When drawing or designing new detail or plan for scales ¾ and smaller round to a ¼”, 1” to full scale, 1/16” is the smallest. Materials suppliers do not round their products lower then 1/16. When field dimensioning an existing building round to the nearest ¼”, because it is easier to do a dimension check right at the site. I have seen spotted elevations on site plans round their plans to 3 decimal point. Example 1’-4” = 1.333’
From A ad B draw equal arcs with radius greater than half AB Join Intersection D and E with a straight line to locate center C Compass system
1. Lightly draw arc CR 2. Lightly draw equal arcs r with radius slightly larger than half BC, to intersect at D 3. Draw line AD, which bisects the angle
Draw a random line and a random angle Trade with your neighbor and bisect both the line and the angle using the compass methods. Check with your protractor and scale
To make and interpret drawings you need to know how to create projections and understand the standard arrangement of views.You also need to be familiar with the geometry of solid objects and be ableto visualize a 3D object that is represented in a 2D sketch or drawing.
Vanishing Points: An Introduction to Architectural Drawing
The outline on the plane of projection shows how the object appears to the observer.In orthographic projection, rays (or projectors) from all points on the edges or contoursof the object extend parallel to each other and perpendicular to the plane of projection.The word orthographic means “at right angles.” Projection of an Object
Specific names are given to the planes of projection. The front view isprojected to the frontal plane. The top view is projected to the horizontalplane. The side view is projected to the profile plane.
The system of views is calledmultiview projection. Each viewprovides certain definiteinformation. For example, a frontview shows the true shape andsize of surfaces that are parallelto the front of the object.
The system of views is called multiview projection. Each view providescertain definite information.
Any object can be viewed from six mutually perpendicular directions,Six Standard Views:1. Top (Plan)2. Bottom3. Right Side4. Left Side5. Front6. Rear
Revolving the Object to Produce Views. You can experiencedifferent views by revolving an object.
One way to understand the standard arrangement of views on the sheet ofpaper is to envision a glass box. If planes of projection were placed parallel to each principal face of the object, they would form a box.
To organize the views of a 3D object on a flat sheet of paper, imagine the six planes of the glass box being unfolded to lie flat.Note the six standard views(front, rear, top, bottom, right side, left side).
Lines extend around the glass box from one view to another on the planes ofprojection. These are the projectors from a point in one view to the same pointin another view.
The front, top, and right-side views of the object shown now withoutthe folding lines.
The three principal dimensions of an object are width, height, and depth. The front view shows only the height and width of the object and not the depth. In fact, any principal view of a 3D object shows only two of the three principal dimensions; the third is found in an adjacent view. Height is shown in the rear, left-side, front, and right-side views. Width is shown in the rear, top, front, and bottom views. Depth is shown in the left-side, top, right-side, and bottom views.
Break up into groups of 2-3 Use the blocks to create a new “part” or “building” Sketch the six standard orthographic views Label the principal dimensions as width, depth, and height Prepare to present your views
On architectural plans, the term elevation is used for all views that show the height The top view is often called the “plan view” on architectural and engineering drawings Label your six standard views as either elevation or plan views if relevant
The top, front, and right-side views, arranged together, are called the three regular views because they are the views most frequently used.A sketch or drawing should contain only the views needed to clearlyand completely describe the object.
The depth dimensions in the top and side views must correspond point-for-point. When using CAD or instruments, transfer these distancesaccurately. You can transfer dimensions between the top and You may find it convenient side views either with dividers or with a scale. to use a 45° miter line to project dimensions between top and side views.
Using a Miter Line (Also see page 186 in text) Place the miter line (fig. 5-10, view B) to the right of the top view at a convenient distance, keeping the appearance of a balanced drawing Draw light projection lines from the top view to the miter line (fig. 5-10, view C), then vertically downward (fig. 5-10, view D) Using the front view, draw horizontal projection lines (fig. 5-10, view E) to the right, intersecting the vertical projection lines The result of this procedure is the outline and placement of the right side view
Using your block creation, transfer the dimensions for three views using both the scale and the miter methods
To understand the two systems, think of the vertical and horizontal planes of projection, as indefinite in extent and intersecting at 90° with each other; the four angles produced are called the first, second, third, and fourth angles (similar to naming quadrants on a graph.) If the object to be drawn is placed below the horizontal plane and behind the vertical plane, as in the glass box you saw earlier, the object is said to be in the third angle. In third-angle projection, the views are produced as if the observer is outside, looking in.Common in the US & Canada Third Angle Projection
Sometimes, drawing three views using the conventional arrangementwastes space.
If the object is placed above the horizontal plane and in front of thevertical plane, the object is in the first angle. The biggest difference between third-angle projection and first-angle projection is how the planes of the glass box are unfolded. Common in Europe & AsiaFirst Angle Projection
Group Project Use transparencies to create 1st and 3rd Angle projections of your block structure
Thick, dark lines represent features of the object that are directly visible.Dashed lines represent features that would be hidden behind other surfaces.
The centerline pattern is used to:• show the axis of symmetry for a feature or part• indicate a path of motion• show the location for bolt circles and other circular patterns The centerline pattern is composed of three dashes: one long dash on each end with a short dash in the middle.
A. Make a hidden line join a visible line, except when it causes the visible line to extend too far. B. Make hidden lines intersect at L and T corners.
C. Make visible line “jump” a visible line when possible. D. Draw parallel hidden lines so that the dashes are staggered.
E. & F. When two or three hidden lines meet at a point, join the dashes.
G. Make a hidden line join a visible line, except when it causes the visible line to extend too far. H. Draw hidden arcs with the arc joining the centerline. There should not be a gap between the arc and the centerline.
Use the Hidden Line Techniques to draw a view with hidden lines of your block project No hidden lines? Draw a view of a coffee mug with hidden lines.
A visible line always takes precedence over andcovers up a centerline or a hidden line when theycoincide in a view (A and B).A hidden line takesprecedence over acenterline (C).
Look over your drawings for today and determine whether you followed the precedence of lines
Centerlines (symbol: ) are used to indicate symmetrical axes of objectsor features, bolt circles, and paths of motion.
There are terms used for describing a surface’s orientation to the plane ofprojection. The three orientations that a plane surface can have to the planeof projection are normal, inclined, and oblique. Note how a plane surface that is perpendicular to a plane of projection appears on edge as a straight line
If an angle is in a normal plane (a plane parallel to a plane of projection) it willshow true size on the plane of projection to which it is parallel.
If a flat surface is viewed from several different positions, each view willshow the same number of sides and a similar shape. This consistency ofshapes is useful in analyzing views.
One method of interpreting sketches is to reverse the mentalprocess used in projecting them.
Many objects need only two views to clearly describe their shape. If an objectrequires only two views, and the left-side and right-side views show the objectequally well, use the right-side view.
Often, a single view supplemented by a note or by lettered symbols isEnough.
The view chosen for the front view in this case is the side, not the front, of theautomobile.
• Review for Test 1• Finish Chapter 5• Chapter 6 – 2D Drawing Representation
On one of your sketches, answer the following two questions: What was the most useful thing that you learned today? What do you still have questions about?