2D ESSENTIALS

Instructor: Laura Gerold, PE

Catalog #10614113

Class # 22784, 24113, 24136, & 24138

Class Start: January 18, 2012

Class 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 . . .

CHAPTER 8 – AUXILIARY VIEWS

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/14040_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 ELLIPSESIN AUXILIARY VIEWS

Circular shapes appear elliptical when viewed at an angle other than 90° (straight on to the circular shape). This is frequently the case when constructing auxiliary views.

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 LINESAND ARROWS

When the drawing sheet is too crowded to show the auxiliary view in direction projection you can use a viewing-plane line or a viewing direction 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 show true length in the auxiliary view. Whenever a line is parallel to the fold line between two 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 the line 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 a true-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 OBLIQUESURFACE

Showing the true size of a surface continues from the method presented for showing inclined surfaces true size, where the edge view is already given. But to show an oblique surface true size, you need first to show the oblique surface on edge and then construct a second auxiliary view to show it true size.

TRUE SIZE OF AN OBLIQUESURFACE

• 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 OBLIQUESURFACE 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 Views

1. 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 Answers

1. secondary

2. at right angles or parallel to the projection lines

3. the principal dimension not shown in the view being projected from

4. dihedral angle

5. to show true size and true shape

6. 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 plane

8. 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

CHAPTER 10 – DIMENSIONING

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/IndProd/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 architecturaland structural drawings are similarin many ways to those for dimensioningmanufactured parts, but some practicesdiffer.

Refer to the following standards:• ANSI/ASME Y14.5-2009 Dimensioning and Tolerancing• ASME Y14.41-2003 Digital Product definition Data Practices• ASME B4.2-1978 (R1999) Preferred Metric Limits and Fits

Automatically Generated Dimensions. Views and dimensions can be generated automatically from a solid model. (Courtesy of Robert Kincaid.)

Three Aspects of Good DimensioningTechnique 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.

A Title Block Specifying Tolerances. (Courtesy of Dynojet Research, Inc.)

ALL TOLERANCES ±.02 INCHUNLESS OTHERWISE NOTED.E

XAMPLES

Geometric Breakdown

Engineering structures are composed largely of simple geometric shapes, such as the prism, cylinder, pyramid, cone, and sphere. 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.theswgeek.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 LINES

a. 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 LINES

Dimensions should be lined up and grouped together as much as possible.

Guidelines for USING DIMENSION

AND EXTENSION LINES

a) Extension and Centerlines must cross visible lines of an object in many cases.

b) When this occurs, do not leaves gaps

ARROWHEADS

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.

• 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

LEADERSA leader is a thin, solid line directing attention to a note or dimension and starting with an arrowhead or dot.

For the Best Appearance, Make Leaders• near each other and parallel• across as few lines as possibleDon’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

Many standard title blocks include a note such as:

DO NOT SCALE DRAWING FOR DIMENSIONS

Drawing scale is noted in the title block. The drawing should not be scaled for dimensions. (Courtesy of Dynojet Research, Inc.)

DIRECTION OF DIMENSIONVALUES AND NOTES

All dimension values and notes are lettered horizontally to be read from the bottom of the sheet, as oriented by the title block.

DIMENSION UNITS

A note stating ALL MEASUREMENTS IN MILLIMETERS or ALL MEASUREMENTS IN INCHES UNLESS OTHERWISE NOTED is used in the title block to indicate the measurement 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

What’s Next?

• Finish Chapter 10 - Dimensioning

Questions?

• 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?

Homework

Chapter 8 Review Questions: 1,6

Chapter 8 Exercises: 8.28