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EF101 Analysis & SkillsModule 2.1

Engineering Graphics

Introduction to CAD

Traditional Drafting vs. 3D Modeling

What are the features that can define this object?

or

How would I make this?

Identifying Features Features – Step by Step

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AutoCAD Mechanical Desktop• AutoCAD is the most widely used CAD package in

industry• Sold by Autodesk (www.autodesk.com)• Mechanical Desktop is an add-on product to AutoCAD

that provides 3D feature based modeling• We are using AutoCAD R2000, Mechanical Desktop 6• Retail cost: ~$5000• Student version: ~$400, NOT recommended• We will provide a network version that you can run from

any Windows based computer.• Version compatibility: files NOT backward compatible

with older versions.

Today’s Objectives• Work completely through a simple design• Start becoming familiar with Mechanical

Desktop• Learn basics of interacting with Mechanical

Desktop• Become comfortable with creating a simple

model and drawing

Create a 3D Model and Drawing MD Quick Reference Card

• A quick reference card listing commonly used commands and procedures will be provided.

• You will be able to use this sheet on quizzes.

• You should familiarize yourself with this resource

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Mechanical Desktop Screen

Graphics Area

Status BarCommand Window

BrowserWindow

ToolbarsMenus

Title bar

Main Steps1 2 3

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Five Basic Steps for Each Feature• Select sketch plane (or use the current one)• Sketch outline (simple, continuous, closed,

approximates the desired shape)• Profile (has MD make assumptions about the sketch,

produces “underconstrained” message)• Add dimensions and constraints

Defines the size, shape, and location of the profile• Create solid (extrude)

Getting Started• Disable the “Today” Box

– Only need to do this once– Assist->Options, System, Set to

“Show Traditional• Display the Browser window (if not

already displayed)– View->Display->Desktop Browser

• Start with efd-inch template– File->New– Select “Use a Template” icon– Select the efd-inch.dwt file

• Disable ORTHO, POLAR, OSNAP, OTRACK on status bar (click if necessary to make button appear “up”)

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Preparing to Sketch• Set sketch plane to be the front view

– 8 (change to iso view)– ss (select sketch plane command)– z (select the ZX plane for sketching)– Enter (accept default axis orientation)– 9 (change to sketch plane view)

• Set window to be approximate size of desired sketchOverall object size is 6x5, so use slightly larger numbers– Z (on the command line, for the zoom command)– W (on the command line, capitalized letter of the Window option– -1,-1 (coordinates of desired lower left)– 8,6 (coordinates of desired upper right)

Coordinate System Confusion• AutoCAD has 1 world coordinate system

– Top (plan) view is XY plane– Front view is XZ plane– Right side view is YZ plane

• To sketch 2D geometry, AutoCAD needs a temporary coordinate system (sketch plane) which defines a new XY plane which corresponds to the view you want to sketch in.

• Usually you can just “follow the steps” to sketch in the desired view.

• Design Polyline (or pl)to start sketching

– Enter 0,0 (on command line)to start at origin of the coordinate system

– Single left click at eachof the other corners.Just get the general shape –you don’t have to be exact.

– Close (on command line) to complete the shape– Common mistakes – double clicking and not using the close option for the last point

• Adjust if necessary– Select the object and use the blue boxes (grips) to adjust all lines to almost horizontal and

vertical. Try to line up the top two horizontal lines.• Part Sketch Solving Single Profile

– Should get a message similar to “Solved underconstrained sketch requiring 5 dimensions or constraints”

– This step makes assumptions about your rough sketch and “snaps” things to be exactly horizontal and vertical.

Creating a Profile

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Check Constraints• Part

2D Constraints Show Constraints

• You should have the same constraints as shown on the right

• You may need to add the horizontal, vertical, or collinear constraint(s)

• Part 2D Constraints

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1

3

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Add Dimensions• Part

Dimensioning New Dimension

• Left click on a line, then left click to place the dimension

• Enter the desired value, the object will re-size to the value you enter

• Add dimensions until you get a “fully constrained sketch” message

2D – 3D

• Switch to two views(2 key)

• Part Sketched Features Extrude

• Use depth of 1 inch• Set Color

– In browser, right click on Part 1, Properties->Color

Create Drawing Views• Switch to front view

(shortcut key 6)• Switch to Drawing Mode

(tab at top of browser window)• Right click on Layout1• Select New view, Base view, scale of 0.5

• V (use current model view)• Place view on the drawing• Right click on base view, select Multiple

views to place other views

Add Placed Features• Part Placed Features Fillet

1.0 inch constant radius

• Part Placed Features Chamfer,1.0 inch equal distance

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Final Touches

• Back to Drawing Mode (via Browser Tab)• Double-click text to edit title, name, date,

section• Right click iso in browser window, choose

edit, remove the checkmark from “Display Tangencies”

• Move other views if required by right-clicking the name in the browser and selecting move

Final Model & Drawing

Extra Questions• What is the object’s volume?• What is the object’s surface area?• What is the object’s weight if it is made of steel?• What if Dr. Raman changes his mind and wants to

change the object to be 2” thick?• What would it look like if it were made of wood?

All of these answers are quick and easy once we’ve created a computer model of the object . We’ll learn how to do these operations in later labs.

Practice• If time permits, do this exercise again• Start with efd-inch template• Sketch plane• Sketch profile• Constrain/Dimension• Extrude• Create Drawing Views• Add Placed Features• Edit Drawing Text• Save File