Coordinate Systems

Coordinate System: One of a set of numbers that determines the location of a point in a space of a given dimension.

Technology Interactions: Locations are specified by sets of letters and numbers. The letter-number combinations that locate points are called Cartesian Coordinates. The letters identify the imaginary lines running through an object. Each line is an axis. The numbers locate points along an axis. The axes are defined by the letters X, Y, and Z. Both the X axis and the Y axis are parallel to the floor. The X axis runs from left to right (on the graph paper) across the work piece. The Y axis runs up and down (on the graph paper), at right angles to the X axis.  The X axis runs the length of the work piece. The Y axis represents the width of the work piece. The Z axis represents the height. It runs vertically (off of the graph paper), perpendicular to the X and Y axes.

Points (numbers) identifying locations can be placed along any axis. The location of a point is identified by its coordinates- the letter of the axis with the number of the point on that axis. When a computer is programmed to control a machine tool (CAM), the programmer identifies the coordinates where the tool is to do its work.

When we use the Inventor Software the following colored arrows are assigned to each axis:

         Red Arrow =X axis           Green Arrow = Y axis            Blue Arrow = Z axis

Computer Aided Drafting

Using CAD

The computer has brought about great changes in drawing and design. It has made drafting much easier. Computer -Aided Design is an important software application that allows people to produce drawings using a computer instead of traditional technical drawing tools. CAD has become an important tool used by engineers, drafters, and designers.

The CAD Workstation

A CAD workstation has many parts. It includes a computer, keyboard, display screen, drawing tablet, and plotter. CAD software offers a variety of drawing tools that can be accessed using either the keyboard and mouse or the drafting tablet. With a keyboard and mouse, the drafter chooses a drawing tool from the assortment shown on the screen. Different tools may produce heavy or thin lines as well as different shapes. A drafting tablet is a special surface and pen allowing the drafter to make lines and drawings that appear directly on the computer screen.

Producing Final Drawings

Once the drawings have been made, they can be changed using keyboard commands or the drawing tablet. Programs can be used to draw lines and arcs, add symbols to a drawing, turn the drawing around or upside down, or zoom in for a closer look at a particular detail. CAD software can produce 3-D models that look solid and realistic. The size and scale of the final drawings can also be changed. These drawings can be stored in a computers memory for later review and revision. When the final design is ready, the drawing is printed on a large sheet of paper. A wide, large-scale printer, called a plotter, is used to print mechanical and architectural drawings.

Applications of CAD

CAD computer programs make it possible to produce clear drawings of almost any designed product. CAD drawings may show mechanical parts, illustrate entire buildings, or detail tiny electronic circuits. Clothing designers use CAD software to create patterns and images for new fabrics and clothing. Engineers often use CAD-generated drawings to label the parts of a machine or indicate how it is assembled using a 3-D exploded view. Landscape architects use CAD to show the arrangement of trees, shrubs, walkways, and lighting in an outdoor area. Urban planners show how new streets and traffic lights will affect the flow of traffic through a city. Other CAD-designed products include cars, aircraft, furniture, rugs and other textiles, and electronic games.

CAD is used to create many different views for a design presentation. Before building begins, an architect may want to have an overall 3-D image that shows the client how the final building and landscaping will appear. Other designers can create physical 3-D scale models from CAD images. This allows clients to see a physical representation of the design. Once construction is ready to begin, the architect used CAD to generate 2-D layouts for others on the project.

Why Use CAD?

Once an architect or engineer has mastered the use of the software, a CAD system can have many advantages over hand-drawn design.

• CAD saves time by combining design and drafting into a single process. Architectural or mechanical drawings can be created much faster with CAD than by hand.

• Information stored in the computer can help prevent errors in the design.

• Because designs can be revised on screen, much less time is needed to change or improve existing designs. All one has to do is create an object only once, and then save it to a file.

• Designs are more accurate. Changes can be made more consistently from one design to the next. In addition, each change can be saved in its own version, in case one wants to refer back to a previous design.

• CAD systems can provide a list of parts needed to make a product, as well as the cost of each.

• A CAD system can help identify a design's strengths and weaknesses. It can show how an electronic circuit will work, or whether a mechanical part will hold up under use.

Because less time is needed to produce layouts and to determine budgets, CAD systems free designers, drafters, and engineers to spend more time creating and thinking about design.

CAD Assessment

Recall and Comprehension

1. What does the acronym CAD stand for? Describe a CAD system in your own words.

2. Discuss the advantages of CAD drawings compared to those that are hand-drawn. )list 5 advantages)

3. How does CAD help with budgeting and manufacturing a product?

Critical Thinking

1. Extending What are the disadvantages of using CAD? When might it help to have hand sketches or a physical 3-D model?

2. Applying You are designing a new series of snow-boards, but your boss does not want to set up a CAD system for the office. Convince her/him that CAD would improve design and manufacturing. Write an outline of the points you will make.

3. Quick Activity Use CAD software to draw an American flag. Draw only one star and use the Duplicate or Copy-andPaste function to draw and properly situate all 50 stars in the blue field

Define the following words in your notebook

 CAD/CAM: A process that combines computer-aided drawing and computer-aided manufacturing. Output from the computer used to design a product is used to operate the machines that manufacture it.

Cartesian Coordinates: A system that allows you to plot points on a drawing. The system is based on an imaginary grid.

(CAD) computer-aided design: The process of using a computer to create drafted documents; The use of a computer to create drawings.

(CAM) computer-aided manufacturing: Using computers to manufacture a product; the use of a computer to generate a code used to control a manufacturing system.

(CNC) computer numerical control: A computer system that uses computers to control the operation of machines during production.

Drafting Tablet: A special surface and pen allowing the drafter to make lines and drawings that appear directly on the computer screen.

(FMS) flexible manufacturing system: A system that allows the manufacturer to make a variety of designs using the same machines.

Plotter: A large-scale printer used to print mechanical and architectural drawings; output device that uses one or more pens to make a drawing.

Simulation Software: Software that can test a product design by simulating the environment in which the product must be able to work.