Comparing CAD to Traditional Drafting

Creating a technical drawing using CAD is very different from making one using a drafting board and traditional drafting instruments. One difference is that CAD drawings can be automatically scaled to fit the paper they are printed on. For traditional drafting, you must use a scale, an instrument that looks like a ruler, to change the size of the drawing. Another major difference in using CAD is the ease with which drawings can be changed or copied. To change a traditional drawing, you must erase or redraw it. With CAD, the computer changes can be entered quickly and the drawing simply reprinted.

For this activity you will make several basic drawings using both CAD and traditional drafting equipment. You and your partner will team up to complete the activity with one of you drawing and the other recording the time it takes for you to finish the task. For the second part of the activity you will switch roles.

Specifications

Drawings must be accurate to within 1/16 inch.

Drawings must be neat and free of smudges.

All drawings times must be recorded.

Prior Knowledge

  1. Become familiar with the use of traditional drafting equipment.
  2. Become familiar with the use of CAD software.

Task I

  1. Secure a piece of 8 x 11 ½ inch paper on the drafting board.
  2. Record the starting time in Table A
  3. Draw a line 6 inches long. Clearly mark the beginning and endings points. Check your accuracy.,
  4. Draw a circle with a 4 inch diameter. Check your accuracy
  5. Draw a base line 4 inches long. Draw another line from it at a 48 degree angle. The second line should be 3 inches long. Clearly mark all beginning and ending points. Check your accuracy
  6. Draw a rectangle that measures 3 x 5 inches. Check your accuracy
  7. Now go back and change the rectangle that you drew in Step 6 so that it will measure 4 x 6 inches. Check your accuracy. If you damage your paper as you make the change, or if your drawing becomes hard to read, make a completely new drawing in another spot.
  8. Draw three additional copies of the rectangle you drew in Step 7.

Task II

  1. Download the CAD software MacDraft.

To download the MacDraft software-

Go to docs.smokyvalley.org

Locate the folder Tech Files

Open the folder and drag the MacDraft file to your desktop

To use the program-

Double click the MacDraft P.E. demo folder

Double click the MacDraft P.E. Demo icon

Under LAYOUT in the Main Menu select Show Rulers

Under LAYOUT in the Main Menu select Show Size

  1. Complete Steps 2-8 using the computer and CAD software MacDraft.
  2. Take a picture of your finished drawing. (The software is a demo and cannot be saved)
  3. Print the picture.
  4. Total the times it took you to make the drawings using the two methods. Note the difference in the space provided.
  5. Compare the drawings made on the computer with those made using traditional equipment. Note those differences in Table B.

Table A

Drafting Task / Times
Traditional / CAD
6-inch line
4-inch line
48 degree angle
3 x 5 rectangle
4 x 6 rectangle
3 copies of 4 x 6 rectangle
Totals
Difference between the two totals
Which method was faster?

Table B

Drafting Task / Traditional / CAD
6-inch line
4-inch line
48 degree angle
3 x 5 rectangle
4 x 6 rectangle
3 copies of 4 x 6 rectangle

Evaluate the Results

  1. What are three advantages of using a CAD system?
  1. Under what circumstances might traditional methods be more appropriate?