Real-Life Math
As its title suggests, technical illustration is a technical career. Illustrators must be able to take an object and break it down into diagrams that make sense to even the least technically inclined.
"A lot of companies ask me to illustrate representations of products that are impossible to photograph or work better as a diagram, where you can see how parts come together," says Chris Ceccarelli.
To accomplish that, you need good math skills.
You work for an industrial company creating drawings of machine parts. You work with Sandra, the person who designed the new part, in order to create a sketch.
You must make an accurate sketch of the new part by listening to her describe how the part should look and by examining pieces that she has machined during the design process.
Once you have a general idea of what she's looking for, you make some preliminary sketches. "That arm is too far over and the baseline is a tad thicker," Sandra says, examining your drawings.
You head back to the computer and make the adjustments. It's important that your diagram is absolutely accurate -- machinists in the back shop will use it to produce the new part.
Because the machinists will be reading the measurements off the drawing, you must note them carefully. Machinists can't always get the exact size when they make a part, but they can come pretty close. The margin of error they are allowed while machining a part is called the tolerance.
Part A
For this drawing, and for most others, you note that you'll accept a tolerance of plus or minus 1/64 of an inch. The base of the part is rectangular and measures 2 and 1/4 inches by 3 and 1/2 inches. What are the minimum and maximum tolerance levels you'll allow for this piece?
Part B
Another section of the part is circular. Sandra wants the diameter of this circle to be 4 inches. In order to draw the circle, however, you'll need to know its circumference.
Circumference
3.14 x diameter = circumference