6.1: Creating Drawings and Sketches
Freehand sketching is an instrumental skill that can be mastered with practice and by following a few guidelines. The ability to interpret drawings is complemented by the ability to sketch information from a drawing to take to your work location. Sketching is also a valuable tool when no drawing is available and you must communicate job information to someone else.
For freehand sketching, you require a pad of graph paper (8 ½ " × 11" sheets with a 5 mm or ¼" grid), a sharp HB pencil, and an eraser. Do not begin any sketch with a dull pencil.
Sketching technique
Sketching provides a quick and straightforward way to express ideas and communicate an object's shape and general size.
Sketching parallel lines
Start by drawing lines parallel to the paper's edges, such as a border line and title block. Use your finger as a guide when you draw along the grid line on the sketch pad (Figure \(\PageIndex{1}\)). Letting the end of your little finger run down the edge of the paper pad as you draw will steady your hand and make it easier to get a straight line.
Sketching non-parallel lines
When sketching lines that are not parallel to the sides of the paper, turn the paper around so that the line you wish to draw is either straight up and down in front of you or straight across the sheet of paper.
Drawing lines this way rather than at an angle across the sheet is much easier. Let the side of your little finger rest on the paper as you draw. This will help you steady your hand (Figure \(\PageIndex{2}\)).
Sketching a rectangle
Locate the corners of the rectangle first. Then place your paper in a comfortable position for sketching and sketch downward for vertical lines and left to right for horizontal lines. Use the grid lines as a guide to help maintain your parallel and at 90 degrees lines to each other (Figure \(\PageIndex{3}\)).
Sketching a circle
First, locate the center of the circle (Figure \(\PageIndex{4}\)), and then very lightly box in the size of the circle (using the diameter as a guide), as in the top right. Sketch in the circle, one quarter at a time, as shown in the bottom row, left to right. You may find it necessary at first to add light points along the projected circumference to help guide you through each quarter. Remember to move your sketch pad to maintain a comfortable sketching position.
Sketching to approximate scale
The full-size square is on the left in Figure \(\PageIndex{5}\). The center square is half size, and the right square is quarter size. Note that the center and right squares are the same shape as the left square, only smaller.
When sketching freehand, your sketches should reflect the actual shapes of objects as much as possible. If you use grid paper, sketching to an approximate scale is not difficult. Assume that the object in Figure \(\PageIndex{6}\) is shown full size. As it is necessary to show all orthographic views on the same sheet of paper, the views must be scaled. Figure \(\PageIndex{7}\) shows the views at approximately one-half the original size.