- Understanding Solid Objects
- Understanding Sketching Techniques
- 3.1 Technique of Lines
- 3.2 Sketching Straight Lines
- 3.3 Sketching Circles, Arcs, and Ellipses
- 3.4 Maintaining Proportions
- 3.5 One-View Drawings
- 3.6 Pictorial Sketching
- 3.7 Projection Methods
- 3.8 Axonometric Projection
- 3.9 Isometric Projection
- 3.10 Isometric Drawings
- 3.11 Making an Isometric Drawing
- 3.12 Offset Location Measurements
- 3.13 Hidden Lines and Centerlines
- 3.14 Angles in Isometric
- 3.15 Irregular Objects
- 3.16 Curves in Isometric
- 3.17 True Ellipses in Isometric
- 3.18 Orienting Ellipses in Isometric Drawings
- 3.19 Drawing Isometric Cylinders
- 3.20 Screw Threads in Isometric
- 3.21 Arcs in Isometric
- 3.22 spheres in Isometric
- 3.23 Oblique Sketches
- 3.24 Length of Receding Lines
- 3.25 Choice of Position in Oblique Drawings
- 3.26 Ellipses for Oblique Drawings
- 3.27 Angles in Oblique Projection
- 3.28 Sketching Assemblies
- 3.29 Sketching Perspectives
- 3.30 Curves and Circles in Perspective
- 3.31 Shading
- 3.32 Computer Graphics
- 3.33 Drawing on Drawing
- Key Words
- Chapter Summary
- Worksheets
- Review Questions
- Sketching Exercises
This chapter is from the book
This chapter is from the book
This chapter is from the book
3.2 Sketching Straight Lines
Most of the lines in an average sketch are straight lines. With practice, your straight lines will naturally improve, but these basics may help you improve quickly.
Hold your pencil naturally, about 1″ back from the point, and approximately at a right angle to the line to be drawn.
Draw horizontal lines from left to right with a free and easy wrist and arm movement.
Draw vertical lines downward with a wrist and arm movement.
Draw curved lines using finger and wrist movements.
Blocking in a Freehand Drawing
Over the years, freehand sketchers have developed all sorts of tricks to improve speed and accuracy. Methods for finding midpoints or quickly blocking in straight vertical and horizontal lines are just a few secrets of the technical sketching craft that can come in handy, even today. When a great idea hits, or you need to sketch quickly at a meeting or on a job site, you might not have access to a CAD system, or even a ruler.
TIPS
Drawing Long Freehand Lines
For long freehand lines, make light end marks and lightly sweep your pencil between them, keeping your eye on the mark toward which you are moving. When you are satisfied with the accuracy of your strokes, apply more pressure to make a dark line.
Blocking in a Border Freehand
Hold your hand and pencil rigidly and glide your fingertips along the edge of the paper to maintain a uniform border.
Blocking in a Border Using a Strip of Paper
Mark the distance on the edge of a card or a strip of paper and use it like a ruler to mark at intervals, then draw a final line through the points.
If your line looks like this, you may be gripping your pencil too tightly or trying too hard to imitate mechanical lines.
Slight wiggles are OK as long as the line continues on a straight path.
Occasional very slight gaps are fine and make it easier to draw straight.
Finding a Midpoint Freehand
Use your thumb on your pencil to guess half the distance. Try this distance on the other half. Continue adjusting until you locate the center, then mark it.
Folding a Paper to Find a Midpoint
Mark the total distance on the edge of a strip of paper, then fold the paper to locate its center at the crease. You can fold one half to find quarter points, and so on.
STEP by STEP: DIVIDING LINES INTO EQUAL OR PROPORTIONAL PARTS
Proportional Parts
To divide the given line shown into proportions of (for example) 2, 3, and 4 units:
Draw a vertical construction line at one end of the line you are dividing.
Set the zero point of your scale at the other end of the line.
Swing the scale so the desired unit falls on the vertical line. In this case it will be the 9th unit, because 2 + 3 + 4 = 9.
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Draw vertical lines upward from the corresponding scale divisions and mark tiny crossbars on the line as shown.
Equal Parts
If you use uniform divisions for the steps above (every third division, for instance) you will get equal parts. Examples of practical applications for dividing lines equally are shown below.
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Calculated Proportions
To divide a line into proportions equal to the square of 1, 2, 3, and 4 (1, 4, 9, and 16), find 16 divisions on your scale.
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Set the zero point of your scale at the end of the line and draw a light construction line at any convenient angle from one end of the line you are dividing to the appropriate division on the scale. In this case the 4 mark is 16 equal divisions from the 0.
Draw construction lines parallel to the end line through each proportionate scale division.
