- 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
3.12 Offset Location Measurements
Use the method shown in Figures 3.44a and b to locate points with respect to each other. First, draw the main enclosing block, then draw the offset lines (CA and BA) full size in the isometric drawing to locate corner A of the small block or rectangular recess. These measurements are called offset measurements. Because they are parallel to edges of the main block in the multiview drawings, they will be parallel to the same edges in the isometric drawings (using the rule of parallelism).
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3.44 Offset Location Measurements
STEP by STEP: DRAWING NONISOMETRIC LINES
How to Draw Nonisometric Lines
The inclined lines BA and CA are shown true length in the top view (54 mm), but they are not true length in the isometric view. To draw these lines in the isometric drawing, use a construction box and offset measurements.
Directly measure dimensions that are along isometric lines (in this case, 44 mm, 18 mm, and 22 mm).
Because the 54 mm dimension is not along an isometric axis, it cannot be used to locate point A.
Use trigonometry or draw a line parallel to the isometric axis to determine the distance to point A.
Because this dimension is parallel to an isometric axis, it can be transferred to the isometric.
The dimensions 24 mm and 9 mm are parallel to isometric lines and can be measured directly.
STEP by STEP: DRAWING OBLIQUE SURFACES IN ISOMETRIC
Find the intersections of the oblique surfaces with the isometric planes. Note that for this example, the oblique plane contains points A, B, and C.
To draw the plane, extend line AB to X and Y, in the same isometric plane as C. Use lines XC and YC to locate points E and F.
Draw AD and ED using the rule, “Parallel edges on a part will appear parallel in any axonometric view.” Because the inclined surface is planar and the surfaces it intersects are parallel to each other, the edges that lie in those planes will also be parallel.
Isometric Drawings of Inclined Surfaces
Figure 3.45 shows how to construct an isometric drawing of an object that has some inclined surfaces and oblique edges. Notice that inclined surfaces are located by offset or coordinate measurements along the isometric lines. For example, dimensions E and F are measured to locate the inclined surface M, and dimensions A and B are used to locate surface N.
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3.45 Inclined Surfaces in Isometric