ISO symbols for weld representations are generally found on drawings prepared with the views shown in first - angle orthographic projection. The symbol for indicating this is illustrated in Figure 26.7.

Dimensioning on drawings is in the metric system, usually given in millimeters (mm).

In first-angle projection, the top view is shown below the front view, the left side view is shown to the right of the front view, and the right side is shown to the left of the front view, Figure 26.8. A typical first-angle projection drawing is illustrated in Figure 26.9.

The three most commonly used views for both first-angle projection and third-angle projection are the front top and right or left side views. Note the second - and fourth-angle projections are not used for working drawings.

FIGURE 26.7 ■ Symbol for first-angle projection.

FIGURE 26.8 ■ Location of views in first-angle projection.

FIGURE 26.9 ■ A typical first-angle orthographic projection three-view drawing.

First-Angle Orthographic Projection

The arrangement and shape of views for first-angle projection is derived from viewing an object located within the three planes of the first quadrant of a circle. An identification of each quadrant and each plane is illustrated in Figure 26.10.

In the derivation of views for first-angle projection drawings, (1) the front view is projected to the verti­cal plane, (2) the top view is projected to the horizontal plane, and (3) the left side view is projected to the profile plane.

When an object is placed within the first quadrant, it is viewed in front of each plane and then projected to the plane for deriving the front, left side, and top views, Figure 26.11. By rotating the profile and horizontal planes 90° to a single plane, the shapes and relative positions of the views are shown as they would appear on a first-angle projection drawing.

FIGURE 26.10 ■ Identification and respective locations of quadrants and planes.

Note: The symbol used to indicate a plane is a straight line with a dot at one end (——-—— •) and placed on the plane.

FRONT VIEW

VERTICAL PLANE

PROFILE PLANE

TOP VIEW

HORIZONTAL PLANE

VIEWING VERTICAL PLANE

FRONT VIEW

VERTICAL. PLANE

FIRST QUADRANT

IMAGINARY HjNGE (4)

PROFILE PLANE

HORIZONTAL PLANE

INDICATES DIRECTION OF ROTATION (90°) FOR SINGLE PLANE

FIGURE 26.11 ■ Deriving views for first-angle projection drawings.

VIEWING ^ PROFILE PLANE

VIEWING HORIZONTAL TOP PLANE VIEW

FIRST-ANGLE QUADRANT UNFOLDED TO A SINGLE PLANE

330 ■ Blueprint Reading for Welders

UNIT 26: REVIEW A

Refer to the drawing, Rotisserie Motor and BRG Stand, page 330. Graph paper is provided at the end of this review for your use.

1. What type of working drawing is illustrated?

2. a. What type of orthographic projection is illustrated?

(3)

b. How was this determined?

3. Identify the views that are shown.

4. a. Give the significance of each of the elements found on the following ISO symbols.

b. Identify whether the welds are to be arrow side, other side, or both sides.

(1)

(2)

(3)

(1)

5. Identify a reference dimension found on the drawing.

6. a. How many millimeters of angle stock are

required to make the part? Allow 2.0 mm for each cut.

b. List the number and length of pieces required.

No. Required	Length

7. List the sizes (in mm) of 9.5 mm plate stock required.

No. Req’d	Width	Length

b. Is it an acceptable AWS standard?

11. Why is a dashed line not shown as a part of the following ISO symbol?

8. a. List dimensions:

®____________________________________

®____________________________________

©____________________________________

b. In which view can dimension © be found without performing any calculations?

9. a. Give the mm size of the tap drill required for

tapping the M8 thread. Refer to Appendix 6 for obtaining this information.

b. What fractional number or letter size of drill could be substituted? Refer to Appendix 4 for obtaining this information.

10. a. I s the following multiple arrow illustration an accepted ISO standard?

13. What is the significance of the note “TYPICAL 4 PLACES”?

14. How would a throat size dimension of 7 mm be shown on the following ISO symbol?

15. What are the maximum and minimum allowable sizes for the following dimensions?

276.0—Maximum________________________

Minimum_______________________________

6.35—Maximum_________________________

Minimum_______________________________

16. Give the significance of M8 as found on the drawing.

M______________________________________

8 ______________________________________

17. How many 13.0 mm drilled holes are required?

18. How many tapped holes are required?

N. T.S. BRG

22. Sketch a right side view of the complete unit. Use graph section for answer.

12. What is the significance of the following abbreviations?

MAT’L _______________________________

STK _________________________________

19. How many bored holes are required?

20. What is the tolerance allowable (plus and minus) for the following dimensions?

a. 9.5

b. 98.0

21. In which view(s) are lines missing for indicating drilled holes?

23. Sketch a right isometric of the complete unit. Use graph section for answer.

24. What is the tolerance specified for the bored-hole?

25. a. Should the threaded holes be tapped before execution of the welds?

29. If an intermittent, other side, fillet weld were required, how would this be shown (exclusive of dimensions) on the symbol that follows?

b. Give reason(s) for your answer.

30. a. I f a flat ground finish were required, how

would this be shown on the ISO symbol that follows?

26. a. Should the drilled holes and bore in part (X be made before welding?

b. Give reason(s) for your answer.

27. What special preparation of part (X is required before welding?

b. Is this symbol shown correctly? If not, correct it.

c. What is the significance of the number found in the tail of the symbol?

28. a. Should the drilled holes in part W be made before welding?

31. Prepare a bottom view (first-angle orthographic projection) of the complete unit. Use graph section that follows.

b. Give reason(s) for your answer.

UNIT 26: REVIEW B

Graph paper is provided at the end of this review for your use. 5. a.

1. a. Sketch the components of an ISO weld symbol.

b. Identify each component.

Sketch the contour symbols that may be applied to ISO weld symbols.

b. Identify each.

2. a. Sketch three “Complimentary Indications” that may be added to an ISO weld symbol. Apply each to an ISO weld symbol.

b. Identify each.

3. a. Sketch two elementary ISO weld symbols that are not included in the basic American Welding Society (AWS) weld symbols.

b. Identify each.

4. Sketch five ISO weld symbols that are identical to AWS weld symbols. Show these in the table format that follows.

6. a. Identify whether the following symbols have application to ISO, AWS, or to both ISO and AWS.

(6)

8. On the following sketch identify which are the arrow side and other side of the joints (as recognized by AWS and ISO).

(7)

b. Describe the welds indicated by the symbols 1 through 7. Identify whether they are arrow side, other side, or both sides.

(1)

(2)

9. a. On the following sketches identify which of the joint members are to be prepared for the weld. Modify each joint to illustrate how the geometry of each joint would appear.

(3)

(1)

(4)

(5)

(6) (7)

(2)

b. Identify the welds required.

(1)

(2)

10. Interpret the following ISO symbols.

7. Sketch the ISO symbol for the following welds.

a. Plug weld

b. Seam weld

c. Single J-butt weld

d. Butt weld between plates with raised edges

e. Surfacing weld

f. Spot weld

13. How is the system of measurement signified on a drawing?

10 X 20 (18)

14. Identify the three most commonly used views for first-angle and third-angle projection drawings.

~V~ : -------------------------------------------------------

Z12 : _______________________________

10 X 10 : _______________________________

(14) : _______________________________

11. What is the most common system of measure­ment found on first-angle orthographic projection drawings?

12. What is the unit most commonly used?

c. Sketch the geometry of the joints to be welded.

16. In the sketch that follows, identify the quadrant 17. a. applicable to:

a. First-angle projection

b. Third-angle projection [6]

As derived from the three-dimensional drawing that follows, prepare a three-view first-angle orthographic projection drawing that includes a front view, top view, and left side view.

Identify (1) the welds required, (2) their location (arrow side or other side),

(3) contour, and (4) method of finish.

18. a. I dentify the type of three-dimensional drawing that follows.

1 9. a. I dentify the type of three-dimensional drawing that is illustrated as follows.

b. Prepare a three-view first-angle orthographic projection drawing including front, top, and left-side views of the three-dimensional drawing.

c. Apply the weld symbols shown on the three­dimensional drawing to the appropriate views and joints of the first-angle orthographic pro­jection drawing.