308A Blueprint Reading for Sheet Metal 4 — Questions and Answers
Question 1: What does 'NTS' mean on a drawing and what precaution should be taken?
- No Technical Specifications needed
- Not To Scale — do not measure dimensions from the drawing; use only the written dimensions (Correct answer)
- New Technical Standard
- No Testing Specified
Correct answer: Not To Scale — do not measure dimensions from the drawing; use only the written dimensions
NTS (Not To Scale) warns that the drawing is not drawn proportionally, so scaling (measuring with a ruler) would give incorrect dimensions. Only the written numerical dimensions should be used.
Question 2: What is the standard third-angle projection used in Canadian and North American drawings?
- The object is always shown from one angle only
- The front view is centered, top view is above, right side view is to the right — each view shows what you see looking at that side (Correct answer)
- Views are randomly arranged
- Only isometric views are used
Correct answer: The front view is centered, top view is above, right side view is to the right — each view shows what you see looking at that side
Third-angle projection places the top view above the front view, the right side view to the right of the front view, and the left side view to the left. Each view shows the object as seen from that direction.
Question 3: What does the abbreviation 'EQ' mean on a sheet metal drawing?
- Equipment
- Equal or equally spaced (Correct answer)
- Equation required
- Extra quality
Correct answer: Equal or equally spaced
EQ means equal or equally spaced. It indicates that features such as holes, stiffeners, or rivets are evenly distributed across the indicated distance. Only one spacing dimension needs to be given.
Question 4: What does a 'weld symbol' on a sheet metal drawing communicate?
- Only the welding rod type
- The weld type, size, location (arrow side/other side), process, and any special instructions (Correct answer)
- Only whether to weld or not
- The name of the welder
Correct answer: The weld type, size, location (arrow side/other side), process, and any special instructions
AWS weld symbols communicate comprehensive welding requirements including joint type, weld type, size, length, spacing, location (arrow side or other side), welding process, and special requirements like field weld or all-around.
Question 5: What is the purpose of 'extension lines' on a dimension?
- To extend the part during fabrication
- To extend from the feature being dimensioned to the dimension line, defining exactly what is being measured (Correct answer)
- To show the direction of airflow
- To indicate areas that need reinforcement
Correct answer: To extend from the feature being dimensioned to the dimension line, defining exactly what is being measured
Extension lines are thin lines that project from the edges or points of a feature to the dimension line. They define the exact start and end points of the dimension without cluttering the object lines.
Question 6: What does the abbreviation 'SIM' or 'OPP' mean on a sheet metal drawing?
- Simple or Optional
- Similar (identical to a referenced detail) or Opposite (mirror image of a referenced detail) (Correct answer)
- Simultaneous or Operational
- Single or Open
Correct answer: Similar (identical to a referenced detail) or Opposite (mirror image of a referenced detail)
SIM (Similar) means the detail is identical to a referenced feature. OPP (Opposite) means it is a mirror image. These abbreviations save drafting time by referencing existing details instead of redrawing them.
308A Blueprint Reading for Sheet Metal 4
What does 'NTS' mean on a drawing and what precaution should be taken?