Blueprint Reading for Sheet Metal Flashcards

What does 'NTS' mean on a drawing and what precaution should be taken?

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.

What is the standard third-angle projection used in Canadian and North American drawings?

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.

What does the abbreviation 'EQ' mean on a sheet metal drawing?

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.

What does a 'weld symbol' on a sheet metal drawing communicate?

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.

What is the purpose of 'extension lines' on a dimension?

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.

What does the abbreviation 'SIM' or 'OPP' mean on a sheet metal drawing?

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.