Orthographic Projection Questions and Answers

Answer: A

The front view is settled first because everything else is projected from it, then how many further views the shape requires, then those views, then the annotation. Dimensioning last avoids reworking it as views change.

Answer: B

Correct answer: 1 and 2 only are correct

Statements 1 and 2 are correct: in first angle the plan falls below the front view, and a visible outline takes precedence over a coinciding hidden edge. Statement 3 is the reverse of the truth - chain dimensioning is precisely the arrangement in which tolerances accumulate, and datum dimensioning is what avoids it.

Answer: C

Correct answer: an auxiliary view of an inclined face

The six principal views are those taken along the three mutually perpendicular axes from either end: front, rear, left, right, top and bottom. An auxiliary view is taken normal to an inclined face rather than along a principal axis, precisely so that the face appears in its true shape, and it is drawn in addition to the principal views.

Answer: D

Correct answer: the wall of a hollow casting

The wall of a casting is exactly what a section exists to show, so it is hatched in the ordinary way. The other three are among the parts conventionally left unsectioned: a bolt, a key and a web cut along its length would all show as meaningless solid hatching, and in the case of the web would wrongly suggest a solid flange.

Answer: A

Correct answer: the projection system was misread

A mirror image with every dimension correct is the signature of a first angle drawing read as third angle, or the reverse: the side views are transposed left for right, so the part is made handed the wrong way round. It is why the projection symbol belongs in the title block of every drawing, and why it should be checked before work begins.

Answer: B

Correct answer: query the drawing, since a dimension must appear once only

Two different figures for the same length mean the drawing is wrong, and nothing on it says which figure is right - one of them is probably a revision that was not carried through. Averaging, or choosing the safer-looking value, is guessing at the designer’s intent. The rule that a dimension appears once exists precisely to prevent this situation arising.

Answer: C

Correct answer: both the assertion and the reason are true and the reason explains the assertion

Both are true and the reason is the whole justification. The same three views arranged the same way describe two different, mirror-image objects depending on which system is in use, and nothing in the geometry reveals which was intended. The symbol in the title block is therefore not a formality but the only thing that makes the drawing unambiguous.

Answer: D

Correct answer: the assertion is false although the reason offered is sometimes true

An additional view does sometimes convey further information, which is why it may be drawn at all. But views beyond the minimum clutter the sheet, cost drawing and checking time, and multiply the chances of two views disagreeing after a revision. The rule is the minimum number that describes the object completely, not the maximum that will fit.

Answer: A

Correct answer: keeps each hole's tolerance independent of the others

Measuring every hole from the same datum face means each position depends on one dimension and one tolerance, so an error in one does not displace any other. In a chain the errors accumulate, and the last hole carries the sum of them all. Datum dimensioning usually needs the same number of dimensions, not fewer, and tolerances must still be stated.

Answer: B

Parallel projectors perpendicular to the plane leave such a face undistorted, which is the whole utility of the method. Perspective converges and cabinet oblique deliberately halves the depth, so neither preserves size.