Machine Drawing Questions and Answers – Elements of Dimensioning

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This set of Machine Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Elements of Dimensioning”.

1. Elements of dimensioning are ___________
a) Extension line, Leader line, Arrowheads
b) Trim, Crop, Construction line
c) Polyline, Helix
d) Donut, Circle
View Answer

Answer: a
Explanation: Elements of dimensioning consist of some important parts: Extension line, Leader line, Dimensional line, Pair of arrows, Dimensional values. Dimension line indicates the direction on which the dimension is to be measured. Extension line extends or elongates the line outside the object. Arrowhead is an important part of the dimension line, extension line & leader line.
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2. _______ lines extend from the object towards outside.
a) Dimension
b) Extension
c) Leader
d) Arrowhead
View Answer

Answer: a
Explanation: Extension line elongates the line outside to the object. Extension line indicates the extreme boundaries of the object where a dimension is to be measured. These lines are continuous and thin which are also used in dimensional line, hence the thickness of the line is the same for both the lines.

3. An extension line should ________ any line.
a) cross
b) not cross
c) pass over to
d) pass below to
View Answer

Answer: b
Explanation: Extension line should not cross with other lines i.e. Leader line or Dimensional line. When extension line crosses the leader line or dimension line or another extension line, they are not shown broken but extension line crosses the arrow, it has to be shown broken.
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4. A leader line is drawn at an angle between _______ and not less than 30 degrees from horizontal.
a) 30 & 45 degree
b) 45 & 60 degree
c) 60 & 75 degree
d) 75 & 90 degree
View Answer

Answer: b
Explanation: A leader line is drawn at an angle between 45 & 60 degrees but not less than 30 degrees from horizontal. A leader line should be drawn at an angle 45 degree from horizontal. This is the standard value of an angle. If more than one leader line is used the angle 45 degrees is used for better view.

5. Leader line is pointed over an area; arrow is replaced by a dot about _____ diameter.
a) 1 mm
b) 2 mm
c) 3 mm
d) 1.5 mm
View Answer

Answer: d
Explanation: Leader line is pointed over an area; arrow is replaced by a dot about 1.5 mm diameter. A leader line is used to indicate the dimension of a circular object, notes, part numbers etc. Leader line is just inclined thin line followed by horizontal line on which the note is to be written opposite side of line.
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6. The rule followed by the leader line is ____________
a) All notes are written in horizontal direction
b) Leader line should cross with other dimension lines
c) Leader line should be very long
d) Leader line is drawn at an angle less than 30 degrees from horizontal
View Answer

Answer: a
Explanation: The rules followed by the leader lines are: All notes are written in horizontal direction. Leader line should not cross with other dimension lines. Leader line should not be very long. Leader line is drawn at an angle 45 & 60 degree but not less than 30 degrees from horizontal. Leader line should be radial to an arc or circle pointing towards its center.

7. Dimension line is drawn slightly away from the object, about _____
a) 4 to 6 mm
b) 2 to 4 mm
c) 6 to 8 mm
d) 8 to 10 mm
View Answer

Answer: d
Explanation: Dimension line is drawn slightly away from the object, about 8 to 10 mm. Distance between the object and dimension line should not be less than 8 mm and not be greater than 10 mm. Dimension line near the object is not suited for the best appearance as well as for too far from the object.
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8. The line which is drawn under the two extension lines, ending with an arrow is called _____
a) leader line
b) dimension line
c) extension line
d) polyline
View Answer

Answer: b
Explanation: The line which is drawn under the two extension line, ending either with an arrow is called dimension line. The dimension line is also ending with oblique stroke or solid dot. The dimensional line is a thin continuous line broken in middle for give there dimensional values or the line may be continuous and dimensional values are written above it.

9. The dimensional line should be _______ to the object.
a) vertical
b) horizontal
c) parallel
d) perpendicular
View Answer

Answer: c
Explanation: The dimensional line should be parallel to the object. Because the dimensional line should not be vertical or horizontal to the object from that point of view proper dimension are not given to the object. It may be given as per the nature of the object. For the best view, the dimension should be parallel to the object.
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10. Preferably a dimension should be placed ______ the view.
a) inside
b) outside
c) left side
d) right side
View Answer

Answer: b
Explanation: Preferably a dimension should be placed outside the view. The dimension line should be placed outside the view because if it is placed inside the object it becomes too confusing for understanding the dimension of the object. Also, it does not coincide with center line.

11. When space is less, the dimensional value may be put outside or adjacent to it.
a) True
b) False
View Answer

Answer: a
Explanation: Putting dimensions value outside or adjacent to line is one of the methods to be used for dimensioning where sufficent space is not available. In this method the arrowheads will turn outside to inside. Here, the direction of arrowhead also changes.

12. Important point on which the arrowhead is to be drawn is ___________
a) They are drawn graphically by using scale
b) Height of arrow is kept about one third of the length of arrow
c) They should be non symmetrical about the dimension line
d) Pointed end of arrow should not touch the extension line
View Answer

Answer: b
Explanation: For better appearance and the limit of arrowhead height of arrow is one third of the length of arrow. Arrowhead is drawn freehand. Length of the arrow is same as the height of the dimensional values. The arrowhead should be symmetrical with a dimension line.

13. _______ are the numbers that are written on the dimension line to specify the size of the object drawn in SI or FPS units.
a) Scales
b) Prime numbers
c) Even numbers
d) Dimensional Values
View Answer

Answer: d
Explanation: The numbers which are written above the dimension line to specify their size is called dimensional values. For mechanical engineering, the unit will be in mm, for civil engineering the unit in meters. It is important to indicate the unit in title for understanding.

14. The dimensional values should be of ______ size.
a) potential
b) approximate
c) actual
d) preferable
View Answer

Answer: c
Explanation: The dimension values should be of actual size. It is because the worker does not make the calculation about the drawing. So it is not multiplied by the factor with dimensional values. Scale should be indicated for the scaled drawing in the title box.

15. For mechanical drawings, the unit is meters while for civil engineering drawings it can be mm.
a) True
b) False
View Answer

Answer: b
Explanation: For mechanical drawings, the unit is mm. For civil engineering drawings it can be meters. Hence it is important to indicate the unit in the title box, ‘All dimensions are in mm/m’ and the unit is not indicating with the numbers, i.e. 40 meaning 40 mm.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter