Engineering Drawing Questions and Answers – Basic Principles in Dimensioning – 2

This set of Engineering Drawing Questions and Answers for Aptitude test focuses on “Basic Principles in Dimensioning – 2”.

1. How is tapped hole of diameter 10mm with 20mm dimensioned?
a) M10
b) M10, 20
c) M10, DEEP 20
d) M10 20 mm deep

Explanation: A tapped hole of 10mm diameter and 20mm deep is dimensioned as M10, DEEP 20. The ‘M’ stands for metric threads. These are standard threads whose pitch is predefined according to the diameter. The ‘M’ indicates that the hole is tapped.

2. How is a blind drilled hole of 15mm diameter and 15mm deep dimensioned?
a) M15, DEEP 15
b) φ15, DEEP 15
c) φ15
d) φ15 x 15

Explanation: Since the hole is not through, it is mandatory to mention the depth of the hole while dimensioning. Hence a blind drilled hole of 15mm diameter and 15mm deep is dimensioned as φ15, DEEP 15. Since the hole is not threaded ‘M’ should not be used for dimensioning.

3. The dimensions of a circular part or arc should be given where the true shape is visible.
a) True
b) False

Explanation: Circular parts and arcs should be dimensioned where their true shapes are visible. Proper notations should be used to dimension circles and arcs. This will help in clarifying the dimension and reduces the confusion if there are any.

4. A chamfer of 3mm thick and angle 45˚ inclination is dimensioned as _____
a) 45˚ x 3
b) 3 x 45˚
c) 45˚
d) 3mm

Explanation: A chamfer of 3mm thickness and angle 45˚ is dimensioned as 3 x 45˚. From this dimension, we can get the information of the angle at which the chamfer is cut and the distance from one of the sides. This helps in the reading of the dimensions easy.

5. The leader should be used to dimension the circle.
a) True
b) False

Explanation: The leader lines should be used to dimension the circle. This helps in identifying the true shape as well the dimension related to the circle. It is advised not to dimension cylinders in the views where it is seen as any shape other than circle but should be dimensioned where its cross-section is clearly visible.
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6. What does dimensioning of a circle depend upon?
a) Shape
b) Length
c) Unit
d) Size

Explanation: The dimensioning of the circle depends upon the size or diameter of the circle. If the diameter of the circle is considerably large, the dimension can be given inside the circle itself. It should be noted that the dimension of the circle should be given in the view where its true shape is visible.

7. The dimensions which are smaller are to be placed _______
a) Nearer to the view
b) Further from the outline of the view
c) Inside the view
d) On the view

Explanation: The dimensions which are smaller should be placed nearer to the view while the larger view should be placed further away. Dimensions large or small should not be placed on the view. Extension lines should be used and the outlines of ht view for dimensioning.

8. While dimensioning, where should the large dimensions be placed?
a) On the outlines of the view
b) Near the view
c) Further away from the view
d) Inside the view

Explanation: The larger dimensions should be placed further away from the outlines of the view. They should be placed beyond the smaller dimensions. This helps in a neat arrangement of the dimensions and can be understood easily.

9. Extension lines should start from which part of the drawing?
a) Away from the outlines
b) From inside the views
c) No need for extension lines
d) Outlines of the view

Explanation: Extension lines should start immediately from the outlines of the views. There should be no gap between the outlines and the extension lines. Dimensions should not be given on the outlines themselves and therefore extension lines should be used.

10. Dimensions can be placed anywhere irrespective of the features visible.
a) True
b) False

Explanation: Dimensions have to be placed where the true shape or features are clearly indicated. For example, if there is a cylindrical hole in the object, the size of the cylinder i.e. the diameter of the base circle should be dimensioned in the view where it is seen as a circle and not in the view where the cylinder is seen as a rectangle.

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