Engineering Drawing Basic | Interview Question and Answers – Part 2
Engineering Drawing , graphics , Machine Drawing Interview, viva , oral Examination Question and Answers For Mechanical Engineering Students .
Q26 – What should be the grade of pencil used for lettering?
Ans26 – HB and H grade pencils sharpened to a conical point should be used for lettering. To keep the stroke of the letters uniform, the pencils should be rotated between the thumb and fingers while lettering. Hard pencils such as 2H or 3H should be used to draw guidelines.
Q27 – What is the importance of dimensioning?
1) Dimensioning expresses all the sizes and other information necessary to define the object.
2) It must be done with due regard to manufacturing processes and inspection requirements.
3) The dimensioning also includes expression of tolerances necessary for the correct functioning of the part given to be assembled.
Q28 – What is dimensioning?
Ans28 – The art of writing the various sizes or measurements on the finished drawing of an object is known as dimensioning.
Q29 – What do you understand by the term notation of dimensioning?
Ans29 – The notation of dimensioning consists of dimension lines, extension lines, arrow heads, dimension figures, notes, symbols etc.
Q30 – What is a leader or pointer line? How a leader should be drawn?
Ans30 – A leader is a thin continuous line drawn from note of the figure to show where it applies. It is terminated by an arrow head or a dot. The arrow head touches the outline, whereas the dot is placed within the outline of the object.
The leader is generally drawn at any convenient angle, usually 30º, 45º, and 60º but not less than 30º.
Q31 – Explain with the help of a simple sketch (i) size dimensions (ii) location dimensions.
- Size dimension – The dimensions which indicate the various sizes of the object such as length, breadth, diameter etc. are known as size dimensions. These dimensions are represented by letter ‘S’.
- Location dimension – The dimensions which locate the position of one feature w.r.t. the other feature are known as location dimensions. Distances between the centre lines of the holes from the edges are given by location dimensions. These dimensions are marked by letter ‘L’.
Q32 – What are the aligned system and unidirectional system of dimensioning?
What are the different methods of dimensioning?
Ans32:-1) Aligned Method: – In aligned system, the dimensions shall be placed parallel to and above the dimension lines, preferably in the middle and not by interrupting the dimension lines. Here the dimensions can be read from the bottom or from the right side of the drawing.
2) Unidirectional Method: – In this system dimensions shall be horizontally placed so that they can be read from the bottom of the drawing sheet. Here the dimension lines may be interrupted preferably near the middle for the insertion of dimensions.
Q33 – What are the general rules of dimensioning?
1) Every dimension must be given, but no single dimension should be repeated.
2) Dimensions should be placed outside the views.
3) Avoid dimensioning to hidden lines wherever possible.
4) Dimension lines should not cross any other line of the drawing.
5) Aligned system of dimensioning is recommended.
Q35 – Explain with the help of sketches (i) chain dimensioning (ii) parallel dimensioning and (iii) combined dimensioning.
- Chain Dimensioning – In this system, dimensions are arranged in a straight line.
- Parallel dimensioning – In this arrangement, all the dimensions are given from common base line. The smaller dimensions are placed nearer the view and the larger further away so that the extension lines do not cross dimensions lines.
- Combined dimensioning – Combined dimensioning is the result of the simultaneous use of chain and parallel dimensioning.
Q36 – What is a scale?
A scale is defined as the proportion by which we either reduce or increases the actual size of the object on a drawing.
1) Full size scale:-The scale in which the actual measurements of the object are drawn to same size on the drawing is known as full size scale.
2) Reducing scale: – The scale in which the actual measurements of the object are reduced to some proportion is known as reducing scale.
3) Enlarging scale: – The scale in which the actual measurements of the object are increased to some proportion is known as enlarging scale.
Q37 – What is the representative fraction (R.F.) or scale factor (S.F.)?
Ans37:-The ratio of the drawing size of an object to its actual size is called the Representative fraction.
R.F. = Dimension of an object on sheet / Actual dimension of an object
Q38 – What are the main uses of scale?
Ans38 – The following are the main uses of scale in engineering practice.
(i) The scales are used to prepare reduced or enlarged size drawings.
(ii) The scales are used to set off dimensions.
(iii) The scales are used to measure distances directly.
Q39 – What are the information necessary for scale?
Ans39 – To construct a scale, the following informations are necessary.
(i) The representative fraction (R.F.) of the scale.
(ii) The units to be presented either in metric or British measures.
(iii) The maximum length of the scale.
Q40 – What is difference between plane scale and diagonal scale?
Plain Scale:- A plain scale is simply a line which is divided into a suitable number of equal parts, the first of which is further sub-divided into small parts. It is used to represent either two units or a unit and its fraction such as km and hm, m and dm, etc.
Diagonal Scale:- A diagonal scale is used when very minute distances such as 0.1 mm etc. are to be accurately measured or when measurements are required in three units; for example dm, cm, and mm.
Q41 – What is the principle of a diagonal scale?
Ans41: – The principle of diagonal scale is to divide a short line into any number of equal parts by following the diagonal division’s method of construction.
Q42 – What is the difference between a quadrilateral and a polygon?
Ans42 – Quadrilateral – A quadrilateral is a plane figure bounded by four straight lines and containing four angles.
Polygon – A polygon is a plane figure bounded by more than four straight lines and containing more than four angles.
Q43 – What is the difference between a parallelogram and a rhombus?
Parallelogram – A parallelogram is a quadrilateral in which the opposite sides are equal and parallel.
Rhombus – A rhombus is a quadrilateral in which all the sides are equal and the angles are not right angles.
However, in this case the opposite angles are equal.
Q44 – What is the difference between regular and irregular polygons?
Regular polygon – A regular polygon is a plane figure in which all the sides and angles are equal.
Irregular polygon – An irregular polygon is a plane figure in which all the sides and angles are not equal.
Q45– Name the principal planes of projections.
There is two planes employed for projection and are known as reference planes or principle planes of projections. These planes intersect at right angles to each other. These are
1) Vertical plane: – The plane which is vertical is called vertical plane and is denoted by V.P. Vertical plane is also known as Frontal Plane as front view is projected on this plane.
2) Horizontal plane:-The plane which is horizontal and at right angle to the V.P is called Horizontal Plane and it is denoted by H.P.
Q46:- What is the principle of projection?
Ans46:-If straight lines are drawn from various points on the contours of an object to meet a plane, the object is said to be projected on that plane. The figure formed by joining in correct sequence the points at which these lines meet the planes is called the projection of the object.
Q47 – What is ground line (G.L.) or intersection or reference line?
Ans47:-The line of intersection of two principle planes of projections i.e. VP and HP is called reference or intersection or ground line and is denoted by x-y line.
Q48 – What is an auxiliary view?
Ans48:-The view obtained on the auxiliary plane which is parallel to the inclined surface of an object is called auxiliary view.
Q49 – What do you understand by missing lines?
Ans49 – The lines which are added in the given orthographic projection in order to complete the drawing of an object are called missing lines.
Q50 – What do you understand by missing views?
Ans50 – The view which is added in the given orthographic projections in order to complete the drawing of an object is called missing views.
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