A CURVE AND CIRCLE Archives | School Portal NG

DEFINTION OF FREEHAND SKETCHING Freehand Sketching is one of the quickest methods by which the shape of an object can be communicated to others. This is done by using a pen or pencil. Architects think more of imaginary objects; they cannot take photographs but express this using freehand sketching. Therefore, the knowledge of freehand sketching is of advantage. A good sketch reduces the task of writing needed to describe the object on the mind of the designer. The ability to make a freehand sketching is a valuable asset acquired through practice. SKETCHING A STRAIGHT LINE A straight line can be defined as the shortest distance between two points. Straight line can be sketched following the procedures below: Put a dash or dot far enough to the right-hand side of the paper. Start to draw a line from the left hand side to join the dash or dot with your eyes fixed on the point. ……………………………………….. EVALUATION Define freehand sketching. Describe how to sketch a straight line. SKETCHING: A CURVE AND CIRCLE Curve: To draw a curve by freehand, it will be necessary to plot some points not too far from each other at different levels like this : With the points in position, attempt to draw curves to join them. Circle: To draw circles, the easiest way is to draw lines which are equal in diameter to the circle in different directions. Each line must be drawn as faint as possible, with each crossing one another at a point, Now join the points by little curves from the tip of each line. SKETCHING: A SQUARE AND AN IRREGULAR EDGE This can be sketched in isometric or oblique view.Isometric view is at 300 to the horizontal the at both sides .Oblique view is at 450 to the horizontal at one side EVALUATION Describe how to sketch a curve and a circle. Describe how to sketch a square and an irregular edge. DEFINITION OF SCALE DRAWING Scale drawing can be defined as the accurate representation of objects in a determined proportion.Scale drawing is different from ordinary drawing in that it presents the object either reduced or enlarged. There are scales for reduction and for enlargement of the size of the object. MATERIALS AND INSTRUMENTS FOR SCALE DRAWING Metric rule This has two flat straight edges. It is usually 30cm long. Each main division on the metric rule is equal to one centimeter (1cm 10mm) and each division is sub divided into 10 units being 1mm.Always start from 0 as the beginning of your measurement. Scale rule These have three straight edges and are triangular in shape. Each edge is graduated and each scale designation is marked on the rule. EVALUATION Define scale drawing State the materials and instruments for scale drawing SCALE Some objects are too big for the actual size to be contained on a drawing paper, while some are too small for the parts to be clearly seen. Hence, such objects should be drawn to an appropriate scale. Scale is usually given as a ratio and they are stated in the title block. TYPES OF SCALE DRAWING A scale is used to draw or read a scale on a drawing paper We have the following scales: Full scale drawing Reduced scale drawing Enlarged scale drawing FULL SCALE DRAWING In this scale drawing, the object is drawn to the same size with the actual size. e.g. 1:1 REDUCED SCALE DRAWING The actual size of the object is reduced in proportion to the drawing. Reduced scale drawing is used when the object is too big, examples include 1:2 , 1:5 ,1:10 , 1:50 ,1:100 Therefore a cupboard of size 1800mm long drawn as 18mm has a reduced scale drawing of 1:100mm ENLARGED SCLAE DRAWING This is used when the object to be drawn is too small to be clearly seen .Here, the actual size of the object is enlarged in the proportion to the drawing. Examples include 2:1, 10:1, 100:1, Drawing size 100:1 actual size EVALUATION QUESTIONS Define scale drawing. Mention three (3) types of scale drawing. WEEKEND ASSIGNMENT _____ is one of the quickest methods by which the shape of an object can be communicated to others.(a) Technical drawing (b) Freehand sketching (c)Scale drawing (d) Isometric drawing _______ can be defined as the shortest distance between two points.(a) Straight line (b) Curve (c)Circle (d) Square Isometric view is at ____ to horizontal at both sides (a) 300 (b)450 (c) 600 (d) 900 Oblique drawing is at ____ to the horizontal at one side (a) 300 (b)450 (c) 600 (d) 900 The following are the advantages of free hand sketches except ………….. A good sketch reduces the task of writing needed to describe the object on the mind of the designer. (b) The ability to make freehand sketching is a valuable asset to practice Engineering work. (c) Laypersons can express themselves by freehand sketches. (d) Materials are wasted by freehand sketches. 6.________ can be defined as the accurate representation of objects in a determined proportion (a) Scale drawing (b) Freehand sketches (c) Technical drawing (d) Isometric drawing In _____ scale drawing, the object is drawn to the same size with the actual size. e.g. 1:1 (a) enlarged (b) reduced (c) full (d) proportioned In ______ scale drawing the actual size of the object is reduced in proportion to the drawing .It is used when the object is too big , examples include 1:2 , 1:5 ,1:10 , 1:50 ,1:100 (a) enlarged (b) reduced (c) full (d) proportioned In the scale expressed below 50 is the _____ of the object 50:1 . (a) actual size (b) drawing size (c) proportioned (d) regular 10._____ scale drawing is used when the object to be drawn is too small to be clearly seen (a) Enlarged (b) Reduced (c) Full (d) Proportioned THEORY Define freehand sketching. Describe how to sketch a straight line, curve and circle. Define scale drawing. State the materials and instruments for scale drawing. b. Mention three (3) types of scale drawing See also BOARD PRACTICES AND SCALE DRAWING DRAWING PRACTICE FRICTIONAL FORCES FRICTIONAL FORCES FORCES