# Geometric Drawing

## The blending of lines and curves

It is usually only the very simple type of engineering detail that has an outline composed entirely of straight lines The inclusion of curves within the outline of a component may be for several reasons to eliminate sharp edges, thereby making it safer to handle to eliminate a stress centre, thereby making it stronger to avoid extra machining, thereby making it cheaper and last, but by no means least, to improve its appoarance This last reason applies particularly to those industnes which...

## Enlarging and reducing plane figures and equivalent areas

Beginning at R. draw the sides of the larger figure parallel to the sides of the original smaller figure. This construction works equally well for reducing the size of a plane figure. Fig. 7 2 shows an irregular hexagon reduced to 4 9 its original size. These constructions are practical only if the figure which has to be enlarged or reduced has straight sides. If the outline is irregular, a different approach is needed. Fig. 7 3 shows the face of a down in two sizes, one twice that of the...

## How To Draw Loci For Crank Mechanism

A locus plural foci is tha path traced out by a point which moves under given definite conditions You may not have been aware ot it but you have met loo meny times before. One of the most common loci is that of a point which moves so that its distance from another fixed point remains constant, this produces a circle Another locus that you know is that ot a point which moves so that its distance from a line remains constant this produces parallel lines. Problems on loci can take several...

## Intersection of regular solids

When two solids Interpenetrate, a line of intersection is formed. H is sometimes necessary to know the exact shape of this line, usually so that an accurate development of either or both of the solids can be drawn. This chapter shows the lines of intersection formed when some of the simpler geometric solids interpenetrate Two dissimilar equare prleme meeting at right The E E. shows where corners 1 and 3 meet the larger prism and these are projected across to the F.E. The plan shows where comers...

## Diagonal Scale Drawing

Three examples of diagonal scales follow. This scale would be used where the drawing is twice the m of the natural object and the draughtsman has to be able to measure on a scale accurate to 01 mm The longest natural dimension is 60 mm. This length is first divided into six 10 mm intervals. The first 10 mm is then divided into 10 pans, each 1 mm wide scaled Each of these 1 mm intervals is divided with a diagonal into 10 more equal parts To construct a diagonal seal , 30 mm 1 mm, 4 m long to...

## Some more problems solved by drawing

This chapter introduces the student to some more drawing techniques It should be emphasized that the topics are only introduced all of them can be studied in much greater depth and any solutions offered in this chepter will apply to simple probleme only. AREAS OF IRREGULAR SHAPES It is possible to find, by drawing, the area of an irregular shape. The technique does not give an exact answer but. carefully used can provide a reasonable answer. Look at Fig. 17 1. The shape is trapezoidal with...

## Further problems in loci

After 1 6 rev. the position of P the intersection of the line Pt Pi and the radius. marked off from 0 . This is repeated for the twelve divisions Fig. 16 1 also shows the beginning of a second cycloid and it can be seen that the change from one cycloid to another is sudden. If any locus is plotted and has an instantaneous change of shape H indicates that there is e cessation of movement Anything that has mass cannot chsnge direction suddenly without first ceasing to move. The point of the...

## Eight-course 125mm Stepped-off Diagonal Method

To construct a regular octagon given the diagonal, i. o. within given circle Fig. 2 29 1. Draw the circle and insert a diameter AE. 2. Construct another diagonal CO, perpendicular to the first diagonal. 3. Bisect the four quadrants thus produced to cut the circle in B. D. F, andH. To construct a regular octagon given the diameter, i.e. within a given square Fig. 2 30 1. Construct a square PORS. length of side equal to the diameter. 2. Draw the diagonals SQ and PR to intersect m T. 3. With...

## Conic sectionsthe ellipse the parabola the hyperbola

Fig. 11 1 shows the five sections that can be obtained from a cone The tnangle and the circle have been discussed in earlier chapters this chapter looks at the remain -ing three sections, the ellipse, the parabola and the hyperbola These are three very important curves. The ellipse can vary m shape from almost a circle to almost a straight line and is often used in designs because of its pleasing shape The parabola can be seen m the shape of electnc fire reflectors, rader dishes and the main...

## The construction of geometric figures from given data

Thi chapter is concerned with the construction of plane geometric figures. Plane geometry is the geometry of figures that are two-dimensional, i.e figures that have only length and breadth. Solid geometry is the geometry of three-dimensional figures. F g. 2 1 To construct a parallel line There are an endless number of plane figures but we will concern ourselves only with the more common ones the triangle, the quadrileteral and the better known Before we look at any particular figure, there are...

## Urheberrechtlich geschDUIes Material

Fig. 2 hows the front elevation and plan of an ink bottle stand. Make e full size isometric drawing of the stand with corner A nearest to you. Hidden details should not be shown. West Midlends Examinations Board 3. Fig. 3 shows the development of a hexagonal box. Draw, in isometric projection, the assembled box standing on its base. Ignore the thickness of the material and omit hidden detail. North Western Secondary School Examinations Board See Ch. 14 for information not in Ch. 3 . 4. Three...