Page 43 - Engineering drawing from first principles using AutoCAD

36 Engineering drawinq [1"'0111 first principles

R120
R12

-R18

R100

25

R100
R18

R12

I~ 90 J

Figure 2.9

the dimensions given that the length of 107 is not readily divisible by 5. The construction
here is one which uses the principle of similar triangles.
Draw vertical lines from points A and B and from a point 0 draw an arc with a radius of
110mm which is divisible by 5. The line OYis now marked off using arcs of radii R22,
R44, R66 and RBB. The vertical lines through the intersections give the required calibra-
tion points.
Line in the outline with polylines 0.4mm wide. The dipstick can be drawn using the
FILLET option for the BOmm radius and the rectangular array for the graduations. The
geometrical method is given here for revision purposes.

Screwdriver

Determine the positions of all the arc centres and draw the profile of the screwdriver
shown in Fig. 2.12.