Tangency and Important Tangential Exercises

Fig a :

Given an acute angle, it is required to obtain a circle of any given radius tangential to both its arms.

Method: Suppose the circle is to be drawn on the given dimension. Obtain lines known as loci parallel to diagonal and base lines.(given distance on figure is 3/4"). These lines intersect each other and provide a point where u can draw a circle tangent to both arms.

Fig b:

Given a circle, it is required to obtain circles tangential to its circumference.

Method : Draw three circles at given dimensions. Draw parallel locus (loci drawn in previous method) lines. Draw parallel circles at there tangents points.

Fig c :

Tangency  to  parallel circles tangents.

Method : Draw three parallel lines as drawn on the fig c. (Both horizontal and vertical lines.) Here you will get the circles center points. These circle will intersect each other at there tangency.

Fig d :

Given two circle which are not tangential , it is required to obtain two other of given rad. tangential to them externally.

Method : Draw horizontal and vertical center lines. Draw two circles with given length radius. Draw two circles arc respectively. then you will get small circle center points.

Fig e :

Obtain a circle which shall be tangential to the larger circle internally and to the smaller circle externally.

Fig f: 

Obtain circles tangential to the mid point of the straight vertical line.

Method : Draw a line perpendicular to the horizontal line. This horizontal line consist of the centers of the given radius circles.

Fig g :

Draw an ogee curve between two parallel straight lines.

Fig h-i-j

Draw fillets or rounds when the angles are acute(fig j) , right (fig h) and obtuse (fig i)

Method: The center of any circle tangential to the arms of an angle lies on the bisector of the angle. Therefore we may bisect the angle.

Common tangency practice in engineering drawing/machine parts is shown in fig.