the equ of spur gear
/*for cartesian coordinate system, enter parametric equation
/*in terms of t (which will vary from 0 to 1) for x, y and z
/*For example: for a circle in x-y plane, centered at origin
/*and radius = 4, the parametric equations will be:
/* x=4*cos (t*360)
/* y=4*sin (t*360)
/* z=0
/*----------------------------------
rb =(PITCH_DIAMETER/2)*cos(PRESSURE_ANGLE)
theta =t*90
theta_rad=(3.1415927/180)*t*90
x=rb*(cos(theta)+ theta_rad*sin(theta))
y=rb*(sin(theta)- theta_rad*cos(theta))