Would you mind please posting your SW part with the curve in it - thanks
I've had issues w/ equation-driven curves not quite adding up when checking slopes (first derivatives). In my case, it was using an equation-driven curve to create an involute gear tooth profile.
I just accepted the, as I assumed it was due to interpolation in the curve. Such is the nature of curves and surfaces in CAD when one departs from simple arcs and lines.
You had me going on this one for a moment!
The equation for the derivative is correct:
Dy/dx = Pi/5.5 * Cos(2Pi)
Since Cos(2Pi) =1
The slope of the curve (derivative) at this point is Pi/5.5 or 0.5711.
Reviewing the value, one of my colleagues pointed out that….You’re not done yet!
I was an engineering student in the days before computers ruled the world. Slope approximates the angle of the line in radians for SMALL angles ( < 5 Degrees ). To properly calculate the angle, you must take the ArcTan of the slope.
That calculation will result in 29.73 degrees.
Here is a link to a website that explains the calculation:
R&D SolidWorks, Modeling, Development Senior Manager