
Re: Inaccurate Curve in Solidworks
14EQZK9 Mar 4, 2013 9:55 AM (in response to Fahd Motlak)Hi Fahd,
Would you mind please posting your SW part with the curve in it  thanks
Mark

Re: Inaccurate Curve in Solidworks
Roland Schwarz Mar 4, 2013 10:16 AM (in response to Fahd Motlak)I've had issues w/ equationdriven curves not quite adding up when checking slopes (first derivatives). In my case, it was using an equationdriven 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.

Re: Inaccurate Curve in Solidworks
Ditmars Veinbachs Mar 4, 2013 11:54 AM (in response to Fahd Motlak)Hi Fahd
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:
http://www.mathopenref.com/coordslope.html
Best Regards,
Ditmars VEINBACHS
R&D SolidWorks, Modeling, Development Senior Manager