Spline Curvature at Midpoint

It looks like these two handles aren't the same length.

Here is my solution. I think maybe your spline point at 12.20 is not coincident with the horizontal construction line?

John,

We need to attract Mark Biasotti's attention to this thread. I swear that in the good (or bad, depending on your point of view) old days, we couldn't control the two sides of a midpoint tangency separately. I thought that when that capability was added that the system defaulted to changing the two sides equally but gave you a way to manipulate them independently. But that doesn't seem to be the way it works and I don't have a clue how to force the two sides to be equal.

Jerry S.

Hi,

I start a new spline and it works fine.

Or, delete 12.200 dimension, in 3rd point of spline uncheck maintain internal continuity and select manualy Tangent Weighting1 and 2. Then add 12.200 dimension and check/or no maintain internal continuity again. This is a spline 

John, splines aren't plotted in a sketch the way lines and other curves are.  With splines, you get different levels of complexity at each point.  So, not only does a 6 point spline change more drastically than a 3 point spline, the fourth point changes more drastically than the 2nd point. 

The "Reset Spline" and "Relax Spline" tools in the Property Managers, redistribute the stress in the spline by repositioning the handles and changing the order of the curvature so that the spline finds a solution that doesn't flake out as easily.

Even with these tools, there's no parameter you can set for a spline that will explicitly establish symmetry within the curve.  Unless you need curve level continuity at the apex of your curve, you should put a center line in there, constrain the apex end of the spline tangent to to a vertical construction line and mirror the curve.