Obtaining "Equal Curvature" on Spline Ends

I've always assumed we had to 'manually' create an equal
curvature condition on the ends of a spline (when made
tangent to another spline or line) until I ran into this
message...
http://www.mikejwilson.com/misc/equal_curvature.jpg

Is there a way to add this relation (spline constraint) that
I'm not seeing?

Thanks!
Mike Wilson

 

A glimmer of (false?) hope, perhaps? I've been waiting and whining
for SW to improve curvature control of splines. I see nothing in the
help or API help for SW2004.

to add this relation (spline constraint) that

 

How did you create this spline?

Zander

 

Here is a simplified way...

*) Start new 2D sketch
*) Draw two horizontal lines, one on the upper right
of your screen, the other on the lower left.
*) CTRL-select each and hit "Fit Spline". Use Constrained.
*) Right-click the newly created spline and select "Split
Entities" and try splitting the spline.

That's when the message pops up.

Mike Wilson

 

Cool! I had never played with fit splines before. It looks like it will be
very useful, providing a workaround for the lack of curvature control.
Strange that the help doesn't point out that the spline matches the
curvature of the underlying geometry, whether it's a line, an arc or another
spline.

Jerry Steiger
Tripod Data Systems

 

Because they cannot guarantee it. All "fit spline" does is to draw a new
spline from "enough" points located on the underlying geometry such that the
distance between the spline and the line/arcs/spline is withing the given
tolerance.
Do a "simplify spline" with a 0 tolerance to see the spline control points.
Remember that splines are polynomial functions, so they cannot have a
constant curvature like a circle (ok, it's easier with a line...)
But you are correct, SolidWorks/D-Cubed could "easily" add start/end
tangency to splines.

FYI, we will "soon" release an addin that does "fit-spline" automatically to
all the chains in a sketch, for example to an "exploded" text or to an
imported dxf...