Parametric Fillet Law Curves

[scotty7]

Putting in a face blend fillet with a law curve, you can define a point for a change in radius. This point can be any of the usual point definitions, but if you pick a point part way along a curve (either an existing point on curve or by % along curve), the law curve "forgets" where it was, so that if the point moves, the fillet doesn't update to match.
We need to run some fairly trick fillets, and having a automated optimisation routine that can change the fillets and re-stress them would be great, but not being able to modify the law curve change points largely scuppers this. Any ideas how to get a parametric change point?

 

[mjcole]

Scotty,

If you create a sketch you can use and create associative points at midpoints or quadrant points or even angle along curve and these will remain associative and not get turned into an x,y,z position like the point on curve or create point option doesn't.

When you exit the sketch you will see the angle or point expresions for the associative points show as p5_x=15 in my model this was an associative point made at 15 degrees. When you change these values the associative points should update as expected.

The points you create don't need to be co planar with your sketch plane so you can create one or many control point sketches and they should work for any type of blend point location you need to use.

When you finish the associative point creation hit Cancel to avoid a duplicate point at the x,y,z position of the last point because that point wont be associative.

Hope this helps. Give it a try and let us know how it turns out.

Michael

 

[scotty7]

Thanks, but the problem is that when the parametric point is created, and used to define the change point for a law curve fillet, the law curve forgets the point (just takes it's position at the time of initial definition). So, if the point moves, the change point doesn't. I can make this work in other CAD systems (CADDS5, CATIA5).
btw, the fillet runs round between 2 NURB surfaces, so sketches aren't in the game plan. Found that setting up a datum, intersecting one of the surfaces with the datum and plonking a point at the end of the intersect curve gives me a parametric point in 3D (clumsily, must be a better way), but then the fillet doesn't follow it.