spline on a surface - tricky

Hi,

SW2005 SP01.1

Has anyone noticed that trying to use the new Spline on a surface tool is
pretty tricky if the surface in question is nice and 'curvey'? I'm having
the old yellow-line unsolvable business, 'returning the sketch to original
position', overdefined, underdefined and generally all over the place when I
try and constrain it.

any tips?

Lee

 

Hi Lee,

I have used this a lot recently and as you describe it is much harder
to control if the surface is complex. Some tricks I used to control it:

1.
If I needed the curve to originate at an edge at a special angle or
direction, I would try this approach: Since you cannot have the curve
cross a surface edge to another surface, I made the surface bigger than
I needed, and create a trim , or notch, or some feature that I can then
mate the end of the surface spline to, and then create a tangent, or CC
relation to the trimmed edge (you may have to convert the edge). That
way you can control the beginning angle with the trim sketch

2
it can get ugly, but sometimes the only solution is more points. As you
have found, minor adjustments in the curve points, or handle weights
can make the whole thing go kabooom.

3.
if parts of the curve can be made as projected curves on surface, do
that. You can make the surface spines have tan or CC relationships to
those curves, and then use those for trim operations (which is what I
assume you are trying to do ultimately)

Hope that helps!
Daniel

 

Hi, With regards to split-lines, that's how I satred out. But I wanted to
maintain tangency around a closed surface, like a curvey cylinder for want
of a better descrition. You can project from a plane, but as the curve
travells round the curve it does funny things, so it only looks right from
the angle of the projection plane. This is where I'd hoped curve on a
surface would sort me out - oh well. Not ready for use yet by the looks of
things.

You got to wonder what they test these things on! I ran into trouble very
quickly on my model, using the tool as I thought it should be used.

 

Adding more points fails to give you enough control?I know, gets messy
+ is not easy. Alias StudioTools is a little easier to control with
spline on surface, but the ability to set contraints in SW makes it a
tossup which I like better.

What I am pushing for are better controls for adjusting spline points
and weights. From my perspective, much of the problem is that the
spline handles are not constrained to on function at a time. When you
manipulate the handle you are changing weight, direction, and rotation
all at the same time. Nightmare.

If you have models or examples, you should send them in. I have given
several product / problems to the development team. I think that is the
best way to communicate what the real world needs.

Daniel