Shell Warning question

Just got a warning when using the Shell command - never had this
wording before in 7 years.

However it is the first time I have used a curvature continous fillet
is a part.

Sw2005 sp3

" To allow shell to complete, an internal tolerance has been relaxed.
Downstream operastions that use this shell's geometry may have
problems."

Is this something to worry about ? What tolerance has been relaxed?

The model then rebuilds fine and no further errors even though there
are about 30 features after the shell.

Anyone seen this before.

Regards

Jonathan Stedman

 

Yes seen it often with swoopy stuff. It usually means the shell has a pinch
point somewhere where the new surface struggles to offset sweetly. Rather
than have the shell fail there the geometric conditions have been relaxed to
allow the shell operation to work anyway. Sometimes if you run a section
view through it or use the curvature display you can actually see a warped,
knotted or distorted region. At a guess in your case a nice offset of the
curvature continuous fillet probably cannot be maintained exactly inside
because it is slightly too sharp there after taking the thickness into
account -so what's been created by SW doing it's best, may be thinned or
thickened there or not particularly tangent or smooth. If your mission is
critical you can often perform some surfacing surgery or it for better
results. Do a Ctrl Q on it before you say it rebuilds fine though because
the errors may be not apparent at the moment. HTH
neil

 

Ditto to what Neil said and I'll add this:

1. I have seen this with legacy models. SW has changed the shell
algorithm over the years. It is possibly more stringent now than it
was.

2. In addition to CTRL-Q rebuilds keep Verification with Rebuild turned
on as this is a very stringent test of the geometry.

3. Run the check command often. Found in TOOLS/CHECK

4. Check into what Ed Eaton has written about shelling in his Curvy
Stuff series. Search google to find it.

 

Neil & Paul

Thanks for this - I'll defiantely turn the verification on for this
model.

Jonathan