vss trouble

[north3]

could someone tell please me why i cannot get this vss to be variable .

i can only get a surface that is constant (which is not what i want)
any help would be appreciated

(wildfire 2)


<a href="uploads/north3/2009-01-13_082334_s_logo2.prt.zip" target="_blank" target="_blank">
</a>2009-01-13_090555_s_logo2.prt.zip
Edited by: north3

 

[tobbo]

did you upload the right part??

i didnt see any VSS...


Anyway, what comes in mind is , in your vss sketch, did you use " create entity from edge" ? Or, is your sketch perhaps "locked" by any dimensions? (like radious..) Use splines in your sketch,then it should work..


//Tobias






Edited by: tobbo

 

[north3]

ive edited to original post ...should have the right file attached now

 

[design-engine]

change one option and your surface preview will follow the path appropriately. There is only one option so don't ask which one.

 

[zpaolo]

I noticed that exchanging origin and chain 1 can solve the problem, if someone has better knowledge to explain this...

 

[tobbo]

i dont really know why...but, if you change "the option" , and then click on the yellow arrow that indicates the sweep direction. (iow, change the startpoint) Then it works...


hmm..strange.



Edited by: tobbo

 

[jeff4136]

I've seen problems like that when an aux traj intersects the section
plane more than once(?). That's not the only probem, though ...





If it's any help ... 2009-01-13_120139_s_logo2a.prt.zip ... (WF2)

 

[jsantangelo]

Have you tried adding a centerline path between the two paths to act as the Origin Trajectory?

 

[dgs]

I think you have a geometry problem, not a Pro|E problem. Your curves are not consistent with one another so a constant section between them isn't possible. Even setting it as variable has issues as the surface folds over on itself trying to maintain normal to one trajectory, as Jeff illustrated above.

A boundary blend may be a better solution here. The center trajectory may hold some promise too.

 

[mstols]

north3,

There is two problems with your model.

First one was under the options flyout in the dashboard. Your model is set to constant section. It cannot be set to constant section with the two trajectories that you made. The distance between them is constantly changing. You need to change the option to variable.



The other problem was with your sketch.
Your sketch was over dimensioned. A dimension limits the sketched entity to a specified size. So if you want the arc to go wider and not go higher, you cannot spcify a radius value, as the radius will have to change due to the changing trajectories.
the sketch below shows how I dimensioned it. Hope it helps

 

[north3]

thanks for your help everyone

jeff; thanks for sending a solution ,it was a great help . is there a reason why you didnt try to do it as one sweep ? also "I've seen problems like that when an aux traj intersects the section plane more than once(?)"
is there a reason why this happens ? i guess the way around it is to start again ....?

thanks again

 

[jeff4136]

> ... intersects the section plane more than once(?).


I can't explain that, just seems to be the reason for failure
sometimes. Seems I've also seen the same with plane / curve
intersection datum points; if there's cause for regen the
point would jump to a different intersection (memory is foggy
though).


That, if it happens, is good reason to break the feature up
and do it as more than one sweep. The other reason is the
self intersecting surface created. I suspect if mstols looks
at his file there will be a Geometry Check. You run the risk
of that happening when the origin traj 'turns into' the aux
traj. You'll note that each of my sweeps keeps the aux traj
on the outside of the bend.
_ _ _





(It did fail on next regen.)

 

[rklatte]

I think there is something else going on here too. In north3's original file, the sketch curves that are used for the VSS are not constrained with any strong dimensions. This isn't necessarily a problem, but I think in this case, the spline curves have some curvature "problems" (for lack of better word, still too early!) that end up affecting the VSS.

In the model Jeff uploaded, the 2 VSS's are based on a different set of sketched curves, which are very similar to the original but slightly different on comparison. The outer curves of the "S" are splines, but the inner, smallers curves are standard arc's. Out of curiousity, I tried to create a single piece VSS based on the revised sketched curves and it did work.

So, I think the original sketched curves need to be tweaked before a single VSS can be used.

 

[jeff4136]

> ... and it did work.


It does work, in that instance, but you still run the risk of
creating a self intersecting (may be the root of the whole
problem?) surface. Just be mindful of Geom Chks.