swept geometry exception

[amate2]

Hello everyone,

I've been working on a plugin written in Java, which will be used with UG NX 7.5. This involves, among other things, the creating of a tube based on a centerline. The problem is for some curves, when the tube is to be drawn, an exception is raised, Could not create swept geometry. I succeeded by adjusting the tolerance for the TubeBuilder. My question is: how could I determine what tolerance to specify - as I've noticed, it depends on the specific curve. Any help/pointers-to-docs would be appreciated. Thanks.

 

[cowski]

Is the radius of your tube smaller than the minimum radius of your curves?

www.nxjournaling.com

 

[ewh]

Are there tangency issues?

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[amate2]

Hello cowski,

yes, it is, both for a curve for which it succeeds in drawing the tube and a curve for which it doesn't.

 

[Toost]

Are you able to create this particular sweep interactively ?
Normally you should not play around with the modeling tolerance. If you create very small objects including freeform shape ( surfaces) then adjust the default setting to a proper value. Else leave the default tolerance as is.

Regards,
Tomas

 

[amate2]

Thanks for all your answers/interest.
>> ewh: could not determine any such issues.
>> Tomas: yes, I am able to create it interactively. Actually, this is how I ended up modifying the tolerance (recorded a journal while creating it through the UI commands). I've read previously the same advice in other threads regarding the modeling tolerance (should not modify it...).
Thanks again

 

[cowski]

Can you post a part file example of one where you had to adjust the tolerances?

www.nxjournaling.com

 

[Toost]

And you are able to create the sweep interactively if you modify the tolerance , or without modifying the tolerance ?
If you have to modify the tolerance, i would look to the used objects, is there anything ( some geometry that the sweep will use) that can be done better before the sweep ?
Proper trimmings, proper metods etc.
If you can do it interactively without modifying the tolerance, i would look into how your program selects the geometry, does it use selection rules, does it get the correct end ( direction) of the guide etc.

Regards,
Tomas

 

[amate2]

Sorry for the delayed answers.
>> cowski: in the attached part file, for the Line and Arc objects Tubes (of 3 mm diameter) could be drawn successfully. The problem is with the JoinCurve.
>> Tomas : yes, I can create the sweep without modifying the value of the displayed tolerance. The part files I was working with were only for test purposes, and, most importantly I'm not an engineer by trade, just a software developer. Most certainly the problem will be with the code I'm using to create the swept geometry - that's why I was/am looking for some docs/explanations for the issue.
Thank you for your interest.

 

[cowski]

The original splines don't meet up quite right, this makes the join curve result in an open curve (it appears to be a closed curve, but it has a start and end point if you look carefully). When the tube is created, the faces overlap resulting in invalid geometry.

If the original splines were tangent continuous, there would be no need for the join curve and no problem with the resulting tube feature.

www.nxjournaling.com

 

[amate2]

>>cowski: this means the plugin should go ahead using the default tolerance of the model and signal to the user that there are errors sweeping the curve.
Thanks for your help.