closed datum curve on quilt

[ThomasPhore]

I would like to make a closed datum curve using the option (in "Attributes") of being a curve on a surface rather than a free curve.

However, no matter how I select my curve points, the start and end of the curve are never tangent to one another. In fact, if I try to make any closed curve, it always fails apparently because of the end conditions. If I remove the final point in the curve so it is not closed, I never have any problems generating the curve. However, any curve I create on a surface fails.

In the case of a free curve rather than a curve on a surface, one has "Tangency" options that they can define so as to make the curve a continuous loop. However, the Tangency option is not available while creating a curve on surface.

This is immensely frustrating. Anyone have any suggestions?

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[KevinBradberry]

Thomas,

This post may help a bit.http://communities.ptc.com/message/12976#12976

You can draw a closed sketch (on a flat plane) and then Edit>Project onto a surface to have the sketch fit the contours of that surface. If nothing happens once you choose the sketch and the surface to project onto, its probably because a Direction needs to be defined. I almost always use one of the axes of a coordinate system.

This solution may not work, it depends on your geometry. Can you post images and/or upload the part?

-Kevin

[ThomasPhore]

The surface I am puting the datum curve is too crazy to project anything onto with sufficient accuracy of intent. Here is an example of the kind of surface I am drawing on (first picture). The one I'm drawing on now is very similar but actually more difficult since it is on a larger surface of comparable "curvaceousness". I really need the precision of being able to place datum points on the surface and then have a curve that goes through them. Or at least something that achieves same effect, and I don't believe there is any method that involves projecting sketches that does.

http://communities.ptc.com/message/178703#178703

[KevinBradberry]

In that case, you will need an entity at the end/start point of your curve that you can apply tangency to, such as an axis or a short length of projected curve. I think the axis technique is the least attractive option here. Do you follow my meaning? I can add some images if needed.

-Kevin

[ThomasPhore]

Ok, I used Style to draw a tiny little COS (line on surface in this case) running through my start/end datum point. However, I do not know how to apply tangency now. The "Tangency" option in the main "Curve: Through Points" menu is not available when drawing a curve that is "Quilt/Surface" rather than "Free".

[KevinBradberry]

That's not the case from my side. Tangency is available with Curve Through Points and Quilt/Surface. See in the image the green arc. It's a projected sketch that I've used to define tangecy.

I can't think of why you can't use it. The menu manager options for Tangecy do don't open by default. You will have to click Tangecy and then Define.

-Kevin

[ThomasPhore]

Very interesting. Apprently the problem is that my curve is on a quilt rather than on a "surface" because after seeing your results I tried making curves just made between two points. If both points are on a common "surface" (panel that highlights when in surface selection mode), then when I select the "Attributes" to be Quilt/Surface and choose the surface panel, I get the tangency option as you do. However, with the same curve, if I select the quilt rather than individual panel, I do not get the tangency option.

ARGH!

Is it conceivable it is to make a continuous closed datum curve on a quilt? I tried taking an almost closed curve and splicing it with a COS using Style mode, but that ends of producing other issues...

[KevinBradberry]

Still not the same result I'm getting. My previous image is showing me placing a curve on a quilt with tangency constraints.

At this point the only difference I've seen between our techniques is that you used a Style feature to create a COS for applying tangency and I projected a curve with an endpoint coincident to the datum point that I used as the end/start of my closed datum curve and used it for tangency. I've never had the Style feature available to me so I can't comment on it.

Can you make a recording of the steps you're going through? Go to screenr.com to instantly make on screen videos. You don't have to download anything, in works from the browser.

-Kevin

[ThomasPhore]

Just reporting back to let people know what I ended up doing:

It turned out to be impossible to create a closed curved on a quilt made up of several surfaces. I'm not sure exactly where the line is between software bug and misleading interface design, but anyway, it appears to be impossible to create a closed curve on a quilt. The reason is that the tangency option does not appear for the ends of the curve. Therefore, when you produce a closed curve, you get a discontinuity at the start/end point, which in turn seems to render it unacceptable by proe for rendering a curve on the quilt.

The workaround I used was creating a COS in Style to close an open datum curve on the quilt. In other words, when creating the datum curve, I left out the final point that would make it close, and then instead closed it afterwards by creating a COS in Style.

I hope this gets changed in the next version of ProE! Thanks for all the help!

[KevinBradberry]

Thomas,

You should post this in the new "Ideas" section. You could pratically just copy what you said above and also provide a link to this thread if anyone wants to get further details to make sense of the problem you encountered.