Trouble with sweeps and guided curves 1

[robperly]

I am fairly new at SW2003. I have ran thru a couple tutorials, but I cannot figure out how to add the "pierce constraint" so I can use a guided curve in a sweep. Since I am unable to upload a sketch of the problem, here's a brief synopsis...

Ellipse - profile
Line - path
Spline - guide curve

An elipse drawn on the front plane. A single line drawn from the top plane starting at the center of the ellipse, extending 2 units. And finally a spline drawn on the right plane starting at the ellipse edge (coincident) from ellipse point to top of line and looping back down to ellipse edge again (coincident).

The one thing I've learned by browsing the web - its best to draw the profile in a sweep last.

I have tried everything, when Im editig a sketch, and click the relations button, and then click the the ellipse and spline, I am unable to add a pierce relationship. I have searched online help, manuals - nothing really covers pierce constraints.

I hope someone can understand what I'm trying to visualize here, if it helps I'll email you a screen shot of what I'm trying to accomplish.

Thanks,

Rob

 

[CorBlimeyLimey]

The following is taken from the Help section of SW2004. I'm not sure if the same applies to SW2003, I will check tommorrow.

"The Pierce Point relation is not required for sweeps with guide curves. You can use guide curves without specifying a pierce point between the guide curve and the profile sketch. You can also create the guide curves and the profile sketches in any order."

from (the City of) Barrie, Ontario.

OK, so….what's the speed of dark?
faq559-863

 

[robperly]

Thanks for the reply, but I'm fairly certain SW2003 guided curve sweeps requre the pierce constraint.

I continually recieve error messages "that the guide does not contain a pierce constraint"

Does anyone know of a site or publication that would have a step-by-step tutorial on guided curve sweeps? I have seen a few tutorials on sweeps, but they always seem to skip the essential parts I'm looking for...

Thanks again,

Rob

 

[DHALE1]

Rob,

To do what you want you need to draw the guide curve and the path first, then draw the ellipse. when you are in the ellipse sketch, pick one of the four quadrant points of the ellipse and the guide curve and put the pierce relation to that. Also, do not have your guide curve loop back to the elipse. The guide curve should go from the pierce relation of the ellipse to the top of the line. The effect of the guide curve will automatically be mirrored to the other side.

 

[TheTick]

Pierce constraint is a 2D sketch relationship between a point and a curve. The curve must pass through the sketch plane (endpoint contact may suffice). The point must be in the sketch.

If you are trying to govern the ellipse shape by where the guide curve intersects the profile plane, you must sketch a point on the ellipse (constrain point coincident to ellipse) and then add the pierce constraint between the point and guide curve. Make sure the guide curve meets or penetrates the sketch plane. Make sure you are selecting the guide curve itself and not the endpoint of the guide curve.

There are two types of people in the world: the kind that believe that people can be categorized into one of two groups and the kind that don't.

http://www.EsoxRepublic.com

 

[DHALE1]

The elipse already has "points" at the major and minor axis of the ellipse. So, it is not necessary to add a point to the sketch unless the guide curve is on an angled plane. Yes, the tick is right, your guide curve needs to end at the plane where your profile sketch is, and pick the guide curve not the end point of the guide curve.

 

[Theophilus]

To avoid trouble in getting pierce relationships, try this.

Create your path--in this case, your line. You might want to draw two construction lines perpendicular to your path (line) in the direction your guide curve (spline) will be placed. This is for length reference.

Create your guide curve--in this case, your spline. Make sure the ends of your spline are coincident with the perpendicular lines you drew in your path sketch (or that they continue past the lines).

Create your profile--in this case, your elipse. First, you must create the plane on which your profile will be placed. For this, click the end-point of your path (of the line), then click the path itself (line). Add your plane "perpendicular to curve". Sketch your elipse on this plane, piercing the center to your path, and a quadrant point to your guide curve. In pierce constraints, you always constrain a point from your profile to a curve (or line or spline) in a path or guide curve.

Create your sweep feature and point out which element is which, and you should have your form.




Jeff Mowry
Industrial Designhaus, LLC

http://www.industrialdesignhaus.com

 

[robperly]

Thanks Jeff- that was the step by step i was looking for!

It Worked ! Yahoo

 

[JNR]

A actual pierce relationship is not necessary even in SW2003. However, the curve does have to end at the right place - which may end up essentially being the same thing geometrically.

John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics

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