Line Perpendicular to changing curve 1

[Jabberwocky]

Hello all, this may have been asked before but I couldn't find the thread if so.

I have a closed 2D contour, call it a jellybean, I want to get a line to be instantaneously perpendicular to this curve at any given point. This is a very simple task with a circular contour, but when my radius changes (fully continuously (the derivative exists!)) the segment follows the old radius and doesn't follow the contour.

An analogy: if I were watching a car race and wanted to see my favorite car in profile for the entire race, following all the twists and turns. 'offset curve' will give you the position, what gives you the orientation (in sketch mode)?

 

[smcadman]

So you want the profile normal to the path? Is this simply a line your are extruding along a path, such as a ribbon laid out in a jelly bean shape? Is this for an animation?

Flores
SW06 SP4.1

 

[dezignstuff]

Perpendicular in what plane? In the sketch plane? Perpendicular to the sketch plane?

Is this a closed contour made up of several sketch entities? If so, you might try a fit spline. In SW06 you can only get a coincident sketch relation to work between one entity and one other. A cam mate can follow multiple segments, but that probably won't help you.

The fit spline will approximate all the sketch entities (lines and arcs usually) with a single spline, and then you can make a sketch line in the sketch plane that is perpendicular to the spline at any point as you drag it around.

Depending on what you are really trying to do, you may find it more useful to create a ruled surface. If you're trying to set up a sweep, the ruled surface will do what you want much more easily.

 

[Jabberwocky]

Sorry, I wasn't thinking in 3D - I want the line to be perpendicular within the same plane as the 2D contour. It's not for an animation, I could likely kludge something together with clever mates in an assembly, I want to stay within the sketch.


Hmm, I just got it to work on an ellipse and spline - maybe there's a problem with my contour...

 

[TheTick]

SW 2D sketch supports constraining a line perpendicular to a spline. This should be no problem.

When I do this, I draw a line roughly perpendicular to the spline, with one endpoint constrained coincident with the spline. Then select the line (not endpoint) and spline, and the perpendicular constraint is available.

Another workaround is to draw a construction line tangent to the spline with an endpoint coincident to the spline, then draw 2nd line perpendicular to the tangent.

 

[Jabberwocky]

Yes I can get that sketch relation to work on random test splines, but not the one I specifically want. It's got to be a problem with that contour.

Thanks all.

 

[Theophilus]

Sometimes things like that happen if you've trimmed your spline or perhaps converted it as an entity of a shape.

Otherwise, I also use TheTick's method mentioned above.

Jeff Mowry

http://www.industrialdesignhaus.com

Reason trumps all. And awe trumps reason.

 

[nodalDOF]

How about drawing a tangent line at that point and then a line normal to above line? (Both could be added as relations that change with cuve)

nodal

 

[nodalDOF]

sorry i didn't read ticks reply...

 

[TheTick]

One more idea...

Draw a circle and constrain tangent to the spline. Draw a line from the circle center to where the spline and circle touch. Constrain one line endpoints to circle center, constrain other endpoint coincident to circle and also coincident to spline.