×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Line Perpendicular to changing curve

Line Perpendicular to changing curve

Line Perpendicular to changing curve

(OP)
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)?

RE: Line Perpendicular to changing curve

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

RE: Line Perpendicular to changing curve

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.

RE: Line Perpendicular to changing curve

(OP)
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...  

RE: Line Perpendicular to changing curve

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.

RE: Line Perpendicular to changing curve

(OP)
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.

RE: Line Perpendicular to changing curve

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
www.industrialdesignhaus.com
Reason trumps all.  And awe trumps reason.

RE: Line Perpendicular to changing curve

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

RE: Line Perpendicular to changing curve

sorry i didn't read ticks reply...

RE: Line Perpendicular to changing curve

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources