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davehaigh13-Aquamarine
13-Aquamarine
January 21, 2025
Solved

Sketch Arc Inversion Problem

  • January 21, 2025
  • 5 replies
  • 1362 views

Sketch Inversion Problem

 

I need some ideas on how to make this sketch robust so that it will not invert on me.

I know this has been a long-time problem since the beginning of ProE.

I would have thought this would have been solved by now.

 

I’m working on creating a UDF for an arc slot.

I also have a different UDF I’m working on for a pattern of these on a bolt circle pattern

 

On the pattern I had a similar problem if I tried to use the start angle dim as the pattern angle. When I switched to an axis angle, the issue went away.

 

Here is how my sketch is constructed.

davehaigh_0-1737481451539.png

 

 

I’m having an issue with the sketch inverting when I exceed a certain dimension on the start angle.

I know this is a bit extreme for the start angle, but I’m trying to exercise the sketch to make sure it works in all cases.

davehaigh_1-1737481451542.png

 

 

At 126 degrees for the start angle the rounds on the end of the slot invert.

davehaigh_2-1737481451545.png

 

 

However, if the slot angle is increased at some point, it fixes itself and I can increase the start angle up to 140 degrees, but then it inverts again at 141 degrees.

davehaigh_3-1737481451550.png

 

Any ideas on how to make this work in all cases would be much appreciated.

I've opened a case with PTC....

 

Dave Haigh

Special Projects for CAD

Office 925-424-3931

Defense Technologies Engineering Division

Working from Home – Part Time ~8-12 hour per week

davehaigh_4-1737481451551.png

 

Best answer by davehaigh

Thanks to all that had suggestion to solve this problem.

Based on the responses, I think I finally have a handle on what is going on.

 

First, Martin’s solution does work, the only downside is the angle dimensions are not part of the sketch.

Braxton’s sketch also works. I downloaded the sketch and used it in a Creo 10 part.

 

After re-dimensioning it to give me the dimension I want it worked also.

davehaigh_0-1737654243158.png

 

I went back to my Creo 4 part and redefined the sketch. I removed the two construction lines that define the angles and recreated them.

 

My initial sketch only had these lines extending to the center of the slot.

See the highlighted comment below. The blue line I added shows where the construction line ends

davehaigh_1-1737654243164.png

The modified sketch now looks like this:

davehaigh_2-1737654243168.png

The slot now works without inverting.

I prefer this because all the dimensions required for the slot are part of the sketch.

davehaigh_3-1737654243171.png

 

Bottom Line

Here is what I think is happening.

Both solutions presented, controlled both ends of the rounds on the end of the arc.

 

By extending my construction line to the outside of the slot, I’m now controlling both ends of the rounds.

My initial sketch was only controlling one end of the rounds, leading to inversion of the sketch.

 

Dave Haigh

Special Projects for CAD

Office 925-424-3931

Defense Technologies Engineering Division

Working from Home – Part Time ~8-12 hour per week

davehaigh_4-1737654243171.png

 

5 replies

tbraxton
22-Sapphire II
tbraxton22-Sapphire II
22-Sapphire II
January 21, 2025

Watch this video sweeping the start angle through a full 360 deg with full regeneration. Would that resolve the issue you are having? Creo 9 sketch enclosed for reference.

(view in My Videos)

    kdirth
    21-Topaz I
    kdirth21-Topaz I
    21-Topaz I
    January 21, 2025

    My guess is that not using tangency for the ends allows for the flip that you are seeing.  The below sketch behaves well at all angles.

    kdirth_0-1737491077377.png

     

    There is always more to learn.
      tbraxton
      22-Sapphire II
      tbraxton22-Sapphire II
      22-Sapphire II
      January 21, 2025

      In Creo 9.0.8 I am able to get the inversion even with the tangency explicitly constrained in the sketch. Do not see exactly why it is happening. I am dragging the sketch using the mouse and the inversion occurs. In my sketch above I was not able to induce the inversion using the same method.

       

      tbraxton_0-1737492249153.pngtbraxton_1-1737492261961.png

       

       

        tbraxton
        22-Sapphire II
        tbraxton22-Sapphire II
        22-Sapphire II
        January 21, 2025

        @davehaigh 

         

        FYI, I have several open SPRs related to axisymmetric features not regenerating correctly when used in UDFs. Some are well over a year old. If you see problems when creating UDFs, I would like to review it with you as I can get more attention on the issue when I can demonstrate other license holders with the same issues,

          M
          MartinHanak24-Ruby III
          24-Ruby III
          January 22, 2025

          Hi,

          the solution is still the same. You need to use a solution that ensures that the sketch doesn't change.

          I attached part created in Creo 7.0.  I hope you can open it in your Creo.

          C
          Chris321-Topaz I
          21-Topaz I
          January 22, 2025

          Martin's method works. The other way I have done this is to create a equation driven curve (arc) and then used the angular dimension in the curve to drive the sketch.

          D
          davehaigh13-AquamarineAuthorAnswer
          13-Aquamarine
          January 23, 2025

          Thanks to all that had suggestion to solve this problem.

          Based on the responses, I think I finally have a handle on what is going on.

           

          First, Martin’s solution does work, the only downside is the angle dimensions are not part of the sketch.

          Braxton’s sketch also works. I downloaded the sketch and used it in a Creo 10 part.

           

          After re-dimensioning it to give me the dimension I want it worked also.

          davehaigh_0-1737654243158.png

           

          I went back to my Creo 4 part and redefined the sketch. I removed the two construction lines that define the angles and recreated them.

           

          My initial sketch only had these lines extending to the center of the slot.

          See the highlighted comment below. The blue line I added shows where the construction line ends

          davehaigh_1-1737654243164.png

          The modified sketch now looks like this:

          davehaigh_2-1737654243168.png

          The slot now works without inverting.

          I prefer this because all the dimensions required for the slot are part of the sketch.

          davehaigh_3-1737654243171.png

           

          Bottom Line

          Here is what I think is happening.

          Both solutions presented, controlled both ends of the rounds on the end of the arc.

           

          By extending my construction line to the outside of the slot, I’m now controlling both ends of the rounds.

          My initial sketch was only controlling one end of the rounds, leading to inversion of the sketch.

           

          Dave Haigh

          Special Projects for CAD

          Office 925-424-3931

          Defense Technologies Engineering Division

          Working from Home – Part Time ~8-12 hour per week

          davehaigh_4-1737654243171.png

           

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