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Sketch Arc Inversion Problem

davehaigh
13-Aquamarine

Sketch Arc Inversion Problem

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.

 

Iā€™m working on creating a UDF for an arc slot.

I also have a different UDF Iā€™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

 

 

Iā€™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 Iā€™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 ā€“ Part Time ~8-12 hour per week

davehaigh_4-1737481451551.png

 

ACCEPTED SOLUTION

Accepted Solutions
davehaigh
13-Aquamarine
(To: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, Martinā€™s solution does work, the only downside is the angle dimensions are not part of the sketch.

Braxtonā€™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, Iā€™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 ā€“ Part Time ~8-12 hour per week

davehaigh_4-1737654243171.png

 

View solution in original post

7 REPLIES 7
tbraxton
22-Sapphire I
(To:davehaigh)

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.

arc slot.mp4
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      (view in My Videos)

      ========================================
      Involute Development, LLC
      Consulting Engineers
      Specialists in Creo Parametric
      kdirth
      21-Topaz I
      (To:davehaigh)

      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 in Creo.
      tbraxton
      22-Sapphire I
      (To:kdirth)

      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

       

       

      ========================================
      Involute Development, LLC
      Consulting Engineers
      Specialists in Creo Parametric
      tbraxton
      22-Sapphire I
      (To:davehaigh)

      @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,

      ========================================
      Involute Development, LLC
      Consulting Engineers
      Specialists in Creo Parametric

      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.


      Martin HanƔk

      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.

      davehaigh
      13-Aquamarine
      (To: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, Martinā€™s solution does work, the only downside is the angle dimensions are not part of the sketch.

      Braxtonā€™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, Iā€™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 ā€“ Part Time ~8-12 hour per week

      davehaigh_4-1737654243171.png

       

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