flipping arcs

[Anonymous]

I have found what appears to be a bug. Projected arcs on a slot flip. The upper arcs are added manually to projected lines.

Inventor Professional 2017 64 bit Build 233 Release 2017.3

[Mark.Lancaster]

@Anonymous

I deleted your projected information and redid it and had no flipping as your indicated.  I might suggest you create a screencast showing your workflow just in case I missing something that you're doing.   The link to Screencast is in my signature and you must come back to the posting to see my signature/link.

[Anonymous]

My first screencast ... enjoy 

http://autode.sk/2kfmnka

[Mark.Lancaster]

@Anonymous

Thanks for the Screencast.  Based on your workflow I'm seeing the same results but if project the geometry not from the arc surface, it works.  I would have to test so more...

[Anonymous]

If you project the sketch geometry it does not stay linked to the skeleton part.

See this idea http://forums.autodesk.com/t5/inventor-ideas/skeletal-modeling-and-updating-the-assembly/idc-p/68210...

[bob_holland]

@Anonymous

When I open your part I am seeing that the circles are projected.

Since the previously select geometry was removed and new geometry was added but not select, I would expect that we would select the close profile that is shown.

My interpretation is that this is working as designed.

If you think that i am missing something can you provide me with the file with your sketch so that all I need to do is Extrude cut and it will product your results.

Thank you.

[Anonymous]

Sorry Bob I'm having trouble understanding your English. If you're looking for my files I attached them to an earlier post. I think the Screencast is fairly clear as to what the problem is.

[RobSinglehurst]

Hi Bob,
There are definitely a couple of issues going on here. If you project the surfaces from skeleton.ipt (bottom of the assembly browser) into the Assembly level cut extrusion sketch then the arcs flip. Also if you project the actual sketch geometry from skeleton.ipt into the Assembly level cut extrusion sketch then the arcs are correct but the sketch doesn't update if any changes are made to skeleton.ipt.

I'm guessing it's to do with the multiple levels of projection that are going on. I expected to perform a Rebuild All and the projected sketch geometry would update to match the skeleton.ipt sketch geometry - but it doesn't.

[bob_holland]

@Anonymous

What I am looking for is an example that I can send to our developers that all they need to do is extrude and then go back and change the sketch and it fails.

When I delete the extrusion and keep the sketch this is what I see:

I need to prove to our developers that those inside arc were not already there.

If they were already there then this is probably working as designed.

Thank you.

[Curtis_Waguespack]

---

@Anonymous wrote:

What I am looking for is an example ...

---

Hi bob.Holland,

I don't know if this helps, but see this video for how to reproduce the "flipping" arc issue in a sketch. This is unexpected  behavior that users consider a bug.

I would guess the issue being discussed here concerning the extrude is related?

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com

[Anonymous]

Bob I don't think you need to delete the extrusion to demonstrate the problem but if you want to that's fine. You will also need to go into the sketch, delete the arcs and project them again from the surface slot geometry. Create the extrude and that is when they flip. It's just like on the video I made.

[Anonymous]

Curtis, I wouldn't consider what you have demonstrated to be a bug. Those arcs stayed just the same way you drew them, they didn't flip by themselves. I did something last night that was a bit similar to what you have done. I created a square ended arc sketch (like a rectangle but the long sides are concentric arcs) and dragged one end across the other and all hell broke loose. Instead of pulling out the same shape on the other side where I was dragging it to it created the opposite geometry going all the way round the other side of arc, i.e. jumped from 0 to 360 degrees. Now that was what I would consider a bug.

Robin

[Curtis_Waguespack]

---

@Anonymous wrote:

 I wouldn't consider what you have demonstrated to be a bug.

---

Hi 50h9j,

That's why a said: "This is unexpected  behavior that users consider a bug."

A bug would be something that is not working as designed. I think this is working as designed, but not as expected. Most users don't make the distinction, and would consider it a "bug".

Anyway, this issue (the one I showed in the video) is something that users have noticed for years, but I have the impression that Autodesk is not aware of this, or is less aware of this. So I wanted to point it out in case it is related. For instance:  let's imagine that maybe behind the scenes the sketch is getting recalculated in a way that produces the result that I produced manually in the video. In which case knowing about the behavior might shed some light on something???

I don't know that it is related or not related one way or another though.

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com

[Anonymous]

I take your point and didn't mean to denigrate your contribution in any way. My concern was not to confuse irrational behaviour with (possibly) unexpected behaviour, but maybe there is a connection in the underlying sketch engine. I think it is probably more to do with the arc constraints having two solutions and for some reason the sketch is losing track of its correct solution that relates to the projected geometry and preferring an alternate one that does not.

[bob_holland]

@Anonymous

I am sorry about the delay.

I have submitted this to our development staff.

Your issue ID with them is:   173943

I have also created an article regarding this:

http://knowledge.autodesk.com/article/Changing-an-unconstrained-slot-in-Inventor-you-can-end-up-with-what-looks-lie-flipped-arcs

This article should be available tomorrow morning.

Thank you for your patience  while we work to make this a better user experience.