Loss of constraints on sketch after close

[llorden4]

I've got a re-occuring issue with losing constraints to projected planes on my sketch, but only with a couple of sketches with my plethra of sketch features.  I've got a rather complex part template to assist with rapid part development with various hole features handled through forms and various iLogic routines that handle feature controls and part numbering/naming structures, among several other tasks.

My re-occurring headache is that I've configured a couple of planes that are used to locate a floating point on a sketch plane that determines a starting point for a work feature being developed (a hole or slot).  The projected planes are correctly displaying but constraints keep falling to the world 0,0 point.  I've attempted to solve this any number of ways and it'll work just fine while I'm in the drawing but as soon as I close and re-open the file it again looses it's association and gets locked to the World 0,0 position again.

I've taken a screen shot showing the projected planes correctly displayed on the sketch planes with a dimension of Zero between the planes and a point and you can see the distance is definitely not zero even though the dimension displays it as zero.  What the heck is going on here and how do I fix it!  I know you'll want the model so I'll attach it.  The feature that always misbehaves can be found on the Forms menu under Face Holes>Rectangular>Pattern 2 tab.

Inventor Pro 2018

[llorden4]

I'm again attempting to re-do the sketch to get it to function correctly and captured a video of the constraint misbehavior so you can have an idea of what I'm fighting.  Here you can see where I create a line and am attempting to constrain the midpoint of the line to the intersection of the two projected planes.  The horizontal plane works fine but the vertical just flies back to World.  Attempting to do do the same with a Point has the same results.  I am not able to create a point at the intersection of the planes, it just doesn't recognize the intersection.

[HermJan.Otterman]

I tried to edit your part,

what I don't understand is the two blue lines. where do they come from?

if they are the projected lines, why don't the line up with the workplanes?

this is what I see (look at my screencast): https://autode.sk/2MeUCXy

[llorden4]

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@HermJan.Otterman wrote:

I tried to edit your part,

what I don't understand is the two blue lines. where do they come from?

if they are the projected lines, why don't the line up with the workplanes?

this is what I see (look at my screencast): https://autode.sk/2MeUCXy

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Those blue lines appear whenever I create a new sketch and they appear to me to represent the World 0,0 axis planes or major Cartesian lines.  What you're video showed is what I expect to see, and usually see but this issue keeps creeping in on me.  I have a gut feeling there's a recovery issue from zero issue that the geometry features are causing confusion with Inventor programming.  So what do I mean by that...   Let's say I draw a line, constrain it to be horizontal with a midpoint at 0,0 and assign the length as a variable.  To start, our length variable equals 5 and for orientation exercise let's call the left end point of the line Side A and the right end point of the line Side B.  If I were to change the variable length to zero and change it again to a non-zero value the line would become a point and then reappear with the new length.  The orientation of the line, however, is random in recovery; sometimes Side A is on the right and sometimes its on the left.  If it's just a simple line it's not big deal, but when it's constrained to other features things get weird.  Creating the slots in this part has been quite the challenge due to this "recovery from zero" issue as we have two parallel lines and two opposing arcs all doing the same recovery and trying to maintain the same relationship.

So back to this issue, I can typically get my shapes restored by recreating this sketch, test my work setting the values to zero with everything working great on several tests, save and close.  Open the file and things start to fail again and the constraints start to act weird again, like in my previous video.  Deleting the previous sketch objects entirely, as you did in your video, tends to provide the best results when attempting to recover from this error, until you save and reload and have to start over again.

Looking back at your video, you should also move shift those work planes off the 0,0 position so that they are not atop the world ucs, which can be done through the Forms dialog box, or from the Parameters menu if you can locate the proper fields from the mountain of variables, or even just manually override the offset values in lieu of the current variables in the constraint.  Doing so might expose those blue lines you see in my video.

[Jon.Dean]

Hi @llorden4,

If I open your BK01.ipt file, I see the Sketch9 feature is suppressed. If I un-suppress it I get an error and then the Bracket Form is displayed. I am most impressed with the design of the form.

I edited Sketch9 like shown in the video and I did not lose any constraints when closing and re-opening the part file.

Cheers.

Jon.

[llorden4]

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@Jon.Dean wrote:

Hi @llorden4,

If I open your BK01.ipt file, I see the Sketch9 feature is suppressed. If I un-suppress it I get an error and then the Bracket Form is displayed. I am most impressed with the design of the form.

I edited Sketch9 like shown in the video and I did not lose any constraints when closing and re-opening the part file.

Cheers.

Jon.

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Glad you liked the form, it has plenty of blood & sweat into it.  The feature suppression is controlled through iLogic, once enough data is provided it would unsuppress and display, likewise with enough loss of data the feature will automatically suppress via iLogic.  Since all features will have a part number placement, a zero value must also be present and handled, the error's typically occur due to a zero length and are handled via suppression or with a driver value in an invisible state to maintain shape relationships.

Since you're unable to duplicate my issue (something I've found very common when reporting bugs) I'm not left with any ideas on how to solve my issue.