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Inventor 2010 - Limit component movement when constraining

21 REPLIES 21
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Message 1 of 22
divingdoug
959 Views, 21 Replies

Inventor 2010 - Limit component movement when constraining

Why is it that when you create the first constraint between any two components, the secondary component moves not only to satisfy the constraint, but also in ways that have nothing to do with the constraint.   This is not occasional behavior, it happens every time.

 

I always have to stop and move the secondary component back out of the way to get to the other features I need to reference to continue.

 

Is there ANY way to change this unnecessary and annoying behavior?  It really slows my work down..

21 REPLIES 21
Message 2 of 22
karthur1
in reply to: divingdoug

Tools>Application options >Defer Update.

 

Part will not move until you pick "Update"

Message 3 of 22
divingdoug
in reply to: karthur1

Yea but that stops the movement for aligning the constraint and when I do update, it still performs the other superfluous moves that occur.  And often times, I have found that I have to manuever parts to near what I am looking for as IV will take and perform a major realignment when I apply a constraint.

 

Some weird algorithms going on there for sure.

 

I'm figuring the functions are imbedded way to deep in the code to try and affect any changes

 

Thanks anyway

Message 4 of 22
JDMather
in reply to: divingdoug

I have not seen any unusual/unexpected behavior.

Can you temporarily ground one of the parts?

Can you attach simple assembly that exhibits unusual/unexpected behavior?


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Message 5 of 22
karthur1
in reply to: divingdoug


@divingdoug wrote:

Why is it that when you create the first constraint between any two components, the secondary component moves not only to satisfy the constraint, but also in ways that have nothing to do with the constraint.  


Can you show us a video of this?  Even if the part does move when you place the first constraint, you can still apply other constraints if a surface is in your way.(right click.. Select Other)

Message 6 of 22
divingdoug
in reply to: karthur1

Will try to capture video and post but may be tomorrow.  Even contraining the first part in an assy provides odd behaviors.  I often do not use the IV default grounded positions becasue of my design intent.

 

I may not be able to post models due to confidentiality rules we have.

Message 7 of 22
ampster401
in reply to: divingdoug


@divingdoug wrote:

I often do not use the IV default grounded positions becasue of my design intent.



That could be the cause of it.  Ground at least one part so when you apply constraints nothing moves except the next part you are adding to the assy.

 

I can recall redoing assy files a few times because the very first item that was grounded didn't work out to well for design intent and applying constraints.  I always try to find some suitable "base" or first part file to load into an assy now because of that.

 

Like JD mentioned too, every now and then you'll need to temp ground something in order to work on applying constraints.

Message 8 of 22
JDMather
in reply to: divingdoug


@divingdoug wrote:

  I often do not use the IV default grounded positions becasue of my design intent.

 


I suspect that temporarily grounding a component will be the solution.
I have to do this all the time on assemblies with components with lots of motion (remaining degrees of freedom).


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Message 9 of 22
divingdoug
in reply to: ampster401

It will be a little more clear when I can provide visuals.

Message 10 of 22
divingdoug
in reply to: divingdoug

Here a a really quick example with screen caps.

 

Pics 1, 2, 3  show the first two parts in assy from different view points.  Larger blue part is grounded. Smaller green part is free.

 

Constraint-1.png

 

Constraint-2.png

 

Constraint-3.png

 

 

Pic 4 shows where I make the first selection of a coincident constraint, the axis of the lower barb on the blue part

 

Constraint-4.png

 

Pic 5 shows that I have made the second selection with the axis of one of the boss features on the green part and the green part moves to satisfy the coincident constraint and ALSO moves in manner that has nothing to do with the constraint.

 

Constraint-5.png

 

Pics 6 and 7 simply show other views of the completed constraint.  The axis of the boss on the green part is indeed aligned with the axis of the barb on the blue part.  The green part had to move in the X and Y axis' (Red and Green axis arrows) to satisfy this constraint.

 

It did NOT have to move in the Z axis (Blue axis arrow).  This puts the green part in a position I did  not want it in and is absolutely not required to establish the constraint.

 

To me, this is a bug, as in behavior that is not desired and is contrary to the intent of the command.  This is a simple example but trust me, when it happens EVERY time I use the constrain command, (think assy's with hundreds of components) it is pretty dammed frustrating.

 

I always have to take te time to move the component back where I want it. And if I am wanting to continue creating constraints, it often thinks I am making a selection for the command and I have to stop and restart the constraint command to clear it up.

 

Constraint-6.png

 

Constraint-7.png

 

Pic 8 shows approximately where the part SHOULD have ended up.  The two axis' are aligned but the green part would be in the same Z position it started in.

 

Constraint-8.png

 

 

One mistake, we are actually on Inventor 2012, not 2010 as I thought.  Though I have been experiencing this behavior since it was mandated by corporate that we use Inventor three years ago.

 

 

 

 

Message 11 of 22
ampster401
in reply to: divingdoug

that comes down to what order the constraints were applied.

 

Consider doing the 1st axis constraint then doing what ever other constraint you'd need to keep the position of the smaller piece away from the larger piece, then doing the last axis constraint.

 

I'll admit that may not work for some reason or another but I've grown used to having to back up every now and then and apply a different constraint in order to keep the position of something in an ideal location for applying constraints later on.

 

I'm not too sure what you are seeing would be considered a bug or not.  I get the feeling it's the way it should be.

Message 12 of 22
divingdoug
in reply to: ampster401


@ampster401 wrote:

 

I'm not too sure what you are seeing would be considered a bug or not.  I get the feeling it's the way it should be.


Think in real world terms.  If I simply want to align two sections of piping so I could add a repair joint, I would not want to have to pull the two sections of pipe together then have to separate them again just to obtain the alignment of the pipe's axis.

 

It doesn't really matter what order I generate the constraints in, the behavior is the same, the secondary component always moves in directions not wanted, needed, or required.

 

At this point, I guess I will just concede that it is yet another annoying IV 'feature' that I have to contend with.

Message 13 of 22
JDMather
in reply to: divingdoug

I think you need to think of assembly constraints in terms of removing Degrees of Freedom.

I have never experienced any behavior that defies this logic.

Computers cannot (yet) think - still require operators to do some of the work.

You might check out Fusion 360 (search Google) and sign up here http://beta.autodesk.com

 


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Message 14 of 22
divingdoug
in reply to: divingdoug

Just becasue it is so blatant, here is another example of contraints gone wild.

 

For ref, each component in this assy is created in the orientation to the WCS as shown.  No rotation is required to orient the parts to the positions shown. The way they appear is teh way they dropped into the assy.

 

I want to align the large green part to the planes in the assy itself, not to planes of other parts.  So I start by selecting the right plane in the assy and then the right plane of the large green part.  The planes are very close to being aligned already. 

 

The results are, for lack of a better word, mind numbing. It flips the part 180 degrees and rotates it to some bizzare angle.  Not looking for a response on this any more, just sharing some of the incredibly poor impementation of software code.

 

 

 

Constraint-10.png

 

Constraint-12.png

 

Constraint-11.png

Message 15 of 22
JDMather
in reply to: divingdoug

Can you post dummy files (if you can't post those actual parts) that exhibit this behavior.

 

Are you aware that workplanes have a front side (normal) and a backside.

Are you aware that each side has a different color to signfy front and back.

Does Mate Flush return the desired behavior.

 

This is interesting problem as I have never experienced it myself in more than 10 years of using Inventor.

I am interested in datasets to see if I can reproduce illogic behavior.


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Message 16 of 22
divingdoug
in reply to: JDMather

If I can find time to create some dumb versions of the parts, I will post. May be next week.  No guarantee as I am already behind getting my concepts prepared.

Message 17 of 22
ampster401
in reply to: divingdoug

while you may choose to ignore any other responses to your thread, I'd really pay attention to what JD has to offer concerning this subject.

 

Don't blame the software code just yet...

 

Just saying.

 

 

Message 18 of 22
graemev
in reply to: divingdoug

I've found this functionality to be both handy and annoying in equal measure.  (I'm using IV2013.)  Handy in that it points up as yet unrestrained degrees of freedom, annoying in that I sometimes need to reposition the part to regain free access to select the next feature for constraint.  It would be nice if we were permitted to click-hold-drag parts while using the constraints dialog.   (Hmmm... may have to journey over to the wish list.)

Message 19 of 22
divingdoug
in reply to: ampster401


@ampster401 wrote:

while you may choose to ignore any other responses to your thread, I'd really pay attention to what JD has to offer concerning this subject.

 

Don't blame the software code just yet...

 

Just saying.

 

 


I am not ignorning any of the responses. It just seems that you guys are taking what I condsider to be abnormal if not unpredictable behavior as an acceptable if not desirable way to work.

Any application is supposed to be an extension of the user's intent. Some accomplish this better than others. When the software behaves in a manner inverse to what is desired, and that behavior cannot be altered (settings, etc) then the usefullness of that software is reduced.

 

In working with SW for close to 15 years, I had to hit the forums for help maybe once a year at most. I never had training but because the application was so inutitive and well written, I never had to. It did what I expected all the time, every time.

 

Unfortunately, I cannot say the same about IV.  It is not nearly so inutitive, requires many more clicks to achieve the same results (as SW) and some functions are simply not available. I won't detail my long list of grievances here. Trust me, there are many things I would rather and need to do besides post on this forum..

 

If I get the time, I will post some sample files but based on the responses here, I'm not expecting any breakthroughs.

Message 20 of 22
SBix26
in reply to: divingdoug

In your first example, the results are not unpredictable-- the Z axis movement was to bring your two selection points as close together as the degrees of freedom would allow.  That is, Inventor appears to always bring your selection points together, even if that's not where you want it to end up.  Since you have to select actual part features for most constraints, that means that they almost always end up in close contact.  It's really not too obtrusive to hit Esc, drag a part to sort of where you want it, then hit C to return to constraining.  Oh yeah, and then click the constraint type if it doesn't happen to be Mate/Mate...  OK, it's kind of annoying. 

 

I've gotten used to this behavior, though I do wish that I could opt for "stay as close to your current position as you can" instead of "put my two select points as close together as you can".  But it's not a bug, nor illogical, just a design that doesn't work as effectively as we might like.

Sam B
Inventor 2012 Certified Professional

Please click "Accept as Solution" if this response answers your question.
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