NX6 assembly constraints

[dougkeuneke]

Looking at the dependencies window for a component in assembly.....how does one quickly distinquish between contraints used to place that component and constraints referencing that component for other component placement. The dependencies window shows all constraints in the child folder. Seems like placement constraints should be in the Parent folder and reference constraints in the Child folder.

Doug
KSC-ORION

 

[cowski]

There is no spoon...

Assembly constraints are solved simultaneously, all constraints on a given component act to position it.

www.nxjournaling.com

 

[JohnRBaker]

As cowski has alluded, there is NO Parent/Child relationships with Assembly Constraints. They are considered to be peer-to-peer, that is, a constraint is a positional relationship BETWEEN two (and in some cases more) Components. Granted, if one of the Components has a 'Fixed' constraint assigned to it one could say that if another Component is constrained relative to that Component that the 'Fixed' Component would be the 'parent' since it's determining the absolute position of both Components. That being said, I could just as easily remove the 'Fixed' constraint from the first Component and assign it to the other, or have NO 'Fixed' constraints at all.

Prior to Assembly Constraints we used something called Mating Conditions and in that situation the FIRST Component placed was assumed to be 'Fixed' and this could NOT be changed so therefore, for all intents and purposes, you could assume parent/child relationships going from the 'Fixed' Component 'outward' in the tree, but with Assembly Constraints that convention is simply not how it works, but as I said, if you 'Fix' certain Components you could emulate a Parent/Child scheme but it would only be an allusion and the software would not treat these relationships in a way which would provide you with Parent/Child date since, as I said, it doesn't really exist.

John R. Baker, P.E.
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[dougkeuneke]

So in other words, and according to the 1st reply....if I interrogate component A in an assembly and see 9 constraints in the dependency list, I am to assume that all 9 constraints are required to position component A?...hmmmmmm.
Only 3 constraints were used to place component A. The other 6 are placement constraints for components that referenced component A.
I just want to know if there is a quick way to find the original 3 placement constraints without having to check each constraint on the list

Doug
KSC-Orion

 

[JohnRBaker]

I would be inaccurate to assume that all 9 constraints were REQUIRED to locate the Component, just that ALL of them could play a role depending what might happen to some of those constraints. It's like my previous comment about 'Fixing' a component. Obviously that single 'Fix' constraint is all that was needed to 'locate' the component and any other constraint referenced by the Component could be thought of as only controlling the 'location' of the other Components that the constraint(s) referenced. However, if a later date the 'Fixed' constraint is removed the other constraints are just as valid as they ever were and if they happened to reference some other Component that happened to also be 'Fixed', that first Component's 'location' would NOW be dependent on this Component. BTW, having multiple fixed Components even if they share other constraints with each other, is NOT a problem with Assembly Constraints, but it is something that was impossible with Mating Conditions since that would have been seen as a 'circular reference' since the when you 'Fix' a Component it's assumed that you are 'Fixing' it to the 'ground' (hence the symbol used for a 'Fix' constraint) and since there can be, by definition, only ONE 'ground' in a parent/child type of system this would result in a circular reference which cannot be solved. However, when constraints are solved simultaneously without respect to order of creation or hierarchy, there is no problem finding a solution.

Note that starting with NX 8.0 we've added an additional 'Navigator' used just for Assembly Constraints which should help people sort-out relationships since more options are provided to view these constraints, such as listing by Component, or by constraint, or by status, or by level (which helps when you've overridden a constraint at some other level in the Assembly.

Generally speaking, since the introduction of Assembly Constraints we feel that there is less of a need to even worry about what sort of 'relationships' are being created since there is NO Parent/Child worries. You just assign the constraint that makes the most sense to the Components of interest irrespective of when the Component or the constraint was added to the Assembly. The only time one needs to really 'worry' about anything close to this is when you're trying leave desgree-of-freedom in your Assembly so that you can move a Component and have the 'linked' Components move like you're expect them to in reality. In other words, when you creating a mechanism which will have moving parts which depend on other parts, like shafts in a bushing or hinged joints or sliders in a slot or piston in a cylinder.

Anyway, I hope this helps.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
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To an Engineer, the glass is twice as big as it needs to be.

 

[dougkeuneke]

Thanks for the help John. I'm sure UG has all this figured out and it is not my intention to question the functionality....just to understand what happens when I make modifications inside a very complicated assembly created by others no longer around. Time stamped component placement and P/C relationships have always provided me a quick way to get up to speed on the design intent. As I'm sure you know, it's one thing to understand and fix your own designs but quite another to fix somebody else's. I'm definitely not in my comfort zone with UG NX right now.

Regards
Doug
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[cubalibre000]

Hi dougkeuneke,
remember that Siemens PLM programmers or Siemens Product Manager aren't designers like us and they don't understand how much time we spent to interrogate, edit, re-associate Assembly Constraints. This is the fight (opened ER) that I start to NX 7, when Assembly Constraints started to become the only method to mate components between itself.

There is a NX8 video to demonstrate the new 'Assembly Constraints Navigator' where an Siemens employee has some lag time to understand which constraints edit to resolve the constraints conflict.

If we need to edit an assembly made by others colleagues, the time become a lot big.

Thank you...

Using NX 8 and TC9.1

 

[JohnRBaker]

Hence one of the reasons why we developed the NX 8.0 Constraint Navigator in the first place.

And as for the problems encountered when having to rework something that someone else modeled; after a year or two, I sometimes have those same problems with the stuff I modeled ;-)

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[cubalibre000]

John,
edit part modeled bad by colleagues, there is the ST.
For assembly constraints problems, there is the patience, not developed by Siemens employees.

Thank you...

Using NX 8 and TC9.1

 

[JohnRBaker]

Well, if you've got a better idea...

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[eex23]

Thats why we are still on nx7 and using old mating conditions...

 

[cubalibre000]

John,
sometime, better ideas came from competitors.
Another thing that I dislike, are navigators (part, assembly and constraints navigators).
I like Catia, SolidWorks and Pro-E solution.
One tab that contain all.
Solid Edge to.
For a NX user switch to navigators to operate simple operations, it's time loosing.

Thank you...

Using NX 8 and TC9.1

 

[JohnRBaker]

You're not seriously suggesting that we combine the Assembly, Constraint and Part Navigators into a single consolidated 'navigator' are you? What about the Sequence Navigator or the Knowledge Fusion Navigator or the Manufacturing Operations Navigator? Should we include them as well? After all, it would eliminate a bunch of tabs from the Resource Bar.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[cubalibre000]

John,
I'm talking about Assembly, Constraint and Part Navigators only.
This navigators are where users take information and make operations in the most time in the daily work.
This idea is not a new revolutionary idea, but it's used in others CAD, like Catia, SolidWorks.
I can list lot of benefits, if you are interested.

Thank you...

Using NX 8 and TC9.1

 

[JohnRBaker]

If we were interested in combining these three navigators together, then why in the world would we have just introduced the Constraint Navigator as a SEPARATE navigator? Based on feedback from many of our customers we see advanatages in them being dedicated. And if you really wished to see multiple navigators at one time just double-click a navigator tab and it will placed on the desktop in it's own dedicated window. You can have all three of the main navigator open at once, and people who work with multiple screens often do just that.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[ewh]

I find that to be one of the biggest advantages of multiple screens (that, and an Eng-Tips window).;-)

“Know the rules well, so you can break them effectively.”
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