Constraints failing - is this an NX 7 problem?

[imagitec]

This is infuriating. I constantly have constraints - usually between datum features, sometimes between geometric features - go bad. The latest case is a simple assembly:

1 - Top Level Assembly
2 -- Coordinate system created in assembly
2 -- Component inserted into the assembly
3 --- Coordinate system created in component

I have two constraints:

- Touch align between the vertical planes of the coordinate systems
- Align between the horizontal planes of the coordinate systems

That's it. Nothing more.

The constraints were fine when I created them.

I open the assembly now and both constraints have red X's.

I can't work like this. Literally: How am I supposed to do my job? This is a one component assembly.

Is it my fault? Am I missing something blatantly obvious?

Thanks,
Rob

Rob Campbell, PE

 

[JohnRBaker]

If this is a ONE COMPONENT Assembly, what are your Constraining your Component with? After all, Constraints are intended to be used to define the position BETWEEN two or more Components. If you are attempting to define a 'fixed' location for the SINGLE Component why are you not actually using a 'Fix' Constraint?

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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

 

[imagitec]

As illustrated in the simple tree in my original post, the top level assembly has a coordinate system feature. The component also has a coordinate system feature. I am constraining the component in the assembly by constraining its coordinate system planes to the corresponding planes in the assembly model.

Why am I doing this? This particular assembly is an optical system in the early stages of design. The z-axis in the assembly coordinate system represents the optical axis. I am constraining relevant components to this optical axis rather than to each other, so that I may suppress & unsuppress them as required without the remaining components being unconstrained.

It's a fairly common technique in many designs, not just optical.

Thanks,
Rob

Rob Campbell, PE

 

[imagitec]

It also happens between components in an assembly. I was just reducing it to the simplest configuration possible.

We are re-using I-DEAS data as JT files in NX assemblies - the promise of this was one of the reasons for upgrading from I-DEAS to NX instead of, say, I-DEAS to SolidWorks. But it has been anything but seamless.

I first noticed the problem when mating to datums that came along with the JT data (although I swear I've seen it with features, too). So I started creating NX data sets for the corresponding parts & adding NX coordinate systems to them. Same failed result.

Just to get work done, I've started exporting IGES files I-DEAS then importing those directly into an NX model. Seems to work so far (an afternoon), but goodbye any associativity.

Rob Campbell, PE

 

[JohnRBaker]

Are you saving the imported files as NX Part files before attempting to build the Assembly?

Also, I assume that when you say "Coordinate System" that you're referring to a FEATURE, as in a 'Datum Coordinate System', right?

Also, your 3rd step states:

3 --- Coordinate system created in component

Are you actually creating a 'Datum Coordinate System' while working in the context of the Assembly or does it already exist in the detailed part file?

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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