nx constraints in assembly

[rahul683]

hi am new user of nx.i am using nx 9.
how to decide most suitable constraints in an assembly so that no error (over constraints,or any other) should come while constraining a part.

 

[IvanNX]

experience.

 

[DonNX]

As Ivan said, experience...

I would suggest that you use the minimum number of constraints possible to achieve the required result.
For instance, I never lock the rotation on a washer as it doesn't have any effect on the finished result.


Remember that good judgement comes from experience & experience comes from bad judgement...

 

[IvanNX]

Remember that good judgement comes from experience & experience comes from bad judgement...

This!

For instance, I never lock the rotation on a washer as it doesn't have any effect on the finished result.

NX10 has nice Align/Lock new constrain for that. It gives clean fully constrained model.

 

[DonNX]

True isn't it Ivan?

My point was just that you should use the minimum constraints that will get the job done.
Also that you must bear in mind that you might want to have some flexibility at a later stage.

 

[IvanNX]

It is true Don.

And Rahul, keep in mind that some of them will become broken, for sure on large assemblies. And that you will have to repair some of them. So make them in manner that allow you to inspect your model easy and to find problems easy.
And try to make them to resemble real world priorities.

So keep it clean, simple, predictable, and you will have control over your model. And every time you make a mess, learn from it.

 

[MFDO]

NX is kind of rigid and doesn’t support the user much by filtering possible conditions at that specific moment/selections. Probably you must have experienced how user-friendly other software is. As IvanNX said above “Experience” is what NX’s relying on and therefore the learning curve is long.

Also I feel that Constrain Manager is still at a very basic development stage. Adding constrains to design are prone to create errors soon or later, and probably that is why users try to avoid them.


Michael Fernando (CSWE)

http://www.solidCADworks.com

Tool and Die Designer
Siemens NX V10.0 + PDW
SWX 2013 SP3.0 X64
PDMWorks 2013
Logopress3
FastForm Advance
FormatWorks

 

[ewh]

Yes, assembly constraints can get complex in larger assemblies and are far from perfect. NX documentation leaves much to be desired in showing how to use them effectively in situations other than simple assemblies.

However, users who avoid constraints are not getting the self-education needed to use them effectively. I have had many hours of frustration creating moderately complex sequence layouts (for example one important lesson I learned the hard way is to avoid the concentricity constraint - I have found that it is very unstable in many situations, especially if your components are subject to any kind of modeling change. The only situation I feel I can confidently use it is when constraining hardware such as a washer to a nut or bolt), and am happy to say that most problems I now come up against can be figured out without too much grief. Creating such sequence layouts (which include 7-10 separate arrangements per layout) without using constraints may be possible, but would be a nightmare without very good file organization (keeping in mind future users who may need to modify the file).

There is much to be said for being able to change constraints (a few or many) and have the assembly update as expected, and as noted the best way to get there is the same as the best way to get to Carnegie Hall - practice, practice, practice. ;-)

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

 

[Xwheelguy]

We make entire exhaust systems from manifold to tailpipe and use 0 constraints. We will, however, use Move by Constraints, which disappear once the component has been moved to the desired position. Most users here can't manage them properly for the assembly constraints to be effective.

Tim Flater
NX Designer
NX 9.0.3.4 Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[MFDO]

Since nobody is using Assembly Constrains, I’m too reluctantly leave my components unconstrained in space hoping that no-one will move them unintentionally.

It’s a big risk, but it seems to be the traditional way to work in NX. I heard that sometime ago Constrains were known as Mates and when you open old designs there is a pop up window asking if it should convert the old Mates to Constrains.


Michael Fernando (CSWE)

http://www.solidCADworks.com

Tool and Die Designer
Siemens NX V10.0 + PDW
SWX 2013 SP3.0 X64
PDMWorks 2013
Logopress3
FastForm Advance
FormatWorks

 

[ewh]

Constraints may be overkill in a static design. In a dynamic design, where components move about and clearances are critical during that movement, constraints can be a very important tool.

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

 

[JohnRBaker]

I would hardly say that "nobody is using Assembly Constraints". The relationship, be it static or dynamic, between Components of an Assembly is as much 'design intent' as is the shape or size of a part model.

John R. Baker, P.E.
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[cowski]

I’m too reluctantly leave my components unconstrained in space hoping that no-one will move them unintentionally.

It's really not as big a risk as you seem to think; in NX it is not so easy to "accidentally" move a component. To move a component you must start the "move component" command or the assembly constraint command. It's not like you can click and drag on a component and accidentally move it.

www.nxjournaling.com

 

[rahul683]

dear all,
thank you for valuable comments.

regards,
rahul

 

[DonNX]

We have a rule in my company that ALL components will be fully constrained even if it is with a "Fix" constraint.

We've had instances where large assemblies fly apart due to components not being locked in place.

Also its impossible to run animations on for instance a door mechanism if the assemblies aren't constrained properly.


Constraints become second nature after a while, always remember to check the type of constraint you're using as well as it's orientation.

 

[IvanNX]

I see people have a problem with broken constrains on part edit. To solve this or to be able to make elegant part family of some not so family friendly parts, like kind of different design but same purpose, same placement parts you can try this solution.
At end of part design, make a points and/or vectors and/or planes on places of features you will use to constrain your part in assembly.
Make them non associative.
Move them right below Datum Coordinate System (0) and Point (1) in Part Navigator.
In assembly use them to constrain your part.
Now if you have to edit design it will stay in place no matter what you do. If you want to make family parts from it, just use save as and edit or make new model without deleting point/vectors/planes you made to constrain model and you will be able to replace component without problems with working constrains.
If you like you can use Remember Constrains for this kind of part which make it much easier to reuse them in other assemblies.

Main issue you can have with this is that if you mess your model and you do not move (Menu>Edit>Move object) your constraining features to new correct positions, you can end with reasonable assembly mess, but with no broken constrains