Best Approach for Modeling in "Rigged" Space - NX12

[randy64]

Hello all,

I am used to modeling all parts at absolute 0, 0, 0 and then placing the components in their position in an assembly file. At my new job, they want us to model parts that are used one time in their assembly position, or what they call "rigged". If a part is used in more than one place in an assembly, we model it at 0, 0, 0 and then place it in the assembly file.

I've thought of a few different approaches to doing this. The hang up, of course, is if the part is modeled as rigged and then needs to move in the assembly, I must actually move it in the part model, which can get messy. I need to somehow offset the original sketch and then have all other features associated to the original extrude/revolve/whatever so that when the part moves, all of those features will move along with it. Here are a few approaches I've thought of:

1) Locate the original/main sketch an offset distance from the Datum Coordinate System at absolute. If the part needs to move, then I can go into the sketch and update the offset dimensions that locate the sketch.

2) Create 3 planes at an offset distance and use that as my "base" for creating sketches. If the part needs to move, then I can update the offset distance of the appropriate plane.

3) Create a Datum Coordinate System at an offset distance and use that as my "base" for creating sketches. If the part needs to move, then I can update the offset distance of the Datum Coordinate System.

Please give me pros and cons on these solutions, or suggest another approach.

Thanks!

 

[Dave K]

That's why I don't like modeling in "rigged" space.

When I have to do it, if I can't wave link the mating data into my file, I usually go with your option 2. That way I can move the datum planes, as needed. If something changes, that requires an angle change that wasn't accounted for, you can add the necessary datum axis, etc., and then re-associate the primary planes.

-Dave

NX 12, Windchill 11

 

[Toost]

The "rigged" method is an older method which is /was frequent in Automotive and possibly other design offices where many designers co-design.
I think the origin of the method is that cars where designed/layouted in full scale on paper. That paper had a grid. The grid zero was in front of the vehicle . The coordinates for ex the rear bumper were close to the total length of that vehicle.
The designer of the rear bumper measured "his" coordinates off that layout. The original Grid values was included in the drawings for the details and therefore also actually included the placement of that detail in the vehicle.
When CAD started being implemented the method stayed at some companies.
When assembling such components, the individual comp is placed at 0;0;0 in the assembly. All components have 0;0;0 as position.

If I would have to use this method , I would choose #3 as the method and name that Offset Csys something logical.
Moving that Csys should then move everything , which rules out non parametric / Non associative features...
If the position is wrong, there's only one person to blame... ( if it's still 0;0;0)

If the assembly file instead carries the component position, the placement can be parametric,
"anybody" with write permission can move the components which is beneficial for several processes.

Regards,
Tomas



Never try to teach a pig to sing. I wastes your time and it annoys the pig.

 

[JohnRBaker]

Yes, when I was working with the people at GM when they first installed UG (AKA NX), and we were teaching them how to use Assemblies & Components, one of their engineers explained that in their older systems, they modeled in 'rigged' space, and while that had some benefits, it also had some unintended consequences, like ending up with something like 27 different part numbers for gas caps. Note that the aerospace industry was also notorious for modeling in 'rigged' space, only they could generally get away with it since there were less common parts shared between different aircraft, at least in term of the main structure. I think ships used the same approach, but I never spent much time with any of our shipbuilding customers.

John R. Baker, P.E. (ret)
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

 

[jerry1423]

A big disadvantage of the Datum Coordinate System (and therefore your part) being out in space, and maybe being at a strange angle, is that the canned views may not be what you want.
There is a way to create a new VIEW SET based on that new Datum Coordinate System so you won't have the headache of reorienting the drawing view. The existing canned views will still be there but NX will create a new set of views that you can work with.
Here is a previous thread that talks about it.

https://www.eng-tips.com/viewthread.cfm?qid=367850

Jerry J.
UGV5-NX1961