Expressions 2

[John2025]

Hi all,
Coming to NX7.0.0.9 from Ideas. I'm recreating some parameter-based family designs. All went well, but now I'ld like to set limits to the variables I've created. I see a column titled Checks in the Expression window but can't find any info in the Help. Can I use this, or something else, to set limits for the variables?

Thanks,John

 

[edgray]

I have two possible solutions for you.

One is to add a comment that describes the limits. this is not very satisfying but I have found that any and all documentation in a model is good.

The other is to create a named expression for the value and then in the feature that uses the expression use an if statement that causes an error if the value falls outside of the limits. It would be nice if it would report a definable text message at the time of the error but as of NX5 there is no such action.

 

[uwam2ie]

search for check requirements in the help.
or define the feature as udf - there you can define you limits.

 

[John2025]

I've read the help files and tried to use the checks, but it seems that the only thing that happens when I enter a value out of the check range is that a red check shows up on the expressions window. It still uses the value in the model. I would have thought that it wouldn't accept a value out of range.
Adding if,thens to each place the values are used is bit of a pain, but it's probably the right way to do it. Adding more comments is always a good idea, even though it's hard to remember to do in the heat of the battle.
Thanks

 

[JohnRBaker]

If you wish to learn more about Expression Requirements, open the Expression dialog and press the F1 key bringing-up the Context Specific Help for Expressions. Go to near the bottom of the page and there is a short sections on 'Requirements'. In this section there is a link to a document which describes in detail how to use Requirements.

There are capabilities here which will provide what I think it is that you're looking for.

Not that there are other things which can be done, such as embedding IF/THEN/ELSE logic in your Expressions, but I would start with this first since this is the new and preferred tool for this capability.

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.

 

[man2007]

I suggest the use of Part Family in your case.

We use Part Family for almost every part that we create because it is a requirement from our customer.

Ug along with spreadsheet functions make a very good combination.

Our Part Family Spreadsheet contains 3 sheets,
1st sheet contains all the variables, attributes that drive the model.
2nd sheet contains drop down boxes (combo box), that an user can select the values from. In your case it is limits of a variable that you can set. These values should be able to produce a unique Part Number as mentioned on the drawing sheet.
3rd sheet contains the Tables (for example, the limit values of the variables) that connect to the combo boxes of the second sheet.

 

[uwam2ie]

@man2007
sound nice / can you provide an example?
thx

 

[man2007]

I have attached an example file and a presentation. Looks complicated at first but is very good method to follow.

 

[uwam2ie]

thx
I will try it,
do you also have exprience with partfamilies based assemblies?
thx

 

[man2007]

Yes, we have created part families of assemblies, typically using - Suppressing a component by expression.

And also creating detailing in the same file (the one which contains Part Family), gives drafting file of each Part Family member. This method typically uses Edit->Suppress drafting object... to suppress dimensions, centerlines etc. by expression.