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Associative datum-csys - controlled by expression?

Valued Contributor
Valued Contributor

Because it appears that the Helix command needs to reference a CSYS - I have tried to create a CSYS that is offset from the Absolute CSYS (in the Z direction). This works fine - but I want the offset position of the new CSYS to be controlled by an expression. I can enter the expression name in the X,Y,Z dialog - but if I change the expression value the newer CSYS does not relocate. If I go back later to edit the newer CSYS - the expression name that I entered earlier has been replaced by a constant value (which does not change as the expression value changes). I may be interpreting the function of the "Associative" check-box incorrectly.

 

What is the best-practice for associatively controlling Datum-CSYS's locations relative to the Absolute CSYS (either translationally or rotationally) ?

 

Thanks!

Steve A.

 

offsetCSYS.jpg

SteveA
DRT Mfg. Co. Inc.
www.drtusa.com
Win7x64 NX8.5.3.3
3 REPLIES

Re: Associative datum-csys - controlled by expression?

Siemens Phenom Siemens Phenom
Siemens Phenom

Attached is an example part (created in NX 8.5) which allows you to parametrically control the location AND the orientation of the Helix curve.  Simply edit any of the six Expressions (three controlling the X,Y,Z location while the other three controls the I,J,K vector direction of the CSYS) which you'll find in the expression editor.  This was done by first creating a second CSYS relative to the original one using the 'Datum CSYS' option titled 'Offset CSYS', with the 'Associative' option toggled ON.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA

Re: Associative datum-csys - controlled by expression?

Valued Contributor
Valued Contributor

** EDIT TO EARLIER POST **

 

I see that you did name the creation method and settings that you used (I read your reply too quickly).

 

Using Edit with rollback - I was able to see which CSYS creation method that you used  ...

 

CSYS-Creation-Dialog.jpg

------------

 

Thanks John,

 

This is what I was trying to do. Which CSYS creation option did you use? As you can see - when I chose the "Dynamic" option an "Associative" checkbox is present - but seemed to not result in an associative result (I believe that I may be misinterpreting the use of the associative checkbox in this context).

 

 

*** Can you tell me which CSYS creation option that you used (and/or provide a screen-shot) of the dialog used to create your example CSYS? ***

 

As an aside - I sometimes wonder why, in NX, when a value is being requested an expression cannot always be used to supply the value. I can usually tell when this is not going to work because, as I begin to type the first few characters of an existing expression name into a value input field, the auto-completion functionality isn't active.

 

Thanks!

Steve A.

SteveA
DRT Mfg. Co. Inc.
www.drtusa.com
Win7x64 NX8.5.3.3

Re: Associative datum-csys - controlled by expression?

Siemens Phenom Siemens Phenom
Siemens Phenom

The easiest way to spot which entry fields will accept an expression name and which one will not is to look for example at the image of the dialog that you posted.  The fields with the units and the downward-pointing arrowhead or what we refer to as 'Design Intent' entries and in those cases you can use many different schemes to define the value of the parameter including using an expression.  You can see the options available to you by simply clicking on that downward-pointing arrowhead and you'll see the list.  The use of any of those will create an associative relationship or feature-based parameter.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA