Scale Model not working 1

[treddie]

Hi.

I was trying to scale a part and Creo goes through the motions, and regens, but the results are unchanged in the end. So I did a test of a simple cube, and the scaling worked fine. The only thing I can conclude is that since my original model has a bunch of relations, Scale Model cannot dig in that deep and change the values inside relations. Is this true?

 

[dgallup]

I believe scale will not change the values in relations.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[treddie]

I can see why, now. For instance, a symbol, like sd47, or d53, would be obviously an angle or a linear dimension and Creo would understand that. However, if the relation had a line that read,

    x = Cos(THETA) + BETA * Sin(THETA)

Creo would understand that the trig functions imply that THETA is an angle, but, BETA is ambiguous in that respect...It could be either.

The rest of this post is purely hypothetical, I suppose:

The only way for Creo to scale linear values in a relation WOULD be if the syntax for applying units was used, as in;

    x = Cos(THETA[deg] + MyScale * Sin(THETA[deg])

where MyScale is implied to be unitless since it has no specified units.

If Creo is allowed to ASSUME unitless parameters when all other parameters have SPECIFIED units applied by the user, then Creo SHOULD have no problem using Scale Model and applying it at the relation level, so long as the user makes sure he/she applied all the units correctly. But that is academic. That would just be a standard programming debug problem.

There IS the following option available for a config file as outlined in the Help system:

   relations_units_sensitive [yes*, no],     Checks for units when solving relations.
     yes—Takes units into account. If units are missing, a warning appears. 
     no—Ignores units.

I have not tried this before, and my first question is, would Creo raise a warning for unitless parameters where required, like for any scalar?

BUT, there is still one caveat, and I do not see how this one could be easily dealt with. ASSUMING the above would even work in principle, Creo still would not understand what order to apply the scaling to the relations. For instance, I have certain "virgin" part files that have numerous relations in them that have default values applied. I wrote a vb program to calculate new values for the parameters and it builds the new relations as text files, when I want to modify those virgin parts for specific uses. I then copy/replace that text into each relation. UNFORTUNATELY, those relations must be modified in a definite order and usually NOT in the order that they occur in the feature tree. Depending on how I modify the virgin part for a particular usage, I sometimes find that I even have to change the usual order by trial and error to get regens to work properly.

So there is really no way for Creo to know what to do in those cases, SOOOOOOOO, it is probably always best that Creo simply leave relations alone when scaling a model. Unless PTC can figure out a way to have those relations modified in any order without regen failures.

 

[mjcole]

The Scale is a feature so all the relations are evaluated first then the scale is performed this should not be causing any issues.

For any equations like your one using unitless you could add parenthesis and the Unit symbol outside of them.
Typically for a model with an angle dim of 30deg a scale of 10 would make it ten times the size but not give a 300deg for the angle

As too relation order there is a sort relations option in Relations dialog that may be used, instead of the trial and ... method.

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[treddie]

Hm, then maybe my assumption WAS right when I thought Creo might hypothetically think that out...I'll try adding units to the parameters and see what happens. Left alone with no explicit units, my relations get ignored during Scale Model.