Equation editor question

[srjacob]

I am trying to scale a part, and am putting a scale faction in the equation editor (call it SF). I am setting SF to .5 (scaling by half).
The extrusion thickness of my model is (1/SF)*8
The scaling of my model is SF

The equation editor DOES NOT LIKE the (1/SF)*8

Why, and how can I do what I want to do?

Thanks,

Steve

 

[srjacob]

Forgot to mention that the model units are in mm, so everything should be in mm.

 

[DavidJ]

Try (1mm/SF)*8 giving 16mm as the result. Equation editor is very strict about dimensionality.

8mm/SF would give same result.

 

[srjacob]

That worked, but I still don't understand the issue. Here is another example shat should have worked, but didn't.

Steve

 

[HaroldL]

It looks like you have two division symbols, /, in the equation. Delete one and see if that works.

 

[DavidJ]

Dimensionality - both the equation and the value that you might try to apply the result to have to have the same dimensionality.

In Alibre the main thing you have to match is whether the equation represents LENGTH or is DIMENSIONLESS

Extrusion thickness must have dimensions of LENGTH, so the equation trying to set that must also do so. Adding the mm units (or could have used inches) forces the dimensionality to LENGTH.

Angles, scale and count variables are all DIMENSIONLESS.

See last part of this article https://help.alibre.com/articles/#!alibre-help-v26/equation-basics

 

[srjacob]

How do I change the type of parameter from scale to length? I am trying to use the equation SFINV in a hole size dimension, but Alibre doesn't like it.

Here is a screenshot of my equations.

Thanks for your help

Steve

 

[NateLiquidGravity]

How Alibre does equations is a little confusing. But just know it is very strict. So that is a scale with no units. To give it units multiply it by 1mm.

 

[DavidJ]

There must be something to tell the EE that you are working with length - so either use the SFINV with a parameter that is a length OR make sure to include a unit to force dimensions of Length as I did in post #3.

Possible example - NewLength = SFINV * 1mm