Plane to Plane distance, just Mesh and no Nominal CAD

[[Ch...]]

First off, I'm kind of a newb and dummy with the GOM software still.   What inspection functions do I use to evaluate the plane to plane distance, in relation to a datum structure?  I'm just trying to figure out best practices for evaluating with no nominal CAD model.  

 

While I'm at it, can anyone explain to me the difference between a Local Coordinate System vs a Datum System?   Why are these two different things and where to I use them?   

Doing evaluations with no nominal CAD model, do I need to covert Mesh to CAD?

 

And for my Calypso folks, does anyone else add an STL machine tab and just do their evaluations in Calypso?   See attached.   

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Edited 4 hours ago

[[Jo...]]

Hi Chad,

plane to plane:

 

Global Datum system vs local coordinate system:

I never thought to much about this honestly, but this is how i use it and it works: Global Datum system is for aligning the mesh to the cad and the local coordenate systems are for gd&t stuff.

 

You can evaluate a mesh without a CAD. Of course with some limitations.

https://www.youtube.com/watch?v=Dt3O6q0dNRc&t=187s

[[Ma...]]

Well - in Inspect you can measure distance of planes only if they are opposing via symmetry plane and GD&T independant.

But for measuring distance as depth i am using kartesian method.
I use selected points on model via Fitted point, right click on nominal plane and select restore points. This will make center point from plane ( honestly i don't know how to obtain exact center of any plane )

Now measure projected distance. Just report ordinary distance without axis definition.

Now the hard part of a question.

If you don't have a cad model, then you have to make your elements via selection on mesh - this will create actual element. Now just show i-Inspect -> Dimensions -> Copy as nominal element.

Now this way you can make alignment. In treeview you can right click on that alignment system and select "Use as Local alignment" - it will correct XYZ cube on left bottom corner.

And if you want you can now make nominal elements with drawing exact dimensions - but instead selecting fitting element you can use existing actual element ( "link existing ... element" )

[[Ri...]]

I would not follow the instructions of that YouTube video for a Plane to Plane distance. The Projected Point Distance is incorrectly built as the Point being reference is not an actual measured point/value (you can see this by looking at the funny looking man ) In addition, if you open up the actual distance that is created, you will see that it is not referencing the actual Plane. 

 

For a standard Plane to Plane, you would utilize the Linear Distance tool, and then select the two surfaces (this would be similar to constructing a Symmetry Plane inside of Calypso - great for the ability to measure the Envelope condition, and also be used for MMC/LMC if needed) . Unfortunately this will not work if the Planes face the same direction (step heights). In those cases, you would most likely use the Project Point Distance, but for one of the Planes, you will need to either just measure that surface as a Point, or a Fitting Point (average of the entire surface). 

 

LCS is essentially like creating an alignment inside of Calypso, and these are very useful if you need the nominal location to change to where that new coordinate system would be located/oriented. Datum Systems are what you will need to construct for any GD&T. Both LCS and Datum Systems can be used for global alignments (Main Alignments - By Coordinate Systems) - great for viewing Surface Comparisons to datum alignments. 

 

No you do not need to convert the mesh to a cad to perform evaluations without a model. Instead of defining nominal geometry, you just hop straight into things like the fitting element. So say for a Plane, you wouldn't use Construct - Plane - Auto Plane; you would use Construct - Plane - Fitting Plane.

 

As for the Calypso questions, yes, but very rarely anymore. It's great if I have a legacy program written in Calypso, and I haven't re-wrote it inside of Inspect (or also great for testing correlation between the two). 

[[Na...]]

One more link from our side 🙂

How to Evaluate the Distance Between Planes?

[[Ch...]]

I'm in business now gentlemen.   The tips in this thread really got me going on way more than just planes.  All was very much appreciated.   Matching my cmm and granite checks.