part not square to coordinate system

[[Be...]]

We have a part that has very few planes that can be aligned to.  What is worse is that to fit it in the cmm and measure things it needs to be NOT square to the cmm.  After a few hours, I am still working on the alignment process.  Without too much detail,I have found that the software is not putting points where i click them!  I think that if I can solve the problem if I can figure this out.

I have a plane that is NOT square to the coordinate system.  I need to place a point on that plane.  I click on the model and the point ends up not on the model and not in the location I clicked.  The point ends up around 0.03" off to the side and about 0.01" above the model by eyeball estimation.

I have tried adjusting the view and this does not fix the problem.  I really don't understand how it is picking that location.  It forces the ijk of the point to be square to the coordinate system.  I can manually fix that even though it fights me.  

Is there a thread for people who have fought this kind of thing before?  I came from using Verisurf, Polyworks, and PCDMIS.  None of them had issues with handling parts that were not square to the coordinate system or did not have nice tidy squarish features to work with.  Why is Calypso so bad at this?

[[Ke...]]

Are you able to share an image of the CAD or part?

[[Ma...]]

Are you clicking only point or surface point?

You can also extract plane from model and do points on it - so vectors will be fine

[[Pe...]]

Are you clicking points on a CAD model with the "Define points" option? This defaults to the Touch Point evaluation method (snaps vector to nearest coordinate axis) and rounds your nominals to the "Round-off measure" setting under Extras->Settings->Measurement...

Instead try the "Define a Space Point" option. This will maintain the nominals from the CAD model and set the evaluation method to Space Point, which also uses the correct vector from the CAD.

Edited 5 hours ago

[[Be...]]

Please sign in to view this quote.

Sorry, I cannot share pictures or really much more information.

[[Be...]]

Please sign in to view this quote.

Thank you.  I will try this as soon as I get a free seat.

[[Ma...]]

You could also do a 3d best fit alignment and loop the alignment

 

[[Jo...]]

The active probe is also considered when clicking points on a model. (If your probe is angled, and constrained to the coordinate system of the CMM, your points obviously will have to be too!) 

[[Be...]]

Please sign in to view this quote.

I really don't know the difference between a point and a surface point.

 

As for extracting planes from models, I cannot.  Most of the surfaces are not recognized as a plane by the software.  I can click on multiple points on the CAD model and iterate through

[[Je...]]

Please sign in to view this username.

, hang in there.  Your problem is real, but it's solvable.

My first CMM gig was measuring large machinery that sounds similar to your current challenge.  It's entirely possible to measure parts that are not orthogonally perpendicular to the CMM's coordinate system, including parts without planes and other prismatics.

What Peter and Martin suggested regarding space points vs CAD points should solve your point placement issue.  There are several different types of points in Calypso.  The CAD point option tends to snap points to the CAD entities as though they're magnetic.  Space points should work better here, even though the names sound counterintuitive.

Regarding the alignment challenge, there are two options I would consider:

1. Non-standard alignment options such as best-fitting / RPS (reference point system).  You can use a cluster of points to define your workpiece and constrain degrees of freedom.  This works well on parts without prismatic features like planes, cylinders, etc..

2. Standard alignment with a defined rotational angle from the "Special" menu.  If you can create a standard alignment but just need to define that it will be clocked at a known angle, you can use the special button in the alignment window to rotate the alignment by this angle.

[[Be...]]

Follow up: I got this picture from ZEISS Portal.

 

They make a distinction between the actual normal and the nominal normal.  They then draw two points. It looks like they label the plane point as using the actual normal.  I would assume that they get that from the force direction applied to the probe.  In the text explanation they don't distinguish which of those two normals they are using.  They also don't give the second point a name.  So which normal vector do they use?

 

Further, if I am using a space point, are they really going to project it out into space like that? Will the software really just screw with the measurement and give you no reasonable answer for what trying to measure the point?

 

[[Ma...]]

Please sign in to view this quote.

Ok, so you can create new plane feature and now you can click on model which will make this "not defined yet" plane position and size adjust by your clicked points.

It's not modifying already created planes, but for new it's doing it.

Same for cylinders, spheres and so on.

[[Be...]]

Please sign in to view this quote.

Sounds like you might have some good insights.  I originally tried an rps alignment.  I came to the conclusion that one of the key regions I am taking data in is a problem.  The customer-defined alignment points are mostly on the edges of thin walls, maybe 0.08" thick so the manual alignment has to be pretty tight and the part has to be made to tight tolerances for this to work.  But there are some key points that are out on a curved surface that have a pretty big affect on the alignment and can cause the alignment to rotate if I don't absolutely nail the initial placement of those points. (They are a floating datum target.)  So I tried to create a start alignment that is more practical.  

It is telling me that my basic alignment and start alignment are something like an inch off from each other.  I am not certain how it figures that out so I want to ignore that.  When it goes into CNC mode to take the base alignment, the first four points that it takes are all at one end of the part.  They are almost enough to fully lock down the alignment, but not quite.  They are enough to know if the alignment is grossly out.  All of those points measure just fine.  They are right where they are supposed to be.  But when the CMM goes to the far end it is just off somehow.  it might be off by an inch.  It is hard to say as the machine errors out.  I used "define points" to create most of this stuff, but people are suggesting that I use space points so I will go that route next.  But the more I think about it, I don't think that is enough to account for the issue.