Looking for strategies measuring a difficult part.

[[Da...]]

Here's the part: 

Sorry about the extensive editing; new corporate rules about sharing of customer prints.

So, Datum A is a plane created from the flat collars of 4 bushings sitting proud of the surface; 2 of them are .095" wide on each edge, and 2 are .039" wide on each edge, in the Z+ surface.

Datum B is also a plane, created by the .095" wide collar edge on 2 separate bushings on the Y+ surface

Datum C is the diameter of the upper bushing on Datum B.

 

My base alignment, all with a 1mm probe tip:

8 points on datumA, 3 on each of the larger collar flanges, and on on each of the smaller flanges.

6 points on datumB; 3 on each of the collar flanges.

4 points for the circle of datumC

 

My DCC alignment, all with a 3mm probe tip:

14 points on datumA; 4 on each larger flange collar, 3 on each smaller flange collar

8 points datumB; 4 on each flange collar

50 points datumC (profile measurement), "circle in cylinder"

 

Then program measures (with 3mm probe tip), all profile measurements:

Position of bushing below datumC

Perpendicularity of both datumC bushing, as well as the one below

Positions of all the circles of the bushings in datumA

 

My issues:

DCC measurement of datumA has difficulty staying on the tops of the bushing flange collars, probably skewing the datum level.

As a result (or maybe not?), positions of all these holes are out. Things on the B datum are good, though.

 

What I was wondering is some way of centering each planar measurements for DatumA in particular, perhaps using an interim alignment of diagonal holes in the pattern to the base alignment plane? Or, is there some way to not only center each planar surface on each bushing, then consolidate them into a "greater datumA"?

Frankly, I'm betting that this weird datum setup is, has, and never will achieve what the print is asking for, nor would anybody at the customer be able to get an accurate measure either. But, new CMM, and so CMM program is to be made.

No rush on this one; I still have some dubious results from a manual check done by in-process inspector that I can go with.

Bushings pictured below. Yeah, I know....

[[To...]]

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  I'll address one issue regarding the scan paths on the planes.  I often use a Circle Path strategy for planes like these and use a formula for the location from the circle in the middle.

[[Da...]]

OK, I know where that is. Due to frequent drips of epoxy, I'll use single points rather than "profile". Is there a method to take the circle first (without taking dimensions) solely as a centering strategy for each plane? DMIS used to have a feature like that. For those flanges that are all of 1mm wide, I need to center it EXACTLY. I suppose I could take each circle and create an alignment just for that, but "ain't nobody got time fo' THAT!"

Also, I seem to have forgotten the method to combine multiple features into a single (in this case, 4 planes into a single plane); my machine sits for 6 weeks at a time, just for me to make one single program, then it sits again. Each time I turn it on I need to refer to my notes and booklets...

Edited June 30

[[Ma...]]

I would use a simple plane - not connected to measured one to obtain base alignment.

It would be nice to set all circle strategies in one plane and machine would obtain point for circular path then run circle then jump to another one.
In reality it can run points first, then circles. But i am not sure - not tested.

After this you can create alignment and run all other features from this alignment.

[[Da...]]

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Edited June 30

[[Ri...]]

To expand on what Tom said, the way Calypso behaves is that if you have a formula inside of a feature that is pulling information from another feature, Calypso will always measure the referenced feature first to gather the correct information. So there is no need for individual alignments for each hole. I would have a Circle for each hole, then in the Circle on a Plane strategy inside of the Plane, I'd pull the X,Y (or whatever space axis you are in) coordinates, as well as the diameter - for the diameter I would offset it a a specific amount from the true diameter of the circle. 

If you do this correctly, Calypso will measure the Circle before it measures the Plane, and then there will be no need for secondary alignments.