Feature alignment

[[Ju...]]

Hello,

I am trying to change a feature alignment to how it is oriented inside a milling machine. I have my part base alignment and then created a new alignment and assigned it to the feature (a bore). The axis directions and zero points for this are different than original the part alignment.

I am now trying to find the position of the bore based on this new alignment, but when I do the 'Y' position callout, its showing out of spec. When I do the caliper distance, it shows within spec (although that uses the original part alignment).

Am I missing something when doing this second alignment? I haven't really worked with multiple alignments in the past. I could reorient the part on the CMM and change the whole part alignment to match the milling machine, but I think due to length I'm not sure it would fit. I appreciate any help.

New alignment with the Y zero point as the inner plane
'Y' position using this new alignment, showing out of spec
Distance showing within spec using the part alignment

[[Mi...]]

Are you trying to measure the purple plane? Or measure something else relative to it? It's always hard to tell what exactly's going on based on screenshots...

Keep in mind the Y-position callout outputs the y-dimensions of the feature's coordinate system, but I think the caliper distance tries to capture the whole feature. This might explain the discrepancy, if, for instance, the purple plane isn't exactly parallel to your base alignment's Planar Rotation feature.

[[Ow...]]

I think Michael is on the right track regarding the differences and I'm not a big fan of reporting distances off the base alignment but, sometimes it's quicker than applying FCF to everything and not really a big issue if the tolerances are loose enough.
So, if it's not causing any issues other than how it's named, you can just re-name the Y characteristic to X or whatever to show it in the same axis the CNC machining center does it.

[[Ma...]]

Best results would come from caliper distance with change of base alignment ( use your alignment2 ).
If you want same result, but from simple X,Y,Z you must recall feature and select it's alignment as alignment2.

But don't forget, that this approach is reporting only feature origin. For plane only one corner.