Correct Tetrahedron Location

[gcr6251]

When I dimension the part below for Position, should the tetrahedron be on my ABC Alignment or in the 0-0 location?

mal snip.PNG

[William Johnson]

If you are using Legacy dimensions Yes. if using Exact then no. You just need to define your datums and build the output to match the print.

[KIRBSTER269]

Not sure what "B" is pointing too, but "C" is pointing to that cylinder? If that's the case then "C" would be controlling X and Y, so if that's the case in Xact you need to make sure that's what its doing and B would just be controlling rotation? A should be a Plane and Level, simple enough. If you are using Xact click on Customize and see what it's doing.

[KIRBSTER269]

Yeah just not sure what B is, can't see what it's pointing at Schlag

[gcr6251]

Datum B is the ID of a post. I'm asking this because I had a problem with basics on the drawing being out. Who ever made the 2D drawing picked the wrong location and everything was out by over 2mm. A few other programmers here where I work stated it was out because I had the tetrahedron in the wrong location. After further review, discussions and some research, I believe that aligning to ABC (dia. in X, plane in Y, dia. in Z) was correct. What William Johnson has stated is what I've been doing for years. A few others here where I work, I believe have been doing it incorrectly. My discussions here at work will continue. Thanks!!

[Schlag]

No discussion needed. Feature Control Frame rules all, if the basics are coming from the wrong surface due to a drafting mistake, o well...

[KIRBSTER269]

tenor[1].gif

Still can't see it Schlag

[oddam]

I always use legacy when dimensioning. If you are aligned per your print to ABC, leaving the origin where it is, you do the FCF's, (you are aligned to ABC). The boxed dimensions do not need to be recorded unless requested. If requested, you will move the origin to the 0-0 feature and make sure the origin is in line with the 0-0, you should then dimension the features and your nominal in the proper axis should be the boxed dimension, you can also distance the feature also. Just make sure the origin is squared to the 0-0, you might have to rotate it. Rarely do I have a problem reporting 0-0 dimensions this way.

[Quality ish]

I would align to (0,0).

It's going to give you your true position in relation to the features you're defining as data, regardless of where the trihedron is.

[gcr6251]

Thank you all for your help. Got it figured out. Please see my reply in KIRBSTER269'S POST.