General Alignment / Symmetry use

[[Jo...]]

 

Hello,

See basic crude sketch. No so much a Calypso question but a correct alignment strategy. If you had a part dimensioned like this (with some depth), would you, based on how the holes are dimensioned from center of part, Level on A and then create two SYMMETRY planes from B & C to create a center zero or Level on A, measure B and C and offset B (10) and C(25) in your base alignment to create your center. Thanks!

[[Ha...]]

choose the first option
Your datums are "plane A",  "symmetry-plane B" and "symmetry-plane C"
 

Edited Monday at 04:59 AM
If the "ISO-GPS-System" was called

[[He...]]

If the reference symbol for B and C isn't on the measurement but on the side next to it, it only applies to that side. I would choose the second option.

[[Ma...]]

If it's like this, then it would be better to contact customer/drawing engineer to consult what was meant.

It's wrong completely. If was meant symmetry, then datums are placed wrong. If was meant as features/planes, then it's missing dimensions from those datums.

Edited Monday at 07:46 AM

[[Jo...]]

 

I've updated the sketch to match closer what I'm seeing if it changes anything regarding alignment. Thanks

[[Jo...]]

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I fixed the sketch to show what I'm seeing if it makes a difference. Thanks!

[[Ma...]]

This corrected drawing applies symmetry for datums B and C.

You have there surface profile allaround from center +/- 0.015

[[Jo...]]

True positions require measuring from the datums, with the nominal as the distance from the datums.   (which are center planes in your latest revision. The position of the leader arrow relative to the line determines if its a center plane) 

Id also like to point out that you can align based on any features you would like, as long as your true positions calculate from the correct datums. Calypso will work all this out for you if you use the GDT feature.