Hole pattern position to a plane only

Looking for interpretation of the attached true position call out for a 4-hole pattern. I am not well versed in GD&T but know enough to get myself in trouble.

I've staged the part and aligned with the bottom as -A- (level and origin Z).
I probed and created 4 cylinders, then created circles at the intersections of the cylinders and -A- respectively, then used the circles to create one circle -B- and translated X,Y to -B-.
I probed plane -C- and controlled rotation around Z with plane -C-.

My question is; How is the true position calculated / reported in this case, when there are multiple holes making up one datum in reference to a plane only?

Thanks.

Attached Files

Parents

markoor99 11 months ago

This is a best fit of the 4 holes while staying level to datum A. Are you using Geotol or reporting in legacy? Rotation will be set by the 4 holes. Think about setting the part on the a datum surface, putting 4 bolts in to the holes. At that point you will not be able to rotate the part any more (too a small degree depending on hole size and bolt size. Not even really sure why there is a C datum in this case. But hard to say without seeing an actual part and how it works.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

Reply

markoor99 11 months ago

This is a best fit of the 4 holes while staying level to datum A. Are you using Geotol or reporting in legacy? Rotation will be set by the 4 holes. Think about setting the part on the a datum surface, putting 4 bolts in to the holes. At that point you will not be able to rotate the part any more (too a small degree depending on hole size and bolt size. Not even really sure why there is a C datum in this case. But hard to say without seeing an actual part and how it works.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

Children

No Data