Perpendicularity

[[Cl...]]

I have a 3.05mm ID diameter x 47.15mm long cylinder, (Datum -B-), that has a perpendicular callout to a plane (Datum -A-) that is 3.0mm x 4.0mm. If I evaluate it as called out, it is o/max. If I reverse the datum's -A-, & -B-, it is in tolerance. I know the parts are good, I verified by other means.

[[Br...]]

If the FCF has Datum feature A as the datum reference, it must be evaluated that way to satisfy the requirement. The problem is probably the drawing. Y14.5 states that datum features that are chosen must be of sufficient size to permit its use. From the sound of it, this is not the case. It will be pretty difficult to hit that tolerance the way its called out. If it's your own drawing I would have a conversation with your engineering department on proper datum feature selection. If not, a phone call to your costumer my be in order. In that case, whoever quoted this drawing should have caught this.

Check out this Tec-Ease video about Datum features being sufficient size.
https://youtu.be/PoWe_ElFgew