Good afternoon,
How would I go about using Datum A, which is a curved surface to level to? Ais the underside of the part, B is a flat spot on the top side of the part and datum C is a slot on the top of the part.
Sorry but for me you are not right, because in real life curved surface will touch opposite part in 3 highest places, if it is datum A, it will never touch complete surface
FYI - Per ASME Y14.5.1 for Y14.5:2009 and later, you are not correct.
The feature is to be solved by least squares fitting AND then moved to the outside of the actual material envelope, so it might not touch in three places.
Also, you can not do Constrained Least Squares with three points (datum targets for a primary), so unless they are specifically ON the engineering document, your customer CAN complain about your inspection decision -IF- the drawing is invoking ASME Y14.5:2009 or later.
If it is from prior to 2009, you can do what you are suggesting and then get into an arguement with your customer about if you are allowed to decide what the design intent of their print was. You are not allowed to, you are supposed to ask the CDA for guidance, not decide you know best, but you can get in the arguement, and on one hand win, but your customer may put you on the list of suppliers they ween off their ASL.
Or they may, in some weird way, fall in love with you for it. Who knows.
But, post 2009, in ASME, your statement is factually incorrect. Doesn't mean I might not do what you are suggesting, but I would know where I was afoul of the standard if I made such a decision. Having had issues with point distribution in the past with a couple customers, I would likely ask their inspection what they were going to do, so I could do it the same way, right or wrong (wrong here not meaning I believe it could cause harm to humans while in use, I'm not trying to crash a plane because a customer's inspector is silly).
FYI - Per ASME Y14.5.1 for Y14.5:2009 and later, you are not correct.
The feature is to be solved by least squares fitting AND then moved to the outside of the actual material envelope, so it might not touch in three places.
Also, you can not do Constrained Least Squares with three points (datum targets for a primary), so unless they are specifically ON the engineering document, your customer CAN complain about your inspection decision -IF- the drawing is invoking ASME Y14.5:2009 or later.
If it is from prior to 2009, you can do what you are suggesting and then get into an arguement with your customer about if you are allowed to decide what the design intent of their print was. You are not allowed to, you are supposed to ask the CDA for guidance, not decide you know best, but you can get in the arguement, and on one hand win, but your customer may put you on the list of suppliers they ween off their ASL.
Or they may, in some weird way, fall in love with you for it. Who knows.
But, post 2009, in ASME, your statement is factually incorrect. Doesn't mean I might not do what you are suggesting, but I would know where I was afoul of the standard if I made such a decision. Having had issues with point distribution in the past with a couple customers, I would likely ask their inspection what they were going to do, so I could do it the same way, right or wrong (wrong here not meaning I believe it could cause harm to humans while in use, I'm not trying to crash a plane because a customer's inspector is silly).
