I tried to create the FCF shown on the print using the Xactmeasure true position, but I had a error message pop up. So I'm just looking for someone to confirm that the print has Bad GDnT.
I tried to create the FCF shown on the print using the Xactmeasure true position, but I had a error message pop up. So I'm just looking for someone to confirm that the print has Bad GDnT.
ASME Y14.5 2009, section 7.5.1 (b) (3) discusses the 2nd tier/lower frame of the composite position dimension, which they call the 'Feature Relating Tolerance Zone Framework' or FRTZF.
""Where datum feature references are specified, one or more of the datum feature references specified in the upper frame are repeated, as applicable, and in the same order of precedence, to constrain rotation of the FRTZF."
So, this is instructions on Doing It Right. The writing style of this standard does not include examples of Doing It Wrong for each and every thing, because that would turn a 214 page document into a 200,014 page document - instead they just assume that people will do it right as written and shown. Unfortunately some designers tend to think that it's like a motorsports rulebook: if it's not explicitly declared Wrong it must be OK, right? Nope. The verbiage states that the datum features are repeated in the same order of precedence. Slapping a different datum in there is wrong.
As noted, your only recourse is to make that 2nd tier a completely separate dimension.
hopefully Josh finds this thread and can shed some light.
I would have never seen it if you had not alerted me to it, thank you. I really should patrol this section more often.
I tried to create the FCF shown on the print using the Xactmeasure true position, but I had a error message pop up. So I'm just looking for someone to confirm that the print has Bad GDnT.
ASME Y14.5 2009, section 7.5.1 (b) (3) discusses the 2nd tier/lower frame of the composite position dimension, which they call the 'Feature Relating Tolerance Zone Framework' or FRTZF.
""Where datum feature references are specified, one or more of the datum feature references specified in the upper frame are repeated, as applicable, and in the same order of precedence, to constrain rotation of the FRTZF."
So, this is instructions on Doing It Right. The writing style of this standard does not include examples of Doing It Wrong for each and every thing, because that would turn a 214 page document into a 200,014 page document - instead they just assume that people will do it right as written and shown. Unfortunately some designers tend to think that it's like a motorsports rulebook: if it's not explicitly declared Wrong it must be OK, right? Nope. The verbiage states that the datum features are repeated in the same order of precedence. Slapping a different datum in there is wrong.
As noted, your only recourse is to make that 2nd tier a completely separate dimension.
hopefully Josh finds this thread and can shed some light.
I would have never seen it if you had not alerted me to it, thank you. I really should patrol this section more often.
