datum reference frame and profile

[DoogieP]

Greetings All,
I hope someone can clarify an ongoing debate on interpretaion of a print.The attached print is a basic representation of an actual part and shows the features in question. As I see the part the datum reference frame is established by A, P3 and P4 since hole P1 has no positional tolerance and notes on the drawings indicate as such. The debate is on the .019 profile of a surface to datum C and how it is referenced to the .002 profile callout and the 5.250 +/-.005. Our Process engineer who also controls our OGP SmartScope says that you cannot have a profile of .019 on datum c because it violates the +/-.005 tolerance. I don't see it this way, the print specifies "dimensioning and tolerancing IAW asme y14.5m-1994. I said it is possible because the 5.250 will move with any deviation of this surface and the 5.250 is a secondary control of form. Our second debate is, he is establishing datum C from the part itself but, I see datum C as being "implied" and should be established using basic dimensions to create theoretical plane because it is there to establish location of the tolerance zone. pleas chime in, any and all feedback is greatly appreciated.

Thanks In Advance,
Doug

 

[DoogieP]

We are meeting with the customer on wednsday. I was talking with someone else about this and they made the statement that use of standards are voluntary in the US but, because my customer has referenced the standard they may be contractually bound to follow this standard. Any input on this statement?

Thanks,
Doug

 

[CheckerHater]

Making good parts from bad drawings is voluntary as well

 

[DoogieP]

I'm just glad the lines of communication are finally open! We have a new executive VP and VP of operations now and are very receptive to people. Where in the past, if you asked for a meeting with the customer the general responce was "No, we don't want them to think we don't know what we are doing". Truth is, we don't, that's why we need to talk to the customer for clarification. The standard is there so there is one interpretation.

 

[Belanger]

Well, you've got to have some standard, so the statement that the "use of standards are voluntary in the US" is not quite right. What does that even mean? Can I put the symbol for infinity in the first compartment of a feature control frame and make up my own interpretation for what that means? Of course not -- unless I reference a standard that I've created on my own and distributed to my suppliers.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

http://www.gdtseminars.com