refine orientation of an angle with an orientation call out or composite the location?

[ronj100]

Hello,
See the link to the sketch

https://dl.dropboxusercontent.com/u/45474807/New folder/sketch3.jpg

The intent is to locate the start of the angle with a position tolerance.
The the tolerance of the angle can be greater, but its important that the angles perpendicularity is refined to datum B.
My question is if the perp refinement is better done by changing the position frame to a composite frame. Maybe both ways work. Maybe not. What do you think?

 

[CheckerHater]

Ronj100,
Like I already said, GD&T doesn’t like positioning holes much, BUT you can control position of two ends of your hole SEPARATELY. This way the “beginning” of your hole will be held to tighter tolerance, and the “end” to the wider one.
If you are in a possession of standard book(s), it’s shown at Fig. 7-27 in ASME Y14.5-2009. (Not sure about other editions)

 

[pmarc]

The positional control should be applied similarly to what is shown in fig. 7-27 of Y14.5-2009 standard. Then you have to add perpendicularity requirement .0015 to A|B, but this requirement must be shown in a cross-section that is perpendicular to the one you have right now.

 

[pmarc]

Oh, I see I was late.

 

[CheckerHater]

Great minds think alike

 

[ronj100]

No, I only have my ASME 1994 and all my books from Lowell Foster when I took his course over 20 years ago. Been out of the business for many years and just got back into it. I have some really crappy customer prints that I have to work with and I am only slightly better myself at trying to fix them for mfg production. But allot of this is coming back to me as I read my books and this post. So I really appreciate the help.
At least I know a bit more than my customer. Attached is thier print and they make parts for airliners. Go figure.

A snap shot of that 7-27 would be appreciated. Still, I’m guessing that these restraints should have been possible under the old spec.

https://dl.dropboxusercontent.com/u/45474807/New folder/cust print.jpg

 

[pmarc]

Fig. 5-40 in Y14.5M-1994.

 

[CheckerHater]

Basically you specify “surfaces” where position is to be measured.

 

[fsincox]

I have always felt this kind of thing shows our manufacturing oriented bias, that we have not achieved tolerance descriptions based on a purely functional requirement. I do read this as the ultimate direction of the standard, in its intent.
Chances are if it has to be positioned to a reference framework installation it has to be oriented to that same installation and not a completely new and different framework.
Frank