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Angle Less than One Degree. 4
- Thread starter SDETERS
- Start date
Sorry to be vague regarding the tolerance zone consisting of only four lines on a 2D cross section of a feature. I pulled a slide from training material to better explain what I meant (which I think will indicate that J-P & I are agreeing on this). Please see the attached file.
I'm sure I will rightfully hear about it if I'm incorrect with the assertions I'm making in the file
.
Dean
www.d3w-engineering.com
I'm sure I will rightfully hear about it if I'm incorrect with the assertions I'm making in the file
.Dean
www.d3w-engineering.com
Hi Dean -- thanks for posting the picture. Are you sure you want to say that splitting the tolerance to both sides of the wedge is the only possible depiction?
I'm not disagreeing; I'm just thinking out loud... what if someone tries to arbitrarily call one side of the wedge an implied datum and then tries to scrunch all the angular tolerance onto the other side of the wedge?
I'm not saying that's wise, because a datum can only be made from high-point contact and thus we can't know the form of that "datum" side. But is an angle with a ±tolerance really meant to control form?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
I'm not disagreeing; I'm just thinking out loud... what if someone tries to arbitrarily call one side of the wedge an implied datum and then tries to scrunch all the angular tolerance onto the other side of the wedge?
I'm not saying that's wise, because a datum can only be made from high-point contact and thus we can't know the form of that "datum" side. But is an angle with a ±tolerance really meant to control form?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
Hi Jean-Paul,
I think you could say that someone may try to scrunch all the angular tolerance to one feature & use the other as a reference surface. I don't think they have any standard to back up what they're doing, so maybe that's the same situation as splitting the tolerance equally on both sides.
Since we have no standard to define a tolerance zone for directly toleranced angles I don't think form can be considered controlled this way... I can imaging features which both have horrible form, but with best-fit lines (one for each feature) at a given cross-section having an acceptable angle between them, I think a supplier could declare the feature to be in spec.
I think it's quote odd, in a bad sort of way, that so many drawings have default tolerance blocks with +/- angle tolerances included. These tolerances don't really mean anything, er, I mean, they may mean several things.
Dean
I think you could say that someone may try to scrunch all the angular tolerance to one feature & use the other as a reference surface. I don't think they have any standard to back up what they're doing, so maybe that's the same situation as splitting the tolerance equally on both sides
.Since we have no standard to define a tolerance zone for directly toleranced angles I don't think form can be considered controlled this way... I can imaging features which both have horrible form, but with best-fit lines (one for each feature) at a given cross-section having an acceptable angle between them, I think a supplier could declare the feature to be in spec.
I think it's quote odd, in a bad sort of way, that so many drawings have default tolerance blocks with +/- angle tolerances included. These tolerances don't really mean anything, er, I mean, they may mean several things.
Dean
Wow - As I look back at my last post, those typo/spelling issues seem to be getting me "quote odd" rather than "quite odd", and "imaging" instead of "imagine". Sorry everyone :-\. Too bad a post here can't be edited. Good thing I'm not doing any drawings tonight... That could be ugly
If you red flag the post and let management know the required change, they will sometimes edit for you.
DeanD3W, you make a valid point, but I wonder if you're over stating it a little.
Certainly for critical stuff with angles I tend to use profile and encourage others to do so. However, I'm hesitant to completely throw out +- dims on angles but maybe I'm pandering to the 'GD&T is too complex/costs money' crowd.
DeanD3W, you make a valid point, but I wonder if you're over stating it a little.
Certainly for critical stuff with angles I tend to use profile and encourage others to do so. However, I'm hesitant to completely throw out +- dims on angles but maybe I'm pandering to the 'GD&T is too complex/costs money' crowd.
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