Unused portion of profile tolerance zone

[Belanger]

Another thing I noticed in the 2018 standard is the graphic on page 264. On this forum we've discussed how having a profile tolerance reference a datum derived from the same surface might make some of the tolerance zone unusable (because the datum plane is created from high-point contact).
But I'm pretty sure they goofed on that picture: It says "Shaded areas show unusable portion of the tolerance zone" -- yet the entire zone is shaded.

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

 

[SeasonLee]

What version of Adobe are you using?

I am using Adobe Acrobat Pro DC Version 2017

Season

 

[3DDave]

I am confident that the printed version proof was closely inspected and that no one gave much thought to reading it off the screen at several resolutions. It seems to be tied to whatever they used to create a synthetic half-tone. It acts as if the half-tone is adaptive but isn't working right.

I'd still like to see the underlying Postscript that was processed to the PDF.

As to document layout I think there was (at least) one sentence that was interrupted by a dozen pages of figures before the last couple of words to end it. They did the same thing in the 1984 version. It was certainly not created as a user document.

 

[SeasonLee]

I am not trying to hijack this thread, but I think its almost the same issue regarding the tolerance applied on the datum features. We are talking about only half of the profile tolerance is applied on the datum feature at Fig. 11-21 for the newly added definition on 2018 version, but please see the figure 11-17 as shown below, why not half of profile tolerance(0.02) is applied here? Thanks for anyone who can help me to understand the differences between them.

Sarson

 

[chez311]

Season,

The 2X 0.04 datumless profile tolerance applies to ONLY the outer 2X surfaces. These surfaces are referenced as datum features A and B in a separate FCF.

The 2X 0.08 profile tolerance wrt |A-B| applies to ONLY the inner 2X surfaces.

The entire profile tolerance zone is available for both, unlike 11-21. For it to be like 11-21 where the tolerance zone is halved, one would have to eliminate one of the profile tolerances shown and instead have 4X profile wrt |A-B| (and the proper associated leader lines). Even then, it would only be halved for the outer 2X surfaces, the full tolerance zone would still be available for the inner 2X surfaces.

Edit: I will conceed there seems to be a poor combination of leader and extension lines, but the 2X on each seems to communicate the intent shown in the "means this" portion.

 

[pmarc]

SeasonLee,

The entire 0.04 wide tolerance zone can be used in this case, because there is no requirement for the zone to by symmetrically disposed about datum feature simulators A and B, because the profile requirement is datumless.

 

[SeasonLee]

Got it. Thanks lot.

Season