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Profile tolerance for outer rectangle surface
- Thread starter Sa-Ro
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3DDave, that paragraph 4.1(l) is only where center lines etc. are subsequently "located or defined by basic dimensions..."
So for the OP issue about coaxial holes, even that won't salvage things
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
So for the OP issue about coaxial holes, even that won't salvage things
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
I misquoted.
But same idea: The implied zero rule only applies where "geometric tolerances establish the relationship between the features."
Thus, no dice for his coaxial holes.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
But same idea: The implied zero rule only applies where "geometric tolerances establish the relationship between the features."
Thus, no dice for his coaxial holes.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
- Thread starter
- #26
Not really. It simply means that we can't leave implied coaxial things without some sort of coaxial tolerance. Check out the 2nd and 3rd sentences in paragraph 5.8.3.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
J-P,
First, my reply was about centering the profile around the hole. I am not re-baselining my replies to the OP for distractions by other responders or further unrelated questions and squirrel darting by the OP. It's up to him to keep track.
to which I replied
Second, "geometric tolerances establish the relationship between the features" as the references to [A] appear in his later drawing as well, establishing what is required.
First, my reply was about centering the profile around the hole. I am not re-baselining my replies to the OP for distractions by other responders or further unrelated questions and squirrel darting by the OP. It's up to him to keep track.
to which I replied
Second, "geometric tolerances establish the relationship between the features" as the references to [A] appear in his later drawing as well, establishing what is required.
To no surprise Y14.5-2018 1.4(l) says "For information on applicable tolerances for zero basic dimensions, see para. 5.1.1.4." which deals with angles and not coincidence of axes and planes.
5.1.1.4, on angles, says "For rules regarding implied 90° or 0° basic angles, see paras. 4.1(k) and 4.1(l)." but 4.1(l) doesn't deal with angles.
Seems like a great gotcha question for the GDTP test.
Create better rules rather than these inverted logic constructions. It is derivable that if features do not share a DRF or have a parent-child relation then any random measurement between them has no specified tolerance and should not be inspected. This restriction applies to 0 and 90 angles, but is not specified in (k). Why not?
5.1.1.4, on angles, says "For rules regarding implied 90° or 0° basic angles, see paras. 4.1(k) and 4.1(l)." but 4.1(l) doesn't deal with angles.
Seems like a great gotcha question for the GDTP test.
Create better rules rather than these inverted logic constructions. It is derivable that if features do not share a DRF or have a parent-child relation then any random measurement between them has no specified tolerance and should not be inspected. This restriction applies to 0 and 90 angles, but is not specified in (k). Why not?
This disccussion only indicates that the next version of the standard should eliminate the whole BS of the non-basic implied 0 mm/0 deg/90 deg dimensions "controlled" by the title block +/- tolerances. This stuff still being in the fundamental rules is a disaster.
The fundamental rules allow that for implied 90º angles (j), but not for implied 0 linear relationships. The verbiage in (l) is always in regard to an implied basic dim that has a geometric tolerance.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
B, you should take time and make an effort to educate them, as you have previously suggested should be done. If it is "many folks" I suggest you post a large number of laminated signs on this topic around the workplace and hold weekly brown-bag meetings to help your ignorant co-workers become fully informed.
3D, I actually do some of the things you suggested (laminated signs not included). You should know that it is not a one-company problem though. Misconception of this type are common in the industry, and standards being slow at getting rid of bad practices doesn't help.
![[bigsmile]](/data/assets/smilies/bigsmile.gif "[bigsmile] [bigsmile]")
3D, does your reaction indicate you know otherwise and disagree that it's a common misconception in the industry?
Have you had previous jobs in the field, and are you in contact with co-workers, vendors, customers? For how long? If for long enough, I doubt you never encountered a design engineer who makes drawings and thinks the title block tolerance is good enough to cover for anything "not otherwise specified" including coaxiality variations.
Have you had previous jobs in the field, and are you in contact with co-workers, vendors, customers? For how long? If for long enough, I doubt you never encountered a design engineer who makes drawings and thinks the title block tolerance is good enough to cover for anything "not otherwise specified" including coaxiality variations.
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