Positional tolerance with annotation
Positional tolerance with annotation
(OP)
What is your opinion I am confused a little. Fastener holes specified with positional tolerance annotated Minor diameter.
I would understood if it will be specified for screw thread typically for drive screw but not for fastener hole.
Perhaps someone direct me to reference doc where it is clarified.
I would understood if it will be specified for screw thread typically for drive screw but not for fastener hole.
Perhaps someone direct me to reference doc where it is clarified.





RE: Positional tolerance with annotation
Normally, MAJOR DIA or MINOR DIA is an easy way to check and the data you measured is rough not precise.
SeasonLee
RE: Positional tolerance with annotation
One reason you might choose 'minor' rather than pitch dia on threaded hole patterns is it can simplify inspection - specifically use of gauges.
Same goes for 'major' on male features.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Positional tolerance with annotation
Burr can be present at profile tips because thread cut is final operation. If position tolerance is critical for fit fastener then better to specify it with project zone or add additional round surface for male and female fastener features. Generally bolt can be used as gauge even if we speak about simplify.
My opinion it is incorrect to specify such annotation and I would reject such drawing. May be someone share other arguments?
RE: Positional tolerance with annotation
Projected tolerance zone is another concept on the threaded parts, normally this is recommended where the perpendicularity of the threaded hole (female part) is important, it will prevent the interference with mating parts.
Of course, there are other factors will cause interference on your assembly, straightness error of the fastener body is one factor, thread to shank runout of the fastener is the other factor will affect assembly.
SeasonLee
RE: Positional tolerance with annotation
Yes there is a hit on accuracy (or is that precision or something) that has to be taken into account with how the position tolerance is specified and the gage made, but it is used.
In fact I was introduced to the concept by a former 14.5 committee member.
I've made use of it, on a piece with a large threaded hole pattern we wanted a gauge to give a quick check if the part was good. It was accepted that some precision would be lost but given that CMM of the part was out due to size limitations & the need to keep it 'clean', it gives a 90% solution.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Positional tolerance with annotation
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Positional tolerance with annotation