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Help with geometric tolerancing
- Thread starter euphnut65
- Start date
More than one way. One way is to first locate it with a basic dimension. Establish your datums. the edge will likely be your secondary or tertiary datum. You can use Positional Tolerance. Since you want to control between 2 planes, do not put the diameter symbol before your total tolerance of .004. This establishes a tolerance zone between 2 planes that are equaldistant about the plane established by the basic dim.
Thanks guys,
Volker, in your 2nd example, is the width of your part 28.2 +0 and -0.4?
Does the symmetry feature frame show symmetry referenced to edge B with a total tolerance of 0.5 (+0.25 and -0.25)?
I have trouble understanding the use of a datum with symmetry or centering because it seems like you would need two datums to reference to, one for each parallel edge or face.
Eric
Hi Eric,
In Volker's example where he uses sym., the datum is the center plane of the feature of size that the datum symbol is on. In the new Y14.5 std the rule for establishing datumes says that when you place the datum anchor directly on the dimension line for a feature of size, then the datum is not the edge but is the center of that feature. For those that did not review the changes when the std was revised, they will easily make this oversite.
For GD&T help. Go to my website and hit the link for Y14.5 Yahoo Users Group. http://candoris.home.comcast.net/page6.html Of course, you can go directly to that site and skip my site.
Hi Eric,
i have not been too happy with the examples i posted before.
The second example is showing a bushing in section view.
Of course there is only shown one direction.
It is the width. Hole is positionned on the centerline.
Centerline is toleranced. (It is exactly what you understood)
In this case the second direction is toleranced by it´s angle.
I have posted a third example right now.
Here the centerpoints are dimensioned using "theoretical dimensions"
(The theoretical "right position" one would say in german)
The tolerance here is discribing the position of the centerpoint.
It has to be into a circle dia. 1mm.
References are the two side surfaces A +B.
Sorry, it`s not to easy for me to explain this in english !
I hope you`ll maybe understand what i am trying to say.
Regards
Volker
Hi Eric,
In Volker's example where he uses sym., the datum is the center plane of the feature of size that the datum symbol is on. In the new Y14.5 std the rule for establishing datums states that when you place the datum anchor directly on the dimension line for a feature of size, then the datum is not the edge but is the center of that feature. For those that did not review the changes when the std was revised, they will easily make this oversite.
For GD&T help. Go to my website and hit the link for Y14.5 Yahoo Users Group. http://candoris.home.comcast.net/page6.html Of course, you can go directly to that site and skip my site.