GD&T mathematically defined datum.
GD&T mathematically defined datum.
(OP)
I have a customer defining datums with zero tollerance gd&t.
Is this considered a mathematically defined datum?
Is this type of callout leagal per ASME or ISO standards?
Please see the attached sketch.
Is this considered a mathematically defined datum?
Is this type of callout leagal per ASME or ISO standards?
Please see the attached sketch.





RE: GD&T mathematically defined datum.
Locating a Ø4mm hole with a zero angle tolerance looks wrong to me. The angle tolerance is a run-out specification for a surface.
You should use position to locate a hole. What controls the 50mm dimension between B and C?
RE: GD&T mathematically defined datum.
RE: GD&T mathematically defined datum.
RE: GD&T mathematically defined datum.
1. The way how angularity tolerance is shown on your customer's print is incorrect per the newest editions of ASME and ISO GD&T standards. The leader of perpendicularity feture control frame should not be attached to a centerline, an axis or whatever it is. It has to be associated with a real feature of the part (e.g. surface). At the moment it is really hard to guess which element has to be controlled by this tolerance.
2. Specifying 0 angularity tolerance without (M) or (L) modifier is illegal because it is unrealistic. Such callout implies that at any circumstances there is no space for angularity deviation, so the characteristic has to be perfect. Since there is no perfect manufacturing process, any tolerance (even very very small) has to be specified.
RE: GD&T mathematically defined datum.