Would like to ask, is this dimensio

[lyx111]

Would like to ask, is this dimensioning valid?
this is for dimensioning the distance between the tab and the flat surface.
How is it different from linear dimensioning of 2+/- 0.25?

 

[dgallup]

The 2 needs to be basic (boxed) to use the position callout. I don't see any advantage in this case to using position tolerance over a simple 2+/-0.25.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[Belanger]

Are you using ISO or ASME dimensioning rules? That might make a difference.
Dgallup -- if datum feature A is bumpy, a traditional ± tolerance wouldn't be clear as to where on that left face the measurement would begin. So one minor advantage is that we'd know to take the measurement from a theoretical plane created from the high points along A.

 

[CheckerHater]

To me the object, Position control is applied to, is neither FOS (as in ASME) or plane (as in ISO).

So no, it's not valid at all.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[drawoh]

lyx111,

What are you trying to control?

That right hand piece has a characteristic angle, which is controlled by your dimension, and by the length of the piece. Is that a weld at the top?

--
JHG

 

[lyx111]

The dimension is done by my customer.
And yes, there's a box for dimension 2.0.
The object is a strip metal with a cutout at the center which is bent.
What they are trying to measure is the height of the bent tab.
I'm just curious why they use a positioning tolerance instead of a simple 2+/-0.25.

 

[drawoh]

lyx111,

We are supposed to use GD&T rather than [±][ ]tolerances, except for features of size. Your dimension is a feature of size. Maybe they don't know what they are doing.

--
JHG

 

[amanz]

I'm still learning GD&T, but I don't think this is right? It's not a feature of size? Because that edge is an axis, and I don't think the edge can be considered a feature by itself. Correct me if I'm wrong.

I would have used angularity. The only intent I can see is that the length of the angled side can vary or is not critical, but the height is the main focus.