Thickness GD&T 3

[Enrico Urru]

Hi everyone,

What control should I add to have a thickness of 4mm?
Is the flatness control good enough to keep it close to 4 mm?

 

[3DDave]

Since the thickness is basic, and there is no tolerance on thickness that might be a problem.

If you want to control thickness either use a directly toleranced size dimension or keep the basic dimension of thickness and use a profile tolerance on both faces.

 

[greenimi]

...and use a profile tolerance on both faces.

Why on both faces and not only on the face where parallelism is applied to?

Highly unlikely the drawing is correct (which I know it is not part of the OP's inquiry). Datum feature B is questionable at best.

 

[Enrico Urru]

Hi Greenimi,

Thank you for your feedback. What is wrong about datum B?

 

[greenimi]

Datum feature B being the outside radii does not seem very repeatable and I am not sure it is functionable too.
I understood that you want to qualify where the holes are, but why relating them to the outside radii?
Could you, please, describe how this part functions and what is its design intent?

 

[Enrico Urru]

The design intent is to fasten 2 extra components to the threaded holes.
They need to be perpendicular to the top and bottom faces of the component.

 

[greenimi]

In that case I would chose one threaded hole (the bottom hole in your latest posting) as a datum feature B and control the other one (the top hole) with position to A|B(M)|. The outside surface I would control it with all around profile to A|B(M)| within a relativelly big tolerance
Is this ASME or ISO drawing?

 

[SDETERS]

Are you using a standard sheet metal gauge, or stock as is without extra machining? What kind of tolerance do you need?

 

[Enrico Urru]

Thank you for your help. There is no particular standards I am following.
The stock used is not specified. I wanted a tolerance of +-0.05mm

 

[Ryan6338]

I strongly recommend reading the standard if you desire to create and/or interpret drawings implementing GD&T. What you're trying to do is fairly trivial, but there's many ways to apply that tolerance which will achieve a different specification. Calling out flatness (or parallelism which is what you've used in the drawing) will not control thickness at all. You could use profile of a surface or a bilateral tolerance as already stated. The definition of what these mean vary depending on whether you're using ISO or ASME standards so not specifying one will create ambiguity. Datum A probably also needs a flatness control if it's important for that to be flat.

Ryan.

 

[greenimi]

....There is no particular standards I am following.....

That's a little dangeous I would say. I think showing on the drawing "the rules of the game" (depict the applicable standard) is a must, but hey...who am I.....

 

[Enrico Urru]

Thank you for all the comments. It's super helpful