Display views and parallelism!

[var10]

Hey Guys

I recently had a folded part on my drawing.

1. I had a fold facing down
2. The side view or the profile view had the parallelism reference (side profile is just a simple U) stating these two faces are parallel to each other with a tolerance.

I was told that it is not correct. The parallelism should be on the front view where you can actually see the length of the profiles.

My question is what difference does it make. I can see that the manufacturer can give me a parallelogram and still comply with the tolerances. But the same applies to the front view?

Any help would be very much appreciated.

Thanks,

Varoon

 

[CheckerHater]

Assuming that your drawing is using correct GD&T callout, the parallelism requires the surface of your part to be contained between 2 parallel planes and it is not dependent on drawing view. You can specify it like shown on the picture.

So, just to be sure, is parallelism called using symbology like Feature Control Frame? I there a datum involved?

 

[var10]

It sort of makes sense but I want a more specific answer relating to sheetmetal. Please see the attachment.

Datum A & Geometric Tolerance A display the parallelism between the two flanges. But my question is why can't I show the same at location B which is the side view of same.

It does makes sense if I consider the parallelogram error (which the supplier might give me a parallelogram instead of a rectangle and still lie within the drawing requirements ) but this can also apply when you show the parallelism in the current view as you can have both the top and bottom flanges still parallel but not rectangle.!

Thanks

 

[pmarc]

varoon10,
You can show it in either view. There is nothing that forbids it from legal point of view.

 

[var10]

Thanks Marc,

Thats what I would say too. But apparently you cannot. There is a difference between the two and I can't see how.

 

[pmarc]

Parallelism, unlike straigntness for example, applies to whole toleranced surface simultaneously (it is 3D tolerance), so there is really no difference which of the two views shown the callout will be applied to.

If EACH ELEMENT (ASME) or LE (ISO) note was placed close to the feature control frame, then there would be a difference, but not in this case.

The only view that I would not appply the callout to is the one where the flange is seen as a rectangle - so the top or bottom view.

In cases like this I usually ask: "Can you show me a place in a standard claiming that you are right and I am wrong?". Try to do the same.

 

[dgallup]

Either view is acceptable.

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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.

 

[drawoh]

varoon10,

I think we are discussing drafting presentation, as opposed to drafting standards. As per the standards, the parallel specification on top view is just as good as on the end view, showing the "U". The specification on the end view, probably is clearer.

We would have to see an example of your drawing to be sure about that.

--
JHG

 

[pmarc]

drawoh,
Could you clarify what is the top view for you in case of Varoon's sketch?

 

[drawoh]

pmarc,

I did not notice the OP's uploaded example until now.

The top view is the one with the FCF and the datum on it. The view that shows the "U" is the end view, as far as I am concerned, anyway. Putting the datum and FCF on the end view is somewhat clearer, in my opinion.

--
JHG

 

[var10]

Thanks guys. I agree with you. I was just brought up with this supplier parallelogram issue and it did not make any sense to me on where I showed the parallelism.