Profile

[[Me...]]

Is the Profile callout + the .310 ± .002 legal?

[[To...]]

To me, it appears they're substituting parallelism with the Profile to A. If so, then I would imagine, this might be legal. I'm sure we'll hear from some more knowledgeable folks soon.

[[Ri...]]

The Profile call out by itself is legal, but it is conflicting with the 0.310+/-0.002 measurement.

The Profile is controlling the 0.310 dimension, the Flatness of the bottom surface, and the Parallelism to Datum A.

[[Ri...]]

I would also raise concern as to why the Datum has more Flatness tolerance than the feature being evaluated. It will affect the results.

[[Me...]]

This is my exact understanding of the dimension according to the standard. I've seen and posted many threads on this occurrence but I wanted more opinions, again lol.

[[Ma...]]

I think Tom was right on track. From the second paragraph of the standard; (Profile) "Where
used as a refinement of a size tolerance created by
toleranced dimensions, the profile tolerance must be
contained within the size limits". (I do not think the callout is in conflict).
The larger flatness of -A- is also OK because GD&T theory relates to a datum simulator, which would theoretically rest on 3 high points of -A- (parallelism of the .31 surface to -A-, as determined by the high points on -A-).

[[Me...]]

If Tom is right then we're guessing the interpretation of the Engineer which is not something I tend to agree with. Either it's right to the standard or it isn't.

Edit:

I can say that if dimensioned as shown on the Print, the Profile of the plane in question reads .0037 because the .310 dimension is around .3117. So Calypso does not agree.

[[Ja...]]

Shawn,

I am thinking of it this way:
-A- is held between two parallel planes at a distance .002 apart.
The plane with the profile callout is parallel to -A- (between two planes sharing normal vector of -A- at a distance of .001 apart).
The centroid of the plane itself is somewhere in [.308, .312] from -A-.

The profile of a plane to a plane (with same unit normal vector) is effectively parallelism.

Just my interpretation.

[[Br...]]

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The only thing I would question is if that .310 dimension is actually a size dimension. You need directly opposed elements for a feature of size and those appear to be offset. I suppose it can be argued that this is a type of irregular feature of size since it could contain an actual mating envelope. Parallelism is a perfectly good geometric tolerance to control parallelism to Datum Feature A. I'm not sure why this is done this way if that's truly the intent. The only advantage would be to connect interrupted surfaces into a single surface. From what I can see, it appears to be a solid uninterrupted surface..

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You wont be able to use a profile characteristic with calypso to do this. Just use parallelism. It's the same thing.

[[Ri...]]

You can... Make sure it's being measured with Datum A as the alignment. Then just drop it into a Free-Form and allow for translation in that axis. Allow it to create an alignment, and use that best-fit alignment in the Profile characteristic.

[[An...]]

Profile tolerance and creating an inner envelope
in order to limit the rotatory degree of freedom.
Just playing around.
See attached.

Contribution_07_06_2019.pdf

[[Me...]]

The more I read this part of the paragraph in the standard, the more I tend to agree that it's simply an orientation interpretation.

Capture.PNG

[[Br...]]

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It is. But if you have Freeform like Richard said, you can actually output it as a profile characteristic. I hadn't thought of doing it that way, but he's right. In your freeform characteristic, select the evaluation button, tick the best fit checkbox, and tick the box for the translational degree of freedom you want to unlock(The direction of the .310" dimension). Now click the "create alignment" button. You can use this alignment now in your profile characteristic instead of datum feature A. There's a few nuances to this though. You may want to create a secondary alignment that uses datum a for the spacial rotation with the proper evaluation filter/outlier elimination ect. that you would want to use for the characteristic which may not be the same as your base alignment.

[[Me...]]

I don't think I have Freeform 😭

[[Ri...]]

You could try making a secondary alignment and using your feature as the axis origin, and evaluating your profile to that secondary alignment. Just make sure that Datum A is your Spatial Rotation.

[[An...]]

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The plus-minus-dimension can be a refinement of profile tolerance .
See attached.

Contribution_11_06_2019.pdf

[[Mi...]]

I've seen this type of callout several times and had more than a few discussions with our engineers. In this instance it's a parallel callout. The .310±.002 call out is a non-basic dimension and therefore has it's own tolerance. The Profile is for the surface and controlled by the datum. If the .310 dimension was a basic dimension then it wouldn't have a tolerance and you would need to hold the .001 profile to the datum, basically turning it into a .0005 tolerance.