Straightness 2x

[[Cl...]]

The print calls out true position for two OD's interrupted by a smaller OD. It also calls out straightness
for the same OD's, but doesn't state 2x. I'm assuming it is 2x, because the positions are? Might be a
stupid question, but it doesn't state 2x.

[[Mi...]]

or is it meaning more of a concentric callout?

[[Cl...]]

I don't necessarily agree with the straightness callout. I don't know how the part functions (used in brain surgery)

[[Da...]]

Would it need to say 2 X if you're checking one to the other?

[[Mi...]]

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I thought straightness couldn't be evaluated relative to a datum

[[Cl...]]

The position of the (2) OD's is called back to the ID datum.

[[Da...]]

I think they are asking for an axial (bend) check. There is no datum reference on the straightness call out.

[[Mi...]]

I think strictly based on what's on the print, it applies only to one OD.

It might be that they want both to be measured, or that they want both to be evaluated as one feature, but that would need to be clarified with the designer/draftsman.

[[Cl...]]

So, it's 2x? I've always reported it twice. I just had to question it.

[[Da...]]

It applies to the centerline of the part.

[[Cl...]]

The ID is Datum -A- which has its own straightness callout (Ø .0005 M/2.0)

[[Ma...]]

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I agree with this. I interpret as centerline.

[[Cl...]]

So you think they want the straightness of the OD (centerline) 1x?

[[Da...]]

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I do, We get this all the time. Straightness of one side without relating it to the other side wouldn't help create a straight part. You could have a huge bend between sections that wouldn't show if each side was separate.

[[Me...]]

The way the print is dimensioned, I read this as 2x TP callouts, and 2x Straightness callouts and I believe it is because it is directly below the circled OD, no different than a TP for a bore & counterbore.

[[Da...]]

Actually it is not to the centerline of the PART, but the derived median line of the FEATURE its self. So if you want to call it two readings ( two separate Features with two separate median lines ) then I could bend the relief area between diameters to 90 degrees and still get two readings that are good for straightness !

[[Cl...]]

It seems we have a few different opinions. Without knowing the function
of the part as it applies to that OD. The best we can do is speculate.

We make several of his type of guide. I'm told that they are used for cranial
(brain) surgery, and its done robotically. So with that in mind, does that help
make the decision on the callout easier?

[[Me...]]

I was under the assumption that you were asking what the print meant. If we're talking what it should be and interpretation then I definitely would go with the straightness as one centerline or maybe even a composite TP instead of straightness and remove the 2x.

[[Cl...]]

Yes, I am asking what the prints is asking for. Sorry for
the confusion.I was just trying to give a better idea of
what the part does and how it might function.

[[Cl...]]

I spoke with the engineer about this. Some sort of device gets
inserted into the part ID, then the part gets inserted into some
other ID for robotically guided surgery.

[[SH...]]

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I hundred percent agree with your words it is two feature with true position and straightness

[[SH...]]

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Straightness is a form tolerance and there is no need of the datum for straightness.

[[Me...]]

The 2X denotes a pattern. It's 1 feature consisting of both sides.

[[Me...]]

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This is where interpretation is relied upon the most. I can't find anything in the standard that backs up that this particular instance is a Pattern. The standard mostly explains patterns in regard to bolt circles or groups of features of size.

[[SH...]]

That diagram does not look like a pattern, it is something like co axial??