GD&T ABC VS. Composite A

[[Ky...]]

All,

Question , I have a .190 thick plate. Surface of plate is Datum A, Bottom Edge is Datum B and Left edge is Datum C.
1st callout is .03 MMC ABC . This is standard. But the composite callout is .01 MMC to Datum A.

I use the basics called on the print to get my position to AB and C.

On the composite callout to Datum A what do I use for dimensioning. Usually They use composite so the hole pattern is good to itself I was told. How do I Figure this out then explain it to others?

Thanks For Your Help
Kyle Hoskins

Composite Call out.png

[[To...]]

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I would use Best Fit Bore Pattern for both levels of the position. For the upper tier, you won't allow any translations or rotation. And for the lower tier, you will allow both translations and rotation.
-

best_fit_bore_pattern_1.jpg

[[Ky...]]

Thanks Tom. Will try in the morning.

[[Me...]]

There are two things to consider with this particular Composite position:

1) The location of the pattern to itself.

2) Orientation to -A-


Most people seem to forget about the orientation part.