Circularity/Roundness as a Datum Feature

[cabrio0209]

Presently trying to figure out the relationship of a spherical profile (.001) GD&T referencing circularity (.001 as Datum A MMC). Does this mean that the profile tolerance follows the circularity tolerance at the circles' (±.001) maximum material condition? Does this imply a bonus? How does this differ from "form"?

 

[PaulJackson]

Presently trying to figure out the relationship of a spherical profile (.001)

"A spherical profile (.001)" means that the actual or measured spherical surface must be contained within a bilateral boundary of .001 wrapped about the specified basic spherical size.

GD&T referencing circularity (.001 as Datum A MMC).)

This comment makes no sense!

Does this mean that the profile tolerance follows the circularity tolerance at the circles' (±.001) maximum material condition? Does this imply a bonus? How does this differ from "form"?

These comments make no sense either! Show us a sketch of the part and its specifications.

Paul

 

[MechNorth]

If you mean that the circularity callout on the spherical datum feature includes a material modifier (MMC), then the callout is not legal. Form controls cannot (in '94) have a modifier of MMC or LMC, and are required to be RFS.

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

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