Composite Tolerancing with Datums

[LargeNCharge86]

Hi all,
On the attached drawing, I need to change the 3x to 2x since it's incorrect. But I still want to have the 0.1 lower tolerance apply to the datum C hole. How can I do this? Thanks!

 

[chez311]

LargeNCharge86,

Is that one hole truly more important than the rest so that it needs to be specified as a datum feature? Why not hold the entire pattern of 3X holes together to a composite tolerance? Theres no relationship between any of the 3X holes and the rest of the profile so clocking two of them to C doesn't seem to buy you anything in that respect - note that you likely care about where the holes end up in relation to the part profile so such a relationship should be specified if it is not already elsewhere on the drawing (as it looks like we are only looking at a part of the drawing).

Side note - pylfrm asked several good questions last time you posted this that weren't answered.

https://www.eng-tips.com/viewthread.cfm?qid=454703