Datum feature simulator requirement

[aniiben]

If datum feature D had been RMB (instead of MMB) in 4 holes pattern positional requirement ( 4x 12 +1/ -1 position within 2mm to A primary, D RMB secondary and B tertiary), would the requirement of datum feature B simulator to have a minimum of two points contact stay unchanged? Or shown datum feature B simulator requirement have to be adjusted such as " minimum of one point contact" or other necessary condition? What would be the "new requirement"? (Again in D RMB scenario).

 

[3DDave]

In either case the part is supposed to be oriented such that datum feature B is generally parallel to the datum simulator for B. On that score, there would be no change.

However, the '2009 standard doesn't seem to have have an example that flips the order the datum features are defined relative to one another from the way they are used in the FCFs. Maybe I missed it?

The similar examples require the use of Profile tolerance to establish the movement of the datum simulator and those examples are in-matching-order.

I don't see why they are using two pins in the gage for B as that isn't identified as a requirement. They don't use three pins for A.

Here's a side-hint. If copying or duplicating double sided pages, fit black paper behind them to eliminate the reflection of light and bleed-through of the graphics on the other side. White paper makes the bleed-through worse.