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Further Tertiary Datum to Lock Rotation Help

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cande119

Automotive
Joined
Mar 10, 2025
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Hi All,

I'm very new to GD&T, and am struggling to set up a datum system based on:
1) A plane surface
2) A cylindrical hole
3) A second face perpendicular to 1) (or if possible only a line connecting two points on that face)

I've attached a sketch showing the set-up

The primary plane surface datum is OK (which fixes 3 DoF), as is the secondary datum hole (another 2 DoF), but I can't work out the appropriate way to include the tertiary datum (only providing 1DoF - the rotation lock). I would like this to be such that one axis (in the plane A) is perpendicular the end face (either the surface or a line on it) and the other axis then parallel to it.

I'd be very grateful if anyone could shed some light on this! (I'm working with the ISO standard).

Thanks in advance.
 

Attachments

Add a height dimension and label it as datum feature C.
 
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