So here is the part loaded against the primary datum "D" (clamped to the left block) and against the secondary datum "A" (loaded against angle plate in rear) Then I have a 1-2-3 block resting on tertiary datum "B".
Notice the measurement on the height gage. I was worried about my measurement, because if the corner has an edge break on it, it wont be to the theoretical sharp corner.
Hopefully this makes more sense?
This pic shows where the demon is measuring datum "B" from.
Your pictures still suck, anyway, but your tertiary datum is just to lock that last axis from moving, if that's a plane at an angle where do you stop your last axis. Primary and secondary have 2 functions. The tertiary has one function. stop the last axis. It can't rotate or level, that is locked down by Primary and Secondary. That's why I still think it's DBA.
Your pictures still suck, anyway, but your tertiary datum is just to lock that last axis from moving, if that's a plane at an angle where do you stop your last axis. Primary and secondary have 2 functions. The tertiary has one function. stop the last axis. It can't rotate or level, that is locked down by Primary and Secondary. That's why I still think it's DBA.