Please see the attached CAD drawing screen shot. I have inserted the datum call outs per the blue print. Are the datum assignments to -A- and -B- correct? The way I see this, they are conflicting datum surfaces. They both "clock" the part in the same plane. My approach to this was to utilize -B-1 and -B-2 as part of an offset primary plane (Datum in Z) with -A-1 and -A-2 then use hole -C- as my origin (datum in XY) and Line to slot -D- as my Y axis alignment (datum in X). I think I am doing this right and I'm getting real low true positions. I've measured 30 parts this way. All holes are to print with the exception of the two weld nuts between A1 and A2 which are only out 0.25mm in the same direction. Our engineer is not in agreement with my approach but has not offered anything better either.

This part is a sheet metal steering gear cross member. It mates to the frame of the car at -A- and -B-. I have not seen this type of datum structure before. Please give your thoughts. Thank you in advance for your time.
Regards,

Geoff
Sr. CMM Programmer
Lapeer Metal Stamping
LMS Metrology Lab
Lapeer, MI

Steering XMBR.doc
CAD drawing Screen Shot in MS word (93,696 bytes)