i need help with a big part with iterative

IMO, measure the 3 holes with sample hits. Use all 3 for level, use the 2 'co-axial' for rotate, and a mid-point of the 'co-axial' for the origin. IF they all have one common axis value (say, all at the same "Z" value) construct a plane from them. If the 'co-axial' holes have 2 common axis values (say, Y & Z) construct a 3D line of them and a mid-point. LEVEL plane, ROTATE line, XYZ origin to the mid-point.

IMO, measure the 3 holes with sample hits. Use all 3 for level, use the 2 'co-axial' for rotate, and a mid-point of the 'co-axial' for the origin. IF they all have one common axis value (say, all at the same "Z" value) construct a plane from them. If the 'co-axial' holes have 2 common axis values (say, Y & Z) construct a 3D line of them and a mid-point. LEVEL plane, ROTATE line, XYZ origin to the mid-point.

Doesn't seem to be listening

thanks matthew, but the tree points doesnt have a common axis value. only two of them have

Like the others already have stated, the tertiary/origin shall only be one circle. One could also argue if this really is a datum target system or if the engineer had a brain fart? It seems they are placed like datum targets, but the construction of the datums seem to be more like common datums (like the alignment Matthew D. Hoedeman described). Is it possible for you to get clarification from the designer?

You have some hefty deviations on your alignment features as well, this is pre-iterative though:

CIR_A2 =ELEM/KONTAKT/CIRKEL/STANDARDVÄRDE,REKTANGULÄRA,INRE,GAUSS
TEOR/< 135.25,0,0>,<1,0,0>,25
MÄTT/< 136.091,-0.196,-0.14>,<0.999958,-0.0085354,-0.0033285>,25.121
MÅL/<135.25,0,0>,<1,0,0>

CIR_A3 =ELEM/KONTAKT/CIRKEL/STANDARDVÄRDE,REKTANGULÄRA,INRE,GAUSS
TEOR/< 135.25,22,200>,<1,0,0>,25
MÄTT/< 136.185,21.793,199.887>,<0.9999188,-0.0070527,0.0106123>,25.125
MÅL/<135.25,22,200>,<1,0,0>

CIR_A1 =ELEM/KONTAKT/CIRKEL/STANDARDVÄRDE,REKTANGULÄRA,INRE,GAUSS
TEOR/< -135.25,0,0>,<-1,0,0>,25
MÄTT/< -134.666,0.425,0.533>,<-0.9999322,0.0116092,0.0008601>,25.121
MÅL/<-135.25,0,0>,<-1,0,0>

It seems like the part is skewed (swedish: skev)​​​ in this alignment.

EDIT: The engineer responsible for the drawing mixes and matches with the datums. Datum target C1 and C2 should be created where the cross-symbol for these targets are located, which is centerline each hole and the OUTSIDE surface. But, looking at your snippet of the drawing, datum C is the midplane of the INSIDE surfaces?



Can you post snippets where we can see datum [A] and datum as well?

"Your" CAD trihedron doesn't match up with the trihedron on the drawing (it is rotated 90° around Z), just a heads-up. It doesn't have to match, but it is way, way easier for you if they did...

When you say that they are spot on, are you really checking them according to the datums?

thanks, we measured up the "concentricity" of A1-A2 and its about 0.05mm (not 0.5mm like ur snippet). maybe its because it was pre-alignment. dunno.
yeah its the engineers fault. stupid morgan, he wont listen tho...

No, no, the distance between the holes, calculated from your origin, shows that the part is skewed. They differ 0.5 mm in the Y-direction in the snippet above (your X-direction). This is without knowing anything about your pre-alignment (the alignment you did before iterative).

vpt.se i dont think u will like these..

You could always try and best-fit the three holes. Then check the XYZ for the three, see if you have any large deviations.

oh oh yeah. these two plates are skewed, but within tolerance since its +- 1.5 mm.
ok ty, BF 2D least square then? not good with BF alignments