Casting datum alignment help

[Msouth91]

Hello everybody I am in a pickle so I have this part and they're using 4 points for the A datums on a cylinder at 45 degrees from the center on a 1.380 dia. And 2 point for B and i point for c

[Msouth91]

20190911_180853~2.jpg

[BKulpa]

Build a fixture!

[Msouth91]

Dont have time or the boss to say yes. Im new and they just need a quick check. How would anyone do this

[RIDER]

4 points for your plane (level), 2 points for your line (rotate) and one point to stop the last translation. 321 or in this case 421. Or you could use the datum targets, if that's what they are, in an iterative alignment.

[UKCMM]

Ride that will not work you cannot take 4 hits on a cylinder and level to it in the way that the sketch shows, BKilpa has it right would be best checked holding in a fixture at the target points.

[Ego Murphy]

Dont have time or the boss to say yes. Im new and they just need a quick check. How would anyone do this

I feel ya, this is a bad situation. Remain calm and ask the boss for leniency as you need to take your time and figure out this complex programming stuff.

I don't see the 45 degrees in your quick sketch so I'm going to ignore it and proceed with the idea that the flange part with B points and C point sticks out the side of the cylinder.

Create circular rings of points at the A datum locations, then construct an A cylinder from these points. Use minimum 4 points per ring, more is always better.
As you pick the points in the dialog, pick the A1-A2 ring points first and the A3-A4 ring points last. Name it A_CYL

Take the 2 B points and construct a 3D (not 2D!) line between them. Name it B_LINE.
As you pick these points in the dialog, pick them in order B1 then B2.

Take the C point. Name it C_PNT.

Alignment:
LEVEL the A_CYL to Z plus. This means the new coordinate system's Z axis will run positive from the bottom of the cylinder to the top.
ROTATE the B_LINE to X minus. This means the new coordinate system's X axis will run negative outward from B1 to B2, but kept perfectly 90 degrees perpendicular to the already-established Z axis.
ORIGIN both X and Y on the A_CYL.
ORIGIN the Z axis on the C_PNT.

Save!

Advanced level:
Now program duplicates of that entire process, with new names. The first one is 'rough', this new second set of features and second repeated alignment will be 'fine' and wipe out much of the error from the first set of features not having any alignment to guide them.

[AndersI]

Just throwing out an idea,

Put the part in 45° V-blocks (are they called that in English?) and measure the primary plane on the blocks. Translate the coordinate system a suitable amount downwards (depending on the dimension of your part and V-blocks)? I don't know the precision of V-blocks, though...

[Douglas]

I have some steel v-blocks that are accurate well within a thou, granite ones are better yet but who really has those