Circle Position issues

[[Da...]]

I am looking for a bright idea on how to get the positions setup as called out in the wire frame. The part is a basic hoop/semi circle with the holes carrying on as seen in the pic and the A datum is the interior of the hoop closest to the holes. Thanks for any help you can provide 😃 [img][/img]

ZEISS HELP.png

[[Cl...]]

I'd measure each of those holes as a cylinder and intersect each one with the A cylinder..

[[Da...]]

The A datum does not extract as a cylinder. Right now I'm using surface points recalled into a freeform surface. My take is that the call out does not really control location, only orientation (perpendicularity). But, there is no other call outs to control location of the holes.

[[Da...]]

Please sign in to view this quote.

It does, position controls location within pattern of holes with respect to datum A.
This is ASME, right?

[[Da...]]

Yes, it is ASME. So, would be placing holes and A position points in a 3d best fit?

[[Mi...]]

Sounds like you have a question somewhat similar to mine a year ago.

viewtopic.php?t=9823

For what it's worth, I elected not to use BFBP as it seemed to be rotating around the wrong axis on parts with only 4 holes (Worked fine on one with 6) and the results didn't make sense.

In a callout like this I use a Secondary Alignment to setup the datum(s). Then a Geometry Best fit that references that secondary alignment, with all the circles/Cylinders selected and the appropriate fitting settings picked.

Then for each Circle I would create a position characteristic with the circle as the toleranced feature and the Geometry best fit as the coordinate system, use the special button to rotate that coordinate system so the axis that makes sense (Z in my case usually) points down the bore. That part will suck with 57 holes, you CAN make it suck less with PCM and a loop if you wanted, however this doesn't create proper references so you may run into dependency errors especially with partial runs.

Slightly different situation, but the loop part would be the same. This only works with careful naming and having the index number last:

Create a Position Characteristic for your toleranced feature. Right click and select Loop, setup your loop. The Loop counter "LOOP1" will be used in two places.
Right click the Feature and hit Formula, put the name in like shown below
Click the Special button, Rotate around axis, use a formula to use the loop counter to rotate around the correct number of degrees. 5.625 comes from 360/64... it seems like you would be using 360/57.