I don't know what this true position on the hole is constraining. Bolt circle diameter or orientation of the hole maybe? Trying to determine if I need to measure the hole as a cylinder. Appreciate the help.
It's essentially the hole pattern to itself.
Probably will have to a manual alignment using two of the bolt holes to offset before going to DCC.
Create a cylinder on Datum A, then level and set the origin on it.
Measure the bolt hole circles and do a 2D best fit rotary alignment. (Terminology may not be correct.)
Then report the position of the bolt hole circles.
If a clocking hole is called out, then you are actually losing tolerance. It forces the hole pattern into a specific orientation. You lose the bonus tolerance from the clocking hole. On the other hand, if all of the bolt holes are used for orientation, then the alignment will shift as needed. Using all the bolt holes for orientation is how the part will mate in the assembly. The clocking hole method does not represent assembly conditions. As far as writing the CMM program, then a temporary alignment using a clocking hole is a good idea. But it needs to be followed up with a 2D best fit rotary alignment so that all of the available tolerance is available.
If a clocking hole is called out, then you are actually losing tolerance. It forces the hole pattern into a specific orientation. You lose the bonus tolerance from the clocking hole. On the other hand, if all of the bolt holes are used for orientation, then the alignment will shift as needed. Using all the bolt holes for orientation is how the part will mate in the assembly. The clocking hole method does not represent assembly conditions. As far as writing the CMM program, then a temporary alignment using a clocking hole is a good idea. But it needs to be followed up with a 2D best fit rotary alignment so that all of the available tolerance is available.
