[pttech]

I'm fairly new with CNC and curious as to any tricks others have to setting part zero in a round part. On my Bridgeport mill I could find an edge and set zero and then find the other side and had a button on the DRO to divide that new number in half and then set it as zero. Then repeat the process for the other axis. I find I have to do a lot of external calculations to do the same things on my Ultimax control.

[BlueChip]

I would say the most common method would be to mount a dial / coaxial indicator in the spindle ... in a collet ... clamped to a tool holder ... whatever ... and sweep the round part.
Like this : https://www.youtube.com/watch?v=X-6v_EkUwt8

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[Kenny Duval]

Depends on how much precision you need. I have better results when flipping parts swinging and centering via an indicator. I have a 3d taster but my results of hitting concentricity on a flipped round part for the second OP has been less than stellar with it.