Arc's and Bolt Pattern Circles on the Mill using the DRO

Though I would post this....
May be of help to some of you

Arc's:
https://www.youtube.com/watch?v=2a78qOTzXYU&t=207s

Bolt Pattern Circles:(Handy for Steam Engine Cylinder Heads)
https://www.youtube.com/watch?v=1SQwTBeViK0&t=89s