I was working on a rod gland for a steam engine I'm working on. Several parts are round plates with a six hole bolt circle. I used my 4" Chinese rotary table in the mill to drill the parts. The rotary table has replaceable inner and outer jaws. The jaws are "labeled" 1, 2, and 3 for their relative positions in the chuck. So as I replaced the inner jaws with the outer jaws, I thought I found the identification number and inserted them correctly into the chuck. Well..... NOPE! My bolt circle is off center. Take this little story as a parable about checking jaw positions. (After the screw up, I punched much more readable numbers into the jaws). It's not the end of the world. I can redrill the holes and use the part as intended without any other issue. The screw up will be hidden on the final engine. ...Ved.